Distribution of soil organic carbon in different size fractions, under pasture and crop rotations with conventional tillage and no-till systems.

摘要: Abstract Soil organic carbon (SOC) is one of the principal indicators soil quality. Its size fractions have been proposed as high sensitivity in order to detect changes generated by different use and management intensities. The objective was compare impact practices after 10 years on SOC distribution its fractions. Treatments consisted two rotation systems (rotations continuous annual crops rotations 3 pastures), performed with conventional tillage (CT) no-till (NT). In 2000, NT treatments were additionally split into C or 4 summer crops. 2003, sampled at 0–3, 3–6, 6–12, 12–18, 18–40, 40–60 60–80 cm depths determined. At first four depths, associated particulate matter (POM-C) mineral fraction (MAOM-C) Changes (SOC fractions) occurred mainly 3 cm soil, exception POM-C, diluted when considering 0–18 cm depth. Inclusion pastures a better alternative cropping CT systems, since it had indicator values. However, improved values compared LC, especially species included rotation; no differences found between crop-pasture rotations. These results allowed discriminate combinations that contribute maintain increase SOC, suggesting sustainable resource.