Forage corn dry-matter yields and N uptake as affected by previous legumes and N fertilizer

Abstract

Field experiments were conducted in 1987 and 1988 on a Rivière-du-Loup sandy gravelly loam (Ferro-Humic Podzol) at St-Anselme and on a Chaloupe silty loam (Orthic Humic Gleysol) at Deschambault in Eastern Quebec. In monoculture, or following a legume, corn (Zea mays L.) Pioneer 3979 was fertilized with 0, 50, 100 or 150 kg N ha−1, and faba bean (Vicia faba L.) Outlook and soybean (Glycine max [L.] Merr.) Maple Amber received 20 kg N ha−1 as NH4NO3. In 1987, the whole-plant dry-matter yields (DMY) of corn increased linearly with the supply of N at St-Anselme and Deschambault. The stover and whole-plant N uptake, also increased linearly with the N levels at both locations, but the supply of N had no effect on the ear N uptake. In 1988, at St-Anselme and at Deschambault, the ear, stover and whole-plant DMY of plants not receiving N and following faba bean were significantly higher than those in monoculture or following soybean and not fertilized with N; these differences between previous crops were more evident at St-Anselme than at Deschambault. At both locations, the DMY of the stover, ears and whole plants of corn were more responsive to the increased N levels following soybean or corn. At both locations, the N uptake of corn following faba bean did not increase with the N levels in contrast to corn following corn or soybean. The N-fertilizer replacement values (NFRV) for soybean (on the basis of corn DMY) were negligible or lower than 0 kg N ha−1 at both locations. At St-Anselme, the values for faba bean were higher than 150 kg N ha−1, but averaged 32 kg N ha−1 at Deschambault (DMY basis). On the basis of corn N uptake, the NFRV of faba bean ranged from 92 kg N ha−1 for ears and was higher than 150 kg N ha−1 for whole plants at St-Anselme, and varied from 37 kg N ha−1 for stover to 44 kg N ha−1 for ears at Deschambault.Key words: Previous crop, forage corn, soybean, faba bean, N-fertilizer replacement value