Sustainable Production Systems under No-till in the Cerrado of Brazil - Mato Grosso

Continuous cultivation of lands under the same monocropping systems tends to promote soil degradation and increase the incidence of crop diseases, pests, and weeds, which in turn reduces crop yield potential. This is a long-term research project looking into various aspects of sustainable agricultural systems. The project focuses on crop rotation and other alternatives to generating long-term profitability. This is believed to be instrumental to many farms located throughout the Brazilian Cerrado. Part of this project is dedicated to the study of soil fertility management under these sustainable agriculture systems. Two experiments, one aiming at the production of fiber and the other at grain production, each containing seven different cropping systems, were initiated in 2008 and general results for the first 2 years are now available.

Results suggest the production of dry matter yield in cover crops during the spring, before cotton, is sufficient to guarantee good soil protection and recycling of nutrients. Amounts of N, P, Ca, Mg, and S recycled by millet and Brachiaria grass were identical, while the amount of K recycled was higher for systems utilizing Brachiaria in the autumn and millet in the spring. The type of cover crop utilized during the spring did not influence cotton yield. The crop intensification system of producing soybean and corn (second crop) in sequence resulted in higher amounts of nutrient export, which should be taken into consideration when planning fertilizer recommendations. There is a trend that cotton cultivated after a series of grass species (with intense root systems) leads to higher yields. Soybean yields were higher in 2009/2010 as compared to 2008/2009 due to climatic conditions and variety. There is a trend for soybean to produce lower yields when its cultivation followed corn intercropped with Brachiaria, which could be related to immobilization of N in corn and Brachiaria residues. This is a long-term project and valuable and more conclusive results will be possible with time. Brazil-53