Abstract

Effective use of rainfall water is a key issue in agricultural development in the arid and semi-arid regions since rainfall water is a precondition for crop production there. This study was conducted in a semi-arid agricultural region with 900 km² in area in Hashtroud, northwest of Iran to determine the relationship between rainwater use efficiency (RWUE) and soil properties. Winter wheat yield and soil properties were determined at 108 plots (40.41 m² in area) installed in thirty six dry-farming lands. RWUE of each plot obtained from the ratio of crop dry matter per unit of abstracted rainfall water volume (ARWV). ARWV was computed from deduction of the rainfall and runoff volume during a two-growth period. Runoff data for each land was obtained from field measurements at the plots under natural rainfalls. Analysis of rainfalls uniformity using four rain gauge stations data showed that spatial distributions of rainfalls were homogeneous in the area. The RWUE values in the lands were ranged from 0.35 kg m^-3 to 1.49 kg m^-3 with an average of 0.84 kg m^-3. Soil properties which considerably affected either the infiltration capacity or the available water controlled the RWUE in the study area. Multi-regression analysis indicated that the RWUE significantly related to silt, organic matter and lime (R²=0.82, p < 0.001). Maintaining crop residues and incorporating with the soil can be proper techniques and sustainable strategies to improve the soil properties and enhance the RWUE in the dry-farming lands.

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