Aporte de carbono ao solo por sistemas de monocultura, sucessão e rotação de culturas

Abstract

Losses in soil quality due to monocropping practice and low diversity among species cultivated. It decreases productivity and increases costs with soil management in order to improve soil quality. The objective of this work was to study the variations of carbon input to soil cultivated with crop combinations in Mato Grosso do Sul The research was conducted at the Experimental Farm of Faculdade de Ciências Agrárias of UFGD, Dourados, MS, Brazil during the crops of 2013/14, 2014/15 and 2015/16. The treatments were arranged in randomized blocks design, each one with ten treatments and four repetitions. The treatments correspond to the following sequences of fall and winter crops of 2013: fallow; maize; maize+Brachiaria; maize; Brachiaria; wheat; fallow, turnip, vetch, Crotalaria ochroleuca. 2014: fallow, maize; maize+Brachiaria; maize; bean; turnip; fallow; safflower; oat; mix (turnip+vetch+oat). 2015: fallow; maize; maize+Brachiaria; maize; Brachiaria+vetch; wheat; fallow; Crotaria spectabilis; mix (turnip+vetch+oat). The following parameters were evaluated: dry matter added to each system, soil organic carbon stocks in different layers of the soil and carbon accumulation annual rate through the equation proposed by Henin & Dupuis (1945). The statistical mean comparisons were made by the Scott-Knott 5% probability test. A numerical comparison was made in order to analyze K1 and K2 coefficients and soil organic matter dynamics. The treatments T3 and T5 present higher values of total carbon stock to the soil, after six years of conduction. According to the model of Hennin and Dupuis (1945) the T1, T2, T4 and T7 systems result in loss of C stock in the soil, and thus are not sustainable under the agronomic aspect.