Investigation of transport modelling and soil structure influencing effect of biodiesel by-product in agricultural soils

Abstract

Our investigations are parts of a complex research work which have been started by Department of Soil Science and Agricultural Chemistry of Szent István University. This research work focuses on agricultural application of biodiesel by-product as an alternative nutrient and its effects on the cultigens and on the environment (Kovács et al., 2011a, Kovács et al., 2011b, Tolner et al., 2011, Kovács et al., 2012). The safety use of this material requires the accurate knowledge of its behavior thence several experiments were performed. The first step of our research was the transport modeling of the biodiesel by-product. The basics of models were column tests where the leaching of biodiesel by-product was investigated in presence of nitrate in different agricultural soils. During leaching tests the byproduct was substituted by glycerol because of its decisive glycerol content. The second part of our research was the geotechnical investigation of soil parameters. In these experiments the soil structure modifying effect of glycerol was determined. According to results of transport modeling the leaching of glycerol mainly depends on the soil type and on the presence of nitrate. The amount of washed-out glycerol is significantly high from sandy soils but it decreases by adding of nitrate. The soil structure influencing effect of glycerol was proven by geotechnical investigations. Changes of soil mechanical parameters were observed in cases where the soils were treated with glycerol.