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 cropresidue management on some physical properties and nitrate leaching of a Typic Haploxerertsoil under winter wheat (Triticum vulgare L.)-soybean (Glycine max L.) double-croppingsystem. The tillage systems consisted of conventional tillage with stubble (CT1), conventionaltillage with stubbles burned (CT2), heavy disc harrow reduced tillage (RT1), rototiller reducedtillage (RT2), reduced tillage with heavy tandem disc harrow fallowed by no-tillage (RNT) andno-till (NT). Each tillage method applied at 480 m2 plot and replicated three times in randomlydistributed 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 andnitrate concentrations at 90 cm depth were determined. Tillage practices significantly affectedthe measured properties at both soil depths. The BD and PR within the conservational managedplots were higher than under conventional managed plot. Whereas, OM content and AS weresignificantly greater under conservational managed plots, indicating improved soil quality.Soybean yield was not affected by tillage practices. The concentrations of NO3-N leached hadstrong variation within sampling dates and significantly different among treatments after thefirst and the third irrigation (P˂0.01). The highest average NO3-N (1440.8b±74.9 mg L-1) inleachate was measured in the CT2 plot while the lowest value (774.8a±56.5 mg L-1) wasobtained in the RT1 plot. The results of this study revealed that reduced tillage and no-tilltreatments could significantly improve soil physical quality and reduce NO3-N leaching ofTypic Haploxerert soil in the Çukurova Region