BULLETIN No. 269JUE14 JUNE 1949 FERTILIZER STUDIES with VEGETABLE CROPS on REPRESENTATIVE SOILS in ALABAMA ' " It',I AGRICULTURA L ALABAMA M. J. the FU D M. J. FUNCHESS, Director EXPERIMENT POLYTECHNIC STATION INSTITUTE A AUBURN, ALABAMA CONTENTS PAGE REVIEW OF LITERATURE............................................ ............. 3 NEED AND USE OF COMMERCIAL FERTILIZERS IN THE SOUTH ................................................. ............... 3 EXPERIMENTS DEALING WITH FERTILIZERS VEGETABLE CROPS........................................... FOR .............. 5 LOCATION, SOILS, CROPS, AND METHODS FIELD FIELD BINS................................................ PLOTS............................................ ....................... 6 ................. 6 ................... 7 ............. 8 CALCULATION OF RETURNS.......................... PRESENTATION OF DATA............................................ .............. 8 8 COMPARATIVE RESPONSE OF VEGETABLE CROPS TO ................. NITROGEN, PHOSPHORUS, AND POTASH STUDIES IN FIELD BINS WITH INDIVIDUAL ELEMENTS FOR DIFFERENT CROPS ON DIFFERENT SOILS.12 PHOSPHORUS STUDIES ON NORFOLK, EUTAW, AND ............... 12 CECIL SOILS.............................................. NITROGEN STUDIES ON NORFOLK SOIL................ 16 19 POTASH STUDIES ON NORFOLK AND CECIL SOILS. FERTILIZER GRADE STUDIES WITH DIFFERENT VEGETABLE CROPS ..................................................................... 22 41 41 STUDIES IN FIELD BINS....................................................... 22 STUDIES IN FIELD PLOTS ...................................................... 29 MISCELLANEOUS FERTILIZER EXPERIMENTS .................................. METHODS OF APPLICATION OF FERTILIZERS .......................... NITROGEN, PHOSPHORUS, AND POTASH REQUIREMENTS OF VEGETABLE CROPS ON THIN SOIL RECEIVING LIGHT APPLICATION OF MANURE ....... RESIDUAL EFFECTS OF FERTILIZER MATERIALS ............. SUMMARY ......................................................................................... 43 45 47 LITERATURE CITED ............................................................................ 49 First Printing 3M FERTILIZER STUDIES with VEGETABLE CROPS on REPRESENTATIVE SOILS In ALABAMA L. M. WARE,* Horticulturist W. A. JOHNSON, Laboratory Technician OTHER GROUP of crops requires as much fertilizer as vegetables require. Use of commercial fertilizers in the production of vegetable crops is very necessary in the South where soils are low especially in available phosphorus and nitrogen. Results reported in this bulletin are from experiments involving use of commercial fertilizers on the principal vegetable crops grown on different soils of the State. Results of studies presented here are confined to the three elements - nitrogen, phosphorus, and potash-which constitute what is generally referred to as a complete fertilizer. NO REVIEW OF LITERATURE NEED AND USE OF COMMERCIAL FERTILIZERS IN THE SOUTH Use of commercial fertilizers in the United States is relatively old. Commercial fertilizers have played an important part especially in the agriculture of the South. During the last 50 years, the South has consumed two-thirds or more of the total amount of fertilizers used in the United States. In recent years, however, the proportion of national tonnage used by the South has declined, even though the actual quantity consumed has continued to increase. This decline is the result of increased use of commercial fertilizers in other sections of the country. While the acreage of truck crops in the United States is small in comparison to that of field crops, the proportion of the ferti* The outlying experiments reported in this bulletin were done under the supervision of Otto Brown, Harold Yates, Fred Stewart, R. C. Christopher (resigned), T. P. Whitten, J. W. Williamson, J. W. Richardson, and Robert Taylor (resigned) of the Agricultural Experiment Station staff. 4 ALABAMA AGRICULTURAL EXPERIMENT STATION lizer used on truck crops is relatively large. For instance, in 1946 the 67.2 million acres of wheat were fertilized with 1.08 million tons of fertilizer, which was an average rate of 32 pounds per acre. On the other hand, 1.0 million tons of fertilizer were applied to 2.6 million acres of potatoes; this was an average acre rate 769 pounds. In the same year, 88.7 million acres of corn were fertilized with 3.2 million tons of fertilizer, which was about 72 pounds per acre, whereas 1.6 million tons were used on 4.1 million acres of vegetable crops, or the average was 780 pounds per acre. Fertilizers are important in the South because the soils are low in certain plant foods, which must be supplied if profitable production is obtained. To supply such needs, makes the cost relatively high. In 1945, the South used approximately 8.5 million tons of fertilizer at a value of about 350 million dollars. Pierre (13) has pointed out the important role of phosphorus in plant nutrition and has discussed the importance of phosphorus fertilization. Scarseth and Tidmore (14, 15) reported that soils of the South were low in available phosphorus and had high phosphorus-fixing power. Fudge (7) showed that acid-forming nitrogenous fertilizers caused a marked decrease in phosphate availability and an increase in water-soluble potassium. He also showed that physiologically basic fertilizers caused an increase in phosphate availability and a reduction in water-soluble potassium. Studies of soils in the various sections of the United States have revealed that soils of the South have low amounts of organic matter and nitrogen (1). Jenny (9) found that the nitrogen and organic content increased 2 to 3 times for each 100 C fall in temperature provided the precipitation-evaporation ratio was constant. He found that the average soil in Canada contained about 0.4 to 0.5 per cent nitrogen, in Iowa and Minnesota about 0.2 to 0.3 per cent, and in Louisiana about 0.05 per cent. The reasons for the low amount of nitrogen and of available phosphorus are well established. The South has long seasons of high temperature and high rainfall. Decomposition of organic matter is rapid and loss by leaching of the nitrogen released is high. High rainfall, likewise, causes high loss of minerals, especially magnesium and calcium. Midgley (12) and Scarseth (16) showed that the loss of magnesium and calcium resulted in an increase in the proportion of aluminum and iron, which causes a decrease in the availability of phosphorus in the soil. FERTILIZER EXPERIMENTS with VEGETABLE CROPS 5 Cooper and others (5) reported that the amount of potash, especially in heavier soils, will often amount to 10 to 20 times the quantities of nitrogen or phosphorus. They also pointed out that it is not necessary to have as high a level of potassium in sandy soils of the Coastal Plain as in the soils of the Corn Belt. Many investigators have studied the basic principles governing fixation of applied phosphorus. Scarseth and Tidmore (14, 15) and Scarseth (16) found that the efficiency of phosphorus decreased with the time of contact with the soil. They also found that the phosphorus-fixing capacity of soil colloids varied inversely with the silica-sesquinoxide ratio of the colloid. Bryan (2), Bushnell (3), Hawkins (8), Ware and others (19), and Ware and Johnson (21) showed that there is an accumulation of phosphorus on heavily fertilized soils and that it is available to crops in later years. From these studies, it appears much may be done in more efficient use, especially of phosphorus. In view of the need in the South to correct certain soil deficiencies by use of commercial fertilizers and in view of the relatively high costs involved, the importance of determining the proper fertilizer for those crops grown in quantity is apparent. EXPERIMENTS DEALING WITH FERTILIZERS FOR VEGETABLE CROPS For some important truck crops, fertilizer needs have been fairly well established on the more important soils. Some work has been conducted with almost all vegetable crops at least on a few soils. Lloyd and Strubinger (10) conducted fertilizer experiments with 25 different vegetable crops in Illinois. They obtained increases sufficient to recommend phosphorus applications in addition to manure and limestone for only nine crops and potash applications in addition to phosphorus, limestone, and manure for only seven crops. Cooper and Watts (6) in fertilizer tests in Arkansas with five vegetable crops on two different soils found that phosphorus gave greater yield increases than nitrogen on one soil and increases about as large as nitrogen on a second soil. Yield increases were usually much less from potash. Mack (11) in his studies on application of phosphorus, nitrogen, potash, and organic materials to cabbage, tomatoes, and 6 ALABAMA AGRICULTURAL EXPERIMENT STATION potatoes found that the response to phosphorus applications was most striking. Skinner and Ruprecht (17) reported that the fertilizer grade giving best results for tomatoes on Calcareous Glade soils of Florida, contained 4 to 6 per cent ammonia, 6 to 8 per cent phosphoric acid, and 6 to 8 per cent potash. He also found that when the nitrogen need of celery is satisfied potash is effective in producing yield of good quality. Celery gave little response to phosphorus applications. White and Boswell (23) pointed out that manure produces the desired yields, but does so at high cost if it must be purchased. Carolus (4), in his work showed that the potato has its maximum nutrient requirement between the 50th and 80th days. In 1936 during the 30-day maximum-absorption period, an acre of potatoes absorbed at the following rates per day: 1.66 pounds of nitrogen, 0.3 pounds of phosphorus, and 3.33 pounds of potash. LOCATION, SOILS, CROPS, AND METHODS FIELD BINS Much of the work reported here was done at the Main Station, Auburn, and most of these experiments were conducted in concrete field bins, each 1/640-acre in size. The bottoms of the bins were open, and the introduced soils rested on the local subsoil, which was a sandy clay of Piedmont origin. The soils used in the bins were Norfolk, Cecil, Eutaw, Decatur, Hartsells, and Chesterfield, which are representative of the Coastal Plain Region, Piedmont Plateau, Black Belt, Limestone Valley, Appalachian Plateau, and Piedmont-Coastal Plain transition, respectively. The Norfolk and Chesterfield soils were local, whereas the Cecil, Eutaw, Decatur, and Hartsells soils were introduced. The soils selected varied considerably in physical and chemical properties. The Norfolk soil was a sandy loam, Cecil a sandy clay, Eutaw a clay, Decatur a clay, Hartsells a fine sandy loam, and Chesterfield a loamy sand. Separate studies of nitrogen, phosphorus and potash were conducted in the first sets of bins constructed in 1933. In the newer sets of bins, built in 1938, studies of the three elements were combined into fertilizer grade experiments. In the first sets of bins, 15 vegetables were grown each year. Fertilizer treatments FERTILIZER EXPERIMENTS with VEGETABLE CROPS 7 included five rates of nitrogen and phosphorus, and four rates of potash. The crops were rotated from section to section in succeeding years. Three successive crops were grown each year in each section. In the fertilizer grade studies, only two successive crops were grown each year. When each element was varied, standard rates of the other two elements were used. The standard rates were 160 pounds per acre of P2O on Norfolk and Hartsells soils, and 320 pounds per acre on Cecil, Eutaw, and Decatur soils. The standard rate of potash was 135 pounds per acre and of nitrogen 90 pounds per acre on all soils. Where two successive crops were grown on the same soil the same year, one-half of the standard rates of phosphorus and potash were applied to each crop, or where three crops were grown, one-third was applied to each crop. The full amount of nitrogen was applied to each crop. All phosphorus and potash and a portion of the nitrogen were applied 10 to 14 days before planting. On the older sets of bins containing Norfolk, Eutaw, and Cecil soils, one-half of the nitrogen was applied with the phosphorus and potash; the other half was used as a side dressing 2 to 4 weeks after crops were up to a stand. Superphosphate was used as the source of phosphorus and muriate of potash as the source of potassium. Nitrate of soda or a combination of nitrate of soda and ammonium sulphate was