Soil Physical Properties Due to Different Tillage Systems in Dryland Regions of Northwestern Iran

Lack of sufficient information on conservation tillage systems leads to the dominating use of conventional tillage practice in most parts of Iran. Testing other management practices may help in decision making regarding the types of tillage systems that reduce soil deterioration. A three- years field experiment was conducted to study the effects of conventional (CT), reduced (RT) and no-till (NT) tillage systems on soil physical characteristics. A split block design with three replications in a soil (fine mixed, mesic, Calsixerollic Xerochrepts) in Maragheh Dryland Agricultural Research Station (northwest of Iran) was used. Soil texture, bulk density (BD), moisture content (MC), penetration resistance (PR), organic matter (OM), mean weight diameter (MWD) and aggregate size distribution (ASD) were measured over a period of 3 years. No differences were obtained among the tillage systems for BD at 0-15 cm depth. At 15-30 cm, NT resulted in a lower (~10%) BD compared to the other treatments. Soil moisture content was about 18% higher in NT and 11% in RT compared to CT. Soil penetration resistance was 0.5 MPa higher in NT than CT or RT. No-till resulted in an increase in OM (~1 g kg-1) compared to the other treatments. No differences were obtained among the treatments for aggregate size distribution. The relatively higher amount of moisture and organic matter for the conservational practices in this dry area may appear to be numerically low and negligible, but in a long run may improve the sustainability of beneficial soil conditions.