Bulletin 676 June 2011 Alabama Agricultural Experiment Station William Batchelor, Director Auburn University, Auburn, Alabama Centennial of Alabama’s Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment C. C Mitchell, D. P. Delaney, and K. S. Balkcom INTRODUCTION Alabama’s Cullars Rotation experiment (circa 1911) was placed on the National Register of Historical Places as the oldest, continuous soil fertility experiment in the South in 2003. Along with its nearby predecessor on the National Register, the Old Rotation (circa 1896), these experiments contain the oldest cotton research plots in the world. Both experiments are located on the campus of Auburn University in east-central Alabama. Treatments on the Cullars Rotation demonstrate dramatically the longterm effects of fertilization and the lack of specific nutrients on non-irrigated crop yields over a 100-year period. The Cullars Rotation is one of the few sites where controlled nutrient deficiencies can be observed on five different crops during the course of a year (cotton, crimson clover, corn, wheat, and soybean). The experiment preserves a site for monitoring nutrient accumulation and loss and soil quality changes and their effects on long-term sustainability of an intensive crop rotation system. THE CULLARS ROTATION ON THE ALVIS FIELD The Cullars Rotation was named for J. A. Cullars who owned and farmed this land in the late 19th and early 20th centuries along with his brother-in-law John P. Alvis. Early records suggest that Mr. Cullars and Mr. Alvis allowed Professor George F. Atkinson of the Agricultural and Mechanical College of Alabama (now Auburn University) and others to conduct numerous early cotton fertility experiments on this property. Professor Atkinson’s research on this site led to the discovery that cotton rust was caused by a deficiency of potassium (Atkinson, 1891, 1892). Mitchell is a professor, Delaney an extension specialist, and Balkcom an affiliate assistant professor in the Department of Agronomy and Soils, Auburn University; Balkcom is also an agronomist at the USDA-National Soil Dynamics Lab. An appropriation by the Alabama Legislature in 1911 enabled the Alabama Agricultural Experiment Station to conduct on-farm research throughout the state. Williams and Funchess (1923) summarized 226 soil fertility experiments on farmers’ fields throughout Alabama. Williams (1929) added to the data available from these tests. An extensive cotton, corn, and legume fertility test begun in 1911 on the Auburn farm of Mr. Cullars and Mr. Alvis is the only one of these experiments that has been continued. Unlike the nearby Old Rotation experiment which was begun by Professor J.F. Duggar, records do not credit any single researcher with designing the Cullars Rotation experiment. Names of professors and researchers that have been associated with the Cullars Rotation, chronologically, include J. F. Duggar, E. F. Cauthen, J. T. Williamson, M. J. Funchess, D. G. Sturkie, E. M. Evans, L. E. Ensminger, J. T. Touchton, C. C. Mitchell, and D. P. Delaney. The site of the Cullars Rotation became known as the Alvis Field. In 1938, the Alvis Field was sold to Alabama Polytechnic Institute (now Auburn University) by Bessie Alvis Emerick and Lillian Alvis Miller, daughters and heirs of Mr. John P. Alvis. In 2000, construction of the Jule Collins Smith Museum of Art occupied most of the Alvis Field but the Cullars Rotation with a 40-foot border is preserved for on-going research and demonstration on sustainable crop production for soils of the southern U.S. AGRONOMICS AND EXPERIMENTAL DESIGN The Cullars Rotation was designed primarily to study the long-term effect of phosphorus, potassium, lime, and other nutrients on a three-year rotation which included cotton, corn, small grain, and summer legumes (cowpeas, crotalaria, or soybean). Today, the experiment is a three-year rotation of (1) cotton followed by crimson clover, (2) corn harvested for grain followed by winter wheat, and (3) soybean double cropped after wheat is harvested for grain. It is A B located on a Marvyn loamy sand (fine-loamy, siliceous, thermic Typic Kanhapludults), a soil associated with Alabama’s Coastal Plain physiographic region. Experimental design. Original design was 11 soil treatments replicated three times, one replicate for each of the three crops in the three-year rotation, in an ordered block design (Figure 1). In 1914, an additional three treatments (designated A, B, and C) were added to include the effect of winter legumes in the rotation. Plot size is 20 by 99 feet with a 2-foot border between each plot and C 20 feet between each tier (block). Plots were originally 110 feet long but were shortened in the 1950s so mechanical equipment could maneuver between tiers. Tillage and other cultural practices. Prior to 1997, all crops were conventionally tilled with moldboard plowing, disking, and regular cultivation. All green manure crops (winter legumes, cowpeas, and crotalaria) and crop residues 11 10 9 8 7 6 5 4 3 2 1 C B A East Tier 340 ft. 11 10 9 8 7 6 5 4 3 2 1 C B A Middle Tier 11 10 9 8 7 6 5 4 3 2 1 C B A 315 ft. West Tier North Figure 1. Schematic of Cullars Rotation (not drawn to scale) and view of experiment looking toward the east with plots A, B and C on the right as in the schematic. Each number indicates a fertility treatment. The plots designatied A, B, and C were added in 1914. Jules Collins Smith Museum of Art were turned under using a moldboard plow. Since 1997, all crops have been grown with minimum tillage and transgenic cultivars. Cotton and corn are planted directly into previous crop residue in 30-inch rows after paratilling or in-row subsoiling. Soybeans are drilled into wheat residue in June using a no-till drill. Since 1996, few insecticides have been applied for insect control. This has been possible because of the boll weevil eradication program in East Alabama and the advent of Bollgard® technology. All crops are machine harvested although cotton and corn yield estimates are made by hand-harvesting portions of each plot. Fertilization. In the early years of the Cullars Rotation, sources of plant nutrients were blood meal (12-1-1) and cottonseed meal (6-1-1) for N, superphosphate (0-18-0) and rock phosphate for phosphorus, and kainit (0-0-12) for potassium. In recent decades, phosphorus as concentrated superphosphate (045-0), potassium as muriate of potash (0-0-60), sulfur as gypsum (18% S), and a micronutrient mix containing B, Zn, Mn, Cu, and Mo are applied to appropriate plots in split applications in the spring prior to planting cotton and in the fall just prior to planting small grain. Nitrogen as ammonium nitrate (34-0-0) is applied to appropriate plots just prior to planting cotton and corn with the remaining N applied as a sidedress application to these crops. Small grain is topdressed with 60 pounds N per acre in late February. Fertility treatments and recent soil test results are presented in Table 1. Historic treatments are listed in the Appendix tables. Table 1. Treatments Since 1985, Mean Soil pH, Mehlich-1 Extractable Plant Nutrients, and Rating from 0- to 6-inch Soil Samples on the Cullars Rotation 1,2 Soil-test rating and Mehlich-1 ——Treatments 3—— Soil extractable nutrients 4 Plot Description N P K S Other pH P K Mg Ca ————mg/kg———— A No N/+legume 0 + + + 6.1 VH 63 M 46 H 28 423 B No N/no legume 0 + + + No legume 6.0 VH 57 M 44 H 23 330 C No soil amendments 0 0 0 0 5.2 L5 L 21 L6 73 1 No winter legumes/ + + + + No legume 6.2 H 46 M 52 H 33 371 +N 2 No P + 0 + + 6.2 VL 3 M 34 H 31 285 3 Standard fertilization + + + + 6.1 VH 51 M 42 H 37 395 4 4/3 K + + + + Extra K 6.2 VH 81 M 47 H 38 525 5 Rock phosphate + + + + Rock P 6.0 EH 200 M 47 H 30 732 6 No K + + 0 + 6.3 EH 101 VL 13 H 43 541 7 2/3 K + + + + 6.2 VH56 M 37 H 34 826 8 No lime + + + + No lime 4.7 VH 68 L 26 L 3 200 9 No S + + + 0 6.2 VH 90 M 50 H 46 1100 10 Standard fertilization + + + + +Zn,Cu, 6.3 VH 85 M 66 H 36 953 + micronutrients Mn, Fe, B & Mo 11 1/3 K + + + + 6.1 VH 67 L 28 H 32 680 LSD.05 0.3 11 16 8 376 Samples taken in November 2004 Particularly relevant values are in bold italics. 