Study on Overuse Degree of Chemical Fertilizers for Food Crops in Hubei Province, China Based on C-D Production Function

Based on the panel data of the output and input of grain production of 12 prefecture-level cities of Hubei Province, China from 2008 to 2019, the Cobb-Douglas production function was employed to evaluate the overuse degree of chemical fertilizers for food crops in Hubei according to the calculation of the marginal production value of chemical fertilizers. The results showed that the output elasticity of chemical fertilizers in Hubei province was 0.14, which was much lower than that of machinery and labor forces, indicating that there was very limited space to increase grain output simply by increasing chemical fertilizers. Although the average amount of fertilizers applied in Hubei province as a whole during the sample period did not exceed the economic optimal level, the average amount of fertilizers used in some of the subordinate cities of Hubei exceeded their economic optimal levels by different degrees: The overuse degree of chemical fertilizers in Ezhou, Yichang, Shiyan, Wuhan and Huanggang city during 2008-2019 was 56.98%, 43.66%, 17.07%, 2.21% and 0.84%, respectively. With the implementation of the fertilizer reduction policy since 2011, the degree of fertilizer overuse in Hubei has been greatly alleviated. The number of cities suffered fertilizer overuse in Hubei has been reduced from 11 before the policy to 3 after it. And the degree of fertilizer overuse has been greatly reduced after the implementation of relevant policies.