resumo
- Specialization within agriculture has been a key factor in increasing farm income. The production systems have become increasingly simple, since farmers only grow a small number of crops which have a favourable market price. However, monocultural systems require increasing use of agrochemicals leading to unsustainable environmental costs. In this work, the soil fertility of two plots in a crop rotation previously grown for 5 years as pasture or maize monoculture was evaluated. In the pasture, the upper 0-20 cm soil layer sequestered 17.4 Mg organic C ha−1 and accumulated 403 kg N ha−1 more than under maize monoculture. Analytical data from pot experiments showed that soil samples from the pasture plot released significantly more mineral N than soil samples from the maize monoculture. Maize dry matter (DM) yields in 2012 and 2013 were 15.3 and 10.0 Mg ha−1 in the pasture plot and 8.8 and 8.4 Mg ha−1 in the maize monoculture plot. Nitrogen recoveries bymaize were 175.4 and 68.0 kg ha−1 in the pasture and 78.3 and 50.3 kg ha−1 in the maize monoculture plot. The pool of organic matter accumulated during the pasture phase immobilized important nutrients which benefited the succeeding crop as the organic substrate was mineralized.