Propriedades físicas de um plintossolo após oito anos de incorporação de biochar

Abstract

One of the most common soils in the region of Araguaia valley is the plinthosol which is characterized by medium texture/sandy in the superficial horizon. One of the biggest limitations of this type of s oil is in regards of grain production due to low water availability. Studies have demonstrated that Biochar, plant charcoal, can contribute to significant changes in physical properties of soil with consequent structure changes allowing more water availability. However, it is still unclear how long those benefits remain in the soil. The current study aimed to clarify the physical properties of soil and the water retention curves of a plinthic soil after 8 years of exposure to Biochar and doses of the formul ate 0-18-18. The study was conducted at Nova Xavantina, MT, Bioma Cerrado, at a dystrophic haplic plinthosol, of medium texture, in which Biochar was added in November of 2008. The study design was random blocks with factorial scheme of 4 doses of the formulate (0-18-18) and 4 doses of Biochar. The formulate doses were 0, 100, 200 and 300 kg ha -1 and for Biochar 0, 8, 16 and 32 Mg ha -1 . Water content was determined in undeformed samples under the following tensions: 10, 30, 60, 80, 100, 300, 600, 1000, 3000, and 5000 hPa. After measurements of water content under different tensions the soil samples were dried in a greenhouse followed by determination of macroporosity, microporosity, total porosity and soil density with soil resistance of penetration (100 hPa). The water retention curves and S index were calculated according to the van Genuchten model. PMG and GMD were determined in preserved samples as well as percentages of macro, meso and microagregates. Results were submitted to variance analysis and submitted to regression analysis in the presence of a significant F test. The use of 0 -18-18 dosage regimens resulted in higher soil structuring with consequent indirect increase in porosity due to higher growth of crops. The use of Biochar lead to higher volumes in macropores and total porosity resulting in a gain of water volume available for plants and consequent decrease on soil density.