Effect of Efficiency Improvement on Pollution Caused by Overuse of Chemical Fertilizers of Rice Cultivation in Guilan Province

The purpose of this study is to compare the experimental results obtained from estimating the technical and profit efficiency of rice farmers in Guilan province and determining the effect of efficiency improvement on pollution caused by overuse of chemical fertilizers in 2018-2019.

For analysis of technical and profit efficiency, the directional distance function has been used. Farms were classified into three groups according to region (east, center and west). Also, the farms were divided into 5 groups based on rice varieties (Hashmi variety, Ali Kazemi variety, Shiroudi variety, Jamshidi variety and Khazar variety). R, GAMS and Excel software were used in this study.

The results showed that improving the technical efficiency lead to the reduction of nutrients surplus discharged into the environment. But, the profit efficiency mostly increases the amounts of nutrients surplus discharged into the environment. Base on results, technical efficiency improvement reduces the amount of nutrients surplus discharged into the environment for Hashemi variety by 3.5 to 38.8 kg/ha, Ali Kazemi variety by 0.4 to 23.3 kg/ha, Jamshidi variety by 7.6 to 42 kg/ha, Khazar variety by 2.9 to 20.7 kg/ha and Shiroudi variety by 18 to 48.6 kg/ha.

If the rice farmers of Gilan province become technically efficient, this will lead to the reduction of pollution in all areas.  Considering that the excessive use of chemical fertilizers leads to the discharge of nutrients surplus into the environment, therefore encouraging rice farmers to perform soil test and optimum use of chemical fertilizers can lead to reduced pollution and increased technical efficiency.