3 Standard lime and fertilizer treatments: • Limed to pH 5.8 to 6.5 • 90 lb. P2O5 per acre per three-year rotation • 240 lb. K2O per acre per three-year rotation • 90 lb. N per acre on cotton • 120 lb. N per acre on corn • 60 lb. N per acre topdress on small grain • 40 lb. sulfate-S per acre applied as gypsum to cotton and small grain 4 Rating based upon cotton on sandy soils (C.E.C. < 4.6 cmol/kg); VL=very low; L=low; M=medium, H=high (desirable range); VH=very high; EH=Extremely High (Adams et al., 1994). 2 1 Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 2 — THE YIELD RECORD Few research areas exist in the U.S. where one can see such dramatic deficiencies of plant nutrients on one site. Historic yields, by year, are included in the Appendix tables. Particularly dramatic are plot C (the treatment where no soil amendment has been applied since 1911), plot 6 (the no K treatment), plot 8 (the no lime treatment), and plot 2 (the no P treatment). Deficiencies sometimes appear on other treatments but are less dramatic. In general, cotton is most sensitive to low soil K in this experiment while corn, soybean, and small grain are most sensitive to low soil P (Table 2). Cotton and soybean seem to be more sensitive to the acid soil (pH = 4.7 in 2004) in the no lime treatment than other crops in the rotation. Since 1955, all plots except treatment 8 (no lime) and treatment C (nothing) receive an application of ground, dolomitic limestone whenever the surface soil pH drops below 5.8. Although B fertilization of cotton and reseeding clover and Zn fertilization of corn are routinely recommended by Auburn University’s Soil Testing Laboratory (Adams et al., 1994), no crop demonstrated a significant response to micronutrient fertilization in the period 1995-2004. Mean yields of cotton, corn, soybean, and small grain from 2001 through 2010 seem to reflect long-term trends (Table 2). Long-term trends as demonstrated by the five-year running average yields in Figures 2 through 5 show periods of yield increases and dramatic decreases. Because this is a non-irrigated experiment, short-term droughts and other weather-related disasters during the growing season can have dramatic effects on yields. Year-to-year yield variability is high as reflected by the coefficient of variation in the 10-year average yields in Table 2. However, the downward yield trend in the late 1970s and early 1980s reflected management problems when the main research farm moved and no one was left to take care of the day-to-day management of these plots. Nevertheless, the relative yields of the different fertility treatments remained about the same. Coincidentally, record crop yields have been recorded on the Cullars Rotation since 1996 when we switched to genetically modified varieties and in 1997 when we switched to conservation tillage (Table 3). These yields are attributed to (1) favorable growing seasons; (2) adoption of deep tillage to disrupt traffic pans; (3) conservation tillage, which allows better moisture infiltration, higher water holding capacity, and cooler soils; (4) higher plant populations; (5) timely planting; (6) better weed control especially through the new genetically modified varieties; and (7) less insect problems as a result of the boll weevil eradication program and the new Bollgard® cotton varieties. Table 2. Mean Crop Yields on the Cullars Rotation, 2001-2010 Cotton Corn Soybean Plot Treatment 1 lint grain grain lb/A bu/A bu/A A No N/+legume 990 56 39.1 B No N/no legume 930 36 38.8 C No soil amendments 20 0 0 1 No winter legumes/ + N 1190 94 41.1 2 No P 520 35 9.3 3 No micronutrients 1220 98 41.0 4 4/3 K 1020 89 39.7 5 Rock phosphate 1080 94 41.6 6 No K 0 36 21.9 7 2/3 K 1030 101 40.0 8 No lime, pH=4.9 220 32 2.7 9 No S 1030 90 41.4 10 Complete fertilization 1150 102 42.8 + micronutrients 11 1/3 K 720 95 37.0 C.V. 33.1 31.3 28.0 L.S.D. (P<0.05) 233 19 7.7 1 Wheat grain bu/A 24.5 18.9 0.4 46.3 21.3 47.3 44.6 47.7 39.6 51.3 9.0 45.9 50.3 49.4 20.5 6.4 Clover dry matter lb/A 3080 – 0 – 1620 3600 3100 2630 1810 3140 870 2820 3970 2840 50.7 1060 Standard lime and fertilizer treatments: • Limed to pH 5.8 to 6.5 (except plots C and 8) • 200 lb. P2O5 per acre per three-year rotation (except plots C and 2) • 270 lb. K2O per acre per three-year rotation (except plots 4,6,7 and11) • 90 lb. N per acre on cotton in split applications (except plots A, B, C) • 120 lb. N per acre on corn in split applications (except plots A, B, C) • 60 lb. N per acre topdress on small grain (except C) Table 3. Record Crop Yields on the Cullars Rotation Since 1996 Crop Yield Plot Treatment 1 A No N/+legume Corn 161.0 bu/A 1 No winter legumes/ + N Cotton lint 1930.0 lb/A (~4 bales) 5 Rock phosphate Wheat 64.7 bu/A 7 2/3 K Cotton lint 1580.0 lb/A (3+ bales) 9 No S Wheat 63.5 bu/A 10 Complete fertilization Soybean 75.1 bu/A + micronutrients 11 1/3 K Wheat 70.0 bu/A Year 1999 2004 2000 1996 1999 1996 2001 Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 3 — Cotton Lint, five-year running averages Figure 2. Long-term cotton yield trends on selected treatments on the Cullars Rotation, 1911-2010. Each point is a five-year running average. g g Corn Grain, five-year running averages Figure 3. Long-term corn yield trends on selected treatments on the Cullars Rotation, 1911-2010. Each point is a five-year running average. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 4 — Soybean, five-year running averages y y Figure 4. Long-term soybean yield trends on selected treatments on the Cullars Rotation, 1960-2010. Each point is a five-year running average. Wheat Grain, five-year running averages THE SOIL TEST RECORD The soil test record goes back to 1955, a year after the Auburn University No P No P Soil Testing Laboratory began full operation. We can find no record of soil tests 50 50 No K No K prior to that time. Initially, only soil water pH (pHw) and Mehlich-1 extractable No lime No lime P and K were run. Magnesium was added to the record in 1965 and calcium in 40 40 Standard 1981. Trends in pHw and in Mehlich-1 extractable P, K, Mg, and Ca on selected Standard treatments are presented in Figures 6 through 9. Mean soil test values across all Nothing Nothing 30 30 three tiers by year and plot are presented in the Appendix tables. Periodic soil organic matter (SOM) analyses on plow layer samples indi20 cate that SOM averages about 1.2 percent (0.63 percent C) across all treatments. 