Evaluation of soybean cultivars under organic management for green manuring and grain production

Abstract

The objective of this work was to evaluate the grain and aboveground biomass production of six soybean cultivars under organic management. A randomized block design was adopted with four replications per treatment (cultivar). By harvest time, 81 days after plants emergence, all tested cultivars (Celeste, Surubi, Campo Grande, Mandi, Lambari, and Taquari) had excellent nodulation ranging from 545 to 760 mg/plant of nodule mass (dry weight). The cultivars Celeste and Taquari, which yielded 8.33 and 7.12 t ha^-1 of dry biomass, respectively, showed other advantageous agronomic characteristics such as: short cycle, a high accumulation of nutrients (N, P, K, Ca and Mg) in green tissues, and good seed setting. These traits indicated potential of 'Celeste' and 'Taquari' to be used as green manure summer crops in organic agriculture systems. Five of the cultivars revealed a tendency for lodging, however within acceptable levels. Cultivars Celeste, Surubi, Campo Grande, Mandi, and Taquari exceeded in 23%, 32%, 33%, 44%, and 70%, respectively, the Brazilian soybean grain yield average of 2,398 kg ha^-1 of the last three years.