The role of crop rotation in soil and water conservation (A case study of Dehestan Dasht in Shahreza)

Crop rotation is an indispensable part of any sustainable land management program. An experiment was conducted in 2014 in Dehestan Dasht, Shahreza, Iran, to study agronomic rotations. For this purpose, rotational efficiency index in the study area was calculated as an ecological criterion, while production efficiency, water use efficiency, and land use efficiency indices were calculated as agronomic criteria. Based on the results obtained, the two rotations of (autumn onion-summer safflower-wheat) and (cotton-fallow-first forage sorghum cultivation) did not record acceptable values of rotational index. This is while the crop rotations of (wheat-summer safflower-barley), (wheat-second millet cultivation-barley), and (wheat-second sunflower cultivation-barley) recorded superior rotation indices of 1.67, 2, and 2, respectively. Except for rotations including forage plants and vegetables, the two rotations of (wheat-intermediate mature corn-barley) and (wheat-second grain sorghum cultivation-barley) were the best rotations with production efficiency indices of 28.07 and 30.7 kg per day, respectively. Water use efficiency recorded its highest and lowest values of 1.54 and 1 kg m-3, respectively, with the two rotations of (wheat-second grain sorghum cultivation-barley) and (wheat-second sunflower cultivation-barley). Finally, land use efficiency in the study area was found to range from 58 to 88%. Short crop rotation chains, implementation of incomplete rotations, and lack of a rotation-oriented approach were identified as the underlying reasons for the inefficiency of the crop rotations practiced in the study area.