20 There is not much difference between treatments except for plot C (SOM = 0.8 percent), which has not received any fertilizer and is unproductive. Estimated 10 10 cation exchange capacity of these soils based on cation summation is 3.8 cmol+/ kg. 0 0 Potassium movement and accumulation in soil profile is presented in 1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010 Figure 10. Soil samples taken in incremental depths to 48 inches from the KYear variable treatments reveal that large quantities of K accumulate in the upper soil Year Figure 5. Long-term wheat yield trends on selected treatments on the Cullars Rotation, 1968-2010. profile in this loamy sand with a CEC of 3.8 cmol/kg. Potassium leaching below Each point is a five-year running average. Rye instead of wheat was grown from 1972-1988. 48 inches does occur with the higher K rates as indicated by Mehlich-1 extractable K. Therefore, routine, plow-layer soil sampling appears to be adequate to predict responses to K fertilization. Note that the application of an anion in the form of sulfate-S (as gypsum) increases K leaching. 60 60 Yield (bushels/acre) Yield (bushels/acre) Yield (bushels/acre) Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 5 — Soil pHw Phosphorus Figure 6. Trends in soil test pHw in selected treatments on the Cullars Rotation, 1955-2010. Figure 7. Trends in Mehlich-1 extractable P in selected treatments on the Cullars Rotation, 1955-2010. Potassium Magnesium Figure 8. Long-term trends in Mehlich-1 extractable K on selected treatments on the Cullars Rotation, 1968-2010. Figure 9. Long-term trends in Mehlich-1 extractable K on selected treatments on the Cullars Rotation, 1968-2010. Sharp increases in Mg are due to periodic applications of dolomitic limestone to maintain soil pH above 5.8. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 6 — LITERATURE CITED Adams, J.F., C.C. Mitchell, and H.H. Bryant. 1994. Soil test fertilizer recommendations for Alabama Crops. Ala. Agric. Exp. Stn. Dep. Ser. No. 178. Auburn University, Alabama. Atkinson, G.F. 1891. Black rust of cotton. Agric. Exp. Stn. Bul. No. 27. Agricultural and Mechanical College of Alabama, Auburn, Alabama. Atkinson, G.F. 1892. Some leaf blights of cotton. Agric. Exp. Stn. Bul. No.36. Agricultural and Mechanical College of Alabama, Auburn, Alabama. Williamson, J.T., and M.J. Funchess. 1923. Fertilizer experiments with cotton. Agric. Exp. Stn. Bul. 219. Alabama Polytechnic Institute. Auburn, Alabama. Williams, J.T. 1929. Fertilizer experiments with cotton. Agric. Exp. Stn. Bul. No. 228. Alabama Polytechnic Institaute, Auburn, Alabama. APPENDIXES 1. Seed cotton yields on Cullars Rotation, 1911-2010 2. Corn grain yields on Cullars Rotation, 1911-2010 3. Soybean yields on Cullars Rotation, 1960-2010 4. Wheat grain yields on Cullars Rotation, 1968-2010 5. Winter legume (mostly crimson clover) dry matter yields on Cullars Rotation, 1986-2010 6. Mean soil pHw in Cullars Rotation since 1955 7. Mean Mehlich-1 extractable soil P in Cullars Rotation since 1955 8. Mean Mehlich-1 extractable soil K in Cullars Rotation since 1955 9. Mean Mehlich-1 extractable soil Mg in Cullars Rotation since 1965 10. Mean Mehlich-1 extractable soil Ca in Cullars Rotation since 1968 11. Mean soil organic matter and estimated CEC in Cullars Rotation 12. History of fertilizer applied to cotton on Cullars Rotation 13. History of fertilizer applied to corn on Cullars Rotation 14. History of fertilizer applied to oats, rye, or wheat on Cullars Rotation 15. Crop rotations used on the Cullars Rotation, 1911-2010 Figure 10. Soil profile K as affected by 90 years of K fertilization and cropping in the Cullars Rotation. SUMMARY The Cullars Rotation experiment continues to document long-term trends in non-irrigated crop yields and soil changes due to variable rates of P, K, S, micronutrients, and lime. It provides a valuable and accessible teaching tool for monitoring crop nutrient deficiencies. It also is a source of uniform soil with variable fertility conditions for allied studies. No other such resource exists in the Coastal Plain of the southern United States. For these and other reasons, the Cullars Rotation was placed on the National Register of Historical Places in 2003. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 7 — Appendix Table 1. Seed cotton yields on Cullars Rotation, 1911-2010 Plot/treatment number Year A No N; + legume. B No N; no leg. C Nothing 1 No leg.; +N 326 156 484 380 600 328 180 520 702 242 648 210 406 719 1042 751 270 546 1236 1737 955 1318 959 1152 1266 1312 1023 1491 422 66 194 48 72 375 166 208 60 124 108 600 173 362 287 210 546 471 279 591 210 84 132 36 52 300 184 238 30 30 150 306 102 378 136 192 282 200 81 210 400 102 324 152 120 282 654 264 39 114 181 366 124 416 242 351 333 313 150 276 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Pounds seed cotton per acre† 1911 1912 1913 1914 1915 1916 1917 1918 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1834 726 1600 360 1384 834 274 1320 1100 486 678 436 602 529 800 381 291 382 315 864 496 586 602 618 468 733 231 507 1922 1922 1690 372 1672 1032 308 2070 1940 828 1352 968 1150 885 1230 940 1053 1030 1032 1797 1114 1454 1514 960 1440 1571 621 1281 284 88 680 106 302 350 180 650 502 160 330 142 244 469 684 358 60 162 382 597 424 465 549 543 465 548 405 333 1802 930 1634 530 1612 922 420 2060 1650 840 1250 842 1070 789 1224 882 873 886 1040 1590 1553 1254 1637 1245 1338 1522 783 1212 1434 592 1340 494 1274 878 290 1650 1114 810 1206 578 1046 783 1206 1069 624 712 1241 1446 1371 1057 1152 1107 990 990 636 480 300 78 414 190 182 344 168 470 282 152 406 102 168 421 656 332 60 172 339 507 233 486 446 363 342 389 327 279 800 538 924 870 722 702 530 1240 1016 302 852 534 828 751 1388 965 438 666 1235 1539 1384 1491 1265 1389 1107 1140 867 1416 768 114 810 786 638 624 318 1150 940 300 820 350 786 637 1240 942 408 592 1191 1482 1286 1489 1297 1359 1197 1328 933 1380 556 70 680 466 384 424 188 940 740 190 710 188 556 607 1056 751 294 318 626 1029 996 1210 1122 1197 873 1183 891 1044 120 44 450 180 90 256 162 550 260 100 292 66 204 378 756 433 51 126 222 396 213 299 448 324 261 394 264 234 continued Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 8 — Appendix Table 1, continued. Seed cotton yields on Cullars Rotation, 1911-2010 Plot/treatment number Year A No N; + legume. B No N; no leg. C Nothing 1 No leg.; +N 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Pounds seed cotton per acre† 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 693 768 1038 1035 1545 576 150 1503 2277 1596 1128 2004 1200 1059 1470 1539 1600 1564 2389 1119 2957 2340 2897 2571 2221 2214 2132 2158 312 267 318 291 510 48 60 456 840 675 810 1626 1152 333 1104 903 842 686 908 409 1511 637 795 1139 690 426 805 409 69 144 117 189 93 24 24 153 405 222 432 249 240 129 480 315 132 129 76 178 261 30 158 185 59 115 205 89 195 228 282 420 195 51 27 381 402 285 495 429 411 237 441 411 518 228 495 614 756 221 528 386 370 244 191 353 297 324 855 585 282 132 30 849 825 825 765 1197 1017 549 750 864 743 878 891 842 1663 1851 1865 1043 1551 1402 802 1406 459 699 1656 1095 417 456 66 1233 1584 1176 1221 1695 1197 681 903 1008 1475 2017 2676 1284 2954 2600 2874 2478 2897 2795 2079 2069 258 306 603 741 480 225 45 573 678 594 501 666 582 300 621 582 314 109 472 347 624 66 92 185 36 0 0 33 480 942 1929 1554 1284 846 75 1431 1857 1410 1308 1908 1203 1059 1074 918 1432 1888 2445 1205 3333 2531 2907 2567 3092 2789 1709 2198 336 666 672 894 807 300 63 732 981 594 852 855 642 435 612 465 545 46 353 347 287 96 277 432 145 158 373 99 231 327 396 639 378 126 60 507 489 462 639 501 471 249 552 570 518 66 719 716 466 198 703 366 165 195 152 162 615 942 1545 1602 2214 576 66 1629 2043 1869 1797 2091 1428 1362 1440 2007 1498 1561 2548 1139 2789 2234 2102 1815 2653 1323 1683 1944 915 933 1575 1563 2070 669 63 1536 2295 1659 1686 2106 1392 1305 1356 1251 1528 1439 2670 1172 2746 2564 2534 2353 2795 2518 2036 2138 921 762 1146 1470 1749 762 63 1284 1800 1389 1416 1590 1203 948 1398 1377 1502 1769 2897 1330 3551 2818 2845 2736 3006 2696 2204 2356 294 219 330 579 345 153 72 522 381 333 546 372 456 282 438 441 350 116 568 521 462 274 445 393 264 261 267 162 continued Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 9 — Appendix Table 1, continued. Seed cotton yields on Cullars Rotation, 1911-2010 Plot/treatment number Year A No N; + legume. 