Measurement Of Rice Production Efficiency Based On Chemical Fertilizer Application Reduction And Its Carbon Emission Reduction

The application of chemical fertilizers promoted rice production,but the excessive input caused its marginal output to decline,and also caused the imbalance of soil organic element structure and soil acidification,which seriously polluted the water and soil resources and the atmospheric environment,hindering the development of low-carbon agriculture.Based on the statistical data of the main rice-producing provinces in China from 2004 to 2017,this study first calculated the actual unit area of fertilizer input for different rice species;secondly,this paper calculated the fertilizer input elasticity by the stochastic frontier method,and based on this it also calculated the amount of economic fertilizer applied per unit area of the main producing area of different rice species;then this research calculated the amount of fertilizer reduction and potential and the amount and potential of carbon reduction of fertilizer per unit area of the main producing area of different rice types;finally,the SBM model of the undesired output and ML index were used to measure the environmental technology efficiency and environmental total factor productivity before and after carbon emission reduction of fertilizers in different main rice producing areas.The results showed that:(1)During the study period,the average reduction of fertilizer per unit area of rice and the average reduction potential of its nitrogen,phosphorus,and potassium fertilizers were relatively large,but the overall middle-season rice was not over-fertilized.Among them,the early rice was 63.60kg/hm~2,27.29%,the late rice was 47.83 kg/hm~2,19.53%,and the japonica rice was18.59 kg/hm~2,0.97%,respectively.The whole showed the distribution characteristics of the early rice>late rice>japonica rice.(2)The average carbon emission reduction per unit area of rice and its potential for carbon reduction are relatively large,but there is no carbon emission reduction for chemical fertilizers in middle-season rice as a whole.Among them,the early rice was 93.80 kg/hm~2,27.31%,the late rice was69.21 kg/hm~2,20.31%,and the japonica rice was 41.19 kg/hm~2,5.01%,showing the distribution characteristics of early rice>late rice>japonica rice.(3)After the carbon emission reduction of fertilizers,the environmental technical efficiency of rice has improved significantly.Among them,japonica rice increased by 14.42%,late rice and early rice increased by 13.60%and 10.35%respectively,and medium rice increased by only 4.47%,showing the distribution characteristics of japonica rice>late rice>early rice>middle-season rice.(4)The ML,MLEFFCH and MLTECH indexes of the four types of rice after carbon emission reduction of chemical fertilizers are generally higher than 1,and the MLEFFCH and MLTECH indexes of some regions have increased significantly.This not only shows that carbon emission reduction of fertilizers helps to optimize the structure of agricultural inputs,and improves the efficiency of rice production and the expansion of its production boundary,but also shows that carbon emission reduction of fertilizers is effective.