Nitrogen for DaIlli sg rass PASTURES In the Black Belt CIRCULAR NOVEMBER 136 1959 74fricu/kurcat experimentl .St aioii -/ THE ALABAMA POL YTECHNIC INSTITUTE E. V. SMITH, Director Auburn, Alabama CONTENT S Page EXPERIMENTAL AREA AND PROCEDURE---------- -- 4 C attle M anagem ent ------- ------- ------- ------- ------- ------- Forage M anagem ent --------- --------- --------- B otanical C omposition ----------------------------------N itrogen Fertilization ---------------------------------RESULTS AND D ISCUSSION -------------------------------------- 5 Forage Prodnction ------------------------------------Beef Produ ction -------- -------------------------------CONCLUSIONS AND RECOMMENDATIONS. ------------------------- 7 8 FIRST PRINTING 3M, NOVEMBER 1959. Nitrogen for Dallisgrass PASTURES in the Black Belt E. M. EVANS, Associate Agronomist L. A. SMITH, Superintendent, Black Belt Substation H. W. GRIMES, Assistant Superintendent, Black Belt Substation' D ALLISGRASS and white clover have been the most important forage crops for improved permanent pasture in the Black Belt area of Alabama for many years. Dallisgrass is so well adapted to this region that the prairie soils are often referred to locally as "Dallisgrass land." White clover is not as hardy and persistent as Dallisgrass, but is well adapted. It is the only perennial pasture legume to achieve widespread usage in the area. During years of favorable growing conditions, white clover produces an abundance of early forage that is high in quality and palatability. With adequate summer rainfall, it usually remains vegetative and lengthens the grazing season 30 to 60 days over that of Dallisgrass alone. With severe summer drought the clover frequently fails to survive as a full stand and natural reseeding is desirable. Since 1950 unfavorable conditions have resulted in erratic clover performance. Many pastures have not had a good clover crop for at least 5 years and Dallisgrass has become rather unproductive because of insufficient nitrogen. In 1952 an experiment was begun at the Black Belt Substation, Marion Junction, to determine the value of supplemental nitrogen in commercial form when applied to Dallisgrass-white clover pasture. 'The contribution of the late W. B. Kelley, Superintendent, Black Belt Substation, is acknowledged. EXPERIMENTAL AREA and PROCEDURE Four grazing paddocks, each 3 acres in size consisting of about 2 acres of West Point Clay 2 and 1 acre of Sumter and Houston clay were selected for study. Prior to the first grazing season, the pastures were treated uniformly with 100 pounds each of P2 0 5 and K 2O per acre. The same rate of mineral fertilization was continued each year to ensure that mineral nutrients were not limiting factors. Cattle Management The plots were grazed by beef type yearling steers except for the 1954 grazing season when 2-year-old steers were used. The "put and take" system of stocking was used to adjust stocking rate. More steers were added as the amount of forage on the paddocks increased beyond the ability of the steers to graze it in a reasonable time. As forage declined in quantity, the stocking rate was correspondingly reduced. Two-day weights of steers were obtained prior to placing them on pastures and again as they were removed from the experiment. While on test steers were weighed at 28-day intervals. Beef yields reported are net gains for all steers used in the experiment for that season. Since a conservative stocking rate was used with gradual adjustment of steer numbers per paddock, these values should be about what might be expected under farm conditions. Forage Management Stocking was usually delayed until sufficient forage growth had accumulated to support two steers per paddock. Nine standard welded wire cages 4 feet square were placed on each pasture prior to grazing for measurement of forage growth. At the end of each 28-day period, forage was harvested from the protected areas with a small sickle bar mower. At the same time a similar harvest was made from grazed areas. The cages were rotated to a grazed area after each harvest. This system is known as the "cage difference technique" and permits measurement of growth made by comparing yields from caged areas with those from grazed areas that were harvested 28 days before. This technique makes no distinction between forage lost because of trampling and that actually eaten, but with 2 Formerly known as Bell Clay. [41 conservative stocking the technique provides a satisfactory index for grazing efficiency. Botanical Composition At the beginning of the experiment in 1952, there was a fair stand of white clover on all paddocks, but it was lost probably because of drought during the first 2 years of the experiment. Although efforts were made to regain the stand by reseeding, close grazing of Dallisgrass, and light disking in the fall, the clover was not satisfactorily reestablished during the course of the experiment. A special effort was made in 1956 to favor the clover. There was a fair stand of seedling clover and stocking was delayed until June 26 to permit clover seed to mature. This plus early removal of steers in the fall (Sept. 10) resulted in a short grazing season for that year. Wild barley (Hordeum pusillum), a