Stock and Carbon Emission in Different Soil Management Systems.

The economically viable options to mitigate the emission of greenhouse gases would increase the stocks of croplands. The use of liming acid soils was essential to correct soil acidity and contributes to the high production, but can result in carbon emission in the atmosphere. The use of lime application with gypsum may improve the balance of soil carbon as compared to the use of lime only. The main objective of this work was to study the changes in the carbon storage of soil profile as well as carbon emission affected by soil acidity amelioration under no tillage and conventional system. The experiment was carried out in an Oxisol in Botucatu, São Paulo, Brazil. The treatments were: control, lime, silicate, gypsum+ lime and gypsum+ silicate. Limestone, silicate and gypsum rates were calculated to raise soil base saturation to 70%. Deformed and underformed soil samples of both areas were taken one year after treatment applications at depths of 0-10, 10-20, 20-40 cm. Total carbon was analyzed and the stock was calculated according to soil bulk density. Carbon dioxide emissions were monitored using vented static chambers after treatment applications from early October, 2012 through late August 2013 and collateral information collected include weather data, soil temperature and volumetric soil moisture at the time of sampling. The soybean yield was also analyzed. Conventional tillage resulted in a decrease soil C stock and more carbon emission when compared with no-till. There was no difference between treatments for soil C stock. The flux varied by the high quantity of carbon emission as observed when gypsum is used, and we did not observe any increase in the soybean production and carbon stock in soil when compared to lime only application or silicate. Moreover, when silicate is used, there is less carbon dioxide emission in both systems and the soybean yield has lowered.  

Acknowledgement: FAPESP – Proc 2012/09550-0 and Capes