The effects of tillage methods on soil aggregation and crop yields in a wheat-corn rotation under semi-arid conditions

Abstract. In this study, the effects of different tillage methods under wheat-corn two-course rotation system on the some soil aggregation properties and yields were investigated. Experiment was laid out in a split plot design with three replications during four crop years. Subsoiler, moldboard, sweep and chisel as main plots and rotary tiller and disc harrow as sub-plots have been used in this study. The results showed that tillage methods were significant at (P < 0.01) as regards crop yields, and the highest yields as 6249 and 11720 kg/ha for wheat and 9891 and 73080 kg/ha for corn grain and biomass were produced in subsoiler treatment, respectively. Subsoiler+rotarytiller treatment was significant at (P < 0.05) with 2.063 mm as to mean weight diameter (MWD) value. The subsoiler and chisel were statistically in the same group with regard of water stable aggregates (WSA) value, and it was significant at (P < 0.05) with 67,83 %. Bulk density, total porosity and air porosity values were significant at (P < 0.01), and 1.38 grcm-3, 51.2 % and 12.5 % values were determined in rotary tiller application, respectively. Field capacity (FC) and permanent wilting point (PWP) were significant at (P < 0.05) and (P < 0.01) with 31.89 % and 17.21 % values in the chisel treatment, respectively. Crop yields and positive effects on the physical properties were considered subsoiler+rotary tiller treatment was the most successful, and it was followed by chisel+rotary tiller treatment according to four-year study results. Key words: Soil quality, subsoiler, chiesel, soil structure