Effect of irrigated rice cultivation on some physical and chemical properties of soils in Gonbad-e- Kavus, Iran

Soil waterlogging and puddling operations affect many soil parameters which may cause major changes in many soil properties. In order to evaluate the effect of irrigated rice cultivation on some physical and chemical properties of soils in Gonbad-e- Kavus، Iran، six profiles were dugged in rice cultivation areas، dryland cultivation، and pasture. These areas had identical conditions in terms of parent material، climate، and topography. After dissecting the profiles، a number of important parameters affecting soil quality including texture، structure، organic carbon percentage، percentage of neutralized solutes، saturated mud acidity، cation exchange capacity، and electrical conductivity were studied. Results showed that rice cultivation using puddling operation and waterlogging method changed many soil properties. Soil processes were intensified in the surface layer of lands under rice cultivation due to moisture and suitable temperature. It caused an increment in clay and CEC، and lime percentage was increased in deep parts of the soil، which led calcic horizons formation. Microbial activity in irrigated rice cultivation areas decreased pH in surface layer of the soil by increasing organic matter and carbon dioxide. The electrical conductivity of the surface layer of soils under rice cultivation was also more than that in dry cultivation and pasture، due to more water evaporation and salts remains. Therefore، rice cultivation decreases the performance of the plants which are in rotation with rice by creating limitation for them.