low-growing, cool-season annual grass, increased on pastures as the experiment progressed. Although variable from year to year, the stand was usually dense during early spring and was competitive with seedling white clover. The severe drought of 1954 limited growth and so weakened Dallisgrass that data were not recorded the following year. Nitrogen Fertilization One of the primary objectives of the experiment was to study the response of Dallisgrass to nitrogen applied in addition to that supplied by the clover. The timing of the nitrogen fertilization was set to follow the normal clover season. Rates of 0, 40, 80 and 160 pounds of nitrogen per acre were used. The first increment of nitrogen was applied around the first of June. Two plots received 40 pounds and a third 80 pounds of nitrogen at that time. Two of the plots received additional nitrogen at the rates of 40 and 80 pounds near July 1. Sodium nitrate was the source of nitrogen, except during 1957 when ammonium nitrate was applied. TABLE 1. ANNUAL AND SUMMER RAINFALL FOR THE PERIOD 1952-57 COMPARED x WITH THE LONG-TIME AVERAGE, BLACK BELT SUBSTATION Item 1952 In. 1953 In. 56.20 24.52 1954 In. 27.43 10.86 1956 In. 41.1 13.98 1957 In. 55.70 32.55 28-yr. average In. 50.56 24.83 42.91 Annual rainfall April 1 to Sept. 30 rainfall-.. 16.39 SRainfall data for 1955 are not shown as forage data were not obtained that year. [5] dir 'lO'.i Ih Ilie ainniial rainf-tai data .ind rinif allcllirinli; Ollis .rass ',easoni tile ill ihnl) 1. RESULTS and DISCUSSION Forage Production Yields ~ ~ oaIc ~ w ~ cdh 95 957r rusir ,~niu'-hc2 h c Iim il Iic a iu cIc tho ," Ics tota li for (' )0J a ii'do e tiUIIJ h utbmi (I 1,500 954id 956 acc.x.1d5y irtc .c ec Lb. U8,26i 40 801 I-I(lb''. 1ll 11ilx I (t) . t Jil 1 ill 111\ LI). 1 1891 : .332 3,:7)1 1. 1,05: ,-9.5 11). 2,9)8 7,211 785(0 ,,08, LbA :3,5:"36 5,1(16 5,591 2 ni u 1,:96) 8,70 9 1 :3 4,2 7 N52 ?11 :39 ( V~font,( w"n I~d lkci ding daavm(lc ~ 95 Oaallisgrass-white clover pasture nitrogen would be expected. typical of areas where little response to Yearling beef animals grazing pasture typical af areas nitrogen would be expected. where gaad respanse ta ai e of tin frilsti in' it 55as (5 11(1 t th at there %issas il carriy son 0511 of nitirogenl frthl c ar toi year. This vvats elw(illy iioticeable lollosyinZ at (h-\si 1111il aid fi all Beef Production griazig sc5(itsio vv55as I70. tis varliedi fro t11 of 77 e~alei hal (las loss ill 19Y56 tio i i of 2:(0 ill 1957. Th gr 4azing pii feced duiiig thll pound, pr atli ~ 19152 Lb. thur-Ii 195.; Il). 1951 I1 . 166 215 28f 285 \\ t,, I19I 1t.56 1.1). 75 1.56 154 I ?1(7 \ cai Iui U 55 21 1 iii 18-S) H(1 1 53 1I 21i5 35: I ntoI of ,[1 /iqTICSt tt I il m,, 22S 168 )9 2S 1.:il 1..57, ; 6 I IS kIth x an of 170 I 16P 77. 311 (lIx tc r(p (lit ck (LIN, Iwoi "w latter season was not all from Dallisgrass. During the first 30 to 40 days of that season, the sward consisted mostly of wild barley. Daily gains of yearling steers were quite satisfactory. However, the grazing was not enough to provide for growth and a high degree of finish on this age animal. Most of the steers would grade standard for slaughter at the end of the season. There was some improvement in the quality of forage on the nitrogen-treated plots over that of the check plot (no nitrogen), as shown by the daily gain of animals. All of this improvement came with the first 40-pound increment. There was a countinuous improvement of beef gains per acre with increasing rates of nitrogen up to 80 pounds per acre. Most of the increase (93 pounds per acre) can be attributed to the first increment of 40 pounds of nitrogen. The second 40 pounds resulted in an average increase of 30 pounds of beef per acre. The cost of the additional nitrogen as related to value of the increased beef production would determine the desirability of applying the higher rate. The relationship between pounds of forage produced to pounds of beef gain realized is a measure of grazing efficiency. A comparison of the treatment receiving no nitrogen with the 40- and 80-pound rates, Table 4, shows a trend to greater efficiency with increasing rates of nitrogen. Increasing the nitrogen rate to 160 pounds per acre reduced the grazing efficiency to about the level of the untreated paddock. TABLE 4. EFFECT OF NITROGEN FERTILIZATION ON GRAZING EFFICIENCY Nitrogen treatment, pounds per acre Forage produced per pound of beef gain 1956 1957 4-yr. av. 1953 1954 Lb. Lb. Lb. Lb. Lb. 11.4 13.5 11.7 15.0 14.0 16.0 15.9 20.8 12.9 17.2 16.2 16.4 19.2 17.9 17.1 19.5 38.6 0 24.9 -40 80 (40 June, 40 July) ........ 24.6 160 (80 June, 80 July) ........ 25.9 CONCLUSIONS and RECOMMENDATIONS Nitrogen applications can be of considerable value in strengthening stands and improving yields of Dallisgrass pastures that do not have productive stands of clover. Applications of nitrogen to such pastures resulted in increased yields of forage and beef, permitted heavier stocking rates, and improved grazing efficiency. It is recommended that 40 to 80 pounds of nitrogen per acre be applied annually to Dallisgrass pastures until productive stands of white clover are established. If moisture supply is adequate and beef prices are favorable, the higher rate of nitrogen would be preferred. [8]