2468 1785 2864 1980 1901 2082 2472 1274 1492 2389 1000 1343 1310 2168 2353 772 2632 2156 1665 1960 1016 1343 2870 3160 2800 1340 559 3270 B No N; no leg. 1066 901 1894 1548 1261 1597 1640 851 1214 1808 1105 1066 1191 2376 2181 924 2149 1577 1371 1597 998 1416 2900 2830 3160 1810 523 3340 C Nothing 1 No leg.; +N 2907 1647 2525 2162 2330 1643 2264 1205 1762 3112 1531 1340 1320 2402 2640 1485 2713 2435 1547 2468 2686 1234 2900 4140 3120 1630 1234 2180 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Pounds seed cotton per acre† 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 195 59 152 66 13 92 129 20 30 221 16 40 73 257 191 99 220 0 139 0 0 0 653 690 360 0 0 0 1700 459 2237 1251 1089 1424 1020 446 1723 1214 330 1254 1026 1260 1683 713 1657 1313 917 1162 1053 580 1670 1560 1780 580 512 1310 2508 1409 2597 1944 1848 1340 2221 776 1835 2805 1353 1257 1356 2402 2409 1432 3329 1892 1723 2614 2650 1525 3010 4030 3380 1340 1053 2720 1795 93 2096 1736 2033 1673 2020 990 1640 2534 1162 1092 1327 2435 2214 1247 3190 2149 1386 2250 2686 1198 3010 3880 2830 1050 878 3230 2666 1581 2666 1964 1990 1657 2224 548 1888 2356 1333 1356 1422 2485 2528 1497 2985 2369 1555 2323 2650 1125 2430 3590 2500 1450 842 2870 86 46 1175 320 228 218 1449 33 53 1485 122 287 719 590 287 383 440 535 278 0 0 690 440 1120 910 0 268 0 2379 1459 2517 1907 1927 1782 2132 1082 1789 2736 1290 773 1419 2409 2637 1320 2728 2156 1393 2468 2250 1561 2580 3850 2500 1420 889 3960 1683 653 2036 947 370 1370 736 439 257 1551 541 129 703 1016 1030 165 1899 374 499 1234 580 472 250 1630 510 870 280 940 2442 1472 2897 1855 1795 1511 1785 927 1587 2132 1155 1082 1403 1920 2373 1201 2449 2200 1430 2686 2468 1125 1520 3380 2870 2110 806 3670 2703 1868 2528 1848 2079 1874 2119 944 1538 2099 1178 1218 1594 1841 2379 1307 3080 2464 1503 2759 2468 1633 2210 4070 3670 2690 926 4060 1931 878 1445 1667 1221 1495 1416 723 1092 2399 1181 1330 1535 2056 2320 1300 2567 2229 1034 1888 1851 1525 1780 3670 2180 1380 1201 1710 continued Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 10 — Appendix Table 1, continued. Seed cotton yields on Cullars Rotation, 1911-2010 Plot/treatment number Year A No N; + legume. 2430 2660 1000 1140 2220 3220 870 3590 2302 2744 2290 1917 2770 1550 B No N; no leg. 1920 2480 1200 1310 2530 2570 1050 2790 1885 6049 1850 2265 2570 1550 C Nothing 1 No leg.; +N 3270 2260 1520 1630 2740 3010 1440 5070 3275 4400 1220 2461 3240 1550 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Pounds seed cotton per acre† 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 0 0 0 0 0 560 0 0 0 0 0 0 0 0 1200 1790 700 410 1260 910 830 1390 3225 522 260 2483 890 650 2690 2440 1480 1060 2310 3050 2530 4810 3600 4966 1350 2330 3030 1680 2500 3130 1480 900 2440 2790 910 3050 2972 4400 1220 2265 2850 1290 2790 2030 1260 820 2570 3050 1180 3660 2722 4356 1330 2766 2790 1420 0 910 0 0 0 0 0 0 0 0 0 0 0 0 3270 2180 1590 820 3090 2960 960 3350 2598 4007 1240 2374 2610 1370 0 0 350 410 1830 740 350 0 162 0 0 1067 780 350 2210 2460 1260 1140 2480 2920 1220 3480 2932 3877 1630 2134 2590 1200 2690 2440 1740 980 2480 2740 1920 3720 3728 4443 1760 2113 3050 1440 2650 1920 1090 980 2570 2570 740 2660 942 1742 1610 2004 1220 1089 † Before the 1990s, the percentage of lint in seed cotton was between 35 and 38 percent. Since the mid 1990s, it has risen to 40 to 45 percent. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 11 — Appendix Table 2. Corn grain yields on Cullars Rotation, 1911-2010 Plot/treatment number Year A No N; + legume. B No N; no leg. C Nothing 1 No leg.; +N 18.8 5.1 23.5 12.5 20.0 22.8 30.7 20.2 24.4 36.4 8.6 37.1 42.0 21.8 43.4 41.9 41.0 24.8 22.7 43.5 32.9 31.1 44.8 53.9 23.4 27.0 25.0 42.3 16.6 13.2 7.1 7.7 9.3 6.2 7.1 9.0 4.7 4.5 11.1 7.0 10.2 4.6 15.0 10.6 2.0 16.9 15.6 5.7 7.6 7.9 12.4 16.9 16.4 8.3 13.3 15.1 5.7 11.8 12.9 5.7 10.7 14.3 11.9 10.8 8.9 16.1 8.4 2.5 12.6 13.3 5.4 5.0 5.1 7.5 20.0 24.8 18.2 24.4 30.0 12.9 23.9 20.9 6.5 18.3 20.8 24.8 11.0 15.9 23.1 18.1 13.4 19.6 15.9 13.2 9.2 7.6 16.4 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Bushels grain per acre 1911 1912 1913 1914 1915 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 36.5 48.6 43.9 17.9 40.7 50.7 51.4 28.7 53.6 39.4 2.6 52.0 41.2 49.4 36.8 30.3 36.6 15.1 31.1 35.0 42.5 30.6 24.3 29.6 22.3 20.6 25.4 20.9 44.9 53.8 46.9 22.9 59.9 59.1 58.8 35.4 63.1 54.0 9.5 61.1 52.2 52.6 60.6 55.2 47.1 29.9 44.2 56.9 59.7 41.3 39.9 50.0 33.2 43.4 42.1 42.2 21.4 9.2 28.8 18.2 20.0 23.8 27.9 20.4 27.8 29.5 11.8 37.7 25.7 12.2 29.2 32.3 33.3 17.0 25.3 40.5 26.6 21.9 32.4 35.1 16.4 15.8 20.0 26.4 39.2 54.8 43.0 22.1 52.0 55.7 59.6 33.6 61.1 51.6 4.5 60.7 48.5 51.6 55.0 50.8 39.1 35.7 45.9 58.2 72.9 42.9 40.3 58.1 36.5 44.4 51.5 50.0 35.2 34.7 45.7 22.9 43.5 43.6 55.5 27.1 52.0 49.5 2.2 56.1 47.6 47.5 58.0 45.3 47.2 30.6 37.5 49.9 61.3 40.4 41.0 49.9 27.9 34.6 41.8 37.6 20.8 9.5 29.1 17.5 20.2 21.0 30.7 15.2 23.4 27.5 9.7 34.6 23.6 12.0 30.4 30.9 29.0 17.9 16.8 35.4 32.2 21.8 33.1 34.6 13.9 13.3 19.0 24.8 28.7 20.7 28.0 21.4 27.6 25.4 35.2 23.9 41.7 38.2 10.2 47.5 46.2 30.1 54.6 48.0 42.4 32.9 34.3 53.9 55.6 31.8 42.2 64.3 21.1 28.3 28.0 44.8 25.7 18.9 33.4 20.7 29.6 28.2 37.7 22.7 43.2 43.8 8.0 50.4 47.1 27.6 52.3 44.8 44.5 34.5 38.7 55.1 48.1 30.7 38.2 67.4 20.5 32.2 32.8 42.3 13.4 12.6 27.7 19.3 23.6 24.3 33.0 23.9 31.8 34.7 8.1 50.0 36.8 21.6 44.8 41.3 39.1 26.4 36.3 49.2 49.1 28.5 37.4 61.7 18.1 27.0 30.3 42.3 17.5 10.8 21.3 16.4 20.9 20.5 22.5 16.1 23.2 25.9 12.2 36.1 24.0 13.9 29.6 25.4 26.5 14.9 20.3 29.9 28.8 18.4 25.7 37.9 12.4 10.4 19.1 24.0 continued Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 12 — Appendix Table 2, continued. Corn grain yields on Cullars Rotation, 1911-2010 Plot/treatment number Year A No N; + legume. 