Aggregate Stability Index of Ultisol Under Sugarcane Bagasse Ash Application.

The Brazilian industry of ethanol and sugar generates their own electrical energy by burning sugarcane bagasse. The process generates sugarcane bagasse ash. In 2013/2014 Brazilian growing season, the sugarcane production was of 530 million tons. Considering that 1 ton of sugarcane yields 25 kg of bagasse ash (10%), the amount of sugarcane bagasse ash produced in 2013/2014 growing season was 13.2 million tons, approximately. It has been disposed on soil without any criteria supported by scientific and/or environmental law. The present study has aimed to evaluate changes in soil aggregation, following sugarcane bagasse ash application. Soil samples have been collected from Ultisol, located in Jaboticabal, São Paulo State, Brazil (21º15’22” S, 48º15’18” W). The experimental design was a completely randomized block. Treatments consisted of a control (without sugarcane bagasse ash) and four rates of sugarcane bagasse ash 5, 10, 20, and 40 Mg ha-1 (dry basis) with five replications. The sugarcane bagasse ash rates were applied to the soil and incorporated by chisel plow. The soil samplings were taken at a depth of 0.0-0.15 and 0.15-0.30 m, twice: six and twelve months after bagasse ash soil application. Data were subjected to analysis of variance and means were compared by Tukey test at 5% probability. Polynomial regression was used to evaluate the effect of the sugarcane bagasse ash rates. The rate of sugarcane bagasse ash application to the soil caused not significant differences on soil aggregate stability index. Higher soil aggregate stability index values were observed at 0-15 cm depth, after six month of the bagasse ash application. The results show that control of the qualitative and quantitative changes that occur in soil aggregation under sugarcane bagasse ash application is important to ensure the environmentally safe and agronomically efficient use of sugarcane bagasse ash as a soil amendment.