Evaluation of the Effect of Improper Land Equipment, Renovation, and Integration Operation on the Fertility Quality of Paddy Soils

One of the practices to improve the agricultural management of paddy fields for sustainable rice production is land equipment, renovation, and integration operations. However, due to some shortcomings, this does not seem to achieve all its goals. Therefore, the purpose of this study was to evaluate the effect of land leveling operations on non-uniformity and severity of changes in soil fertility using fuzzy logic and integrated fertility quality index, in paddy fields of Khosroabad village which is located in fouman city in Guilan province where the land equipment, renovation, and integration operation has been done. In two stages, before and after land leveling operations, 95 and 126 soil samples were prepared from surface horizons, respectively, and then some soil properties related to rice fertility (electrical conductivity, clay, organic carbon, total nitrogen, available phosphorus and available potassium) were measured. In the next step, using fuzzy functions, soil quantitative characteristics were converted into qualitative variables and by using the effect of weight on qualitative variables, the integrated fertility quality index was calculated. The results of measured properties, calculated indices, and the produced maps from them, showed that due to the land leveling operation, the average amount of clay increased (76/9%), and organic carbon, nitrogen, available phosphorus, and available potassium decreased (37, 32%, 41/7 %, and 20/3%, respectively) significantly. One of the main reasons for this is excavation operations and the placement of subsurface soil with more clay and lower concentrations of nutrients in the lower horizon. The integrated fertility quality index also decreased (from an average of 0.31 to 0.18) in most of the studied areas. As a result, it seems that improper implementation of agricultural land equipment, renovation, and integration operations, by reducing the fertility of topsoil, will have long-term negative effects on agricultural land, that elimination of which, will increase the cost of production.