Accumulation of fitomass and nutrient, and more appropriate developing stage of management of jack bean for green manuring

Abstract

The study was developed in agroecosystems managed under ecological basis in Mato Grosso do Sul State, in Dourados (22º16’ S e 54º49’ W, with average altitude of 408 m, in a Distroferic Oxisol), season 2007/2008 and Itaquiraí (028° 23' S and 011º 54' W), altitude of 340 m, in a Dystrophic Red Latosol or Oxisoil, in 2008/2009. The objective was evaluate the accumulation dynamics of mass and nutrients in the shot of the jackbean and to identify the best stage for the management (cut), with the purpose of increasing the utilization of its potential in order to be used as green manure. The experimental design used was randomized blocks with four replications.The accumulation of fresh and dry mass, N, P, K, Ca, Mg and S, in the shot plants were evaluated every 15 days, corresponding to 45, 60, 75, 90, 105, 120 and 135 days after the emergency (DAE). The obtained results showed that jack bean has high accumulation of fresh and dry mass and nutrients in the shot of the plants, and indicate that the most appropriate stage for its management for green manuring corresponds to the formation of the first pods and early seed formation, since the beginning of flowering continues accumulating significant amounts of mass and nutrients, especially N, K and Ca, maximizing their potential to promote improvements in soil, and benefits to subsequent crops.