used as a source of nitrogen. The position of the rows remained about the same from year to year. During the course of the experiment, 27 different vegetable crops were studied in the phosphorus, nitrogen, and potash series in the old plots. From 7 to 13 crops were included in the fertilizer grade studies in the new bins. As previously reported (20), field bins used in this study were satisfactory as compared to field plots. Results from the basic study of phosphorus utilization have been published by this Station (21). Earlier reports (18, 22) based on results from these studies have been issued. FIELD PLOTS At the Gulf Coast Substation, Fairhope, fertilizer studies were conducted w'ith the more important commercial truck crops grown in the Gulf Coast area. The experiments were on Norfolk and Orangeburg soils. Fertilizer experiments were conducted with potatoes, cabbage, 8 ALABAMA AGRICULTURAL EXPERIMENT STATION and sweetpotatoes on Decatur soil at the Tennessee Valley Substation, Belle Mina, and on Hartsells soil at the Sand Mountain Substation, Crossville. Sweetpotato fertilizer studies on Norfolk and Orangeburg soils were carried on at the Brewton and Monroeville Experiment Fields, respectively; on Red Bay soil at the State Farm, Atmore; and on a Chesterfield soil at the Main Station, Auburn. Cooperative field experiments with fertilizers involving a number of vegetable crops were conducted on a Ruston soil at Thorsby. In field plots only one record crop was grown each year and the full annual application of all three elements was applied to the one crop. CALCULATION OF RETURNS In the final analysis, the farmer measures the value of a fertilizer in dollars returned for dollars spent. Occasionally relationships are pointed out between the amount and value of increased yield from different fertilizer increments and cost of increments. Fertilizer costs are based either on the highest price or the price range during the past 20 years. Values for the products are assumed. PRESENTATION oF DATA Location, type of plot used, soil type, rates of application of the three major elements, average number of years, and crop yields are presented in the tables. COMPARATIVE RESPONSE OF VEGETABLE CROPS TO NITROGEN, PHOSPHORUS, AND POTASH In Tables 1, 2, and 3 are given the average relative yields of a large number of vegetable crops grown on a number of different soils when receiving different rates of nitrogen, phosphorus, and potash. The yields are expressed in percentage of the yields from the highest rates of each element. The Norfolk, Eutaw, and Cecil soils used in the studies of single elements were soils that had received low fertilizer rates or no fertilizers in previous years. The Hartsells, Decatur, and Chesterfield soils had been used in recent years for growing field FERTILIZER EXPERIMENTS with VEGETABLE CROPS 9 crops and had received applications of fertilizers commonly used on general field crops. Yields at the zero rates of nitrogen, phosphorus, and potash reflect past fertilizer treatments to a large exent. On the soils to which no fertilizers or small amounts had been applied in recent years, phosphorus appeared to be the most limiting factor and nitrogen second. The response to potash was small. The average relative yields of 26 crops in the no-phosphorus treat- ments were only 31 per cent on Norfolk soil, 14 per cent on Eutaw soil and 8 per cent on Cecil soil. In the no-nitrogen treatments, the average relative yield of 27 crops was 27 per cent on Norfolk soil. The average relative yields of 25 vegetable crops in the noTABLE 1. RELATIVE YIELDS OF VEGETABLE CROPS FROM INCREASED APPLICATIONS OF NITROGEN ON DIFFERENT SOILS, FIELD BINS, MAIN STATION, AUBURN, ALABAMA, 1933-42 Nitrogen (N) applied per acrei Pound 0 30 60, 90 120' 0 40 60 80' 0 60 80 100 120' Yields in per cent of that from maximum nitrogen rate Chesterfield Chesterfield (A)3 (B)s Norfolk Hartsells Decatur Per cent 27 58 79 93 100 Per cent 33 62 81 95 100 Per cent 40 65 81 93 100 42 81 95 100 11 75 95 106 100 Per cent Per cent 2 1 Amount applied to each of three crops grown each year on the Norfolk and to each of two crops per year on the Hartsells, Decatur, and Chesterfield soils. Amounts of phosphorus and potash considered necessary for maximum yields were added to all treatments. 2 Number of crops on Norfolk 27, on Hartsells 11, on Decatur 12, on Chesterfield (A) 9, and on Chesterfield (B) 4. Percentages under each soil were calculated from combined total yields for all crops grown on that particular soil. SChesterfield soil (A) represents area of medium fertility; Chesterfield soil (B) represents area of low fertility. 'Maximum rate. 10 ALABAMA AGRICULTURAL EXPERIMENT STATION potash treatments were 85 and 89 per cent, respectively, on Norfolk and Cecil soils. On soils that had received usual amounts of fertilizers for field crops in recent years, average relative yields of plots receiving no phosphorus ranged from 40 to 49 per cent, those receiving no TABLE 2. RELATIVE YIELDS OF VEGETABLE CROPS FROM INCREASED APPLICATIONS OF PHOSPHORUS ON DIFFERENT SOILS, FIELD BINS, MAIN STATION, AUBURN, ALABAMA, 1933-42 Phosphorus Yields in per cent of that from maximum phosphorus rate 2 (P 2 0 5 ) applied per acre ' Norfolk Eutaw Cecil Chesterfield Decatur Hartsells Pound Per cent 0 31 73 13.33 91 26.67 100 40.00 100 53.33 3 Per cent Per cent Per cent Per cent Per cent 0 26.67 53.33 80.00 106.67 ' 0 60 80 100 120 $ 0 40 80 120 160' 0 20 40 60 80 3 14 75 89 98 100 8 72 92 98 100 45 92 91 101 100 40 95 104 101 100 49 82 97 101 100 SAmount of phosphorus applied to each of three crops grown each year on the Norfolk, Eutaw, and Cecil soils and to each of two crops on the Chesterfield, Decatur and Hartsells soils. Amounts of nitrogen and potash considered necessary for maximum yields were added to all treatments. 2 Number of crops on Norfolk, Eutaw, and Cecil 26, and on Chesterfield 7, on Decatur 12, and on Hartsells 11. Percentages under each soil were calculated from combined total yields of all crops grown on that particular soil. ' Maximum rate. FERTILIZER EXPERIMENTS with VEGETABLE CROPS 11 TABLE 3. RELATIVE YIELDS OF VEGETABLE CROPS FROM INCREASED APPLICAAUBURN, ALABAMA, 1933-42 TIONS OF POTASH ON DIFFERENT SOILS, FIELD BINS, MAIN STATION, Potash (K 24Y) applied per acre1 Pounds 0 15 30 453 0 22.5 45.0 67.5 3 40 60 80 3 Yields in per cent of that from maximum potash rate Norfolk Per cent 85 117 94 100 Cecil Per cent 89 99 103 100 82 93 95 100 82 92 101 100 Decatur Per cent Hartsells Per cent 2 Chesterfield Per cent 72 96 101 100 ' Amount applied to each of three crops grown each year on Norfolk and Cecil soil and to each of two crops per year on other soils. Amounts of phosphorus and nitrogen considered necessary for maximum yields were added to all treatments. 2 Number of crops on Norfolk and Cecil 25, on Decatur 12, on Hartsells 11, and on Chesterfield 13. Percentages under each soil were calculated from combined total yields for all crops grown on that particular soil. ' Maximum rate. nitrogen ranged from 11 to 42 per cent, and those receiving no potash ranged from 72 to 82 per cent. Irrespective of past fertilizer treatments, small applications of phosphorus and potash satisfied more quickly the requirements of vegetable crops for maximum or near-maximum yields than small applications of nitrogen. Applications of phosphorus as low as 26.67 pounds per acre of P 205 gave yields that were 72 to 91 per cent as high as those from the highest phosphorus rates. Treatments of 40 to 53.3 pounds per acre of P205 resulted in yields of 89 to 100 per cent of those from the highest rates. Potash applications of 15 pounds per acre on Norfolk and Cecil soils gave yields as high as the highest rates, while applications of 22.5 pounds on Decatur and Hartsells soils gave relative yields of 93 and 92 per cent, respectively. Considerably higher amounts of nitrogen were required to give maximum or near-maximum yields. 12 ALABAMA AGRICULTURAL EXPERIMENT STATION Applications of 30 pounds per acre of nitrogen gave relative yields of only 58 to 64 per cent. Relative yields from the 60-pound rate ranged from 75 to 81 per cent on all soils except one, in which case a higher yield was obtained. Applications of 80 to 90 pounds per acre gave relative yields of 93 per cent or higher. Increases in relative yields of 5 to 7 per cent were obtained from applications up to 120 pounds per acre on three soils, and up to 100 pounds on one soil. STUDIES IN FIELD BINS WITH INDIVDUAL ELEMENTS FOR DIFFERENT CROPS ON DIFFERENT SOILS Phosphorus Studies on Norfolk, Eutaw, and Cecil Soils Results of the phosphorus phase of the study are presented in Table 4. The yields of 24 different vegetable crops grown on three soils of radically different physical and chemical characteristics and fertilized at five different rates of phosphorus are given in the table. In a companion study (21), great differences were found among vegetables in their phosphorus requirements, phosphorusfeeding capacities, phosphorus-utilization efficiencies, and responses to increased applications of phosphorus. Crops differed greatly from each other in their ability to get phosphorus when none was added and in their need for phosphorus for maximum production on different soils. These differences may be observed by comparing the total yields of beans and lima beans from different rates of phosphorus, Table 4, page 13. The total yields of beans on the Norfolk soil were increased more than 2.5 times by increasing the application of phosphorus. On the other hand, phosphorus did not increase the yields of lima beans grown on the Norfolk soil. Continuing the comparison, it may be observed that on the Eutaw soil, the total yield of beans was increased over 5 times from applications of phosphorus, and on the Cecil almost 15 times, whereas the total yields of lima beans were increased only a fourth on the Eutaw soil and only two times on the Cecil soil. The contrast in response of crops to phosphorus on different soils is illustrated still further by the yields of beets, Table 4, page 13. It may be observed that the yields of beet roots were increased about 10 times on the Norfolk soil, 85 times on the TABLE 4. YIELDS OF DIFFERENT VEGETABLE CROPS FROM APPLICATIONS OF DIFFERENT AMOUNTS OF PHOSPHORUS ON DIFFERENT SOILS, FIELD BINS, MAIN STATION, AUBURN, ALABAMA Yields per acre applied20 Beans Lima Beans (4-yr. av.) aper ared (4-yr. av.) Early Early to each and Total and Total crop 1 med. med. Lb. 0 13.33 26.67 40.00 53.33 0 26.67 53.33 80.00 106.67 0 26.67 53.33 80.00 106.67 Bu. 28 58 91 116 127 35 114 164 199 224 6 41 71 97 107 Bu. 72 132 153 175 190 53 152 211 250 273 10 66 98 136 148 B 156 157 145 154 161 124 172 187 183 188 54 90 119 135 148 Bu. u. 213 207 193 203 205 167 200 211 205 211 96 145 170 190 201 Beets (3-yr. av.) Roots Bu. 10 71 85 101 104 2 62 116 154 170 1 90 154 169 168 Total . 