No abstract

Winter legumes can substitute for applied nitrogen fertilization of corn. Stochastic dominance was used to order net revenues from legume and applied nitrogen alternatives. Stochastic dominance orderings indicate that systems combining vetch with low applied nitrogen fertilization (50 and 100 pounds/acre, respectively) were risk inefficient. By contrast, vetch and 150 pounds/acre applied nitrogen maximized expected net revenue and was risk efficient for a wide range of risk-averse and risk-seeking behavior. Farmers with these risk attitudes may not reduce applied nitrogen if they switch to a vetch cover. Extremely risk-averse or risk-seeking farmers would not prefer winter legumes.

Although the influence of different defoliation management schemes on the productivity and digestibility of summer annual grasses has been studied extensively, little is known about the effects of management on the yield components of these plants. To determine the relative contribution of leaf, stem, and head components to total yield, and to ascertain the digestibility of these plant parts, ‘Sudax SX‐11’ and ‘Trudan’ forage sorghums (Sorghum bicolor (L.) Moench) were seeded in the field in May and in June and subjected to four defoliation schemes: 1) 75‐cm growth cut to a 2.5‐cm stubble and 2) to a 15‐cm stubble; 3) 50‐cm growth cut to a 15‐cm stubble; and 4) early bloom growth cut to a 10‐cm stubble. Dry matter (DM) yields of the first growth and subsequent regrowths, and estimated digestible dry matter (% EDDM) measured with an in vivo nylon‐bag technique, were estimated for leaf blades, culms and leaf sheaths, and inflorescences. Both cultivars produced more DM yields with 75 cm than with 50 cm of growth. Sudax SX‐11 produced less than Trudan when 2.5‐cm rather than when 15‐cm stubbles were used and this was more evident when seeding was delayed one month. Both 50‐ and 75‐cm vegetative growths produced mostly leaf yield of about 80% EDDM throughout the season. Plants cut at early bloom produced much larger DM yields than those cut at vegetative stages. Leaf % EDDM was slightly lower in the early bloom than in the other treatments but stem and head materials were of lower digestibility than leaf blades.

No abstract