黑河中游绿洲区地膜残留特征及农户行为分析

近年来我国地膜施用量及覆盖面积快速增加,在提高农业产量的同时也产生了严重的农膜污染,在西北干旱区的表现尤为突出。论文利用实地采样数据及农户调查数据,建立Probit模型与多元线性回归模型,分析黑河中游绿洲区地膜的残留水平与影响农户地膜施用行为的主要影响因素。结果表明：1）目前张掖市农用地膜覆盖现象已经非常普遍,有69.9%的农作物播种面积覆盖了地膜;2）仅2014年1 a研究区地膜的残留率平均为25.7%;耕地中地膜的残留总量达到了63.75 kg/hm²,相当于2014年单位玉米种植面积的地膜用量,已经接近我国国家标准限定值（75.0 kg/hm²）,明显高于内蒙古与华北地区;3）在低温少水的黑河中游山区,农户并未大规模施用地膜进行保温保湿,而是采用种植春小麦与大麦作物应对气候不足。地膜施用与否的高程界线约为2 100 m。从多元线性回归模型的结果来看,农户地块数量和农户的非农工资水平对农户地膜回收率有明显的负面影响,农业劳动投入时间与高程则具有明显的正面影响。从原因上看,农户非农收入水平的高低对地膜回收率具有决定性的影响。值得注意的是,农业补贴与户主的受教育程度对地膜回收率的影响不明显。为提高地膜回收率,减少地膜污染,需要提高地膜质量,防止破碎以便于捡拾;加快地膜回收机械的研发与推广,替代逐步提高的人工费用;加快研发与推广可快速降解的地膜技术。

Plastic Film Residue and Farmers’ Willingness of Film Recycling in the Oasis Area of the Heihe River Basin,China

Plastic film mulching plays an important role in China’s increasing agricultural production due to its soil warming and moisture conservation effects. According to China Agricultural Statistical Yearbook 2014, the volume of plastic film mulch used in China increased to 136.2×10⁴ t in 2013, and the total crop area covered with plastic film mulch similarly increased to 1 765.7×10⁴ hm². Now, China ranks the top in the world in terms of the use of plastic film mulch. While producing huge benefits, plastic film mulch technology has also brought on a series of pollution hazards.
In order to investigate the status quo of mulch residue, a detailed household survey in the oasis area of the Heihe River Basin, China, was conducted by the authors with the help of Hexi University in July, 2014, and 131 valid questionnaires were obtained. A Probit model and a multi-variable regression model were built to understand the influencing factors of mulch recycling rate.
Based on the survey data and regression models, some conclusions about plastic film residue and the factors affecting farmers’ willingness of film recycling were obtained. Firstly, agricultural plastic film mulching is widely used for almost all crops in Zhangye. The crop area covered with plastic film mulch accounted for 69.9% of the total in 2014. Secondly, the rate of residual film in Zhangye was 25.7% on average in 2014, and the amount of residual film in Zhangye in 2014 reached 63.75 kg/hm², equal to the amount of plastic film applied on the corn field in this area. The level of residual agricultural film is obviously higher than the level in Inner Mongolia region and the North China, nearly reaching the limit of national standard. Although plastic film can increase soil temperature and conserve moisture, corn covered with plastic film mulch still cannot cope with low temperature and less water in the hilly regions of Zhangye. So farmers in the counties of Shandan and Minle prefer to plant wheat and barley rather than plant corn. The height limit of film application is about 2 100 m.
In the plain region of the middle reach of the Heihe River, higher wage has a negative impact on the rate of film recycling. Higher wages reduce the dependence of farmers on agricultural income and increase the opportunity cost of farming. Farmers are unwilling to input more labor in the field. Farmers prefer to apply black film in vegetable fields and the recycle rate in vegetable fields is higher than that in grain fields, because vegetable can bring higher profit than grain crops and vegetable fields need higher soil quality. More plots mean more commuting time. So farmers with more plots usually manage their lands extensively, which caused the low recycling rates. Agricultural labor input and the elevation of farmer’s houses have positive impacts on the rate of film recycling. It is worth noting that the educational level of the household head and agricultural subsidy have no impacts on the recycling rate of agricultural film.
The policy implications are as follows: 1) the quality of plastic film should be improved obviously so that it can be easily picked up; 2) the development of plastic film recycling machine should be sped up in order to reduce the increasing labor cost; and 3) research and development of biodegradable mulch film should also be improved