"A sea of plastic" - China Dialogue
Food

“A sea of plastic”

Short-term profit motives have led China’s farmers to use polluting plastics, chemical fertilisers and herbicides in abandon. The country needs sustainable farming to preserve the quality of its food – and its land, writes Jiang Gaoming.

During my recent visits to villages in the Chinese provinces of Henan, Hebei, Tianjin and Shandong, I saw the phenomenon of “white pollution” with my own eyes. This “white terror” is the sea of plastic that covers our land and blows on the breeze along the highways.

This plastic membrane used in agriculture can be seen strewn between fields, in ditches and beside roads – you even see it on streets in towns and in household courtyards, piled layer upon layer. I have visited dozens of countries, but never seen plastic used on such a scale as it now is in China. And it looks as if the country’s five millennia of agricultural history may now be destroyed by the excessive use of plastic membrane, fertiliser, pesticides and herbicides. 

Plastic has two main uses in farming – to construct plastic greenhouses for growing crops out of season, and covering the ground to increase the value of crops. In the provinces of Shandong and Hebei, I saw it used to grow almost every crop, apart from cereals like wheat and maize. Peanuts, potatoes, watermelons, garlic, eggplants, peppers and tobacco are all grown under plastic.

The farmers say that covering the ground with a plastic membrane increases the temperature and humidity of the soil, extending the growing season and increasing harvests by 20% to 50%. When growing crops such as peanuts, they say, it can even double production. This method of farming may be a new scientific advance, but nobody has considered whether our environment can cope with the plastic waste that results. Currently, about half a million tonnes of the plastic is left in the soil every year, almost 40% of the total plastic used. This forms a layer in the earth which is less permeable to water and air, making it harder to farm.

More careful farmers will remove the membrane from their fields at the end of the growing season, but they only go so far as to throw it to the edge of their land. The plastic is light and covered with earth, so it is difficult to sell for recycling. When there is a big enough pile of the stuff, the farmers generally burn it – polluting the environment even further.

Plastic can be seen across China's fields

Organic compounds which do not biodegrade are known as Persistent Organic Pollutants (POPs), and 12 of the most harmful of these chemicals were restricted or banned by the 2004 Stockholm Convention on POPs. These compounds linger in the environment for long periods and can enter the human body through food or respiration, causing poisoning, cancers and even death. Burning plastic membrane results in the release of at least five of the 12 POPs listed by the Stockholm Convention.

Ten years ago, officials from the Ministry of Agriculture and Ministry of Science and Technology expressed hopes that scientists could develop a microorganism to break down plastic waste – but there has been little success. Despite frequent and promising-sounding reports to the contrary, these methods are expensive and ineffective, and the farmers simply do not use them. Officials and their scientists have both made a fundamental error: plastic is not something that can be dealt with by the natural world. The solution is to look for an alternative material or use policy measures to stop its use, and control the pollution at the source.

While it may be true that the large-scale use of plastic membrane increases production, it also lowers quality. All living organisms will suffer and lose quality if you force them to grow in an unnatural manner, such as cultivating them very rapidly. It can mean a loss of flavour, as well as pollution in the fields. Thanks to the use of plastic membrane and fertiliser in agriculture, I have seen garlic shoots thicker than my thumb – impossible 20 or 30 years ago – but the farmers themselves will tell you that the flavour is not the same. In the past, garlic would be covered with straw and natural fertiliser, but now plastic membrane and chemical fertilisers are used, and the taste has suffered.

Some will say that since the harvests are bigger, the farmers can earn more. But in reality, the extra income is divided up among other parties, with little left for the farmers themselves – even though they bear the risks. In practice, the merchants who sell the plastic, exporters, wholesalers, local traders and retailers all want to divide the extra income. Extra earnings that come from waiving agricultural taxes or from increased subsidies are quickly swallowed up by increases in the cost of raw materials – and the farmers are left to deal with the pollution. They remain at society’s lowest level, and never earn as much from greater harvests as they can by leaving the land and working in the cities. In one area, I saw the price of garlic shoots drop from 1 yuan (US$0.15) a kilogram to 0.6 yuan over the course of two days. Last year, freshly-picked garlic sold for 2.4 yuan a kilogram; this year it only fetches 1.4 a kilogram. With every household planting the same crops, the farmers are unable to withstand the market risk.

Covering the ground with plastic and chemical fertiliser is comparable to feeding it with opium: crops grow bigger and faster, but the land becomes unhealthy and reliant on artificial support. Nowadays, farmers often say that nothing will grow without lots of fertiliser. The plastic, fertiliser, pesticide, herbicide and additives accumulate in the soil and sap its vitality in the long term.

Farmers rely on the land for their living, and it is vital that we protect the land, rather than encouraging farmers to use unnatural methods for the sake of short-term profit. Yet the widespread use of plastic membrane has been promoted by the Ministry of Agriculture and government.

Instead of turning the earth white with plastic, we should be using organic material to make it darker: feeding straw to livestock to produce meat, milk and dung. This dung can subsequently be used to produce methane, and the residue can fertilise the fields. Increasing the organic content of the soil and improving its structure will allow high levels of sustainable – rather than short-term – production. Livestock and energy production will be increased, and the value added to the land will be much greater than using plastic. The use of organic fertiliser will reduce the volume of chemical fertilisers used, and eliminating the use of plastic will reduce costs and put a stop to this “white pollution”. These are all needed to provide a healthy path forward for China’s agriculture, and must be considered by the Ministry of Agriculture, the State Environmental Protection Administration (SEPA), Ministry of Land and Resources and the Ministry of Science and Technology.

Farmers’ income must be increased through appropriate measures, with increased production and increased efficiency going hand in hand, the land being protected and pollution reduced. Short-term methods such as the use of plastic membrane exploit the land without caring for it. In fact, these methods destroy the land – and should be discontinued altogether.


Jiang Gaoming is a professor at the Chinese Academy of Sciences’ Institute of Botany. He is also vice secretary-general of the UNESCO China-MAB (Man and the Biosphere) Committee and a member of the UNESCO MAB Urban Group.