1,815 8,445 9,912 10,958 11,066 286 7,829 12,662 15,969 16,948 447 9,352 16,322 16,316 16,624 Chinese Cabbage (3-yr. av.) Total Cabbage (4-yr. av.) Heads Total Lb. 10,860 20,080 26,820 27,360 27,260 2,860 27,000 32,520 33,120 35,400 1,280 19,380 27,500 28,880 30,020 Carrots (4-yr. av.) Roots Market- Total able Lb. 2,537 1,770 6,028 4,812 4,444 10,825 7,115 9,244 14,999 8,935 11,400 18,464 9,082 11,667 18,166 3,825 8,289 9,977 11,679 12,303 2,655 10,803 13,785 17,240 18,881 8,346 16,441 19,620 22,383 23,559 Chard (4-yr. av.) Total Lb. 807 7,158 12,288 14,403 14,447 560 3,983 5,543 8,195 8,781 643 10,559 15,380 17,905 20,738 Collards (4-yr. av.) Early and Total med. Lb. Lb. 1,453 8,120 11,229 11,567 11,525 178 15,106 18,636 20,354 21,116 119 10,477 13,945 14,715 14,591 1,549 10,613 13,970 15,164 14,929 256 20,445 24,505 25,978 26,908 172 14,098 18,755 19,247 19,441 Lb. Lb. Norfolk Soil 2,680 6,184 24,943 9,180 14,040 35,347 14,740 37,685 13,760 36,203 Eutaw 1,489 31,223 36,002 38,908 41,146 Soil 110 14,160 18,220 18,900 19,540 Cecil Soil 0 962 7,980 26,731 13,200 34,087 34,118 14,060 31,077 14,520 1,370 1,010 3,234 5,588 6,592 11,671 10,344 14,744 20,005 11,786 17,239 22,300 11,458 17,521 22,809 (Continued) 1Amount of phosphorus applied to each of three crops grown on same land the same year; 90 pounds per acre of N and 45 pounds per acre of K 20 were applied to all treatments. TABLE 4. (Continued) YIELDS OF DIFFERENT VEGETABLE CROPS FROM APPLICATIONS OF DIFFERENT AMOUNTS PHORUS ON DIFFERENT SOILS, FIELD BINS, MAIN STATION, AUBURN, ALABAMA OF PHOS- Yields per acre P 20 5 English apid Eggplant Kl Lettuce Pepper Peas aos Okra Ono to eache (3-yr. av.) (4-yr. av.) (4-yr. av.) (2-yr. ay.) (4-yr. av.) (4-yr. av.) (2-yr. av.) (4-yr. av.) crop 1MarketTotal Total Total able Total Total Total Total Total Lb. Bu. Bu. Lb. Lb. Lb. Lb. Lb. Lb. Lb. Norfolk Soil 1,205 93 3,669 756 5,257 591 47 0 2,230 410 3,145 12,009 1,553 123 3,937 13.33 15,745 4,178 4,227 5,236 2,153, 93 147 5,039 26.67 20,104 6,420 6,820 13,501 158 3,596 2,354 106 6,962 7,787 19,224 40.00 18,882 7,889 6,665 4,520 117 164 8,169 16,490 2,405 20,868 8,079 53.33 Radish (4-yr. av. ) Roots Lb. 1,495 3,977 4,729 4,592 4,236 533 5,938 6,815 Total Lb. 2,617 6,404 6,767 7,234 6,736 1,042 9,138 10,502 69 Eutow Soil 26.67 53.33 0 2,333 20,824 20,133 251 6,182 8,951 393 3,023 5,009 7,387 17,090 30,405 80.00 106.67 0 26.67 53.33 80.00 106.67 25,269 24,940 519 9,229 11,846 16,020 18,409 10,377 11,160 132 5,939 7,324 7,705 8,525 8,253 9,349 755 4,309 8,192 10,444 13,599 19,600 23,104 2,015 14,639 17,511 19,318 20,467 1,301 3,532 3,609 55 117 181 79 148 216 3,587 5,252 5,312 1,856 4,368 8,365 c) C C 3,679 3,599 571 2,780 3,780 3,640 3,887 203 203 24 89 125 138 156 245 251 45 123 165 180 196 5,693 6,482 1,443 3,386 5,245 4,994 4,676 9,789 10,581 876 4,067 7,243 9,481 9,306 6,698 6,102 176 3,880 4,140 4,112 4,127 10,483 9,524 573 6,025 6,523 6,400 6,733 Cecil Soil n 'Amount of phosphorus applied to each of three crops grown and 45 pounds per acre of K 2 0 were applied, to all treatments. -on Z ZI rn CA (Continued) same land the same year; 90 pounds per acre of N cn m TABLE 4. (Continued) YIELDS OF DIFFERENT VEGETABLE CROPS FROM APPLICATIONS OF DIFFERENT AMOUNTS PHORUS ON DIFFERENT SOILS, FIELD BINS, MAIN STATION, AUBURN, ALABAMA OF PHOS- 'N'1 -4 N rn m P20 applied to each crop 1 Lb. 0 13.33 26.67 40.00 53.33 0 26.67 53.33 80.00 106.67 0 26.67 53.33 80.00 106.67 Rutabaga (2-yr. av.) Roots Lb. 11,872 27,399 32,080 33,332 34,365 2,432 31,185 32,749 33,543 32,534 506 34,109 34,180 34,278 36,199 Total Lb. 20,122 49,107 57,709 58,640 59,661 4,816 55,441 59,732 59,424 57,968 1,379 61,840 62,416 62,064 64,640 Squash (4-yr. av.) Total Lb. 2,374 9,284 16,832 16,355 18,542 1,096 10,280 14,118 16,464 16,650 8 6,661 11,124 12,063 12,806 Yields per acre N. Z. TenderSweetpotatoes Spinach green (4-yr. av.) (4-yr. av.) (4-yr. av.) Marketable Bu. 342 426 Total Bu. Norfolk 469 495 571 447 500 Total Lb. Soil 4,471 13,370 16,300 18,396 19,027 Total Lb. 4,149 10,921 13,903 13,514 12,096 142 17,457 19,521 21,421 21,134 161 12,246 14,148 15,746 15,308 Tomatoes, sum. (3-yr. av.) Early and med. Lb. 1,068 3,113 5,461 8,264 8,920 370 3,778 6,927 10,207 9,329 86 2,115 4,467 2,357 4,457 Total Lb. 3,367 6,268 10,862 12,647 14,912 1,020 7,022 12,889 18,401 18,110 455 5,728 8,613 8,009 12,084 Turnips (4-yr. av.) Roots Lb. 5,037 10,652 11,680 11,740 12,074 1,091 13,035 .14,778 15,601 14,598 262 9,832 11,350 12,522 11,745 Total Lb. 13,648 27,224 30,359 29,985 31,152 3,438 36,225 42,529 45,108 42,583 835 26,858 31,672 35,106 34,207 m 1"Io z m m -4 -° rn 429 385 422 346 331 367 0 r= mn n 370 359 157 259 311 368 286 Eutaw Soil 453 511 428 24,216 27,341 440 444 31,047 453 29,244 Cecil Soil 227 261 376 16,415 392 18,172 436 22,575 399 17,584 Amount of phosphorus applied to each of three crops grown on same land the same year; and 45 pounds per acre of K 2 0 were applied to all treatments. 90 pounds per acre of N 16 ALABAMA AGRICULTURAL EXPERIMENT STATION Eutaw soil, and 168 times on the Cecil soil by the highest applications of phosphorus. Crops differ in a third important respect in the way they respond to phosphorus. With some crops very large increases resulted from small applications of phosphorus, but further increases were relatively small from the higher rates. For instance, the yield of turnips from the no-phosphorus treatment was 1,091 pounds of roots on the Eutaw soil, Table 4, page 15. This yield was increased 12 times by application of 26.67 pounds per acre of P205. At the higher rates of phosphorus, the yield increased only from 13,035 to 15,601 pounds per acre. In contrast, the yield of lettuce increased materially at each higher rate of phosphorus, Table 4, page 14. The response of each crop to phosphorus is shown by the data in the tables. Since the amounts of phosphorus added represent those applied to each of three crops grown each year on the same area and since crops consumed only a portion of the amounts added, each crop had the benefit of at least a portion of the phosphorus added to previous crops (21). The cost range during the past 20 years for each increment of phosphorus on the Norfolk soil was approximately $.54 to $.93, and on the Eutaw and Cecil soils it was $1.08 to $1.87. Some idea of returns from expenditures for phosphorus may be obtained from data on peppers grown on the Eutaw soil (Table 4). Assuming a maximum cost of $1.87 for each increment of phosphorus and assuming a value of 2-1/2 cents per pound for pepper, the value of the increased yield per $1 of cost from the first increment was about $130, from the second about $34, from the third about $47, and from the fourth about $98. Nitrogen Studies on Norfolk Soil The nitrogen studies in the older bins were confined to one soil type. The yields of 27 different vegetable crops from applications of five different rates of nitrogen on a Norfolk soil are given in Table 5. The rates of application consisted of 0, 30, 60, 90, and 120 pounds per acre of nitrogen. The cost range of each increment was $2.50 to $6.30. Yields of the different crops in most instances increased with each increment of nitrogen applied up to the full rate of 120 pounds per acre. However, most crops at the 90-pound rate reached yields 90 to 95 per cent of those from the maximum nitrogen rate. FERTILIZER EXPERIMENTS with VEGETABLE CROPS 17 TABLE 5. YIELDS OF DIFFERENT VEGETABLE CROPS GROWN ON NORFOLK SOIL FROM APPLICATION OF DIFFERENT AMOUNTS OF NITROGEN, FIELD BINS, MAIN STATION, AUBURN, ALABAMA Yield per acre on Norfolk soil from different rates of N 1 0 lb. 30 lb. 60 lb. 90 lb. 120 lb. per acre per acre per acre per acre per acre Crop Beans (4-yr. av.) Early and medium, bu. Total, bu. Lima Beans (4-yr. av.) Early and medium, bu. Total, bu. Beets (2-yr. av.) Roots, lb. Total, lb. Cabbage (4-yr. av.) Marketable, lb. Total, lb. Chinese Cabbage (4-yr. av.) 56 68 92 114 750 2,338 3,200 11,000 110 140 127 143 4,050 10,019 8,320 19,060 166 207 155 178 5,600 12,580 12,860 26,120 192 241 189 219 6,150 13,476 16,840 32,360 211 270 193 227 6,900 14,930 20,700 35,820 Total, lb. Carrots (4-yr. av.) Marketable, lb. Roots, lb. Total, lb. Chard, Swiss (4-yr. av.) Total, lb. Collards (3-yr. av.) Total, lb. Corn, sweet (5-yr. av.) Marketable, lb. Total, lb. Eggplant (3-yr. av.) Early and medium, lb. Total, lb. Endive (3-yr. av.) 7,144 1,601 2,622 5,611 3,982 7,847 747 1,679 1,277 1,833 1,435 2,423 1,485 2,207 20,641 6,428 6,137 11,918 7,868 11,920 2,095 4,610 7,363 10,560 5,501 5,537 5,760 7,231 31,067 9,668 8,201 16,126 7,501 16,140 3,589 7,540 12,492 16,901 8,393 7,413 10,137 11,700 40,062 11,829 9,239 18,516 6,554 16,973 5,893 9,013 15,152 21,667 10,310 8,138 8,637 10,771 45,459 14,278 10,307 21,314 7,766 18,556 7,216 10,261 12,952 19,032 9,805 9,105 9,072 11,800 Total, lb. Kale (4-yr. av.) Total, lb. Kohlrabi (3-yr. av.) Enlarged stems, lb. Total, lb. ments. (Continued) ' Amount applied to each of three crops grown each year on same land; 80 pounds of P 2 0 5 and 45 pounds of K 2 0 per acre were added to all treat- 18 ALABAMA AGRICULTURAL EXPERIMENT STATION TABLE 5. (Continued) YIELD OF DIFFERENT VEGETABLE CROPS GROWN ON NORFOLK SOIL FROM APPLICATION OF DIFFERENT AMOUNTS OF NITROGEN, FIELD BINS, MAIN STATION, AUBURN, ALABAMA Yield per acre on Norfolk soil from different rates of N 1 0 lb. 30 lb. 60 lb. 90 lb. 120 lb. per acre per acre per acre per acre per acre Crop Lettuce, (4-yr. Total, Lettuce, (3-yr. Total, Pepper spring av.) lb. fall av.) lb. 2,789 4,008 6,217 6,399 10,729 14,237 1,783 119 168 2,521 4,290 5,491 4,522 7,231 20,084 31,610 6,695 8,068 299 349 13,178 13,378 14,140 16,380 11,443 25,385 6,857 6,852 13,139 17,462 2,183 151 207 4,056 6,614 6,503 4,777 7,502 25,524 41,556 11,176 13,466 350 412 16,674 17,269 15,086 18,593 14,250 32,899 7,319 8,511 13,706 19,536 2,533 184 246 3,813 6,217 7,729 5,292 8,172 30,298 54,813 15,109 18,656 380 455 20,510 18,379 14,180 18,326 15,017 37,398 8,759 8,884 15,096 23,418 2,525 191 259 4,180 6,585 7,886 5,171 8,021 30,762 60,254 16,069 18,986 432 505 18,320 18,592 16,228 21,236 14,804 38,960 3,129 Early and medium, lb. 4,188 Total, lb. English Peas (4-yr. av.) 523 Total, lb. Potatoes (4-yr. av.) 66 Marketable, bu. 90 Total, bu. Okra (2-yr. av.) 1,526 Early and medium, lb. Total; lb. 2,490 Onion (4-yr. av.) 3,064 Total, lb. Radish (3-yr. av.) 2,616 Roots, lb. 4,512 Total, lb. Rutabaga (2-yr. av.) 8,864 Roots, lb. 14,864 Total, lb. Squash (4-yr. av.) 915 Early and medium, lb. 1,625 Total, lb. Sweetpotatoes (4-yr. av.) 165 Marketable, bu. 203 Total, bu. New Zealand Spinach (4-yr. av.) 6,273 Total, lb. Tendergreen (3-yr. av.) 4,619 Total, lb. Tomatoes, summer (3-yr. av.) 8,158 Early and medium, lb. 10,221 Total, lb. Turnip (3-yr. av.) 5,880 Roots, lb. 12,878 Total, lb. (2-yr. av.) I Amount applied to each of three crops grown each year on same land; 80 pounds of P 2 0 5 and 45 pounds of K 0 per acre were added to all treatments. 2 FERTILIZER EXPERIMENTS with VEGETABLE CROPS 19 Increases in yield of most crops from increases in nitrogen applications were rather uniform up to the 90-pound rate. Some crops however, gave larger increases from the first 30 pounds applied than from the same increment at higher rates. The increases in yields of beans (Table 5, page 17) are typical of the responses of most of the crops to the additional increments of nitrogen applied. Without nitrogen the bean yield was 68 bushels. From the first 30-pound increment, the increase was 72 bushels per acre; from the second, 67 bushels; from the third, 34 bushels; and from the fourth, 29 bushels. Assuming a maximum cost of $6.30 for each 30 pounds of nitrogen added and a value of 5 cents per pound for the beans, the increase in yield per $1 of cost from the first increment was worth about $17, from the second $16, from the third about $8, and from the fourth about $7. Potash Studies on Norfolk and Cecil Soils The potash studies were conducted on Norfolk sandy loam and Cecil sandy clay soils. The results from 21 crops are given in Table 6. The rates of potash used were 0, 15, 30, and 45 pounds per acre of K2O. The cost range of each increment was from $.45 to $.80. The response of different crops was much less pronounced from applications of potash than from applications of the other two fertilizer elements. Some crops produced about as high yields without potash as with any amount. Other crops, however, gave material increases in yield from potash applications. Beans, lima beans, cabbage, kale, English peas, and tendergreen with no potash produced yields about as high as those from any amount applied. Potash applications on Norfolk soil resulted in yield increases of 24 per cent for rutabagas, 74 per cent for sweetpotatoes, 34 per cent for beets. (roots), and 31 per cent for carrots. An application of 30 pounds per acre of potash increased the yield of No. 1 potatoes on Norfolk soil 47 bushels. Sweetpotatoes produced yield increases of 148 bushels per acre of No. l's from 45 pounds per acre of potash on Norfolk soil and 92 bushels per acre from 30 pounds of potash on Cecil soil. It is pointed out that, although the increases in yields are small from applications of potash, the cost of the potash required is so low that the value of the increase may be many times the 20 ALABAMA AGRICULTURAL EXPERIMENT STATION TABLE 6. YIELDS OF DIFFERENT VEGETABLE CROPS GROWN ON NORFOLK AND FIELD BINS, MAIN STATION, AUBURN, ALABAMA CECIL SOILS FROM APPLICATION OF DIFFERENT AMOUNTS OF POTASH, Yields per acre for different rates of potash (K 2 0) Crop Pounds of K2 0 per acre applied to Norfolk soils 0 Beans (4-yr. av.) Early and 187 medium, bu. 224 Total, bu. Lima Beans (4-yr. av.) Early and 176 medium, bu. 194 Total, bu. 15 30 45 Pounds of K 2 0 per acre applied to Cecil soil 1 0 15 30 45 193 232 197 234 193 231 90 122 96 131 96 131 95 132 195 212 172 193 186 208 97 182 100 179 106 183 104 194 Beets (2-yr. av.) Roots, lb. 7 ,450 8,450 9,350 9,950 4,450 5,850 5,300 5,100 14 ,731 15,852 17,071 18,071 9,269 11,378 10,696 10,480 Total, lb. Cabbage (4-yr. av.) Marketable, lb. 12 ,680 13,560 13,660 13,580 14,580 15,720 15,040 16,280 Total, lb. 28 ,560 27,380 27,880 30,400 28,380 28,880 28,880 30,220 Chinese Cabbage (3-yr. av.) Total, lb. Carrots (4-yr. av.) Marketable, lb. Roots, lb. Total, lb. Chard, Swiss 23 ,354 25,654 25,990 25,604 24,056 24,974 27,024 25,996 5,710 7,655 7,597 7,485 5,302 8,533 7,946 9,601 5 ,366 6,524 6,562 6,014 5,849 7,232 7,745 8,427 11 ,112 13,297 13,173 12,419 12,617 15,141 16,454 17,008 (3 -yr. av.) Total, lb. Collards (3-yr. av.) Total, lb. Endive (2-yr. av.) Total, lb. Kale (3-yr. av.) Total, lb. English Peas (3-yr. av.) Total, lb. Potatoes (4-yr. av.) Marketable, bu. Total, bu. 4,281 6,233 8,550 7,886 17,388 25,157 23,520 23,425 12 ,363 14,562 14,356 12,845 15,016 17,096 16,847 17,396 5 ,311 7 ,523 8,251 7,012 8,606 6,760 8,404 7,198 7,129 7,734 8,573 9,060 8,849 9,013 8,852 8,751 2 ,489 163 220 2,794 190 254 2,533 210 271 2,281 195 256 3,915 139 185 4,421 4,344 151 195 4,231 155 201 148 188 (Continued) SAmount of potash applied to each of three crops grown on same land the same year; 80 pounds per acre of P2 0 5 and 90 pounds per acre of N were applied to all treatments. FERTILIZER EXPERIMENTS with VEGETABLE CROPS 21 TABLE 6. (Continued) YIELDS OF DIFFERENT VEGETABLE CROPS GROWN ON POTASH, FIELD BINS, MAIN STATION, AUBURN, ALABAMA NORFOLK AND CECIL SOILS FROM APPLICATION OF DIFFERENT AMOUNTS OF Yields per acre for different rates of potash (K2O) Crop Pounds of K. O per acre 2 applied to Norfolk soil 1 0 15 30 45 7,054 4,718 7,580 7,553 5,069 8,605 7,514 5,241 8,049 Pounds of K 2 0 per acre applied to Cecil soil 30 45 0 15 Onions (4-yr. av.) Total, lb. Radish (2-yr. av.) Roots, lb. Total, lb. Rutabaga (2-yr. av.) Roots, lb. Total, lb. Squash (2-yr. av.) Early and medium, lb. Total, lb. Sweetpotatoes (4-yr. av.) Marketable, bu. Total, bu. 7,890 10,288 10,632 10,208 11,200 4,732 7,858 3,678 6,425 4,060 6,980 4,184 7,284 4,012 6,894 23,482 24,973 26,186 29,069 25,130 31,287 28,941 30,134 45,236 49,937 51,313 56,026 51,114 56,414 55,376 57,364 7,414 10,076 8,782 10,461 10,443 12,623 11,088 13,280 4,121 5,351 4,433 6,190 5,016 7,690 4,888 6,891 245 289 306 361 346 417 393 502 210 277 267 322 302 365 300 369 N. Z. Spinach (4-yr. av.) 6,900 7,616 6,402 8,766 12,005 11,962 15,378 15,951 Total, lb. Tendergreen (2-yr. av.) 16,785 17,144 17,862 17,996 12,750 13,260 13,441 11,354 Total, lb. Tomatoes (4-yr. av.) Early and 4,984 4,905 4,995 5,700 2,260 4,951 3,572 4,161 medium, lb. 14,205 13,672 12,862 13,714 11,869 15,315 14,744 16,685 Total, lb. Turnips (3-yr. av.) Roots, lb. Total, lb. 8,746 8,804 8,654 9,224 5,910 6,686 5,873 6,162 26,525 26,672 26,331 28,534 17,698 19,421 18,275 19,222 Amount of potash applied to each of three crops grown on same land the same year; 80 pounds per acre of P 2 0 5 and 90 pounds per acre of N were applied to all treatments. ' cost of the material. For example, there was an increase of 2,199 pounds per acre in the yield of collards on Norfolk soil from an application of 15 pounds per acre of K20. At $25 per ton for collards and at the maximum price for potash, the increase would be worth about $35 for $1 expenditure for potash. 22 ALABAMA AGRICULTURAL EXPERIMENT STATION FERTILIZER GRADE STUDIES WITH DIFFERENT VEGETABLE CROPS Studies of fertilizer grades were conducted both in field bins and in field plots. Some of the experiments were carried on at the Main Station, others at outlying points. Studies in Field Bins The three soils used in the field bin studies were Decatur, Hartsells, and Chesterfield. The first two were introduced, while the third was a local soil. The fertilizer treatments used on the Hartsells and Decatur soils were in duplicate, and on the Chesterfield they were in quadruplicate. EXPERIMENTS ON DECATUR SOIL. The rates applied to the Decatur soil were as follows: 0, 30, 60, 90, and 120 pounds per acre of N; 0, 40, 80, 120, and 160 pounds per acre of P205; and 0, 22.5, 45, and 67.5 pounds per acre of K20. Results on 12 crops are presented in Table 7. The cost during the past 20 years for each increment of nitrogen has ranged from about $2.50 to $6.30, of phosphorus from $1.60 to $2.80, and of potash from $.68 to $1.20. Nitrogen and phosphorus gave pronounced increases in yield of most crops. In general, higher rates of nitrogen were required to reach maximum yields than those of phosphorus. The response of the different crops to applications of potash on the Decatur soil was about the same as that obtained on the Norfolk and Cecil soils as previously described. Potash gave but small increases in yield with most crops on Decatur soil; the exceptions were lettuce, broccoli, tendergreen, and sweetpotatoes. A few crops might be used to illustrate the effects of the three elements on crop yields. Yields of beans were increased from 118 bushels per acre to 235 bushels as the rates of nitrogen were increased from 0 to 120 pounds per acre. The increases were 45, 39, 11, and 22 bushels per acre for the four successive increments. Yields were increased from 155 to 201 bushels as the rates of P205 were increased from 0 to 160 pounds per acre. The increases were 22, 9, 12, and 3 bushels per acre for the four successive increments. The yields of this crop from the no-potash treatment were practically as high as those from any rate applied. Increases in yields of sweetpotatoes were 75, 31, 4, and 45 bushels per acre for the four successive nitrogen increments, 5 TABLE 7. YIELDS OF DIFFERENT VEGETABLE CROPS GROWN ON DECATUR SOIL FROM APPLICATION OF DIFFERENT AMOUNTS NITROGEN, PHOSPHORUS, AND POTASH, FIELD BINS, MAIN STATION, AUBURN, ALABAMA OF Yields per acre on Decatur soil for different rates of nitrogen, phosphorus and potash Amount applied per acre 1 Lb. Nitrogen (N) Beans (2-yr. av.) Early Bu. 82 108 127 125 139 100 116 120 135 129 125 125 125 127 Total Bu. 118 163 202 213 235 155 177 186 198 201 218 215 213 224 Lima Beans (2-yr. av.) Early and Total medium Bu. 114 141 126 149 161 142 131 142 137 169 162 170 132 165 Bu. 141 174 175 193 193 162 170 182 172 214 207 223 173 203 Beets (2-yr. av.) Roots Lb. 365 2,741 5,622 6,711 7,498 1,252 6,980 6,861 6,138 5,175 4,101 5,466 5,581 7,155 Total Lb. 1,636 7,194 11,424 14,675 16,675 3,674 15,360 15,085 12,912 11,431 10,365 12,877 12,761 14,361 Broccoli (2-yr. av.) Market2 able Lb. 1,188 1,984 3,133 4,202 4,528 246 3,799 4,346 4,010 4,426 3,290 3,965 3,885 3,930 Total2 Lb. 7,155 12,381 17,098 18,407 22,983 916 17,146 19,424 19,824 18,893 15,587 17,930 17,264 21,047 Cabbage (4-yr. av.) Heads Lb. 1,498 5,557 14,363 22,034 26,081 1,058 17,583 20,209 20,455 17,258 16,733 16,415 18,740 20,594 Total Lb. 6,954 12,575 20,472 26,706 30,258 4,655 22,562 24,660 26,695 22,666 22,355 21,384 23,141 24,906 Lettuce (2-yr. av.) Heads Lb. 269 2,951 2,522 3,072 2,871 0 346 1,709 1,626 3,651 858 2,250 2,470 3,056 Total Lb. 7,386 15,533 15,088 17,488 15,562 1,402 7,658 13,482 13,082 15,277 7,347 13,328 15,565 16,362 0 30 60 90* 120 0 40 80 120 160* Potash (KO) z 0 22.5 45.0 67.5* Phosphorus (P 05 2 s) (Continued) Amount applied to each of two crops grown same year on same area. Rates of each element applied when other elements were varied are indicated by asterisk (*). 2 Marketable yield consists of flower parts and total yield consists of whole plant less flower part. TABLE 7. (Continued) YIELDS OF DIFFERENT VEGETABLE CROPS GROWN ON DECATUR SOIL FROM APPLICATION OF DIFFERENT AMOUNTS OF NITROGEN, PHOSPHORUS, AND POTASH, FIELD BINS, MAIN STATION, AUBURN, ALABAMA Yields per acre on Decatur soil for different rates of nitrogen, phosphorus and potash Amount Amount pplied pplied acre 1 Lb. Nitrogen (N) 0 30 60 90* 120 Phosphorus (P Os) 2 0 40 80 120 160* Potash (KzO) 0 22.5 45.0 67.5* Onions (4-yr. av.) Total Lb. 7,162 9,153 10,876 12,693 12,720 5,167 8,272 10,159 11,239 11,540 11,827 13,233 11,979 11,396 Potatoes (4-yr. av.) Marketable Total Bu. 75 100 136 152 168 92 114 129 144 161 147 164 166 153 Bu. 104 131 168 183 204 118 140 163 178 194 178 194 200 184 Sweetpotatoes Porto Rico (3-yr. av.) Marketable Total Bu. Bu. 241 313 327 333 348 311 347 368 330 285 254 303 324 368 295 370 401 405 450 414 419 459 412 411 338 362 376 430 Sweet Corn (2-yr. av.) Marketable Total Lb. Lb. 487 3,488 6,842 7,859 10,269 3,584 8,103 8,602 9,261 9,936 6,983 8,778 8,803 8,765 1,466 6,087 9,280 10,848 12,298 6,144 11,421 11,597 12,301 11,824 11,005 11,834 11,882 11,194 Tendergreen (4-yr. av.) Total Lb. 5,243 11,109 15,260 19,094 20,891 1,985 18,190 18,553 13,867 12,102 10,815 15,174 18,131 19,789 Turnips (4-yr. av.) Roots Lb. 7,878 10,982 11,681 12,418 12,934 1,888 12,687 13,328 13,011 13,312 12,277 13,134 12,189 11,992 Total Lb. 15,520 23,427 27,684 29,991 31,689 4,838 29,075 30,191 30,855 31,150 29,162 31,358x 29,617 30,930 z 0 SAmount applied to each of two crops grown same year on same area. Rates of each element applied when other elements were varied are indicated by asterisk (*). FERTILIZER EXPERIMENTS with VEGETABLE CROPS 25 and 40 bushels for the first two phosphorus increments, and 24, 14, and 54 bushels per acre for the three potash increments. Highest yields were obtained from 120 pounds per acre of nitrogen applied to beans, beets, broccoli, cabbage, potatoes, sweetpotatoes, sweet corn, tendergreen, and turnips; highest yields of lima beans, lettuce, and onions were obtained from 90 pounds per acre of nitrogen. Yields of beans, lettuce, and potatoes continued to increase from applications as high as 160 pounds per acre of P205. Maximum or near-maximum yields of beets were obtained from 40 pounds per acre; of broccoli, onions, turnips, tendergreen, sweetpotatoes, and cabbage from 80 pounds; and of sweet corn from 120 pounds. Maximum or near-maximum yields were obtained from the following rates: beans, no-potash rate; onions, lima beans, sweet corn, broccoli, and turnips, 22.5 pounds per acre of K20; potatoes, TABLE 8. YIELDS OF DIFFERENT VEGETABLE CROPS GROWN ON HARTSELLS SOIL FROM APPLICATIONS OF DIFFERENT AMOUNTS OF NITROGEN, PHOSPHORUS, AND POTASH, FIELD BINS, MAIN STATION, AUBURN, ALABAMA Yields per acre on Hartsells soil for different rates of nitrogen, phosphorus, and potash Amt. Beans Lima Beans Broccoli Cabbage Lettuce applied (3-yr. av.) (2-yr. av.) (2-yr. av.) (4-yr. av.) (2-yr. av.) per acre 1 Early Total Lb. 0 30 60 90* 120 Bu. 74 98 110 120 118 Bu. 109 178 202 209 222 Early and Total MarketHeads Total Heads med. able Total Bu. 101 122 146 154 171 144 148 152 146 123 140 140 153 165 Bu. 137 160 191 184 216 176 182 195 179 176 179 178 189 199 Lb. 1,293 2,394 3,655 4,640 5,629 147 3,223 4,182 4,259 4,640 4,480 4,192 4,522 4,375 Lb. Lb. Lb. Lb. Total Lb. Nitrogen (N) 7,088 630 6,898 13,219 8,255 16,044 17,747 16,806 23,264 21,968 22,228 27,305 25,050 27,230 31,379 464 12,064 17,635 18,778 18,996 17,504 19,507 18,759 19,155 627 14,092 18,836 20,310 18,477 17,308 18,733 24,853 22,465 4,899 20,692 24,566 26,153 24,353 23,701 25,425 28,954 27,584 80 3,514 615 7,335 1,495 11,005 3,248 17,709 3,744 17,187 0 391 0 1,623 474 6,029 1,252 9,623 1,834 11,671 256 6,535 1,287 11,811 2,650 15,152 1,866 13,850 Phosphorus (P 05 ) 2 0 76 124 20 80 135 40 100 166 60 100 174 80* 96 175 Potash (K 0) 2 0 111 22.5 107 45 110 67.5* 108 181 179 189 189 (Continued) 'Amount applied to each of two crops grown same year on same area. Rates of each element applied when other elements were varied are indicated by asterisk (*). 26 ALABAMA AGRICULTURAL EXPERIMENT STATION TABLE 8. (Continued) YIELDS OF DIFFERENT VEGETABLE CROPS GROWN IN HARTSEI 4LS SOIL FROM APPLICATIONS OF DIFFERENT AMOUNTS OF NITROGEN, PHOSPHORUS, AND POTASH, FIELD BINS, MAIN STATION, AUBURN, ALABAMA Yields per acre on Hartsells soil for different rates of nitrogen, phosphorus, and potash SweetAmt. ppedOnon Potatoes potatoes Tender- Turnips applied Porto Rico Sweet Corn green (4-yr. per (4-yr. acre 1 av.) (4-yr. av.) (3-yr.av.) (2-yr.av.) av.) (4-yr.av.) Total MarketMarketMarketable Total able Total able Total Total Lb. Lb. Lb. Bu. Bu. Bu. Bu. 58 97 118 119 130 76 92 112 114 118 116 113 119 116 81 131 153 165 184 115 132 150 155 163 155 147 161 158 254 375 447 467 441 424 409 407 434 393 316 352 363 389 316 465 532 558 549 531 516 523 522 535 0 608 4,237 3,191 5,741 10,471 6,147 9,197 15,115 8,794 10,736 18,336 8,666 11,459 20,646 3,792 6,650 6,612 6,855 6,451 7,027 9,056 9,216 9,242 9,015 2,536 14,578 16,955 17,770 14,313 Root Total Lb. 6,726 12,348 14,699 14,939 14,245 4,342 11,956 13,644 14,278 12,751 Lb. 11,920 23,745 30,196 35,066 36,267 10,797 25,339 31,688 31,774 30,419 Lb. Lb. Nitrogen (N) 5,025 0 30 8,313 10,371 60 90* 13,104 120 11,826 Phosphorus (P Os) 2 0 3,822 20 4,941 8,269 40 60 8,253 9,502 80* Potash (KzO) 10,741 0 22.5 11,517 45.0 11,766 67.5* 10,808 408 4,372 8,887 9,368 15,285 31,846 421 6,832 9,277 16,538 15,036 34,060 472 6,586 9,712 17,723 15,607 35,436 505 7,578 10,582 18,078 15,298 34,761 1Amount applied to each of two crops grown same year on same area. Rates of each element applied when other elements were varied are indicated by asterisk (*). 