Interseeding bermudagrass pastures with alfalfa or clovers for growing calves

Abstract Text: Bermudagrass (Cynodon dactylon[L.] Pers.) pastures (n=8; 0.8 ha) were interseeded with 13 kg red clover/ha (Trifolium pretense, cv. Morningstar, Cal/West Seeds, Woodland, CA) and 3.3 kg ladino white clover/ha (Trifolium repens, cv. Regal Graze, Cal/West Seeds) or with 28 kg alfalfa/ha (Medicago sativa, cv. PGI 459, Producers Choice, Woodland, CA in yr 1 and cv. Rebel, Producers Choice, Woodland, Cain yr 2). Twelve additional bermudagrass pastures received 0, 56, or 112 kg N/ha as ammonium nitrate. Beef steers (n = 283, BW = 243 ± 30.5 kg) were used for BW gain analysis and grazed treatment pastures through the summer over 4 yrs in this put and take experiment. In the fifth year of the experiment clovers and alfalfa were killed before grazing and steers (n = 80, BW = 223 ± 13.3 kg) grazed pastures to determine the carryover N benefit to the bermudagrass following these legumes.  Data were analyzed as a completely randomized design with the mixed procedure of SAS. Single df contrasts were used to determine the linear N fertilization rate effect and the effects of alfalfa and clover. Over the 4-yr experiment, ADG, BW, gain per hectare and grazing days per hectare increased (P < 0.01) linearly with increasing N rate. Yet ADG and BW of alfalfa and clover additions did not differ (P ≥ 0.14) from the 112 kg N rate or each other. During the 4-yr experiment, grazing-d/ha was greater (P < 0.01) for alfalfa than clover which was greater than all N fertilization rates (P ≤ 0.05). Gain/ha of alfalfa and clover did not differ (P ≥ 0.31) but were greater (P < 0.01) than all fertilization rates. In the final year of the experiment, ADG, grazing-d/ha, and gain/ha were not affected (P ≥ 0.19) by N fertilization rate or carryover N from previous legume stands, indicating that benefit of carryover N from legumes to subsequent grass crops is minimal. Both clovers and alfalfa produced equivalent BW to the 112 kg N/ha fertilization rate and produced more grazing-d/ha and BW gain/ha than N fertilization, indicating improvements in diet quality with greater levels of fertilization or legume additions.  Increases in grazing-d/ha and gain/ha with alfalfa or clovers were primarily through extension of the grazing season due to an earlier start of grazing.

Keywords: Alfalfa, bermudagrass, clover, growing steers