Effect of row spacing and tillage direction on water and soil losses in rainfed land

Determination of the row spacing cultivation for each tillage direction is essential to prevent water and soil losses in rainfed lands. Therefore, this study aimed to investigate the simultaneous effects of cultivation direction and row spacing on wheat field for preventing soil and water losses in rainfed lands. To this end, twenty plots with dimensions of 5×5 m2 were planted to investigate the effect of two tillage direction (along slope and on contour lines) and two row spacing (20 and 25 cm) early autumn 2015. Soil and water loss were measured after each natural rainfall resulting runoff during the growing period of rainfed wheat (from October 2015 to July 2016). Data analysis showed that both the tillage direction and row spacing significantly affected on soil and water loss (P<0.001). Soil and water loss in tillage on contour line was 5.9 and 3.5 times less than that the tillage along slope, and for the 25-cm row spacing was 47 and 34% less than the 20-cm row, respectively. Soil and water loss in the contour lines tillage with 25-cm row spacing decreased about 2.6 times and 90.3% as compared with the along slope tillage with 20-cm row spacing, respectively. The role of tillage on contour lines and cultivation with 25-cm row spacing was very obvious early cultivation, when sufficient vegetation cover wasn’t formed on the soil surface. Wholly, this study revealed that tillage on contour lines and cultivation with 25-cm row spacing is an effective strategy to control runoff and soil loss in wheat rainfed lands especially early growth period.