Chemical Properties of a Calcareous Soil as Affected by Tillage Practices in Saudi Arabia

Abstract

Limited information is available regarding changes in soil chemical properties occurring under different tillage systems in arid regions such as Saudi Arabia. We conducted afield experiment to compare the effects of five tillage systems on chemical properties of sandy loam ( Fluventic Camorthid ) soil after four years of applying those systems. Tillage treatment were: on-tillage (NT), harrowing (HR), chisel (CH), disking (DS), and moldboard plowing (MB). Soil samples were taken at two depths, surface (0-15 cm) and subsurface (15-30 cm ). Organic matter content (OM); pH; cation exchange capacity (CEC); exchangeable cations; total N, P, K, and extractable Zn, Cu, Mn, Fe, P, and K were determined. Significant differences due to tillage practices occurred mainly in the surface layer. Soil OM and CEC were higher and pH values were lower with NT, HR, and CH than with DS and MB. Total N, P, and K NH4HCO3-DTPA extractable Zn, Cu, and P were higher with NT, HR, and CH, but total Mn, Fe, and extractable Fe were lower with those systems. In the subsurface (15-30 cm), most of the soil properties examined were not significantly affected by tillage practices, but values were lower than in the surface layer. Soil pH remained the same total Fe and K increased significantly with DS and MB. We concluded that accumulation of OM in the surface layer coupled with the increased CEC and decreased pH induced by NT, HR, and CH were mainly responsible for the enhanced total and extractable nutrients