Given the importance of diversity in the sustainability of agricultural ecosystems, the present study empirically investigates the economic and environmental effects of crop diversification and integration of crops and livestock on the farm in Mahidasht plain of Kermanshah province. Required data have been collected with completing 210 questionnaires in 2017–2018. Results showed that increasing the level of crop diversification led to a decline in the partial and multiple sustainability indices of chemical fertilizers, pesticides and water resources consumption. Furthermore, our findings indicated that higher crop diversification can improve the partial and multiple productivity of mentioned inputs use as well as total factor productivity (TFP) in crop sector and whole farm. The results of econometric approach indicated a positive and significant relationship between crop diversification and livestock ownership along with crops activities and TFP of crop sector. Therefore, diversified farming systems, by increasing in sustainability indicators and crop productivity, greatly contribute to improvement of the welfare of rural households and environmental quality. The results of regression model clearly showed that farming experience, education, credits access and family members have a positive influence, while production scale and off-farm income have a negative influence on crop productivity. Accordingly, design policies to promote crop diversification, especially for small farms, must be prioritized and as far as possible, push regional, provincial and national policies toward greater diversity of farm products. Along with diversity, formal and informal education, farmer-centered training workshops as well as easy and low-cost access to credit are strategies that can improve productivity.
