Estoques de Carbono em solos sob sistemas de produção integrados no Leste Maranhense

Integrated crop-livestock-forest systems are efficient in accumulating soil organic carbon in tropical light-textured soils of Matopiba region "It is farm-scale study with the following treatments: - Crop-livestock - Crop-forest - Livestock-forest - No-till soybean - Livestock (pasture)" "For soybeans and maize: Two lines (0.5 m spaced) 4 m long For pasture: 3 quadrats 0.5 m2 in each replication " 4 replications Soil dephts: 0.0-0.20 m; 0.20-0.40 m "pH in water (1:2.5 soil:solution); total organic carbon (TOC) determined by wet digestion with potassium dichromate; K and available P extracted with Mehlich-1 (H2SO4 0.0125 mol L?1 and of HCl 0.050 mol L?1) and the determination of K concentration through flame photometry and P by colorimetry; Ca, Mg, and Al extracted with KCl 1 mol L?1 and Ca and Mg determined by atomic absorption spectrometry and Al by titration; potential acidity (H + Al) via extraction with 0.5 mol L?1 of calcium acetate and quantified by titration" "Soil dephts: 0.0-0.20 m; 0.20-0.40 m; 0.40-0.60 m; 0.60-1.00 m Total organic carbon (TOC) determined by wet digestion with potassium dichromate. Undisturbed soil samples will be collected for the determination of soil bulk density (DS). Carbon stocks will be calculated using the equation: E = DS x C (or N) x e where: BD = soil bulk density (g cm?3), C = carbon content (g 100 g?1), N = nitrogen content (g 100 g?1), and e = soil layer (cm). " Undisturbed soil samples will be collected for the determination of soil bulk density (DS) None "Soil depth: 0.0-0.10 m - Soil basal respiration - Microbial C and N biomass - Microbial quocient (qMic) - Metabolic quocient (qCO2)"