浙江省近期农作物播种面积的变化及其主导因素分析

Factors Related to Changes in Sown Area of Major Crops in Zhejiang Province

利用1978年～2005年农产品成本收益资料和农业统计资料，研究了浙江省稻谷和棉花播种面积变化情况，及其与纯收益相关性和对劳动力投入的弹性。结果表明：近年来浙江省农作物播种面积下降迅速，除耕地面积减少原因外，农业劳动力投入下降造成的耕地复种指数降低是主要原因；从播种面积和纯收益的相关性分析看出，稻谷播种面积受纯收益影响较小，棉花播种面积变化一定程度上受到纯收益影响，但影响程度不大；而稻谷与棉花播种面积对劳动力投入的敏感性较大，且弹性系数呈显著增高趋势，棉花由于耗工量较大，对劳动力投入逐渐由缺乏弹性过渡到富有弹性。文章认为，目前促进我国农业生产的关键是推进土地适度规模经营，在加速机械替补劳动力投入不足的同时，提高农业的劳动回报率。

The study of changes in cropland area is at the core of research on grain security and land-use/ land-cover change. We used the cost-income data of fram products and rural statistical yarebooks to analyze changes in area sown in rice and cotton in Zhejiang province from 1978 to 2005. We calculated the correlation between sown area and net financial return, and the elasticity of labor inputs. The area sown in crops in Zhejiang shrunk rapidly from 4.5 million hm2 in 1978 to 2.8 million hm2 in 2005, a decline of 37.63 % . Except for conversion of arable land, the main cause was a reduction of the multiple cropping index value, which declined 40.39% from 1997 to 2005, the largest decline in the country. Based on correlation coefficients, the impact of net return on area sown in rice was insignificant. Although net return rose at several points over the years, area sown in rice has declined steadily. Net return for cotton has had some positive impact on sown area, but not significant. These results suggest that net return is a factor, but not the most important influence on planting decisions. Sown area of rice and cotton is sensitive to labor inputs, which have a significant positive effect. When labor inputs increase, sown area expands; if labor input is reduced, sown area decreases accordingly. The elasticity coefficient for labor input increased during the study period, for rice production it rose from 0. 004 during 1978 - 1984 to 0.70 during 1999 - 2005. The elasticity coefficient of labor input for cotton production changed to high flexibility （1.05） from low flexibility （0.72） during the same period because cotton production requires more labor input than rice production. These results suggest that labor input became a key factor influencing cropland area during the period when large numbers of young agricultural workers shifted to off-farm employment. Furthermore, consolidation of production into medium-scale agricultural systems may be an important development, as increased use of machinery would reduce labor input requirements and improve agricultural labor returns.