58.6 32.0 39.1 47.7 52.3 42.9 78.2 63.0 34.3 42.7 57.9 34.9 51.5 51.0 53.5 92.0 71.3 114.7 102.6 71.6 48.9 100.7 97.0 25.1 98.5 80.0 46.7 23.4 B No N; no leg. 11.5 7.5 12.6 19.3 11.1 5.7 30.3 19.4 14.7 21.6 17.9 14.6 23.6 6.2 9.0 13.6 10.5 2.5 24.3 9.2 4.9 17.9 7.6 5.6 25.8 6.9 9.4 3.6 C Nothing 1 No leg.; +N 13.6 11.9 15.5 14.2 16.5 15.4 17.4 20.0 20.6 13.7 18.3 14.7 16.5 8.5 24.0 8.6 7.2 17.7 6.4 12.3 7.5 4.5 19.0 8.0 3.4 74.0 64.5 23.4 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Bushels grain per acre 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 6.3 6.9 8.3 7.1 6.6 2.1 10.3 9.9 9.0 10.2 7.6 13.0 13.2 3.0 5.3 1.3 3.0 1.4 0.3 6.3 1.4 0.9 1.5 1.9 1.0 1.3 1.6 0.0 31.7 15.0 31.4 39.6 28.9 25.8 36.5 30.4 40.0 22.8 30.6 20.5 30.1 15.3 31.7 17.4 14.6 41.2 25.8 38.6 18.5 21.8 37.8 16.5 16.9 30.8 34.5 2.3 54.1 31.1 0.0 52.6 56.7 47.8 70.0 56.2 56.5 36.1 50.6 32.9 46.2 58.8 88.3 95.4 72.8 117.3 98.6 82.0 59.9 96.6 113.7 42.0 84.7 79.1 88.9 27.2 34.2 24.9 27.4 32.7 43.8 30.7 54.8 42.7 31.3 36.2 35.1 30.0 45.3 33.7 42.2 28.0 17.2 20.4 14.9 26.9 7.7 8.4 6.8 1.0 1.6 51.1 51.9 9.8 56.1 37.8 55.0 62.3 72.8 59.3 82.4 59.4 78.2 45.9 71.1 40.6 51.6 59.5 101.7 102.7 70.9 119.3 97.7 80.6 57.4 96.5 109.6 45.1 79.4 81.0 95.3 23.2 45.1 25.8 33.1 38.6 61.7 45.8 50.9 48.3 68.2 41.5 50.5 34.1 34.3 38.8 30.9 17.7 27.9 39.4 12.3 25.8 27.2 11.4 34.0 26.2 15.3 16.1 12.4 1.3 22.9 21.4 23.8 27.3 38.5 27.4 43.1 41.2 32.4 34.7 37.0 26.5 37.0 30.2 44.2 18.1 30.1 42.0 13.2 25.2 20.0 9.3 45.4 22.8 12.4 65.1 86.8 14.5 41.9 36.8 46.9 50.1 69.0 42.2 78.4 74.4 57.9 43.9 77.4 33.8 70.6 65.7 86.6 94.8 67.8 84.6 86.8 73.1 43.3 62.3 88.8 21.8 59.9 67.2 52.0 7.5 48.6 35.6 44.5 49.2 69.2 43.9 84.2 72.8 65.8 47.4 73.0 35.1 71.0 70.2 83.3 108.5 73.7 106.8 98.9 78.5 52.4 96.0 119.9 35.5 85.3 79.2 92.1 25.9 44.0 32.3 45.6 42.6 64.7 42.2 64.8 66.7 50.8 46.1 61.7 33.0 67.3 66.3 73.2 108.9 69.1 111.6 100.8 87.9 56.8 96.4 100.2 33.7 90.5 83.4 85.7 27.7 22.7 21.9 24.9 21.5 38.9 24.5 33.3 39.7 26.4 29.7 35.1 22.7 26.9 28.2 34.5 20.6 25.3 29.8 7.2 30.0 11.6 8.6 40.7 19.6 17.1 70.9 56.9 6.7 continued Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 13 — Appendix Table 2, continued. Corn grain yields on Cullars Rotation, 1911-2010 Plot/treatment number Year A No N; + legume. 104.5 72.1 85.7 58.3 106.0 72.0 36.0 38.0 54.5 33.0 33.0 120.0 82.0 40.0 43.0 45.1 73.3 51.0 132.0 48.0 112.0 85.0 88.0 59.0 44.0 106.0 54.0 51.3 B No N; no leg. 13.8 16.5 20.6 23.6 12.0 19.0 14.0 4.0 11.3 8.0 6.0 36.0 20.0 16.0 28.0 12.1 19.0 7.0 23.0 34.0 46.0 94.0 62.0 25.0 35.0 82.0 30.0 37.9 C Nothing 1 No leg.; +N 103.4 54.2 79.8 61.9 92.0 68.0 29.0 38.0 64.8 23.0 34.0 123.0 71.0 38.0 54.0 44.2 48.4 56.0 135.0 73.0 121.0 102.0 84.0 71.0 36.0 143.0 101.0 89.1 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Bushels grain per acre 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 3.7 2.4 0.0 0.0 0.3 1.0 1.0 0.0 0.5 0.3 5.0 1.0 0.3 0.0 3.0 0.0 0.0 0.0 0.0 0.0 0.0 21.0 17.0 0.0 9.0 0.0 0.0 0.0 62.8 32.2 36.9 25.4 32.0 22.0 19.0 5.0 13.6 10.0 6.0 44.0 25.0 38.0 11.0 6.6 20.8 13.0 54.0 29.0 31.0 44.0 54.0 42.0 9.0 63.0 55.0 21.0 120.2 73.8 83.0 57.7 95.0 85.0 26.0 54.0 65.5 24.0 31.0 126.0 68.0 105.0 43.0 32.0 67.2 65.0 156.0 58.0 118.0 81.0 83.0 80.0 32.0 137.0 73.0 75.1 108.9 59.2 87.8 47.8 95.0 60.0 27.0 47.0 65.1 16.0 26.0 123.0 74.0 93.0 44.0 44.0 62.4 51.0 126.0 67.0 105.0 84.0 89.0 78.0 40.0 132.0 75.0 69.3 113.9 79.6 84.5 59.9 101.0 78.0 29.0 55.0 62.5 20.0 30.0 121.0 73.0 98.0 58.0 43.4 69.9 50.0 155.0 60.0 109.0 82.0 79.0 78.0 30.0 141.0 72.0 76.3 76.8 41.6 31.9 14.7 90.0 22.0 14.0 36.0 7.7 6.0 18.0 23.0 37.0 49.0 4.0 16.6 33.3 34.0 25.0 34.0 31.0 50.0 63.0 38.0 10.0 23.0 36.0 8.2 95.6 78.1 90.8 65.2 96.0 71.0 29.0 47.0 61.9 19.0 15.0 127.0 75.0 98.0 55.0 44.0 68.2 53.0 155.0 53.0 99.0 83.0 79.0 76.0 40.0 140.0 89.0 71.6 90.4 18.0 7.7 10.7 20.0 4.0 9.0 13.0 38.3 1.0 3.0 85.0 18.0 0.0 22.0 13.9 11.4 28.0 54.0 24.0 43.0 44.0 30.0 20.0 13.0 59.0 23.0 23.9 114.3 82.1 92.8 62.9 106.3 83.0 26.0 41.0 65.0 20.0 28.0 121.0 69.0 74.0 58.0 45.8 64.2 56.0 138.0 58.0 93.0 77.0 84.0 81.0 24.0 142.0 71.0 86.2 116.1 73.7 89.2 55.7 110.0 75.0 29.0 39.0 67.9 22.0 25.0 125.0 79.0 89.0 67.0 43.9 59.4 69.0 142.0 53.0 124.0 87.0 73.0 84.0 16.0 155.0 87.0 83.9 103.8 50.7 57.3 62.5 135.0 53.0 30.0 34.0 60.1 22.0 28.0 113.0 83.0 89.0 26.0 61.7 50.1 35.0 114.0 54.0 105.0 99.0 64.0 80.0 32.0 137.0 94.0 93.2 continued Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 14 — Appendix Table 2, continued. Corn grain yields on Cullars Rotation, 1911-2010 Plot/treatment number Year A No N; + legume. 161.0 30.8 96.0 88.0 62.0 64.0 28.0 43.0 46.1 35.8 65.0 36.6 B No N; no leg. 130.0 14.7 102.0 31.0 25.0 40.0 27.0 11.0 33.0 42.3 31.0 18.0 C Nothing 1 No leg.; +N 108.0 24.1 159.0 79.0 108.0 106.0 109.0 94.0 79.1 39.8 126.5 37.6 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Bushels grain per acre 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 39.0 0.0 51.0 25.0 45.0 25.0 26.0 50.0 12.1 0.0 107.4 17.7 135.0 26.1 152.0 98.0 104.0 94.0 151.0 110.0 55.8 39.8 132.0 45.5 128.0 26.8 153.0 90.0 63.0 102.0 148.0 85.0 67.9 45.4 112.0 24.4 126.0 34.1 138.0 106.0 115.0 104.0 144.0 96.0 52.0 41.4 113.0 34.2 122.0 0.0 49.0 58.0 57.0 33.0 33.0 54.0 14.0 0.0 58.0 4.3 135.0 32.8 149.0 109.0 131.0 108.0 172.0 93.0 51.4 42.6 123.0 32.7 72.0 0.0 77.0 37.0 23.0 63.0 26.0 25.0 31.5 13.4 29.0 0.0 98.0 28.8 168.0 83.0 100.0 102.0 144.0 102.0 51.7 39.5 109.0 24.1 100.0 30.1 167.0 94.0 134.0 116.0 154.0 96.0 52.3 50.7 111.0 42.1 64.0 26.8 162.0 102.0 134.0 107.0 128.0 96.0 40.8 33.0 118.0 33.0 Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 15 — Appendix Table 3. Soybean yields on Cullars Rotation, 1960-2010† Plot/treatment number Year A No N; + legume. 27.5 36.7 36.1 29.2 39.4 30.3 35.8 47.3 33.0 39.3 24.0 35.5 30.9 19.3 36.3 25.0 24.0 37.0 27.0 25.0 14.0 34.0 28.0 36.0 9.0 35.6 18.3 28.1 B No N; no leg. missing missing missing missing missing missing missing missing 29.6 40.1 27.7 31.1 29.1 24.8 36.3 26.0 16.0 40.0 25.0 24.5 11.0 32.0 29.0 36.0 18.0 38.1 23.0 32.3 C Nothing 1 No leg.; +N 6.7 9.2 6.1 13.1 8.3 7.8 10.3 12.0 23.4 34.4 24.9 32.2 26.8 24.6 38.5 28.0 19.0 37.0 17.0 26.8 11.0 34.0 31.0 41.0 13.0 32.8 18.8 34.2 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Bushels grain per acre 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1985 1986 1987 1988 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3.4 11.8 3.9 2.6 3.9 3.5 2.4 1.0 0.0 2.0 2.0 1.7 2.0 2.0 3.0 7.0 4.0 0.0 2.1 0.0 12.5 15.0 11.0 14.8 12.8 10.4 13.2 14.8 9.3 14.0 12.5 10.7 12.0 15.1 7.7 6.0 7.0 4.0 16.0 3.3 4.0 14.0 13.0 14.0 13.0 12.5 8.5 14.8 30.0 35.0 31.3 23.9 34.3 23.9 37.3 56.8 32.1 41.0 20.8 39.6 35.1 22.4 41.8 34.0 25.0 35.0 23.0 27.9 14.0 34.0 32.0 43.0 13.0 41.7 20.0 27.8 5.0 5.2 2.9 8.8 0.0 0.0 0.8 0.0 15.0 34.0 24.7 35.5 29.0 21.7 42.9 26.0 20.0 38.0 20.0 27.4 15.0 34.0 30.0 49.0 11.0 42.0 19.2 20.2 27.5 31.7 29.5 14.8 35.0 25.8 37.5 51.1 29.0 42.0 19.0 38.8 30.6 24.2 40.7 32.0 22.0 35.0 24.0 28.3 11.0 35.0 32.0 44.0 16.0 43.3 20.0 33.5 9.2 15.8 11.4 15.1 10.9 14.3 10.3 19.2 10.3 11.2 24.9 12.0 16.5 15.4 17.6 1.0 17.0 4.0 8.0 11.3 11.0 25.0 23.0 30.0 12.0 42.4 12.9 15.3 10.0 17.5 11.8 13.5 10.8 10.5 17.8 16.9 28.6 37.4 16.8 31.8 30.1 20.7 36.3 29.0 18.0 30.0 25.0 27.5 13.0 34.0 32.0 47.0 14.0 46.2 20.6 24.0 25.8 22.5 16.0 20.5 2.3 15.0 21.8 5.9 6.7 14.7 9.8 5.9 7.0 7.0 4.4 0.0 0.0 2.0 5.0 3.5 6.0 9.0 12.0 17.0 15.0 10.6 12.8 11.0 29.2 35.8 26.8 25.4 36.2 20.9 35.7 52.4 31.7 44.6 20.2 42.7 34.9 23.3 44.0 33.0 25.0 39.0 19.0 22.7 13.0 34.0 30.0 47.0 12.0 43.6 23.0 29.0 36.7 37.5 29.3 28.5 34.3 27.8 41.3 54.8 34.7 46.9 23.6 39.4 35.6 27.1 48.4 21.0 25.0 39.0 21.0 24.3 16.0 35.0 33.0 50.0 10.0 46.6 21.8 35.0 13.3 15.0 10.3 16.9 10.8 11.4 17.4 19.0 21.3 28.2 27.5 20.5 42.5 23.0 29.7 22.0 12.0 28.0 8.0 14.7 11.0 32.0 32.0 47.0 14.0 40.7 22.8 26.8 continued Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 16 — Appendix Table 3, continued. Soybean yields on Cullars Rotation, 1960-2010† Plot/treatment number Year A No N; + legume. 24.2 15.3 10.1 43.0 11.4 0.0 16.7 63.8 23.2 14.1 18.2 0.0 29.5 24.3 33.4 63.8 49.0 51.2 27.9 43.1 50.8 18.2 B No N; no leg. 26.6 0.0 11.4 33.0 10.5 0.0 14.4 68.0 22.4 6.3 15.4 0.0 27.4 28.4 25.9 63.3 52.0 53.8 22.1 41.3 55.4 18.0 C Nothing 1 No leg.; +N 33.3 11.9 18.0 42.0 6.7 0.0 15.0 68.7 20.8 15.2 14.1 22.7 23.6 25.8 54.1 61.8 56.1 48.5 20.0 40.9 67.2 18.2 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Bushels grain per acre 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9.2 0.0 0.0 3.