Beating plastic pollution in agriculture

The application of razor-thin sheets of polyethylene film across farmlands began in the 1950s when agronomists noticed that it could successfully moderate soil temperature, limit weed growth and prevent moisture loss. All essential factors in crop production, this method was found to increase cotton, maize and wheat yields by an average 30%. The promise of increased yields at a relatively low cost formed a multi-billion dollar industry for agricultural plastics. According to Food and Agriculture Organization experts, agricultural value chains use 12.5 million tonnes of plastic products each year. Crop production and livestock combined accounted for 10.2 million tonnes (Mt) per year of plastics, followed by fisheries and aquaculture with 2.1 million tonnes and forests with 0.2 million tonnes .

Dangerous toxins released from the polyethylene film can remain in the soil for centuries. Known as white pollution, polyethylene residue is becoming increasingly prevalent in treated soils at levels of up to 300 kilogrammes (661 pounds) per hectare. Over time, this decreases soil porosity and air circulation, alters microbial communities, and compromises soil fertility. Polyethylene also releases carcinogenic phthalate acid esters into the soil, which, together with other synthetic pesticides can be easily absorbed by the crops. This is a significant risk to human health. What’s more, the polyethylene films used in the coverings are low density by design, which makes the plastic extremely difficult to biodegrade. Any waste from this process is rarely accepted by recycling facilities and often ends up in landfills and oceans, wreaking havoc on ecosystems around the world.

Plasticulture ie the application of plastics in agriculture cultivation, is fast becoming the most sought out technique to augment farm yields and consequent farm income. In India, it can come in handy to realize the overall aim of doubling farm income.

A wide range of plastics are used in agriculture including, polyolefin, polyethylene (PE), Polypropylene (PP), Ethylene-Vinyl Accetate Copolymer (EVA), Poly-vinyl chloride (PVC) and, less frequently, polycarbonate (PC) and poly -methyl-methacrylate (PMMA). These plastics are used in a wide range of applications including:

Micro-irrigation: This includes the use of drip irrigation and sprinklers in farms. With proactive steps being taken by various state governments such as making it mandatory for farmers cultivating sugarcane to switch to drip irrigation (Maharashtra) and further streamlining of subsidy disbursal mechanisms, the domestic micro-irrigation industry is on a firm footing with robust prospects.

Artificial ponds: Creation of artificial ponds using plastic to conserve water during the monsoons. Domestically, Rajasthan and Maharashtra are at the forefront of promoting pond liners in a big way and are witnessing robust growth prospects.

Greenhouses: A farming technique wherein the crop is grown in a controlled environment and is covered through firm nets or plastics through a frame.

Plastic mulching: A farming technique in which crops are grown through holes in a sheet, laid across the ground. It prevents the contact of soil with atmosphere and, hence, helps prevent moisture loss.

As with the concerns with plastics in other sector, there are issues with their application in agriculture also. Over time, film residue can decrease soil porosity and air circulation, change microbial communities, and potentially lower farmland fertility, scientists have found. Fragments of plastic film have also been shown to release potentially carcinogenic phthalate acid esters into the soil, where they can be taken up in vegetables and pose a human health risk when the food is consumed. Film fragments left in fields can also accumulate pesticides and other toxins applied to crops.

According to a study from a report released from the University of California and Santa Barbara, as of 2015, approximately 6300 Mt of plastic waste had been generated in the world, around 9% of which had been recycled, 12% was incinerated, and 79% was accumulated in landfills or the natural environment. If current production and waste management trends continue, roughly 12,000 Mt of plastic waste will be in landfills or in the natural environment by 2050.

The key benefits of plasticulture include:

Increase in crop yields (in excess of 20%, water saving (~30-40%) and

Saving in other agri inputs viz. agro chemicals & fertilizers. Plasticulture can well be imbibed as the mainframe system within the ambit of sustainable agriculture practices domestically.

Its effective implementation is likely to result in robust food grain production and consequent rise in agriculture GDP in excess of 4%.

Plastics are no doubt a ubiquitous and a ‘necessary’ material for humankind. The country has taken a slew of steps in recent months to ban use of single use plastics, mainly in the form of polythene bags and bottles. The use of plastics in agriculture could be the next big segment for plastic manufacturers to target, and that is going to be disastrous considering the effects on soil health, microbial communities, potential release of carcinogenic compounds into the food chain and also loss of commercial value to crops such as cotton.

There are alternatives. A recent UN Environment report discusses the use of:

Alternative natural materials obtained from plants and animals

Newer generation bio-polymers which are plastics made from biomass sources

The report highlights some relatively conventional alternatives to plastics – such as paper, cotton, and wood – as well as less obvious solutions including algae, fungi, and pineapple leaves – among others.

With regard to agriculture in particular, some of the solutions might come with a little more physical effort (using organic mulch) or others that come at slightly higher cost (biodegradable materials). Therefore, state and national policies have to come to the rescue to incentivize good and responsible behaviour. Steps such as those taken by smart cities like Muzzaffapur and progressive states like Maharashtra in banning single use plastics and enforcing penalties for non-compliance will certainly help. But we need to go beyond just ban of plastic bags and address its use across all sectors if we are to make a difference to contamination of our soil, water, food and air.

And while research and development helps develop more alternatives as commercial options, the traditional resource management principles of reuse, reduce, recycle will continue to hold true.

(The article has been authored by Arjuna Srinidhi, associate thematic lead, ecosystem-based adaptation at Watershed Organization Trust Center for Resilience Studies (W-CReS) and Divya Nazareth, researcher, climate change adaptation.)

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