Economic implications of replacing synthetic nitrogen with clovers in a cool-season annual pasture production system 1

The objective of this research was to determine the effects of white clover additions to wheat-ryegrass pastures on steer performance and pasture production economics. Over 4 yr, wheat (Triticum aestivum L.) and annual ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] pastures were established either with white clover (WRG + CL) or with commercial N fertilizer (WRG + N). Each fall steers (243 ± 14.3 kg) were placed on pastures at a stocking density of 3.7 steers/ha. In the spring, a second set of steers (243 ± 20.8 kg) was placed on pasture with stocking density adjusted as necessary to maintain equivalent forage mass across pastures. Data were analyzed as a randomized complete block design with year as the block and pasture as the experimental unit. In the fall ADG (0.99 ± 0.13 kg/d) and total BW gain per calf (54.7 ± 6.4 kg) did not differ (P ≥ 0.16) by treatment. Spring BW gain per steer (80.8 ± 9.9 kg) did not differ (P = 0.37) between WRG + N and WRG + CL, although steers grazed WRG + CL pastures 10 d longer (P < 0.01) than WRG + N. During the spring, ADG on WRG + N was 0.23 kg/d greater (P < 0.01) than that on WRG + CL. Grazing days per hectare did not differ (P = 0.67), but WRG + N tended (P = 0.10) to produce greater BW gain per hectare. Net return per hectare of WRG + CL was $140/ha greater (P = 0.03) than that of WRG + N. Reduced N fertilization cost with subsequent reduction in cost of gain led to increases in net return even in light of reduced productivity with WRG + CL.