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Written by the Gansu PPMO team
Edited by: Bo Zheng, Liu Ke and Susan Beccio

Plastic-sheet mulching is an agricultural technology used to retain soil moisture, reduce weeds and raise soil temperatures. Sheets are stretched over raised vegetable beds and holes are punched into them to make room for seeds or seedlings. In Guanghe County, which is between the Loess and the Qinghai-Tibet Plateau in Gansu Province, plastic mulching has been extensively adopted in upland crop farming. 
 
Lan Cuiren, 71, is a farmer in Huinin County, Gansu Province, China. In this area, plastic mulching has not been used. ©IFAD/Qilai Shen


The area suffers from limited rainfall and low temperatures during the spring planting season, and plastic mulching has proved beneficial. In 2013, it was used to cultivate 356,000 mu (approximatley 23,730 hectares) for 300,000 mu of corn and 56,000 mu of potato crops. According to the provincial agricultural department, the average yield of fully-mulched corn reached 834.3 kg/mu, which is 36 per cent higher than a half-mulched cornfield. And the average yield of fully-mulched potato registered 3,085.3 kg/mu, an increase of 51.5 per cent compared with growing in an open field. The widespread use of plastic mulching meant the per capita income of farmers increased on average by CNY 1,272 (approximately US$207) in 2013.

The increase in crop yield and farmers’ incomes, however,  also means increased use of plastic sheeting, which is a source of environmental pollution. The Guanghe County Agriculture Bureau estimates that over 2,000 tons of sheeting is used each year and this figure is increasing. Large amounts of plastic were discarded at the end of each harvest, severely polluting the environment. Lots of the material was also left in the soil, causing soil compaction and reducing land productivity. Some farmers even burned the used plastic, causing secondary pollution to the atmosphere. In 2011, there was no effective way of recycling the sheeting.


Landscape view of terraced hillside where plastic mulching is used, Guanghe County, Gansu Province, China.  ©Gansu PPMO

It became know as “white pollution” and it was a big headache for farmers and local government officials. But in 2011, the implementation of the IFAD/GEF project: Integrated Ecosystem Management Approach to the Conservation of Biodiversity in Dryland Ecosystems started to adress the problem. Guanghe County - one of the two counties implimenting the project - has been actively involved in public awareness building and policy studies to enhance ecosystems and environment protection. Leaders of the county government and the agriculture bureau who taken part in training and public awareness campaigns have been inspired by this integrated approach to conservation. 
After debate and consultation, the county government issued a policy measure in late 2011 that included some financing for the collection of used plastics throughout the countryside. At the same time, a large-scale awareness campaign was launched to motivate farmers to take part in the program. Since then, the county has invested over CNY 5 million (approximately $814,000) in collecting and recycling of 3,700 tons of used plastics. The collection rate of used plastics has increased from 46.9 per cent in 2011 to 85 per cent in 2014.

In this respect, the county government and its agriculture bureau adopted the following three measures. 

The first was awareness-building and advocacy among farmers. Agricultural extension agents, and county and township officials, took every opportunity to educate farmers on the harmful effects that discarded plastic sheeting can have on the environment. Farmers are encouraged to participate in the program in an interests of developing sound, environmentally-smart farming practices. 

The second measure was to establish plastic collection stations that also provided a small reimbursement for the discarded material. Each village in the county now has one functioning collection station and each township has a larger station. After detailed analysis, the county government decided on a standard buy-back price of CNY 1.2/kg (approximately $ 0.20 per kilo) for the plastic sheeting. The price was set high enough to motivate farmers to recycle without placing too high a financial burden on the county budget. 

The third measure included government-initiated negotiation with private enterprises to establish a process to recycle used plastics. Lanzhou Golden Land Plastic Products Company Ltd was selected to work with farmers and the county government. The recycling process requires that at the main collection center soil is removed from the sheets, and the material is processed into bales, transported to the company and traded in for new sheeting. The company recycles the used plastics to produce sheeting and other products for agricultural use, significantly increasing the effective use-rate of plastics while preserving the soil and landscape.

Guanghe County can boast a significant reduction in white pollution with over 95 per cent of collectible plastics now being recycled. Today, it is hard to spot scraps of white plastic mixed into the soil or blowing about in the trees and countryside. Plastic mulching, a technique that greatly increases yields while conserving soil and water, is no longer harmful to the environment in the long term.



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