Water and Soil Productivity in the Crop Rotations Practiced in Isfahan Province

Fort the purposes of this study, data were collected using a questionnaire on crop rotations in Isfahan Province alongside field observations and commonly used indices. It was found that the rotations common in all the three cold, temperate, and warm climatic zones identified in the province were often short-termed with two or three crops grown. The temperate zone, however, is characterized by 30 dominant types of rotation. Land use efficiencies of 43-98%, 60-95%, and 50-81% were recorded for the temperate, warm and cold zones, respectively. Production efficiency in the rotations was found to have declined to levels below 40 kg per rotation day depending on the type of crop grown, cultivation of small grains such as wheat and barley or certain oilseeds such as rapeseed and safflower, and fallow periods allowed between rotations. The presence of high-yield forage crops (such as fodder corn), especially when combined with tuberous crops (such as sugar beet) and summer crops (such as watermelon and honeydew melon), was found to increase the production efficiency of the rotations (sometimes to more than 200 kg day-1 in the temperate zone). Water productivity in crop rotations across the three zones rarely ever exceeded 6 kg m-3. Crop diversification in the rotations, therefore, seems to be the most urgent measure that should be taken in the three climatic zones. Finally, more extensive cultivation of tuberous crops in the temperate and warm zones as well as wider growth of pulses in the cold zones seem not only to be feasible but also economically rewarding.