45 pounds; and lettuce, sweetpotatoes, tendergreens, cabbage, and beets, 67.5 pounds. EXPERIMENTS ON HARTSELLS SOIL. With one exception, the ex- periments on the Hartsells soil were identical to those on the Decatur soil. The rates of phosphorus used on the lighter Hartsells soil were one-half of those used on the heavier Decatur clay. Yields of 11 crops are given in Table 8. Responses to the three elements were about the same as those obtained on the other soils. However, responses of most crops on the Hartsells soil were higher from nitrogen applications and lower from phosphorus applications than those obtained on the Decatur clay. Except for lettuce, sweetpotatoes, and tendergreens, responses to potash applications were small. TABLE 9. YIELDS OF DIFFERENT VEGETABLE CROPS GROWN ON CHESTERFIELD SOIL OF MEDIUM FERTILITY FROM OF DIFFERENT FERTILIZER GRADES, FIELD BINS, MAIN STATION, AUBURN, ALABAMA APPLICATIONS Yields per acre on Chesterfield soil of medium fertility for different rates of nitrogen, phosphorus, and potash Fertilizer grade grade, 1,000 pounds per acre 1 N-P-K 8-10-6 8-10-0 8-10-4 8-10-6 8-10-8 0-10-6 4-10-6 6-10-6 8-10-6 8-0-6 8-8-6 8-10-6 8-12-6 8-10-6 12-15-9 Pole Beans (3er yPorto (3-yr.av.) Early Total and med. Bu. 231 111 243 249 251 84 204 244 261 147 234 223 240 223 215 Bu. 365 212 391 402 399 191 337 403 418 293 383 371 389 371 372 Sweetpotatoes Rico Triumph (2-yr.av.) (2-yr. av.) Marketable Bu. 295 219 332 311 319 127 281 315 332 278 300 314 312 314 325 Total Bu. 460 296 431 445 450 188 364 420 457 388 431 413 423 413 483 Marketable Bu. 253 183 256 274 301 222 283 271 292 205 264 271 273 271 253 Sweet Corn (4-yr.av.) Total Lb. 4,881 2,976 5,149 5,170 5,323 1,173 4,042 5,016 4,989 3,258 5,209 5,046 5,022 5,046 5,385 Tendergreen (3-yr.av.) Total Lb. 15,521 12,548 15,270 14,399 15,466 4,415 9,911 12,982 13,727 11,754 13,483 13,336 13,400 13,336 16,720 Tomatoes (3-yr.av.) Marketable Bu. 419 367 424 395 427 146 282 347 422 341 427 373 432 373 466 Total Bu. 585 509 550 547 553 214 417 493 572 553 555 535 559 535 618 Turnips (5-yr.av.) Roots Lb. 10,777 12,077 11,219 11,397 11,255 4,843 9,749 11,400 11,292 9,226 10,895 10,811 10,946 10,811 11,076 Total Lb. 27,487 25,078 28,581 29,116 28,871 10,262 22,896 27,756 29,262 22,512 28,085 28,274 27,847 28,274 29,502 n -4 rn Total Marketable Bu. 563 335 537 564 548 338 523 583 541 411 560 514 551 514 563 Lb. 2,305 1,371 2,679 2,633 2,584 384 1,771 2,688 2,332 1,446 2,608 2,758 2,448 2,758 2,576 a M 'Amount applied to each of two crops grown each year on same area, with the exception of one crop of sweetpotatoes per year. TABLE 10. YIELDS OF DIFFERENT VEGETABLE CROPS GROWN ON CHESTERFIELD SOIL OF Low FERTILITY FROM APPLICATIONS OF DIFFERENT FERTILIZER GRADES, FIELD BINS, MAIN STATION, AUBURN, ALABAMA Yields per acre on Chesterfield soil of low ferYields per acre on Chesterfield soil of low fertility for different rates of nitrogen, phosphortility for different rates of nitrogen, phosphorus, and potash us, and potash Fertilizer Beans Broccoli Cabbage Mustard Fertilizer Kohlrabi Onions Potatoes (2-yr.av.) (2-yr..) (2-yr..) (2-yr.av.) (2-yr..) av.) (2-yr. av.) (2-yr. av.) 1,000 pounds (2-yr. av.) (3-yr. 1,000 aoundss(2-yr av.) 1,000p per acre 1 Early per acre 1 and Total Total 2 Market- Total Total Crown Total Total Market- Total med. able able N-P-K 8-10-0 8-10-4 8-10-6 8-10-8 0-10-6 6-10-6 10-10-6 12-10-6 8-0-6 8-6-6 8-8-6 8-12-6 6-6-4 12-15-9 Bu. 94 115 123 137 19 111 146 142 101 130 129 134 109 140 Bu. 122 160 170 177 23 142 201 199 138 171 171 181 142 206 Lb. 7,917 10,858 11,264 10,855 1,332 8,896 12,746 11,338 2,992 10,250 10,115 11,315 9,670 10,448 Lb. 6,243 6,595 8,198 7,395 0 5,562 8,707 9,066 4,163 7,626 6,803 8,522 5,533 9,543 Lb. 11,386 14,742 16,998 15,991 1,981 13,232 18,186 17,991 9,590 14,897 14,941 16,656 13,472 18,515 Lb. 4,749 8,067 10,061 12,032 1,172 8,387 12,135 11,092 640 8,490 8,157 10,327 8,727 11,248 N-P-K 6-10-0 6-10-4 6-10-6 6-10-8 0-10-6 2-10-6 4-10-6 8-10-6 6-0-6 6-6-6 6-8-6 6-12-6 4-6-4 9-15-9 Lb. 506 1,011 1,178 1,024 35 387 733 1,277 467 980 1,188 1,027 605 813 Lb. 3,037 4,666 4,963 4,861 1,043 2,528 3,664 5,392 2,131 4,585 4,371 4,714 3,514 4,086 Lb. 4,106 6,138 6,291 6,279 1,978 3,878 5,280 6,400 2,746 5,850 6,163 5,700 5,216 6,215 Bu. 54 73 71 67 27 43 58 85 35 70 68 76 57 87 Bu. 78 100 102 95 39 63 83 110 -- 56 100 94 100 79: 114 c -I Z z Amount applied to each of two crops grown same year on same area. 2 Broccoli consists of whole plant, no flower parts. z FERTILIZER EXPERIMENTS with VEGETABLE CROPS 29 EXPERIMENTS ON CHESTERFIELD SOIL. Experiments were con- ducted on two Chesterfield soils, one of medium fertility and the other of low fertility. The rates of the three elements in the fertilizer are expressed as grades rather than as pounds of each. The basic application consisted of 1,000 pounds per acre of fertilizer. The rates were 0, 40, 60, and 80 pounds of N; 0, 80, 100, and 120 pounds per acre of P205; and 0, 40, 60, and 80 pounds per acre of K20. Results of the studies on the better Chesterfield soils are given in Table 9, and those on the poorer soil are presented in Table 10. Responses of crops to potash on both Chesterfield soils were considerably higher than those obtained on the other soils studied. Increases in yields from 40 pounds per acre of K20 applied to the better Chesterfield soil were as follows: pole beans from 212 to 391 bushels per acre, sweetpotatoes (Porto Rico variety) from 296 to 431 bushels, sweet corn from 2,976 to 5,149 pounds, and marketable tomatoes from 367 to 424 bushels. Similar responses were obtained on the Chesterfield soil of low fertility. In general, response to phosphorus applications on both Chesterfield soils were less than those on other soils except on the Hartsells. Response to nitrogen was about the same on the Chesterfield soil of medium fertility as it was on the other soils, but it was much greater on the soil of low fertility than on any of others studied. Studies in Field Plots Fertilizer experiments have been conducted in regular field plots at the Main Station, Auburn, three substations, two experiment fields, and at Thorsby and Atmore. Results of a number of these experiments are given in Tables 11 to 19, inclusive. EXPERIMENTS AT MAIN STATION. Results of fertilizer studies with the Porto Rico variety of sweetpotato on a Norfolk and on a Chesterfield soil and with the Triumph variety on a Chesterfield soil, are reported in Table 11. Rates of nitrogen, phosphorus, and potash are expressed as fertilizer grades. The base application was 1,000 pounds per acre. The rates were 0, 40, 60, 80, and 100 pounds per acre of N; 0, 60, 80, and 100 pounds per acre of P,0; and 0, 40, 60, and 80 pounds per acre of K20. Material increases in yield of both varieties of potatoes on the Chesterfield soil and of the Porto Rico on both soils were obtained from applications of potash and nitrogen. Yield increases were small from applications of phosphorus. Increased yields of 30 ALABAMA AGRICULTURAL EXPERIMENT STATION 30 ALABAMA AGCUTRLEPIMNSAIO TABLE 11. YIELDs OF SWEETPOTATOES GROWN ON NORFOLK AND CHESTERFIELD SOILS FROM APPLICATIONS OF DIFFERENT FERTILIZER GRADES, FIELD PLOTS, MAIN STATION, AUBURN, ALABAMA Yields per acre Fertilizer Amount per Chesterfield soil Porto Rico (3-yr. average) Norfolk soil Porto Rico (2-yr. average) Chesterfield soil Triumph (3-yr. 1 uraaes av.) - acre Lb. MarketTotal able N~ ~ ~ Bu. 134 142 160 166 77 134 168 185 175 169 180 155 152 130 168 142 Bu. 169 193 208 220 121 189 2]1 229 219 216 232 200 193 188 214 192 Marketable Ru. 157 178 166 196 104 160 183 191 178 174 174 170 166 150 Total Bu, 188 212 214 235 130 195 223 225 214 215 213 205 204 183 222 209 Total Bu. 253 301 325 342 171 297 321 356 355 324 330 319 306 257 318 310 N-P-K 6-10-0 6-10-4 6-10-6 6-10-8 0-10-6 4-10-6 6-10-6 8-10-6 10-10-6 6-0-6 6-6-6 6-8-6 10-10-6 6-10-6 6-10-6 6-10-6 1,000 1,000 1,000 1,000' 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 600 600 1,200 800 185 169 as superphosphate, all potash as muriate of potash, and one-third nitrogen as amnmonium sulphate were applied prior to planting ; two-thirds of nitrogen as nitrate of soda was applied as side Illphosphorus to 4 weeks after plants were up to stand. application 3 each variety on both soils were obtained from applications up to 80 pounds per acre of potash and of nitrogen. EXPERIMENTS AT THE GULF COAST SUBSTATION. The crops studied at the Gulf Coast Substation consisted of those of commercial importance in the truck-growing area of the Gulf Coast region. The more important crops studied were grown on freshly cleared land, referred to as "new land," and on land that had been in cultivation for a long period, designated as "old land." Experiments were also conducted on new land after it had been cleared and in cultivation for 5 or more years. FERTILIZER EXPERIMENTS with VEGETABLE CROPS 31 The studies were conducted on Orangeburg and Norfolk sandy loam soils. The Orangeburg soil was old land and the Norfolk was new land. Fertilizer treatments consisted of different grades and rates of fertilizers. The rates varied with different crops. Results are given in Tables 12 to 14, inclusive. One of the most pronounced differences among the three elements was in response to phosphorus. With the exception of sweetpotatoes, near failure and in most cases complete failure of crops resulted on new land without the addition of some phosphorus. On old land receiving some phosphorus in previous years, fair yields were obtained without phosphorus. For example, at the no-phosphorus rate, cabbage yields were 0.26 tons on new land and 10.56 tons per acre on old land (Table 13), while Irish potatoes produced 28 bushels on new land and 109 bushels per acre on old land (Table 14). Sweetpotatoes, however, produced fair yields on new land with no phosphorus added. Fair yields of all crops were produced on new land without potash. However, applications of potash gave material increases in yields. Pronounced potash deficiencies were observed with some crops where potash was not applied. Cabbage showed typical potash deficiency at the leaf margins. Foliage of Irish potatoes receiving no potash was several shades greener than those receiving some potash. With most crops, 3 per cent K20 at the commonly applied rate of application of a complete fertilizer gave near-maximum yields. Exceptions were sweetpotatoes and Irish potatoes, where 6 or 8 per cent was needed. On new land 24 pounds per acre of K20 increased the yield of beans from 116 to 151 bushels per acre (Table 12); 36 pounds increased the yield of cucumbers from 94 to 155 bushels per acre; 45 pounds increased the yield of No. 1 potatoes from 68 to 129 bushels; 30 pounds increased the yield of watermelons from 10,642 to 12,227 pounds; 45 pounds increased the yield of head cabbage from 3.13 to 6.61 tons; and 24 pounds increased the yield of roasting corn from 31 to 44 crates per acre. Although yield increases from potash were low as compared to those from either nitrogen or phosphorus, applications of potash gave high returns. An application of 90 pounds per acre of K20 resulted in an increased yield of 92 bushels of No. 1 potatoes (Table 12). The value of the increased yield would range from TABLE 12. YIELDS OF DIFFERENT VEGETABLE CROPS FROM APPLICATIONS OF DIFFERENT FERTILIZER GRADES, FIELD PLOTS, GULF COAST SUBSTATION, FAIRHOPE, ALABAMA Fertilizer grades 1 Yields per acre, Norfolk soil, new land WaterPotatoes 32 Beans 3 Cucummelons 3 bers 3 (5-yr. av.) (2-yr. av.) (5-yr. av.) (2-yr. av.) Total Total Bu. 124 94 155 145 163 66 143 127 140 1 109 167 160 143 165 105 130 No. 1's Bu. 147 68 129 156 160 61 128 153 148 11 122 160 150 150 179 99 147 Total Bu. 189 110 175 196 201 94 174 196 191 27 166 202 193 192 223 142 190 Total Lb. 12,089 10,642 12,227 12,557 12,591 8,932 11,764 11,981 13,425 12,648 13,850 13,618 13,502 11,841 11,754 12,351 Yields per acre, Norfolk soil, new land Cabbage3 Roasting Corn 3 Fertilizer grades' (4-yr. av.) Marketable Total Ton 7.01 3.13 6.61 6.89 7.37 1.21 4.47 8.68 7.83 0 5.75 7.68 7.00 7.23 8.63 3.92 6.89 Ton 16.13 9.34 15.33 16.34 17.05 4.02 10.99 18.66 15.04 0 13.90 16.32 15.00 16.48 19.63 10.38 15.93 (5-yr. av.) Marketable Total Crt. 40 31 44 49 44 6 33 43. 