Casual effect of crop choice on farmers’ adoption of biodegradable mulch film China

Abstract

Objective This paper aims to explore the casual effect of crop choice on farmers’ willing to adopt (WTA) and willing to pay (WTP) for biodegradable mulch films (DMFs) in Yunnan province, China, by using a multi-valued treatment effects model. Three crop choices, i.e. tobacco, fruit & vegetable or staple food crop, were used as the multi-valued treatments to measure the influence of crop choices on farmers’ decision-makings of BBDMFs. Understanding the crop choice differences may help the government adapt policy design to different growers to facilitate the use of BBDMFs and reduce the environmental pollution of plastic film residues. Background There has been an increasing concern about the large use of plastic mulch films in agricultural production in China. To tackle the ‘white pollution’, the government has attempted to introduce DMF technology as a substitute to the areas with large use of plastic mulch films. Considering the economic returns to and use of plastic mulch films are significantly different across crops, farmers’ decision-makings to adopt or not adopt DMFs may differ across sectors, in our case tobacco, fruit and vegetable, and staple food crop (e.g. rice and wheat). Notably, some farmers growing high return while high economic risk crops (e.g. fruit) may tend to adopt innovative technologies, leading to selection bias. Methods To model the casual effect of crop choice, this paper extended the bivariate treatment propensity score matching technique to a multi-valued context using a generalized-boosted-model and the inverse probability of treatment weighted estimation to estimate propensity scores. The estimated propensity scores were then used to estimate the average treatment effects (ATEs) to compare farmers’ WTA and WTP among tobacco, fruit and vegetable, and staple food sector. A sample of 1347 farmers surveyed in 2018 was included in the analysis, with 22.5% of vegetable and fruit grower, 39% tobacco grower and 38.5% staple food grower. A total of 22 covariates, including farm and farmer characteristics and farmers’ attitudes to plastic mulch films, were considered in the matching process. Results and conclusions The propensity score weighting approach successfully balanced most of the covariates and addressed the selection bias issue. Based on the estimated ATEs, the odds of adopting DMFs were 1.6 times higher for staple and fruit and vegetable growers than the tobacco growers. The tobacco growers’ low WTA is possibly due to: 1) the strong support of tobacco industry regarding plastic mulches, for instance, tobacco farmers have received more training to use and recycle plastic mulches compared to other crop growers; 2) tobacco growers have invested more time and money in plastic mulches as than other crop growers and may resist to switch to DMFs. The WTP results were consistent with our WTA results. The staple food and fruit and vegetable growers were willing to pay 0.8 and 1.2 (RMB/kg) more than tobacco farmers for DMF. In addition, being the highest-earning farmers in the sample, the vegetable and fruit growers had the highest WTP. This is in line with previous studies showing farmers with higher income have a higher WTP for sustainable and improved agriculture practice as compare to their counterparts.