Consorciação de culturas de cobertura na safrinha em sistema de produção de soja : fitomassa e ciclagem de nutrientes

Abstract

The practice of intercropping of cover crops promotes the diversity of phytomass residues for no-tillage that, in addition to increasing the productivity of soybeans, improves the physical, chemical and biological attributes of the soil. The objective was to evaluate the phytomass production, accumulation and release of nutrients promoted by cropping systems with cover crops and grain yield of soybeans grown in succession. The experiment was conducted at the Federal University of Mato Grosso (UFMT), Campus Rondonópolis-MT, in the 2017/18 harvest. The systems were arranged in a randomized block design, with seven systems with cover plants in succession to the soybean and three replicates, being: Fallow in no-tillage; Pennisetum glaucum; Crotalaria spectabilis; Urochloa ruziziensis; P. glaucum + U. ruziziensis; P. glaucum + C. spectabilis; C. spectabilis + U. ruziziensis. The phytomass accumulation was evaluated in the flowering and senescence of the crops and, now of desiccation in pre-sowing of soybean. The soil cover rate as well as the nutrient cycling provided by the systems were evaluated at desiccation at 15, 30, 60, 90 and 120 days after desiccation. Soya was grown in succession to the cover crops and grain yield was quantified. U. ruziziensis showed higher phytomass production at desiccation, followed by C. spectabilis + U. ruziziensis. In general, the systems with U. ruziziensis showed a high sprout capacity after the initial spring rains, which made them stand out in the systems with P. glaucum and C. spectabilis on phytomass productivity. The P. glaucum presented higher accumulations of nutrients during flowering and senescence; however, U. ruziziensis provided a greater quantity of macronutrients and micronutrients from the moment of desiccation of soybean pre-sowing. Single systems of C. spectabilis and U. ruziziensis promoted an increase in yield of soybeans in the 2017/18 crop.