Effects of crop residue burning on soils physical and chemical properties in Sistan plain

Crop residue management plays a significant role in sustainable crop production of agricultural ecosystems. The present study was performed to investigate the effect of crop residue burning on physical and chemical properties of different soils in Sistan plain. The experiment was carried out using a randomized complete block design with three replications. Soil texture was considered as the main factor at three levels (clay, silty loam and sandy loam) and burned and unburned crop residue treatments were considered as the secondary factor. Soil electrical conductivity, bulk density, pH, available P, K and Ca contents in burned plots were significantly increased compared with unburned plots and had no significant effects on soil organic carbon. There was a significant reduction in saturated hydraulic conductivity, soil water capacity and sorptivity factor in burned plots compared with unburned plots. The reduction was 28.1, 15.9 and 27.5 % for saturated hydraulic conductivity, 28.8, 27.0 and 53.7 % for water content and 41.7, 48.4 and 59.9 %for sorptivity factor in clay, silty loam and sandy loam texture, respectively. The soil water repellency was similar for both burned and unburned treatments and water drop penetration time was less than 5 seconds. In general, burning crop residues have detrimental effects on many physical and chemical characteristics of the soil. These effects were more obvious in light-textured soils. Thus, crop residue burning after plant harvesting is not recommended.