41 0 23 49 40 48 47 21 44 Crt. 46 37 51 55 50 7 37 48 47 0 27 56 47 54 58 25 50 3 to 4 N-P-K 6-10-6 6-10-0 6-10-3 6-10-9 6-10-6 0-10-6 3-10-6 9-10-6 6-10-6 6-0-6 6-5-6 6-15-6 6-10-6 6-10-6 9-15-9 3-5-3 6-10-6. 'Al Bu. 133 116 151 149 161 49 114 151 147 8 92 157 164 154 177 102 149 N-P-K 8-10-6 8-10-0 8-10-3 8-10-9 8-10-6 0-10-6 4-10-6 12-10-6 8-10-6 8-0-6 8-5-6 8-15-6 8-10-6 8-10-6 12-15-9 4-5-3 8-10-6 -4 c rn phosphorus as superphosphate, all potash as muriate of potash, and one-third of the nitrogen as ammonium sulphate were applied prior to planting; two-thirds of nitrogen as nitrate of soda was applied as side weeks after plants were up to stand. 2 By "new land" is meant recently cleared land. applications z ifi CA -I I $Beans and roasting corn were fertilized at rate of 800 pounds per acre, cucumbers at 1,200 pounds, potatoes and cab- bage at 1,500 pounds, and watermelons at 1,000 pounds. TABLE 13. YIELDs OF DIFFERENT VEGETABLE CROPS FROM APPLICATIONS OF DIFFERENT FERTILIZER GRADES, FIELDPLOTS, GULF COAST SUBSTATION, FAIRHOPE, ALABAMA Yields per acre, Norfolk soil, new land after 5 yr. 2 Friie Fertilizer geradliernls Fertilizer English grades grades Peas applied at Beans Roasting Corn applied at 800, (4-yr. av.)1pounds1 (4-yr. av.) (4-yr. av.) per acre' pounds 1,500 pounds rn -1 Yields per acre Orangeburg2 soil Norfolk soil -- new old land land after 5 years 2 (4-yr. av.) CabgCbae rn rn Market- Market- Total N-P-K 8-10-6 8-10-0 8-10-4 8-10-8 8-10-6 0-10-6 6-10-6 10-10-6 8-10-6 8-0-6. 8-8-6 8-12-6 8-10-6 8-10-6 10-12-8 6-8-4 8-10-6 Bu. 101 87 105 95 99 19 106 96 102 17 64 110 107 101 100 105 100 able Crt. 78 37 76 78 79 21 73 81 80 2 65 77 68, 73 76 66 73 Total Crt. 92 45 91 96 97 31 82 101 100 5 81 98 87 93 99 84 95 Total Lb. 4,229 3,382 4,298 4,197 4,354 1,087 4,047 3,903 4,102 323 3,804 4,487 4,184 4,349 4,353 3,673 4,993 N-P-K 10-10-6 10-10-0 10-10-4 10-tO10-10-6 0-10-6 8-10-6 12-10-6 10-10-6 10-0-6 10-8-6 10-12-6 10-10-6 10-10-6 12-12-8 8-8-4 10-10-6 able Total Marketable (4-yr. av.) Total z --i C Ton 9.66 8.17 8.45 7.86 8.84 3.59 8.65 9.39 9.23 4.76 8.42 9.41 8.38 7.93 8.32 7.03 7.97 Ton 16.23 16.12 16.22 15.75 16.73 10.01 16.37 16.24 16.75 10.56 16.13 15.99 15.75 15.84 15.98 13.65 15.03 Ton 12.03 3.66 11.86 12.19 12.45 7.01 13.29 11.69 12.42 0 10.48 13.67 11.59 12.32 13.03 10.99 11.78 Ton 21.41 8.21 21.41 20.79 21.44 13.27 26.57 20.02 21.48 .26 18.37 22.76 21.13 21.57 22.45 19.19 20.03 rn n 0 Cd) x'All phosphorus as superphosphate, all potash as muriate of potash, and one-third of nitrogen as ammonium sulphate were applied prior to planting; two-thirds of nitrogen as nitrate of soda was applied as side application 3 to 4 weeks after plants were up to stand. 2 By "new land after 5 years"s means land that has been in cultivation 5 years or more; by "old land" is meant land in cultivation for maniy years. TABLE 14. YIELDS OF SWEETPOTATOES AND POTATOES FROM APPLICATIONS OF DIFFERENT FERTILIZER GRADES, GULF COAST SUBSTATION, FAIRHOPE, ALABAMA FIELD PLOTS, Yields per acre Norfolk soil, new land Fertilizer applied'1 Yields per acre, Orangeburg soil, old land'Orangeburg Triumph Porto Rico Fertilizer grades Yields per acre Norfolk soil soil, new land after Fertilizer grades Triumph Grades Rate per old land Triumph per acre aple t sweetpotato ons 1,0 1pud early crop 1,0 5-year av. sweetpotato sweetpotato appliedeat late crop late crop 1,500 pounds 3-yr. av. 2-year av. 'peyer ______ per___ Potatoes,Poaes 5 years Mare-acre able acre-er a-eacar4-er'v No. Total Total Total N-P-K 6-10-6 6-10-0 6-10-3 6-10-9 6-10-6 0-10-6 3-10-6 9-10-6 6-10-6 6-0-6 6-5-6 6-15-6 6-10-6 6-10-6 9-15-9 3-5-3 6-10-6 Bu. 170 97 157 177 171 133 148 173 187 70 174 186 173 190 185 164 193 Bu. 222 129 208 242 223 173 197 213 235 92 219 239 228 238 262 200 241 N-P-K 4-10-6 4-10-,0 4-10-4 4-10-8 4-10-6 0-10-6 2-10-6 6-10-6 4-10-6 4-0-6 4-8-6 4-12-6 4-10-6 0-0-0 4-10-6 4-10-6 4-10-6 Lb. 600 600 600 600 600 600 600 600 600 600 600 600 600 0 800 400 600 Bu. 400 199 384 489 468 414 466 452 421 264 425 408 451 357 484 409 420 Bu. 332 172 298 395 372 318 339 347 391 366 351 331 353 181 403 284 295 N-P-K 6-10-6 6-10-0 6-10-4 6-10-8 6-10-6 0-10-6 4-10-6 8-10-6 6-10-6 6-0-6 6-8-6 6-12-6 6-10-6 6-10-6 8-12-8 4-8-4 6-10-6 Ru. 117 111 139 131 141 72 138 140 I's Triumph v No. 1's Total Total Bu. 155 152 180 171 182 109 178 180 Bu. 129 39 115 132 122 59 117 118 Bu. 170 72 153 173 160 93 155 158 rr a N-4 0 -- U D a 133 73 131 144 142 143 147 126 135 175 109 177 186 183 185 187 168 177 118 9 99 141 132 121 126 100 118 161 28 138 184 175 161 165 140 159 c -4 U, 'All phosphorus as superphosphate, all potash as muriate of potash, and one-third of nitrogen as ammonium sulnitrate of soda was applied as side application 3 to 4 weeks phate were applied prior to planting; two-thirds of nitrogen after plants were up to stand. as 0 Z FERTILIZER EXPERIMENTS with VEGETABLE CROPS 35 about $140 to $185; the cost of the potash would range from about $3 to $5. Response of crops to potash was less pronounced on old land that had received some potash than on new land that had received no potash. On old land (Orangeburg), an application of 60 pounds per acre of K20 increased the yield of cabbage from 8.17 to only 8.45 tons per acre, whereas on new land 60 pounds increased the yield from 3.66 to 11.86 tons. The increased yields of potatoes were from 111 to 139 bushels per acre on old land and from 39 to 115 bushels on new land from 60 pounds per acre of K20. Nitrogen applications markedly affected yields of crops on both new and old land. In most cases 6 per cent nitrogen seemed adequate for most crops at the fertilizer rate used. Maximum or near-maximum yields were obtained on new land from the following nitrogen rates: beans, 48 pounds per acre of N; cucumbers, 36 pounds; potatoes, 90 pounds; watermelons, 60 pounds; cabbage, 180 pounds; early sweetpotatoes, 72 pounds; and roasting corn, 64 pounds. On new land 5 years after clearing, maximum or near-maximum yields were obtained from 48 pounds per acre of nitrogen applied to beans, 64 pounds to roasting corn, 48 pounds to English peas, 120 pounds to cabbage, and 60 pounds to Irish potatoes. The nitrogen requirement on old land was not materially different from that on new land. Maximum or near-maximum yields of potatoes and cabbage on old land resulted from 60 and 150 pounds per acre of nitrogen, respectively. Practically no crop yields were obtained on new land without phophorus with exception of sweetpotatoes. Maximum or near-maximum crop yields were obtained on new land from applications of 80 pounds per acre P205 for beans, 120 pounds for cucumbers, 150 pounds for potatoes, 100 pounds for watermelons, 225 pounds for cabbage, and 120 pounds for roasting corn. On new land, 5 years after clearing, maximum or near-maximum yields resulted from applications of phosphorus at 80 pounds per acre of P205 for beans, 96 pounds for roasting corn and for English peas, 180 pounds for cabbage, and 150 for potatoes. Crop yields were much higher on old land from no-phosphorus treatments than on new land, although about the same amount of phosphorus was required on old as on new land for maximum or near-maximum yields. 36 ALABAMA AGRICULTURAL EXPERIMENT STATION TABLE 15. YIELDS OF DIFFERENT VEGETABLE CROPS ON RUSTON SOIL FROM FIELD PLOTS, APPLICATIONS OF DIFFERENT FERTILIZER GRADES, THORSBY, ALABAMA Yields per acre Beans Potatoes (4-yr. av.) No. l's Bushels 83 75 90 90 89 20 78 93 92 41 90 97 101 101 105 92 (4-yr. av.) Total Bushels 113 109 121 124 123 36 110 121 126 61 122 131 134 129 137 124 Fertilizer grades N-P-K 6-10-6 6-10-0 6-10-3 6-10-9 6-10-6 0-10-6 3-10-6 9-10-6 6-10-6 6-0-6 6-5-6 6-15-6 6-10-6 9-15-9 6-10-6 2 6-10-6 1 (4-yr. av.) Total Hampers 72 71 78 74 76 10 62 84 74 46 76 82 82 83 77 72 1Beans were fertilized at rate of 800 pounds per acre, and potatoes at 1,500 pounds per acre. All superphosphate, muriate of potash, and one-third nitrogen as ammonium sulphate were applied at planting; two-thirds as nitrate of soda was applied 2 to 3 weeks after plants were up to stand. 2 All nitrogen was derived from ammonium sulphate and was applied before planting. EXPERIMENTS AT THORSBY. Experiments at Thorsby were conducted cooperatively on a truck grower's farm. The soil was a Ruston of fairly high fertility. Results of fertilizer studies with beans and potatoes are given in Table 15. Maximum or near-maximum yields of beans were obtained from applications of 24 pounds of K20, 72 pounds of N, and 80 pounds of P 0 5 per acre. For potatoes, applications of 45 pounds of K20, 90 pounds of N, and 150 pounds P205 per acre gave maximum or near-maximum yields. 2 EXPERIMENTS AT TENNESSEE VALLEY SUBSTATION. Fertilizer studies with a number of vegetable crops were conducted at the Tennessee Valley Substation. The soil is a good grade Decatur FERTILIZER EXPERIMENTS with VEGETABLE CROPS 37 clay. Results from the work with potatoes, sweetpotatoes, and cabbage are given in Table 16. Applications of 90 pounds K20 per acre, 60 pounds N, and 150 pounds P20s gave maximum or near-maximum yields of Irish potatoes. Treatments of 30 pounds of K20, 40 pounds of N, and 100 pounds of P 2 0 6 resulted in maximum or near-maximum yields of sweetpotatoes; while 72 pounds of K20, 108 pounds N, and 120 pounds P20 gave maximum or near-maximum yields of cabbage. By increasing the application of 4-10-6 fertilizer from 1,500 to 2,250 pounds (equivalent of 1,500 pounds of 6-15-9) the yield of potatoes was increased from 144 bushels to 170 bushels per acre. TABLE 16. YIELD OF DIFFERENT VEGETABLE CROPS ON DECATUR SOIL FROM APPLICATIONS OF DIFFERENT FERTILIZER GRADES, FIELD PLOTS, TENNESSEE VALLEY SUBSTATION, BELLE MINA, ALABAMA Yields per acre Fertilizer grades N-P-K 4-10-6 4-10-0 4-10-3 4-10-9 4-10-6 0-10-6 2-10-6 6-10-6 4-10-6 4-0-6 4-5-6 4-15-6 4-10-6 4-10-6 4-10-6 6-15-9 4-10-6 1 Potatoes (5-yr av.) Total Bushels 144 131 142 156 149 72 126 156 153 111 138 152 152 Sweetpotatoes (5-yr av.) Total Bushels 333 279 286 293 282 276 285 289 315 272 293 284 305 307 310 315 336 Fertilizer applied at 1,200 pounds per acre' N.P-K 6-10-6 6-10-0 6-10-3 6-10-9 6-10-6 0-10-6 3-10-6 9-10-6 6-10-6 6-10-6 6-0-6 6-5-6 6-15-6 Yields per acre Cabbage (3-yr. av.) Total Tons 6.84 6.30 6.87 7.78 7.99 3.96 6.69 8.61 6.34 7.60 3.03 6.38 8.03 3 2 136 147 170 144 6-10-6 4 All manure Ca 6-10-6 9-15-9 + 8.17 5.51 8.19 8.07 'Potatoes were fertilized at the rate of 1,500 pounds per acre and sweetpotatoes at 1,000 pounds. All phosphorus as superphosphate, all potash as muriate of potash, and one-third of nitrogen as ammonium sulphate were applied at time of planting; two-thirds of nitrogen as nitrate of soda was applied after planting. 2 All nitrogen as cottonseed meal was applied before planting. SOne-third of nitrogen as cottonseed meal was applied before planting. Stable manure was applied at rate of 20 tons per acre. SLime added. 