Long-term tillage and residue management effect on soil compaction and nitrate leaching in a Typic Haploxerert soil

A field experiment was conducted to compare the effects of long-term tillage and crop residue management on some physical properties and nitrate leaching of a Typic Haploxerert soil under winter wheat (Triticum vulgare L.)-soybean (Glycine max L.) double-cropping system. The tillage systems consisted of conventional tillage with stubble (CT1), conventional tillage with stubbles burned (CT2), heavy disc harrow reduced tillage (RT1), rototiller reduced tillage (RT2), reduced tillage with heavy tandem disc harrow fallowed by no-tillage (RNT) and no-till (NT). Each tillage method applied at 480 m2 plot and replicated three times in randomly distributed plots. In the experiment, organic matter content (OM), aggregate stability (AS), penetration resistance (PR), porosity, bulk density (BD) in 0-15 cm and 15-30 cm depth and nitrate concentrations at 90 cm depth were determined. Tillage practices significantly affected the measured properties at both soil depths. The BD and PR within the conservational managed plots were higher than under conventional managed plot. Whereas, OM content and AS were significantly greater under conservational managed plots, indicating improved soil quality. Soybean yield was not affected by tillage practices. The concentrations of NO3-N leached had strong variation within sampling dates and significantly different among treatments after the first and the third irrigation (P˂0.01). The highest average NO3-N (1440.8b±74.9 mg L-1) in leachate was measured in the CT2 plot while the lowest value (774.8a±56.5 mg L-1) was obtained in the RT1 plot. The results of this study revealed that reduced tillage and no-till treatments could significantly improve soil physical quality and reduce NO3-N leaching of Typic Haploxerert soil in the Çukurova Region.