Previous legumes and N fertilizer effects on mineral concentration and uptake by forage corn

Abstract

The beneficial effects of legumes grown in rotation with cereal crops can, in part, be attributed to soil N increments through the fixation of atmospheric N2 and conservation of soil N. Other rotation effects have been suspected, but have not all been characterized. The objectives of the present study were to determine the impact of faba bean (Vicia faba L.) and soybean (Glycine max [L.] Merr.) on the mineral composition and uptake of a subsequent forage-corn (Zea mays L.) crop. Field experiments were conducted in 1987 and 1988 on a Rivière-du-Loup gravelly sandy loam (Ferro Humic Podzol) at St-Anselme and on a Chaloupe silty loam (Orthic Humic Gleysol) at Deschambault in eastern Quebec. In continuous cropping or following soybean Maple Amber or faba bean Outlook, N rates applied to corn Pioneer 3979 were 0, 50, 100 or 150 kg N ha−1. In 1987, generally, the corn mineral composition and uptake were not significantly affected by N treatments. Soil mineral concentrations were measured in spring 1988 at both sites, but only a few differences were observed among treatments. In 1988, at St-Anselme, the K concentration of stover and whole plants increased following legumes at all N levels applied, but decreased at Deschambault as the N level increased up to 100 kg N ha−1 for all previous crops. At St-Anselme, the Ca uptake of the corn stover following faba bean was higher than that following corn. At the same location, the K uptake by stover was higher following legumes than following corn. The Mg uptake by subsequent corn at St-Anselme was higher following faba bean than following corn and soybean, while at Deschambault, it generally increased with N application following all previous crops. At both sites, the stover and the whole-plant P uptake varied with N application that also affected Fe and Mn concentrations and uptake. Key words: Forage corn, faba bean, soybean, N fertilizer, mineral concentration and uptake