Moniki Campos Janegitz; Ciro Antonio Rosolem, Natalia Rodrigues Ferreira, Camila da Silva Grassmann

São Paulo State University, College of Agricultural Sciences, C.P.237, Botucatu,

AL 18603-970, Brazil

Liming is paramount in soil remediation and to increase crop yields in acidic tropical soils, but it may increase C emissions to the atmosphere. However, the plant response to lime, with  increased root growth and yields can counter-balance C emissions. If gypsum is used mixed to lime, it may further improve the balance of soil carbon as compared to the sole use of lime. The objective of this work was to study changes in carbon storage in the soil profile and soybean yields as affected by soil acidity amelioration under no tillage and conventional systems. The experiment was carried out on a Oxissol in Botucatu, São Paulo State, Brazil. The treatments were: control, lime, silicate, gypsum +lime and gypsum+silicate. Limestone, silicate and gypsum rates were calculated to rise soil base saturation to 60 %. Soybean was planted after 30 days of treatment application  (November, 2012). Deformed and underformed soil samples of both areas were taken at depths of 0-10, 10-20, 20-40 e 40-60 cm, before soybean planting. Soybean roots were samples at R6, weighed and C was determined. Total carbon was analyzed the stock was calculated according to soil bulk density. Conventional tillage resulted in decreased soil C stock and root amounts compared with no-till. There was no difference between all treatments for soil C stock. However, the soybean highest yield was observed in the conventional system. In addition, when lime was applied, gypsum increased soybean yields, root carbon content and root weight.

Acknowledgement: CNPQ- Proc – 2012/121224-5 ; FAPESP – Proc 2012/09550-0, CAPES