38 ALABAMA AGRICULTURAL EXPERIMENT STATION EXPERIMENTS AT SAND MOUNTAIN SUBSTATION. Studies on the Sand Mountain Substation were conducted on a Hartsells sandy loam soil of fair fertility. Results of fertilizer experiments with sweetpotatoes, potatoes, and cabbage are given in Table 17. On this soil maximum or near-maximum yields of sweetpotatoes were obtained from applications of 90 pounds of K20, 60 pounds of N per acre, and zero phosphorus. Applications of 90 pounds of K20, 90 pounds of N, and 150 pounds of P205 per acre for potatoes resulted in maximum or near maximum yields. Treatments of 72 pounds of KO20, 108 pounds of N, and 180 pounds of PO2s per acre gave approximately the highest yields of cabbage. TABLE 17. YIELDS OF DIFFERENT VEGETABLE CROPS ON HARTSELLS SOIL FROM APPLICATIONS OF DIFFERENT FERTILIZER GRADES, FIELD PLOTS, SAND MOUNTAIN SUBSTATION, CROSSVILLE, ALABAMA Fertilizer grades Yields per acre Sweetpotatoes Potatoes (5-yr. av.) (5-yr. av.) No. l's Total Bu. 220 167 214 231 149 200 201 236 224 223 201 186 204 207 208 239 195 No. l's Bu. 110 72 103 111 27 93 84 125 53 98 101 106 108 122 118 111 93 Total 2 Bu. 133 97 127 134 48 115 103 148 70 123 124 131 132 166 143 135 116 Yields Fertilizer per acre grades Cabbage 1200 pounds (2-yr.ay.) peracre1 N-P-K 6-10-6 6-10-0 6-10-3 6-10-9 6-10-6 0-10-6 3-10-6 9-10-6 6-10-6 6-10-6 6-0-6 6-5-6 6-15-6 Total Tons 8.50 6.44 7.27 7.66 6.79 1.25 5.76 8.84 8.49 7.14 .78 7.30 9.47 N-P-K 4-10-6 4-10-0 4-10-3 4-10-9 0-10-6 4-10-6 2-10-6 6-10-6 4-0-6 4-5-6 4-10-6 4-10-6 4-15-6 4-10-6 s 4-10-6 6-15-9 4-10-6 Bu. 165 121 159 167 102 149 151 185 167 165 152 133 151 151 156 191 150 6-10-6 9.48 All manure 7.36 6-10-6 10.50 12.35 9-15-9 ' were fertilized at the rate of 1,000 pounds per acre and potatoes at 1,500 pounds. All phosphorus as superphosphate, all potash as muriate of potash, and one-third of nitrogen as ammonium sulphate were applied at time of planting; two-thirds of nitrogen as nitrate of soda was applied after planting. 'Total includes only No. l's and No. 2's. All nitrogen as cottonseed meal was applied before planting. One-third of nitrogen as cottonseed meal was applied before planting. Stable manure was applied at rate of 20 tons per acre. 'Sweetpotatoes ' ', FERTILIZER EXPERIMENTS with VEGETABLE CROPS 39 When the application of the 4-10-6 fertilizer was increased from 1,000 pounds to 1,500 pounds per acre (equivalent to 1,000 pounds of 6-15-9), yields of No. 1 sweetpotatoes were increased from 150 to 191 bushels per acre. Similarly, the yield of cabbage was increased from 10.50 to 12.35 tons per acre by increasing the application of 6-10-6 fertilizer from 1,200 to 1,800 pounds per acre (equivalent to 1,200 pounds of 9-15-9). EXPERIMENTS AT STATE FARM. Fertilizer studies at the State Farm, Atmore, were confined to sweetpotatoes. The soil is a fertile Red Bay sandy loam, which had received liberal applications of fertilizers in previous years. Results are presented in Table 18. On this well fertilized and productive soil, quite satisfactory yields of the Triumph and the Porto Rico varieties were obtained even when any one of the three elements was omitted. The yield of the Porto Rico variety was not increased by applications of potash although the yield of Triumph was increased somewhat by 40 TABLE 18. YIELDS OF SWEETPOTATOES ON RED BAY SOIL FROM APPLICATIONS OF DIFFERENT FERTILIZER GRADES, FIELD PLOTS, STATE FARM, ATMORE, ALABAMA Fertilizer Grades' N-P-K Amount per acre Pounds Yields per acre Porto Rico (3-year average) Total Marketable Bushels Bushels Triumph (2-yr. av.) Total Bushels 6-10-0 6-10-4 6-10-6 6-10-8 0-10-6 4-10-6 6-10-6 8-10-6 1,000 1,000 1,000 1,000 1,000 1,000 1,000 1,000 298 272 299 309 252 303 297 288 402 404 411 429 362 421 424 407 310 338 316 336 317 343 305 358 10-10-6 6-0-6 6-6-6 1,000 1,000 1,000 272 271 275 390 399 402 351 334 345 6-8-6 1,000 600 600 1,200 800 600 290 302 267 284 298 282 411 415 369 415 408 390 323 306 332 337 321 332 '10-10-6 6-10-6 6-10-6 6-10-6 12-10-6 phosphorus as superphosphate, all potash as muriate of potash, and one-third of nitrogen as ammonium sulphate were applied at planting; two-thirds of nitrogen as nitrate of soda was applied as side application. 'All 40 ALABAMA AGRICULTURAL EXPERIMENT STATION pounds per acre of K20. An application of 40 pounds per acre of N increased the yield of the Porto Rico variety 51 bushels and the yield of the Triumph variety 26 bushels per acre. Applications of phosphorus did not materially increase the yield of either variety. Increasing the rate of a 6-10-6 fertilizer from 600 to 1,200 pounds per acre increased the yield of the Porto Rico variety from 369 bushels to 415 bushels per acre. The yield of the Triumph variety was not increased by the larger application. EXPERIMENTS AT BREWTON AND MONROEVILLE EXPERIMENT FIELDS. Fertilizer experiments with sweetpotatoes were conducted on both the Brewton and Monroeville Experiment Fields. The soil at Brewton is a Norfolk sandy loam, while that at Monroeville is an Orangeburg sandy loam soil. Results are presented in Table 19. TABLE 19. YIELDS OF TRIUMPH SWEETPOTATOES FROM APPLICATIONS OF DIFFERENT FERTILIZER GRADES, FIELD PLOTS, BREWTON AND MONROEVILLE EXPERIMENT FIELDS Fertilizer Rate per acre Pounds 600 600 600 600 600 600 600 600 600 600 600 600 600 0 800 400 600 Grades' N-P-K 4-10-6 4-10-0 4-10-4 4-10-8 4-10-6 0-10-6 2-10-6 6-10-6 4-10-6 4-0-6 4-8-6 4-12-6 4-10-6 0-0-0 4-8-6 4-8-6 4-10-6 Yields per acre Brewton Monroeville Norfolk soil Orangeburg soil (7-year average) (7-year average) Total Total Bushels 141 76 134 144 150 105 140 155 160 123 154 145 160 74 172 138 163 Bushels 276 244 279 291 291 214 268 276 264 266 280 278 275 178 284 251 276 All fertilizer applied at time of planting. FERTILIZER EXPERIMENTS with VEGETABLE CROPS 41 Yields of sweetpotatoes at Monroeville were about twice as high as those at Brewton. Maximum or near-maximum yields of sweetpotatoes were obtained at Brewton from applications of 36 pounds of K20, 24 pounds of N, and 48 pounds of P205 per acre. An application of 36 pounds per acre of K20 increased the yield 74 bushels per acre over that of the zero-potash treatment; 24 pounds of N increased the yield 55 bushels over the zero-treatment; and 48 pounds of P205 increased the yield 31 bushels per acre over the zero-phosphorus treatment. Unfertilized sweetpotatoes yielded an average of 74 bushels per acre in a 7-year period at the Brewton Field. When 4-8-6 fertilizer was applied at 400-, 600-, and 800-pound rates, sweetpotatoes produced yields of 138, 154, and 172 bushels per acre, respectively. At Monroeville, maximum or near-maximum yields were obtained from applications of 36 pounds of K20, 36 pounds of N, and 48 pounds of P205 per acre. An application of 36 pounds of K20 per acre gave a yield increase of 47 bushels per acre; 36 pounds of N resulted in a 62-bushel increase, whereas the increase from phosphorus was 14 bushels. MISCELLANEOUS FERTILIZER EXPERIMENTS Two studies were conducted at the Main Station, Auburn, dealing with methods of applying fertilizers and with the effects of manure on the fertilizer requirements of vegetable crops. Studies at the Main Station, and at the Gulf Coast Substation, Fairhope, provide data on effects of residual phosphorus and potash. Methods of Application of Fertilizers Experiments to determine value of dividing fertilizer materials and value of a complete fertilizer when used with and without animal manure were conducted on a Chesterfield (loamy-sand) soil of low fertility. The study included both spring and fall crops. Yields of all crops on this soil were low, especially in the spring. Results of chemical tests made after heavy spring rains showed that most of the nitrogen had been lost. Three treatments were used, each with and without manure. In one treatment, all fertilizer materials were added 10 days before planting. In a second treatment, one-fourth of the nitrogen plus the full amounts of phosphorus and potash were applied 42 ALABAMA AGRICULTURAL EXPERIMENT STATION before planting, the remaining nitrogen being applied in three equal applications at 2-week intervals after the crops were up to a stand. One fourth of the complete fertilizer was added before planting in the third treatment, and the other three-fourths were added in three equal applications at 2-week intervals after stands were established. Results are presented in Table 20. Without manure, spring crops on the light soil used in the study practically failed when all fertilizer materials were applied before planting. Dividing the nitrogen increased the yield of car- rots almost 3 times, increased the yield of beets about 15 times, and the yield of mustard about 3 times. Somewhat further increases were obtained by dividing the complete fertilizer. Manure increased materially the yield of each crop with each method of applying the fertilizer materials. Satisfactory yields of spring crops were not obtained until manure was used and the nitrogen or complete fertilizer was divided into several applications. Yields were affected less in the fall by dividing the fertilizer materials. Manures, however, doubled the yields of fall crops receiving comparable fertilizer treatments. TABLE 20. CROP RESPONSE TO DIVIDED APPLICATIONS OF FERTILIZER MATERIALS ON CHESTERFIELD SOIL, FIELD BINS, MAIN STATION, AUBURN, ALABAMA Total yields per acre Methods of Spring crops Fall crops Spring crops fertilizer Manure Tenderappliper cations 1 acre 2 Carrots Beets Mustard greens Turnips Radishes (2-yr. (4-yr. (4-yr. (4-yr. (4-yr. (4-yr. av.) av.) av.) av.) av.) av.) (1) (2) (3) (1) (2) (3) Tons 0 0 0 12 12 12 Pounds Pounds Pounds 43 2,026 2,102 6,231 6,173 663 7,263 7,675 1,051 7,416 14,588 15,984 3,802 9,235 10,752 3,648 12,244 12,504 Pounds Pounds Pounds 4,243 10,872 15,384 6,624 10,594 16,896 17,386 8,784 12,067 20,712 22,449 22,179 32,185 31,565 32,813 12,231 11,261 11,386 1 Fertilizer (6-8-4) applied at rate of 1,500 pounds per acre to each of the spring and fall crops: (1) All fertilizer applied before planting. (2) All phosphorus and potash, and one-fourth nitrogen applied before planting, and three-fourths nitrogen applied in three equal applications at 2-week intervals after crops were up to stand. (3) One-fourth of complete fertilizer applied before planting, and three-fourths applied in three equal applications at 2-week intervals after crops were up to stand. SManure applied in August of each year. FERTILIZER EXPERIMENTS with VEGETABLE CROPS 43 Nitrogen, Phosphorus, and Potash Requirements of Vegetable Crops on Thin Soil Receiving Light Application of Manure Results of other experiments had shown that satisfactory yields of some crops grown on Chesterfield soil of low fertility were not produced irrespective of the amounts of commercial fertilizer used. However, the addition of a small amount of manure resulted in a satisfactory yield. To determine how nitrogen, phosphorus, and potash requirements of crops were affected by manure, an experiment was conducted on this soil. From 1938 to 1944 regular commercial fertilizer studies were conducted in which no manure was added. Beginning in 1945, stable manure at the rate of 6 tons per acre was included in all treatments. Prior to 1947, two-thirds of the nitrogen and all of the phosphorus and potash were applied under the crops before planting; the remaining one-third of nitrogen being applied 3 to 4 weeks after the crop was up to a stand. Beginning in 1947, one-half of the PzO5 and K20O and one-third of the N were applied before planting and a similar amount applied as a side application after planting; the remaining one-third of the nitrogen was applied as a second side application. In this experiment, Irish potatoes, beets, and carrots were grown as spring crops, and turnips and kohlrabi as fall crops. Yields of the five vegetable crops from different rates of nitrogen, phosphorus, and potash are given in Table 21. From the data it may be observed that, in general, the yield of each crop was much higher after the manure was applied than before. Seasonal conditions and different methods of applying the complete fertilizer, in all probability, played some part in causing these differences. Quantitative comparisons, therefore, of yields before and after applying manure are not warranted. Yields, however, ranged from about 50 to 400 per cent higher after the manure was applied than before. This was true regardless of the method used in applying the complete fertilizer. The 6 tons of manure apparently provided sufficient amounts of potash for maximum or near-maximum yields. Increases in yield from different rates of potash applications averaged about 39 per cent without manure and about 11 per cent with manure. With most crops the greatest increases in yields were from the first increment of potash. TABLE 21. FERTILIZER GRADES STUDIES ON POOR SANDY SOILS WITH AND WITHOUT MANURE, AUBURN, ALABAMA. FIELD BINS, MAIN STATION, T Total yields per acre tment No. 1,000 . pounds per N-P-K 6-10-0 6-10-4 6-10-6 6-10-8 acre1 Manure 6 tons, None, 2 crops 1 crop 1940-43 1946 Potatoes 2 Beets Carrots Kohlrabi Turnips Manure 2 6 tons, None, 1 crop 1 crop 1939 1948 Pounds 7,610 6,174 8,294 7,213 Manure 2 6 tons, None, 2 crops 1 crop 1947 1941-44 Pounds 3,601 4,516 4,327 4,128 Manure 2 6 tons, None, 2 crops 1 crop 1939-42 1945 Pounds 3,037 4,666 4,963 4,861 None, 1 crop 1943 Pounds 4,416 6,259 4,531 6,163 Manure 2 6 tons, 6 tons, 1 crop 1 crop' 1948 1946 Pounds 18,822 22,016 23,117 Pounds 28,454 29,107 30,867 30,573 1 2 3 4 Bushels Bushels Pounds 78 135 2,137 100 130 3,750 102 140 3,270 95 133 3,545 Pounds 14,611 15,994 17,696 15,827 Pounds 7,610 8,787 8,518 8,858 24,563 5 6 7 8 9 10 11 12 13 14 0-10-6 2-10-6 4-10-6 8-10-6 6-0-6 6-6-6 6-8-6 6-12-6 4-6-4 9-15-9 39 63 83 110 56 100 94 100 79 114 107 118 123 146 103 133 134 129 133 140 358 1,760 3,014 5,318 2,503 4,102 4,269 3,456 3,123 4,339 3,488 5,645 7,782 8,096 7,277 7,821 7,616 7,283 6,592 8,845 2,365 3,757 3,927 4,326 2,883 4,307 7,386 11,635 14,650 19,469 12,794 17,850 1,043 2,528 3,664 5,392 2,131 4,585 4,371 4,714 3,514 4,086 2,995 4,954 6,823 8,934 7,264 8,889 8,678 9,452 3,226 2,035 3,648 5,952 1,670 3,264 8,864 12,403 19,558 25,850 17,754 23,213 7,168 16,218 23,962 31,610 28,685 31,200 -4-4 zdz r 3-I D cn a 5,092 3,975 3,907 3,905 17,536 18,131 14,368 18,784 8,063 8,281 5,126 4,070 3,898 7,776 21,523 23,317 19,834 29,600 31,270 30,790, 25,306 33,747 C 4-I 6-4 ' Beginning in 1947, the complete fertilizer was divided, one-half P2 05 and K 20, and one-third of nitrogen being applied under the crop two weeks prior to planting and similar amou nts applied 3 to 4 weeks after planting; the remaining -onethird of nitrogen was applied as a second side application. Before 1947, all P 2 05 and K 2 0, and two-thirds of the nitrogen were applied before planting; one-third of the nitrogen was applied as a side application. 