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 6.6 3.0 4.3 26.0 0.0 0.0 7.3 30.2 15.4 7.6 10.1 0.0 5.7 0.0 11.2 22.0 0.0 11.6 11.9 10.9 9.0 10.7 27.8 11.7 15.8 40.0 13.7 0.0 19.9 70.0 23.5 16.0 13.6 24.0 27.4 15.1 56.5 64.2 55.7 47.5 21.8 41.8 62.2 17.9 29.0 11.1 12.1 44.0 9.2 0.0 25.5 67.2 24.0 12.6 14.7 28.2 26.2 14.4 53.0 54.9 53.7 49.9 21.0 43.9 65.2 15.1 25.4 13.8 14.7 45.0 16.4 0.0 23.3 68.5 21.6 16.0 14.7 27.0 27.8 17.2 53.8 61.6 58.8 48.2 18.8 45.2 67.9 17.1 20.6 10.1 5.3 25.0 7.0 0.0 15.6 37.6 23.3 5.3 8.5 24.9 7.6 0.0 38.2 46.1 12.6 21.3 7.3 22.8 53.4 10.1 27.8 13.2 13.4 48.0 9.6 0.0 14.7 66.8 22.0 12.8 15.6 28.3 26.5 14.0 56.8 57.6 21.3 50.3 22.0 42.4 63.7 15.9 8.5 3.3 0.4 0.0 0.0 0.0 0.0 24.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 15.5 7.8 4.1 31.5 13.4 16.8 40.0 6.8 0.0 25.2 61.7 21.9 13.6 14.8 21.3 22.8 17.9 60.1 65.1 52.5 50.6 24.7 42.7 62.2 15.1 29.6 16.6 20.3 42.0 12.6 0.0 26.9 75.1 23.3 15.8 16.1 23.5 25.8 21.7 58.3 62.6 53.8 54.0 30.5 41.0 62.9 17.8 22.4 12.2 8.9 35.0 7.1 0.0 25.3 62.5 20.7 10.0 15.4 24.8 15.3 22.5 51.3 57.7 47.0 50.8 21.2 41.7 49.1 13.8 † Prior to 1960, cowpea was the summer legume of choice on the Cullars Rotation; soybean always followed a grain harvest of wheat, oats, or rye. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 17 — Appendix Table 4. Wheat grain yields on Cullars Rotation, 1968-2010† Plot/treatment number Year A No N; + legume. 19.4 12.1 6.3 6.7 4.3 13.3 24.4 13.9 17.5 3.7 18.9 26.1 18.5 58.1 9.9 20.3 21.5 19.1 34.5 17.8 B No N; no leg. 4.9 9.2 6.4 3.7 0.8 6.0 19.0 5.8 15.8 18.3 11.8 28.8 17.4 21.3 10.9 24.6 11.7 18.3 28.8 15.2 C Nothing 1 No leg.; +N 28.2 23.7 25.3 25.2 12.7 33.0 55.8 44.2 50.5 56.2 49.1 65.6 42.5 46.2 33.4 45.3 44.7 38.7 57.6 39.8 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Bushels grain per acre 1968 1969 1970 1971 1972 1989 1992 1997 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 1.5 0.6 3.2 1.0 0.4 0.0 0.0 0.0 0.0 0.0 1.6 2.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9.8 11.3 9.0 13.8 7.5 17.0 35.7 26.1 20.9 24.0 22.3 25.3 15.6 13.8 14.4 14.9 36.1 19.1 18.8 32.7 19.3 29.4 23.6 22.1 13.5 34.3 42.7 51.4 56.9 52.2 30.4 71.0 37.5 48.1 40.8 53.3 46.1 45.6 57.4 42.7 24.3 26.0 26.4 28.6 13.8 31.7 35.4 48.0 54.6 57.4 49.2 61.8 35.0 41.1 36.7 46.0 46.8 41.0 47.7 40.2 19.8 22.8 15.6 20.3 10.3 34.0 46.1 55.8 55.0 64.7 66.9 62.9 34.2 43.6 41.1 47.6 55.1 38.2 45.8 41.1 9.3 25.6 24.8 21.3 8.1 18.1 32.2 0.0 43.8 44.4 38.1 46.0 31.9 44.9 31.7 40.3 48.4 26.6 47.0 40.8 18.9 26.1 22.7 24.6 11.9 28.2 41.5 41.6 61.7 60.1 50.5 69.3 41.9 53.2 45.8 46.1 53.0 45.9 57.0 50.1 20.0 19.8 5.3 5.4 6.7 9.0 14.5 8.8 29.9 19.3 8.9 20.2 8.6 4.0 7.5 0.0 14.3 15.4 11.3 0.0 22.4 20.8 14.3 22.0 11.3 32.9 42.7 50.8 63.5 52.7 49.6 73.0 38.6 54.1 39.1 41.0 43.9 50.2 54.8 44.8 17.7 25.3 14.8 23.2 11.5 32.6 41.9 46.5 60.9 61.1 51.2 68.1 37.5 50.6 40.6 47.1 53.0 49.1 51.2 54.9 19.6 22.2 20.9 21.2 10.5 26.9 55.8 41.3 57.6 55.4 70.0 69.2 42.6 36.5 37.0 45.3 50.9 48.1 47.8 46.9 † Prior to 1968, oat and rye were the cool season grains of choice on the Cullars Rotation. Wheat has been planted periodically since then but always double-cropped with soybean. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 18 — Appendix Table 5. Winter legume (mostly crimson clover) dry matter yields on Cullars Rotation, 1986-2010† Plot/treatment number Year A No N; + legume. 1849 3080 3510 2670 4020 3560 2590 3684 1920 890 3570 3400 3280 4170 2540 5560 1320 1490 3000 B‡ No N; no leg. 0 0 0 0 0 4970 0 0 0 0 0 4080 0 0 0 0 0 0 0 C Nothing 1‡ No leg.; +N 0 0 3062 0 0 3280 0 0 0 0 0 3690 0 0 0 0 0 0 0 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Pounds dry matter per acre 1986 1987 1988 1990 1991 1992 1993 1994 1995 1996 1997 2001 2002 2003 2005 2006 2008 2009 2010 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 777 234 1100 630 1300 810 620 1429 50 0 1750 1030 600 2020 1230 4740 282 1440 1580 1318 3650 3140 2290 2770 4170 2720 3426 2340 900 2700 3140 3150 5380 3990 5580 2090 2660 2800 1953 3720 2890 2440 2970 3760 2550 3241 2550 1460 3880 3340 2090 3750 4210 5060 1321 2240 2820 2178 3460 2980 2620 3880 3960 2440 3968 2600 1060 3870 3220 3120 4630 5710 6230 1221 1720 3160 1652 1860 2310 1220 2470 1120 1840 1750 1130 780 3250 1710 1530 4130 2370 3130 0 750 890 2192 3610 3110 3093 3020 2810 2660 4036 2260 1440 3370 3350 2790 6390 5640 510 1038 2240 3200 796 0 620 0 0 0 0 0 0 0 0 0 1600 1780 3560 0 0 0 0 2187 3760 2800 2336 3230 3780 2440 3083 2120 970 3100 3520 1390 3790 5620 4580 425 1150 2820 1964 3640 3712 2320 3630 2720 3010 3109 3270 1430 3750 3310 2430 5800 4870 6780 1545 2620 4400 2067 3260 2970 1800 2650 2090 2400 2847 1480 1290 3440 2650 2740 4580 4270 2490 1164 1610 3240 † Prior to 1986, winter legume yields were recorded as pounds green weight per acre. ‡ Winter legumes were planted on these plots by mistake in some years. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 19 — Appendix Table 6. Mean soil pHw in Cullars Rotation since 1955† Plot/treatment number Year A No N; + legume. 5.3 5.7 5.6 5.7 6.1 5.5 6.0 5.9 5.8 6.1 5.9 5.7 • 5.0 5.9 5.9 6.1 5.6 5.5 6.1 5.9 5.7 6.3 6.1 6.3 B No N; no leg. 5.4 5.7 5.7 5.9 6.2 5.5 6.1 5.9 5.7 6.2 6.0 5.6 • 5.1 5.9 5.7 5.7 5.7 5.2 6.3 5.9 5.8 6.1 6.1 6.0 C Nothing 1 No leg.; +N 5.4 5.8 5.7 6.0 6.1 5.7 6.0 6.0 5.7 6.1 6.1 5.6 • 5.4 6.1 5.8 . 6.0 5.6 6.1 5.7 5.6 6.2 6.1 6.5 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Soil pH 1955 1958 1959 1961 1962 1965 1968 1969 1970 1971 1974 1978 1980 1981 1983 1985 1986 1988 1992 1994 1998 2002 2004 2006 2008 5.9 . 5.6 5.5 5.5 5.4 6.1 5.6 5.8 5.5 5.4 5.3 • 5.1 5.1 5.2 5.2 5.4 5.1 5.1 5.3 5.1 5.2 5.1 5.0 5.8 5.7 5.7 6.0 6.1 5.5 6.1 5.9 5.8 6.1 5.9 5.7 • 5.3 5.9 5.7 6.5 6.0 5.6 6.3 5.8 5.8 6.2 5.8 6.3 5.5 5.8 5.6 5.8 5.9 5.6 5.8 6.0 5.8 6.2 6.0 5.7 5.6 6.0 6.1 5.8 6.2 5.9 5.5 6.2 5.9 5.9 6.2 6.1 6.2 5.4 5.2 5.0 4.8 5.1 4.7 6.2 5.8 6.0 6.3 6.1 5.9 5.5 5.5 6.0 5.8 6.4 5.9 5.4 6.3 6.0 5.9 6.2 5.9 6.0 5.5 5.8 5.8 5.9 6.1 5.7 6.2 6.0 5.9 6.1 5.9 5.8 • 5.6 6.2 5.7 6.3 6.0 5.6 6.4 6.2 6.1 6.0 5.9 6.2 5.5 5.9 5.6 5.8 5.9 5.5 6.1 5.8 5.6 5.8 5.8 5.6 5.7 5.1 5.7 5.7 6.0 5.7 5.3 6.2 6.0 5.8 6.3 6.1 6.2 5.3 5.7 5.6 5.8 5.9 5.6 5.8 5.9 5.8 6.1 5.8 5.6 5.6 5.4 6.0 5.7 6.2 5.7 5.4 6.1 6.0 5.8 6.2 6.1 6.4 5.4 5.5 5.4 5.0 5.2 4.8 5.2 4.9 5.0 4.9 4.8 5.0 • 4.1 4.8 4.8 4.1 4.9 4.5 5.0 4.9 4.8 4.7 4.5 4.4 5.3 5.7 5.6 5.8 6.0 5.5 6.0 6.0 5.7 6.1 5.9 5.6 • 5.1 6.1 5.6 6.3 5.8 5.4 6.2 5.7 5.7 6.2 6.1 6.2 5.3 5.7 5.6 5.7 6.1 5.5 6.0 5.9 5.8 6.1 5.9 5.7 • 5.0 5.9 5.9 6.1 5.6 5.5 6.1 5.9 5.7 6.3 6.1 6.3 5.4 5.7 5.7 5.9 6.2 5.5 6.1 5.9 5.7 6.2 6.0 5.6 • 5.1 5.9 5.7 5.7 5.7 5.2 6.3 5.9 5.8 6.1 6.1 6.0 † No data are available on soil tests prior to 1955. The A.U. Soil Testing Lab began routine operations in 1954. Values are the mean of soil samples taken from plots in the three tiers of the Cullars Rotation. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 20 — Appendix Table 7. Mean Mehlich-1 extractable soil P in Cullars Rotation since 1955† Plot/treatment number Year A No N; + legume. 