Flávia Dias Terra
Abstract:
The use of conservation tillage systems favors the increase of the levels of C and N as well as stocks and activity of microbial biomass. Consequently improving soil structure increases levels of order. But for levels on order to increase the soil needs is a set of factors that contribute simultaneously to the larger structures as macroaggregates are formed. The macroaggregation occurs with the addition of microaggregates and intertwining of hyphae, roots and mucilage exuding microorganisms and plants, respectively. With this system the soil quality wins, observed the greatest amount of microbial biomass and its activity so that immobilizes nutrients in the microbial cells and is efficient in this conversion. The conversion efficiency is achieved in stable systems where the flows of energy and carbon (inputs and losses) are equivalent and microbial population does not lose power to the middle (CO2). The scientific basis and application of knowledge in the cultivation of grain producing areas and meat support the increased productivity of the areas of growth and sustainability of production systems. The applications of this knowledge day-to-day deserve increased attention, particularly for the management of soil and its agricultural potential and can be used without environmental impacts. Given this scenario goals were to evaluate the fractions of soil organic matter in two systems of use and management and two soil types in the Cerrado. After two years of introduction of Integrated crop livestock were found lower values in relation to TOC stocks when the grazing was intensive (P-25) was smaller than when grazing animals (P-35 or P-45) or not grazing (n/ grazing) treatments. Stocks of particulate C (POC) varied between treatments with a behavior similar to the total stock of C. stocks of NT (total nitrogen) showed lower values for high intensities (P-25) and low (P-45) while the remaining intensities did not differ. The MWD showed differences in the depths 0-5 and 5-10 cm and 10-20 cm depth in the similarities. The grazing 25 cm (P-25) had lower MWD layer 0-5 cm, while the depth 5-10 cm, P-45 showed lower diameter of the aggregates. The MWD was directly related to the xvii increase in TOC stocks well with the carbon management index also showed improvement of soil quality with moderate grazing Brachiaria (p-35). The biomass was influenced by grazing intensities, because when there was no entry of the animals were observed lower microbial levels. As for the no-tillage system in succession culture were observed that after 12 years of implementation of the PD total stocks C equaled native area and subsoiling area with 8 years of PD (PD8) did not reduce the average diameter aggregates. The calculation of stocks in soil layer may overestimate the values actually found in the treatments. The cultivation area in conservation management system favored increasing BMI, proving that such a system helps to improve soil quality. The active fraction of MOS (microbial biomass) showed differences where the area with 12 years of PD had values equal to or greater than reference area (Top) for C and N-BM. The CO2 flux was higher in areas with only 8 years of PD, showing that even after this time system deployment microbial population was under stress, evidenced by higher metabolic quotient (qCO2). At 17 years of PD increased the fraction living in total MOS in the soil. These results shows us that areas suffering or human action that is being conducted in an exploratory manner as was the area of Integrated crop livestock may take over a decade to recover.
