Tillage impacts on organic matter and plant nutrients in a loam soil of dryland in Turkey

Tillage operations for different soils, sites and agroclimatic conditions can show different effects. We have studied for 3 years (2001 - 2003) the effects of three tillage systems on soil organic matter (OM) and nutrition of crops, in ( Helianthus annuus L.) - barley ( Hordeum vulgare L.) - Hungarian vetch ( Vicia pannonica Crantz ) + triticale mixture rotation, established in a loam soil (typic Xerofluvent) of passage zone between coastal belt and the continental climate of Central Anatolia in Turkey. Tillage treatments were chisel ploughing (C); chisel ploughing + disc harrowing (CD) and chisel ploughing + combine harrowing (CH). Crops were not fertilized. Soil samples taken from 0 - 20 cm depths at four different periods of the experiment were used for OM and available nutrients (P, K, Fe, Zn). Plant nutrient analysis (N, P, K, Fe, Zn) were conducted on sunflower and Hungarian vetch + triticale samples at harvesting. In tillage treatments, there were no significant differences either for OM and available nutrients in soil depth studied nor nutrient contents of plants. Accordingly nutrient uptakes of plants depend on OM and available nutrient contents of soil, it seems that the mineralization rate of OM was lower in C treatment. It is concluded that the lack of clear differences could be associated with low OM content in relation to xeric soil moisture regime of experimental soil and the short-term of the experiment.