63 118 88 102 90 86 108 100 99 118 115 87 • 97 118 124 • 124 114 119 121 146 127 142 146 B No N; no leg. 69 81 86 110 109 108 126 120 105 124 124 90 • 88 110 129 132 113 108 117 108 131 115 150 154 C Nothing 1 No leg.; +N 10 1 4 3 6 3 15 28 27 28 35 33 • 34 57 54 • 58 57 48 51 99 93 83 72 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Pounds per acre or parts per 2 million 1955 1958 1959 1961 1962 1965 1968 1969 1970 1971 1974 1978 1980 1981 1983 1985 1986 1988 1992 1994 1998 2002 2004 2006 2008 12 • 8 7 9 6 9 8 12 9 7 11 • 5 6 6 6 10 16 11 19 18 11 13 10 10 0 5 4 7 3 8 8 9 6 6 8 • 4 6 5 4 9 20 7 7 13 7 11 16 15 14 30 35 37 45 72 57 46 60 71 50 64 52 77 79 83 84 76 92 78 110 102 116 107 46 16 33 26 34 17 35 53 46 59 75 52 53 68 89 106 81 140 136 140 133 174 164 155 133 192 202 202 202 327 380 445 430 454 352 690 208 • 333 222 349 870 223 282 205 400 352 3574 1665 605 155 114 148 1582 163 144 168 166 149 218 208 157 180 113 154 179 219 193 173 193 188 203 202 223 229 18 11 20 40 25 13 24 40 46 57 57 48 44 48 72 73 73 86 101 101 114 137 113 134 124 110 78 92 74 96 79 96 91 79 106 121 94 • 98 109 116 109 130 125 132 121 158 137 149 161 182 171 183 185 212 217 208 224 157 213 219 171 • 129 164 176 155 194 143 168 162 189 180 178 174 202 171 189 189 194 131 190 195 167 224 209 169 • 131 167 176 144 177 145 179 149 166 172 168 173 22 14 24 26 30 78 33 39 65 58 69 59 • 45 80 93 67 89 94 110 99 132 134 145 125 † No data are available on soil tests prior to 1955. The A.U. Soil Testing Lab began routine operations in 1954. Values are the mean of soil samples taken from plots in the three tiers of the Cullars Rotation. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 21 — Appendix Table 8. Mean Mehlich-1 extractable soil K in Cullars Rotation since 1955† Plot/treatment number Year A No N; + legume. 30 28 109 94 80 89 93 118 101 123 86 117 • 96 129 150 • 110 106 106 139 169 93 151 142 B No N; no leg. 30 23 64 72 48 62 78 100 91 100 94 89 • 64 112 117 118 87 111 101 106 143 88 123 99 C Nothing 1 No leg.; +N 21 18 38 37 25 32 63 83 73 73 80 97 • 69 121 109 • 95 96 91 79 120 105 134 107 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Pounds per acre or parts per 2 million 1955 1958 1959 1961 1962 1965 1968 1969 1970 1971 1974 1978 1980 1981 1983 1985 1986 1988 1992 1994 1998 2002 2004 2006 2008 21 . 25 33 21 27 32 39 29 21 29 25 • 20 27 30 22 21 29 27 34 44 44 43 35 36 28 71 77 59 43 73 95 85 95 79 93 • 60 96 98 100 82 105 92 93 121 68 130 86 26 28 71 69 62 71 78 97 93 96 93 118 98 41 126 119 155 111 105 99 80 139 86 181 118 21 13 31 28 28 27 51 80 76 98 83 115 111 101 124 119 143 111 113 97 78 166 94 144 141 20 28 83 77 62 76 69 99 85 101 75 117 • 50 136 104 158 102 91 95 95 152 94 151 115 15 13 25 31 25 3354 25 37 29 27 24 23 20 18 30 30 30 24 31 28 29 36 27 42 34 16 7 35 30 25 29 49 68 54 69 58 70 53 79 85 75 71 58 74 71 62 113 74 116 105 26 33 92 60 68 68 71 70 66 67 57 60 • 39 64 73 60 66 81 60 77 90 53 76 65 25 28 87 93 93 92 81 105 92 120 103 142 • 96 156 123 205 139 109 113 107 164 101 150 116 28 23 81 83 77 62 83 102 92 120 91 114 • 50 118 120 126 106 102 99 81 133 112 141 131 14 13 28 33 31 51 44 52 50 48 50 52 • 44 59 66 46 42 53 54 48 73 58 85 63 † No data are available on soil tests prior to 1955. The A.U. Soil Testing Lab began routine operations in 1954. Values are the mean of soil samples taken from plots in the three tiers of the Cullars Rotation. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 22 — Appendix Table 9. Mean Mehlich-1 extractable soil Mg in Cullars Rotation since 1965† Plot/treatment number Year A No N; + legume. 1965 1968 1969 1970 1971 1974 1978 1980 1981 1983 1985 1986 1988 1992 1994 1998 2002 2004 2006 2008 53 126 72 72 119 80 51 • 53 110 88 • 48 36 53 68 49 53 126 72 B No N; no leg. 66 81 52 64 49 37 26 • 42 105 88 • 44 22 64 46 34 66 81 52 C Nothing 1 No leg.; +N 41 58 34 26 59 55 28 • 24 89 48 • 58 29 50 36 49 67 83 95 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Pounds per acre or parts per 2 million 15 16 18 20 15 13 12 • 8 15 20 16 13 10 10 20 18 15 16 18 37 58 42 38 74 50 26 • 33 73 60 164 49 27 40 33 46 64 64 77 45 68 78 54 108 70 34 49 54 107 75 110 59 29 50 49 77 74 98 85 4 157 62 76 92 80 34 • 27 93 63 148 50 27 50 52 90 77 87 63 54 91 58 52 73 68 38 • 30 130 86 83 71 34 50 64 77 60 80 74 44 105 61 44 78 65 38 56 41 91 90 93 59 36 66 73 91 87 161 90 52 86 56 50 79 72 28 57 42 114 74 129 54 32 47 58 82 73 122 85 8 15 12 12 11 7 6 • 5 9 16 12 11 9 8 19 14 6 16 12 45 107 74 56 98 68 27 • 47 137 77 116 61 35 78 50 77 92 115 96 37 84 62 54 97 77 30 • 39 89 84 79 38 37 58 55 58 73 103 90 44 72 44 42 99 62 28 • 30 92 74 52 41 24 76 55 80 64 137 63 † Extractable Mg was not determined on routine soil samples prior to 1965. Values are the mean of soil samples taken from plots in the three tiers of the Cullars Rotation. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 23 — Appendix Table 10. Mean Mehlich-1 extractable soil Ca in Cullars Rotation since 1968† Plot/treatment number Year A No N; + legume. 491 700 • 530 1057 903 • 600 477 810 900 813 847 1322 845 B No N; no leg. 523 517 • 430 873 893 690 540 427 1050 597 527 660 1331 1176 C Nothing 1 No leg.; +N 257 330 • 260 637 433 • 450 300 617 373 487 743 847 914 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Pounds per acre or parts per 2 million 1968 1978 1980 1981 1983 1985 1986 1988 1992 1994 1998 2002 2004 2006 2008 166 153 • 90 147 163 100 77 103 90 147 163 147 152 83 241 240 • 230 410 393 637 313 230 523 330 353 570 480 865 387 390 513 340 790 643 717 487 343 810 693 707 790 1047 1045 190 397 420 270 653 637 673 573 503 1043 917 1027 1050 1086 920 437 1650 • 1700 2707 2147 1795 1963 1657 2150 2497 2217 1873 2362 2330 328 547 560 490 707 787 740 577 583 1273 953 893 1083 1695 1049 313 333 410 250 713 557 750 440 350 707 730 803 827 1294 963 110 147 • 170 177 220 143 143 137 147 227 255 200 214 163 385 540 • 460 1060 813 727 650 470 1443 660 810 1100 1241 1035 360 600 • 470 873 883 790 573 493 927 857 700 953 1233 1153 263 297 • 220 573 570 360 350 257 880 543 660 680 1185 663 † Extractable Ca was not determined on routine soil samples prior to 1968. Values are the mean of soil samples taken from plots in the three tiers of the Cullars Rotation. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 24 — Appendix Table 11. Mean soil organic matter and estimated CEC in Cullars Rotation† Plot/treatment number Year A No N; + legume. 1.2 1.3 2.3 2.1 4.57 3.98 B No N; no leg. 1.0 1.0 1.7 2.1 3.48 4.50 C Nothing 1 No leg.; +N 0.9 1.1 – – 3.36 3.32 2 No P 3 Complete fertilization 4 4/3 K rate 5 Rock P 6 No K 7 2/3 K 8 No lime 9 No S 10 + micros 11 1/3 K Soil organic matter (%) 1992 1994 2008‡ 2009‡ 2002 2008 0.7 0.8 0.9 1.1 2.38 1.40 1.0 1.0 1.4 1.4 2.85 2.99 1.1 1.2 1.6 1.9 4.21 4.72 1.2 1.2 – – 5.02 3.56 1.0 1.3 – – 7.71 7.50 1.0 1.2 1.5 1.8 4.50 4.29 1.2 1.2 – – 4.49 3.74 1.2 1.3 – – 3.50 2.52 1.2 1.3 – – 4.68 3.72 1.2 1.2 1.7 1.7 4.11 4.57 1.1 1.2 – – 3.94 3.49 Estimated soil cation exchange capacity (cmol/kg) † These values have only been run periodically because of the added cost. Soil organic C x 1.9 = soil organic matter. ECEC is calculated based on Mehlich-1 extractable cations plus exchange acidity. ‡ Data from Kumi (2011) dissertation; higher values are the result of converting from conventional tillage in 1997 to strip tillage and sampling 0 to 10 cm. