26
Apr

A ‘trash’ course on Ag Plastics

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The last time I attended a talk on trash was at the ICRISAT headquarters based in India, where a group had come together to work towards making the campus plastic-free. While I did know of the many dangers of polythene use on the environment, I had never thought of its effect on soil health, which is of prime importance in the field of agriculture research.

Early this week, in view of Earth Day, there has been a media drive on ending plastic usage. However, the reportage tilted heavily towards plastic pollution in the oceans and I couldn’t find much about its impact on soil.

So, what does plastic left on the soil do to it? We know that it can turn oceans into plastic soup  and make a mess of the climate, so imagine what it does to our farms where the use of plastic is growing by the day.

Ironically, plasticulture was introduced in agriculture to mitigate extreme fluctuations in weather, especially temperature, rainfall and wind – to help grow crops in hot desert-like conditions and even in cold regions by providing the needed protection against frost.

When you read through the many benefits of plastic film mulch, the feeling you get is akin to somebody waving a magic wand on a farm to fix all problems: Weeds suppressed, water conserved, soil temperature and moisture controlled, and near-zero soil erosion and fertilizer wastage.

This technology that seems like a boon, comes with loads of pollution risks. A study shows that large amounts of residual plastic film negatively impact soil structure, water and nutrient transport and crop growth, disrupting the agricultural environment and reducing crop production.  Even the soil fauna, such as bacteria, fungi and earthworms that help nourish the earth, are in serious trouble.

What if the only soil you had was made of plastic bits…

The growing use of plastics in agriculture i.e. ‘ag plastics’ is a big cause for concern – from irrigation drip tubes, nursery pots, silage bags, plastic mulch film and row coverings to plastic greenhouses, it’s uses are manifold. Right now they are life-savers for farmers, but we urgently need to continue with research to find alternatives.

The global agricultural plastic films market alone was estimated to be US$ 7.92 billion in 2017 and is projected to reach US$ 10.57 billion by 2022 (Business Wire). The highest growth is predicted in the Asia Pacific region.

Seems like a plastic epidemic is in the making. An article in Bloomsberg shows how plastic mulch has ruined the soil on Chinese farms. Yields grew by 30%, but the long-term damage was massive. Plastic residue, known locally as ‘white pollution’, is present at levels of 60-300 kg per hectare in some provinces. In China, about a fifth of arable land contains levels of toxins exceeding national standards (2014 government estimate).

Plastic in your spinach

Most Hyderabadis like me often worry over our vegetables, we know they are grown on polluted lake beds (read dried up drainage canals). All along I was worried about the heavy metals in my spinach, now I am wondering is there plastic too? Are our wastewater treatment plants even equipped to deal with it? And I find an article that gives me more cause for worry.

The Norwegian Institute for Water Research says that the consequences of transfers of microplastics from urban wastewater to agricultural soil barely have been considered by researchers and authorities, particularly in lieu of the extended attention directed at microplastics in the ocean. That’s a surprising knowledge gap.

Is bioplastic a better alternative to petroleum-based plastics?

All news need not be bad. There are some that bring a ray of hope, like my first encounter with bioplastic. It was at a Women’s Day event on campus – millet kichadi served in a biodegradable sugarcane bagasse bowl. Impressive, but I did recall my brief chats and mails with ICRISAT scientist Dr Ashok Kumar, and I knew that something even more eco-friendly was in the making.

When I first heard of high biomass sorghum and pearl millet varieties with potential for ethanol production for use in biofuels, it was great news. And that the bagasse from ethanol production is perfect raw material for bioplastics is even better news. ICRISAT’s ‘power plants’ unlike the water-guzzling sugarcane, thrive with less irrigation and do not compromise on food security as the grain is used for human consumption.

While innovations like these are promising, there are many issues that are open to debate. For starters, how biodegradable is bioplastic? Does it need special equipment or does it decompose in your regular compost pile?

And then there’s the debate on – should we go in for biodegradable bioplastics to abet our use-and-throw culture or is the fully reusable/recyclable ‘plantbottle’, partially made from plants, a greener option? Questions always…

Author:

Jemima Mandapati,
Senior Communication Officer,
Strategic Marketing and Communication,
ICRISAT.

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