2 Manure was applied first in 1945. FERTILIZER EXPERIMENTS with VEGETABLE CROPS 45 With three exceptions, increased yields of all crops resulted from each additional increment of nitrogen - from lowest to highest applications. This was true of yields from treatments with or without manure. While relative increases from nitrogen without manure were somewhat larger than those from nitrogen plus manure, the actual increases were higher when manure was included. The relative increases in yields of the several crops resulting from adding 60 pounds per acre of P205 over the no-phosphorus application ranged from approximately 50 to 120 per cent without manure, and from approximately 8 to 30 per cent with manure. For most crops, the 100-pound rate of P2Os was adequate irrespective of application of manure. Residual Effects of Fertilizer Materials Fertilizer materials may exert a considerable influence on crops following those to which the materials were applied. This is an important point in fertilizing truck crops grown on the same land for many years. The residual effects of nitrogen, phosphorus, and potash differ greatly. The form in which the element is applied, especially of nitrogen, likewise influences residual effects. The residual effects of phosphorus and potash are more pronounced than those of nitrogen. Midgley (12), Scarseth, and Tidmore (14, 15) have shown that large quantities of phosphorus are fixed in the soil. Other investigators (2, 3, 8) have shown that plants may utilize much of this fixed phosphorus at later periods. A companion report to this bulletin (21) presents considerable evidence on the accumulation of phosphorus in soil and its later availability to plants. An earlier report presented data on the residual effects of phosphorus on yields of Irish potatoes at the Gulf Coast Substation (19). Data in Tables 13 and 14 give some evidence on residual effects of phosphorus. Sweetpotatoes on new ground (Table 14) produced a total of 92 bushels per acre without phosphorus and 219 bushels from 60 pounds per acre of P20 5. On old land that had received phosphorus applications in past years, sweetpotatoes produced 366 bushels per acre without phosphorus and 353 bushels from 60 pounds per acre of P205. Cabbage, (Table 13) on land that had received no phosphorus, produced 0.26 ton per acre without phosphorus and 21.13 tons from 150 pounds per acre of P2O5. On old land previously receiving phosphorus, the yield was 10.56 46 ALABAMA AGRICULTURAL EXPERIMENT STATION 46 ALABAMA AGCUTRLEPIMNSAIO tons per acre without phosphorus and 15.75 tons from 150 pounds of P2O5. Irish potatoes (Table 14) on new ground yielded 28 bushels per acre from no-phosphorus treatment, and 175 bushels from 150 pounds per acre of P2O. On old land without phosphorus, the yield was 109 bushels; and from 150 pounds of P2O5, it was 183 bushels per acre. Residual effects of potash also continue for many years (Tables 13 and 14). The yield of cabbage on land that had received no potash was increased from 8.21 to 21.41 tons per acre by an application of 60 pounds per acre of K2O. On old land previously fertilized, the yield was 16.12 tons per acre from the no-potash treatment and 16.22 tons on the plot receiving 60 pounds per acre of K2O. Potatoes (Table 14) on new ground produced only 72 bushels without potash, and 160 bushels from 90 pounds per acre of K2O. On old land, however, the yield was 152 bushels per acre without potash and 180 bushels from 60-pound application of K2O. Residual effects of nitrogen are limited and of short duration. At the Main Station, Auburn, on a light Chesterfield soil, yields were increased in the spring from 2 to 15 times by dividing the application even to a single crop (Table 20). FERTILIZER EXPERIMENTS with VEGETABLE CROPS 47 SUMMARY Results of fertilizer experiments with vegetable crops at the Main Station, Auburn, and at seven outlying points in the State are reported in this bulletin. Nine soil types and 27 different crops were involved in the study. The studies were confined to rates of nitrogen, phosphorus, and potash and to different rates and grades of fertilizers. A major portion of the work was done at the Main Station in field bins filled with soils shipped in from several agricultural sections of the State. A few of the experiments at the Main Station and all of those at outlying points were conducted in field plots. Only one crop was grown each year in field plots; either two or three successive crops were grown in field bins. In all experiments certain rates of nitrogen, phosphorus, and potash considered adequate to measure the requirements of each crop or group of crops were established. The full amounts of nitrogen were applied to each crop. Where two successive crops were grown on the same land within a year, one-half of the full amounts of phosphorus and potash was applied to each crop; and where 3 successive crops were grown, one-third was applied. The choice of this method of application, based on earlier experiments, proved to be fortunate. On soils that had received no fertilizers or low applications in past years, phosphorus limited production more completely than did the other two elements. Nitrogen was second, while potash seemed adequate in most soils to give 80 per cent of maximum yields without an application. Small applications of phosphorus and potash more quickly satisfied requirements of vegetable crops for maximum or nearmaximum production than did nitrogen. Crops were found to differ greatly in their phosphorus requirements and in the amounts required to give maximum or nearmaximum yields on different soils. Vegetable crops as a group on most soils continued to give increased yields from increased applications of nitrogen up to 120 pounds per acre. Yields, however, were generally 90 per cent or more of the maximum when 90 pounds per acre of N was added. Considered as a group, vegetable crops responded to potash only to a limited extent. In general, soils apparently supplied 48 48 ALABAMA AGRICULTURAL EXPERIMENT STATION ALABAMA AGCUTRLEPIMNSAIO enough potash to give 80 to 90 per cent of a maximum yield without the addition of K20. Some crops on some soils gave about as high yield without potash as with potash additions. Most crops, however, gave increases from potash additions that justified the cost several times. Most crops on most soils gave increased yields from applications of nitrogen, phosphorus, and potash worth many times the cost of the materials applied. Even small increases in yields returned several times the cost of the material. Dividing the nitrogen into several applications increased several times the yield of spring-grown vegetables on light, sandytype soil. Phosphorus and potash applications affected the yield of crops for many years, whereas nitrogen effects were of short duration, especially on light soils. At the Gulf Coast Substation on newly cleared land that had never been fertilized, complete or nearly complete failure resulted when no phosphorus was added with all crops except sweetpotatoes. On the other hand, old land fertilized only moderately for several years produced fair yields on no-phosphorus plots. Response to potash on the new land was relatively low in comparison with responses to phosphorus and nitrogen. On land at the State Farm, Atmore, that had been heavily fertilized in recent years, high yields were obtained without the application of either phosphorus, nitrogen, or potash. Response to the three elements at other points in the State varied according to the crop, soil, and past fertilizer treatment. In general, the largest response to applications were obtained from nitrogen, second largest from phosphorus, and third from potash. FERTILIZER EXPERIMENTS with VEGETABLE CROPS 49 LITERATURE CITED 50 ALABAMA AGRICULTURAL EXPERIMENT STATION (1) (2) ALBRECHT, WILLIAM A. Loss of organic matter and its restoration. U. S. Dept. of Agr. Yearbook. 347-361. 1938. BRYAN, O. C. The accumulation and availability of phosphorus in old citrus grove soils. Soil Sci. 36: 245-259. 1933. BUSHNELL, J. Possibility of reducing the proportion of phosphate in fertilizers applied to sandy soils. Amer. Potato Jour. 20: 153-155. 1943. CAROLUS, R. L. Chemical estimation of the weekly nutrient level of a potato crop. Amer. Potato Jour. 14: 141-153. 1937. COOPER, H. P., SCHREINER, OSWALD, AND BROWN, B. E. Soil potassium (3) (4) (5) in relation to soil fertility. 1938. (6) U. S. Dept. of Agr. Yearbook, 397-405. COOPER, J. R. AND WATTS, V. M. Fertilizers for Irish potatoes, sweet- potatoes, tomatoes, muskmelons, and watermelons. Sta. Bul. 333. 1936. (7) Ark. Agr. Expt. FUDGE, J. F. The influence of various nitrogenous fertilizers on the availability of phosphate and potassium. Ala. Agr. Expt. Sta. Bul. 227. 1928. HAWKINS, A. Nutrient status of soils in commercial potato producing areas of the Atlantic and Gulf Coast. III. Plant response to fertilization. Soil Sci. Soc. Amer. Proc. 10: 252-256. 1945. JENNY, HANS. A study of the effects of climate upon the nitrogen and organic content of the soil. Mo. Agr. Expt. Sta. Bul. 152. 1930. (8) (9) (10) LLOYD, J. W. AND STRUBINGER, L. H. Fertilizing twenty-five kinds of vegetables. Ill. Agr. Expt. Sta. Bul. 346. 1930. (11) MACK, W. B. Fertilization of truck crops in rotation. Expt. Sta. Tech. Bul. 210. 1927. Penn. Agr. (12) MIDGLEY, A. R. Phosphate fixation in soils. Sci. Soc. Amer. Proc. 5: 24-30. 1940. A critical review. Soil (13) PIERRE, W. H. Phosphorus deficiency and soil fertility. U. S. Dept. of Agr. Yearbook, 377-396. 1938. (14) SCARSETH, G. D. AND TIDMORE, J. W. The fixation of phosphates by clay soils. Jour. of Amer. Soc. Agron. 26: 152-162. 1934. (15) . The fixation of phosphates by soil colloids. Jour. of Amer. Soc. Agron. 26: 138-151. 1934. .The machanism of phosphate retention by natural alumino-silicate colloids. Jour. of Amer. Soc. Agron. 27: 596-616. 1935. (16) FERTILIZER EXPERIMENTS with VEGETABLE CROPS 51 (17) SKINNER, J. J. AND RUPRECHT, R. W. Fertilizer experiments with truck crops. Fla. Agr. Expt. Sta. Bul. 218. 1930. (18) WARE, L. M. Fertilizer requirement of the potato on different soils of Alabama. Amer. Potato Jour. 16: 259-266. 1939. (19) ., BROWN, OTTO, AND YATES, HAROLD. Residual effects of phosphorus on Irish potatoes in South Alabama. Proc. Amer. Soc. Hort. Sci. 41: 265-269. 1942. AND JOHNSON, W. A. Use of Field Bins for Experimental studies with vegetable crops. Proc. Auburn Conference on Statistics Applied to Research (etc.). 54-60. 1948. .Phosphorus studies with vegetable crops on different soils. Ala. Agr. Expt. Sta. Bul. 268. 1949. . Nitrogen requirements of different groups of vegetables. Proc. Amer. Soc. Hort. Sci. 44: 343-345. 1944. (20) (21) (22) (23) WHITE, T. H. AND BOSWELL, V. R. Amounts of fertilizer and manure required for maintenance of fertility for vegetable production. Md. Agr. Expt. Sta. Bul. 309. 1929.