农业机械与农业劳动力投入对粮食产出的影响及其替代弹性
Impact of Agricultural Machinery and Agricultural Labor Investment on Grain Production and Its Elasticity of Substitution

利用1978-2015年13个粮食主产区的省域面板数据，采用超越对数生产函数分析了中国农业劳动力与机械利用变迁对粮食生产的影响。并在测算出机械与劳动力替代弹性的基础上分析弹性变化的原因，论证农业机械对劳动投入与粮食生产的影响。研究表明：农业劳动力与农业机械均对粮食产量具有显著正向影响，但是两者对粮食产出的边际影响不显著。农业机械与劳动力之间存在显著的替代关系，农机具购置补贴不仅使农业机械对劳动的替代作用变强，而且显著提高了农业机械化水平。1978-2015年农业机械与劳动力的替代弹性呈现出四个较明显的阶段性特征，并与中国农业劳动力转移的阶段性特征相一致。但粮食主产区域内农业机械与劳动力的替代弹性变化存在显著差异性。为适应农业生产方式转变、保障国家粮食安全，粮食主产区应采取差异化的农村剩余劳动力转移政策，将农业机械化支持政策偏向农机具购置补贴与农业机械示范推广。
Based on provincial panel data in 13 main grain producing areas between 1978 and 2015,this paper uses trans-log production function to analyze the impact of China’s agricultural labors and the evolution of machinery utilization on grain production. Further this paper calculates the elasticity of substitution between agricultural machinery and agricultural labor,and analyzes the effects of agricultural mechanization on labor investment and grain production. The result shows that both agricultural labor and agricultural machinery exert a significant positive impact on grain production,but its marginal effect presents no significant trend. There was a significant substitution relationship between agricultural machinery and agricultural labor. Moreover,the subsidy of agricultural machinery purchase not only causes a stronger substitutive effect of agricultural machinery on agricultural labor,but increases the agricultural mechanization ratio. Elasticity of substitution of agricultural machinery and agricultural labor in main grain producing areas showed four obvious stage characteristics and was consistent with the trends of the rural labor transfer in the past decades. But there are some obvious differences of elasticity of substitution of agricultural machinery and agricultural labor in main grain producing areas. Therefore,transfer policies of differentiated rural surplus labor in main grain producing areas should be adopted and supporting policy of agricultural machinery should focus on purchase subsidy of agricultural machinery and demonstration and extension of agricultural machinery in order to adapt the changes of agricultural production methods and ensure the food safety.