基于水足迹的作物生产生态效率评价——以陕西省为例

传统生产函数很少考虑农业生产中自然资源的要素功能,也无法表达化肥、农药的使用对环境产生的损害。研究将绿水、蓝水和灰水足迹,分别代表降水资源、灌溉水资源和作物生产的环境影响,引入农业生产函数,采用随机前沿方法测算陕西省作物生产生态效率,并分析其影响因素。结果表明：1）1985-2018年间陕西省作物生产总水足迹呈上升趋势,作物生产单位面积用水强度不断增强。单位面积水足迹及蓝、绿、灰水占比与气候、种植结构,灌溉条件和农业污染相关。2）研究期内,陕西省作物生产生态效率以2003年为分界点呈现先降后升趋势,陕西省作物生产生态效率的U型波动对应政府对耕地资源保护和农业污染管控政策变化。3）作物生产生态效率低下的区域集中在生产落后的农业区和农业条件差的工业区,农业耕地质量差,灌溉条件匮乏,低效率（产值角度）的灌溉和化肥农药施用以及落后农业生产方式是导致作物生产生态效率低下的主要原因。4）研究期内,陕西省作物生产经历了从规模报酬递增,到规模报酬递减2个阶段,与耕地面积的变化基本对应。短期内,考虑各投入要素的产出弹性调整种植结构和化肥农药施用量是提高作物生产生态效率的有效措施,而促进农业产业升级和技术革新是推动作物生产生态效率提升的根本路径。

Assessing crop production eco-efficiency based on water footprints: The case of Shaanxi Province

Traditional production functions rarely consider the role of natural resources in crop production and the damage to the environment caused by use of fertilizers and pesticides. This paper introduces green, blue, and grey water footprints representing natural water resources, irrigation water resources and the impact of crop production on the environment, and assesses crop production eco-efficiency and its influential factors in Shaanxi Province through the stochastic frontier approach. The results showed that:1) From 1985 to 2018, the crop production water footprint of Shaanxi Province presented an upward trend and the water intensity per unit area was continuously enhanced. The water footprints per unit area and the proportions of blue, green, and gray water were related to climate, planting structure, irrigation conditions and crop production pollution. 2) During the research period, the eco-efficiency of crop production in Shaanxi Province demonstrated a trend of decreasing first and then increasing, taking 2003 as a cut-off point. The ecological efficiency of crop production in Shaanxi Province fluctuates in "U" shape, which corresponds to the changes of the government''s policy of protecting cultivated land resources and agricultural pollution control. 3) Low eco-efficiency regions are concentrated in agricultural areas with backward production mode and industrial areas with poor agricultural conditions. The main reasons for the low eco-efficiency of crop production lie in the poor quality of agricultural arable land, scarce irrigation water resources, inefficient irrigation water, fertilizer and pesticide application, and backward mode of production. 4) During the study period, crop production in Shaanxi Province experienced two stages, from increasing returns to scale to decreasing returns to scale, basically corresponding to the change of cultivated land area. In the short term, adjusting the planting structure and controlling fertilizers and pesticides applications are effective ways to improve the eco-efficiency of crop production. However, the fundamental path is the upgrading of agricultural industry and technological innovation.