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 25 — Appendix Table 12. History of fertilizer applied to cotton on Cullars Rotation† Plot/Treatment 1911-1923 A B C 1 2 3 4 5 6 7 8 9 10 11 0-42-24, SP & kainite 0-42-24, SP & kainit, no legume 0 0 108-0-74, DB & kainite 108-64-74, DB, SP, kainite 0 108-42-74, DB, RP, kainite 54-42-37, DB, RP, kainite 0 12-42-24, CSM, SP, kainite 12-29-24, CSM, RP, kainite 9-29-12, CSM, RP, kainite 0 1924-1932 0-42-30, SP & muriate 0-42-30, SP & muriate 0 0 128-0-169 soda & muriate 128-32-169, soda, SP, muriate 0 128-65-169, soda, RP, muriate 128-0-0, soda 0 12-43-30, CSM, SP, muriate 12-29-30, CSM, RP, muriate 6-29-15, CSM, RP, muriate 0 Years and fertilizer added (pounds per acre N-P2O5-K20) 1933-1955 0 0-68-30, SP & muraite 0 0 38-0-0, soda 38-0-0, soda 0 38-0-0, soda 38-0-0, soda 0 0-68-30 0-68-30 0-68-30 0 1956-1966 120-200-200 120-200-200 0 120-0-0 120-0-200 120-200-200 120-0-0 120-400-200 Rock P120-200-0 No K 120-0-0 120-200-200 No lime 120-200-200 No S (TSP) 120-200-200 + micros 120-0-0 1967-1984‡ 0-100-135 + legume, no N 0-100-135 No legume, no N 0 120-100-135 No legume 120-0-135 No P 120-100-135 Complete 120-100-180 4/3 K 120-200-135 Rock P 120-100-0 No K 120-100-90 2/3 K 120-100-135 No lime 120-100-135 No S (TSP) 120-100-135 + micros 120-100-45 1/3 K 1985-2010§ 0-100-135 + legume, no N 0-100-135 0 90-100-135 No legume 90-0-135 No P 90-100-135 90-100-180 4/3 K 90-200-135 Rock P 90-100-0 No K 90-100-90 2/3 K 90-100-135 No lime 90-100-135 No S/ no gypsum 90-100-135 + micros 90-100-45 1/3 K †The early records indicate pounds per acre of material, not nutrients applied. We have estimated the nutrient concentrations (percentage N-P2O5-K2O in the materials as follows: superphosphate (SP) 0-18-0; rock phosphate (RP) 0-6-0; kainit 0-0-12; muriate 0-0-60; cottonseed meal (CSM) 6-1-1; sodium nitrate (soda) 16-0-0; dried blood (DB) 12-1-1; triple superphosphate (TSP) 0-46-0; ‡ In 1967, the sources of all nutrients were ammonium nitrate (34-0-0), superphosphate (0-20-0), triple superphosphate (0-45-0) on plot 9, and muriate of potash (0-0-60),. The micronutrient mix used on plot/treatment 10 applies approximately 1 lb. B, 1.25 lb. Cu, 2.4 lb. Mn, 3 lb. Zn, and 0.2 lb. Mo per acre per three-year rotation. § Triple superphosphate (0-46-0) became the source of P for all plot in 1985 and gypsum was added as a source of S for all plots except for plot C and plot 9 (no S). Nitrogen rates for cotton were increased to 120 lb. N per acre in 2004. Rock phosphate applications to plot 5 ceased in 2002. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 26 — Appendix Table 13. History of fertilizer applied to corn on Cullars Rotation† Plot/Treatment 1911-1923 A B C 1 2 3 4 5 6 7 8 9 10 11 0-42-24, SP & kainite 0-42-24, SP & kainite 0 0 95-0-64, DB & kainite 95-49-64, DB, SP, kainite 0 95-33-64, DB, RP, kainite 47-33-32, DB, RP, kainite 0 18-42-24, CSM, SP, kainite 18-29-24, CSM, RP, kainite 9-29-12, CSM, SP, kainite 0 1924-1932 0-42-30, SP & muriate 0-42-30, SP & muriate 0 0 112-0-79, soda & muriate 112-49-79, soda, SP, muriate 0 112-32-79, soda, RP, muriate 112-0-0, soda 0 18-29-30, CSM, SP, muriate 18-29-30, CSM, RP, muriate 9-14-15, CSM, RP, muriate 0 Years and fertilizer added (pounds per acre N-P2O5-K20) 1933-1955 0-68-30, SP & muriate 0-68-30, SP & muriate 0 0 38-0-0, soda 38-0-0, soda 0 38-0-0, soda 38-0-0, soda 0 0 0 0 0 1956-1966 0-0-0 + legume 0-0-0 No legume 0 120-0-0 120-0-0 120-0-0 120-0-0 120-0-0 Rock P 120-0-0 120-0-0 120-0-0 120-0-0 120-0-0 120-0-0 1967-1984 0-0-0 + legume 0-0-0 No legume 0 120-0-0 No legume 60-0-0 60-0-0 60-0-0 4 /3 K 60-0-0 Rock P 60-0-0 No K 60-0-0 60-0-0 No lime 60-0-0 TSP No S 60-0-0 + micros 60-0-0 1/3 K 1985-2010‡ 0-0-0 + gypsum + legume 0-0-0 + gypsum No legume 0 120-0-0 + gypsum No legume 60-0-0 + gypsum No P 60-0-0 + gypsum 60-0-0 + gypsum 4/3 J 60-0-0 + gypsum Rock P 60-0-0 + gypsum No K 60-0-0 + gypsum 2/3 K 60-0-0 + gypsum No lime 60-0-0 TSP No S 60-0-0 + gypsum + micros 60-0-0 + gypsum 1/3 K †The early records indicate pounds per acre of material, not nutrients applied. We have estimated the nutrient concentrations (percentage N-P2O5-K2O in the materials as follows: Superphosphate (SP) 0-18-0;Rock phosphate (RP) 0-6-0; kainit 0-0-12l; muriate 0-0-60; cottonseed meal (CSM) 6-1-1; sodium nitrate (soda) 16-0-0; dried blood (DB) 12-1-1. ‡ N rates for corn were increased to 120 lb. N per acre in 2004. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 27 — Appendix Table 14. History of fertilizer applied to oats, rye, or wheat on Cullars Rotation† Plot/Treatment 1911-1923 A B C 1 2 3 4 5 6 7 8 9 10 11 0 0 0 0 75-0-61, soda & kainite 75-34-61, soda, SP, kainite 0 75-23-61, soda, RP, kainite 37-23-30, soda, RP, kainite 0 16-0-0, soda 16-0-0, soda 16-0-0, soda 0 1924-1932 0 0 0 0 75-0-0, soda 75-0-0, soda 0 75-0-0, soda 37-0-0, soda 0 16-0-0, soda 16-0-0, soda 16-0-0, soda 0 Years and fertilizer added (pounds per acre N-P2O5-K20) 1933-1955 0 0 0 0 38-0-0, soda 38-0-0, soda 0 38-0-0, soda 38-0-0, soda 0 38-0-0, soda 38-0-0, soda 0 0 1956-1966 0 0 0 60-0-0 60-0-0 60-0-0 60-0-0 60-0-0 60-0-0 60-0-0 60-0-0 60-0-0 60-0-0 60-0-0 1967-1984 0-100-135 0-100-135 0 60-100-135 60-0-135 No P 60-100-135 Complete 60-100-180 4/3 K 60-200-135 Rock P 60-100-0 No K 60-100-90 2/3 K 60-100-135 No lime 60-100-135 No S (TSP) 60-100-135 + micros 60-100-45 1/3 K 1985-2011‡ 0-100-135 0-100-135 0 60-100-135 60-0-135 No P 60-100-135 Complete 60-100-180 4/3 K 60-200-135 Rock P 60-100-0 No K 60-100-90 2/3 K 60-100-135 No lime 60-100-135 No S/ no gypsum 60-100-135 + micros 60-100-45 1/3 K †The early records indicate pounds per acre of material, not nutrients applied. We have estimated the nutrient concentrations (percentage N-P2O5-K2O in the materials as follows: Superphosphate (SP) 0-18-0;Rock phosphate (RP) 0-6-0; kainit 0-0-12; muriate 0-0-60; cottonseed meal (CSM) 6-1-1; sodium nitrate (soda) 16-0-0; dried blood (DB) 12-1-1. ‡ All N is applied as a topdressing in February. Rock phosphate applications ceased in 2002. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 28 — Appendix Table 15. Crop rotations used on the Cullars Rotation, 1911-2010 Years 1911-1931 1932-1955 1955-1966 1967-2010 Year 1 crops Cotton – oats in fall Cotton – winter legume† Cotton – winter legume Cotton – winter legume Year 2 crops Oats harvested for grain – cowpeas turned under – winter legume† Corn – cowpeas planted in middles – oats in fall Corn – oats Corn – rye or wheat Year 3 crops Corn – cowpeas planted between rows Oats harvested for grain – cowpeas turned under – winter legume Oats harvested for grain – crotalaria Rye or wheat harvested for grain – soybean †Winter legume species varied and included crimson clover, hairy vetch, Austrian winter peas, and annual yellow malilotus. Centennial of Cullars Rotation, the South’s Oldest, Continuous Soil Fertility Experiment — 29 — Acknowledgement The Cullars Rotation is one of several long-term, soil fertility experiments maintained by the Auburn University Department of Agronomy and Soils and the Alabama Agricultural Experiment Station in cooperation with the USDA-ARS National Soil Dynamics Laboratory. This experiment has received periodic support through the commodity checkoff programs of the Alabama Wheat and Grain Crops Committee, the Alabama Soybean Committee and the Alabama Cotton Commission. Web publication, June 2010 Auburn University is an equal opportunity educational institution/employer. http:www.auburn.edu http:www.aaes.auburn.edu Website for Cullars Rotation: http://www.ag.auburn.edu/agronomy/cullars.htm