Crop Residue Recycling

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Agricultural activities generate waste from animal husbandry, crop harvests, fertilizer or pesticide emissions to air, soil and water and even food spoilage.

Harvest waste, also referred to as crop residue, is generated at the time of harvesting and processing the crop. For standing crops that are harvested by mechanised harvesters, this consists of crop stalks left standing in the field.

There is usually a narrow pre-monsoon window during which farmers needs to harvest, prepare the land and sow the next crop. Let’s say a farm grows paddy and wheat in rotation. After the paddy is harvested, the wheat is to be sown. Sowing must happen before the monsoons arrive. While harvester machines speed up paddy harvesting, they leave behind paddy stalks that then need to be cleared before the sowing can begin.

Due to shortage of time or to avoid the expense of employing labour and more machinery to clear the fields, farmers have found it more convenient to burn their fields instead.

Burning causes more problems than you think

While seemingly cheaper and better, burning harvest waste, especially on the field actually isn’t, for various reasons.

Most visibly, crop residue burning emits very large amounts of air pollutants, which travel for hundreds or even thousand of kilometres, affecting the health of millions in their wake.

Burning also leads to loss of biodiversity, microorganisms, nutrients and moisture; the soil hardens and soil erosion increases. In time, these effects increase the requirement for water and fertilizers, further increasing the farmers’ cost of production.

Farmers in China, Brazil, India, Indonesia, Mexico, Nigeria, Thailand, the US and the Russian Federation have contributed substantially to crop residue burning and its associated downstream problems.

What’s the solution?

Rather than burning the residue, there are alternatives, which when implemented can possibly contribute to soil health or even supplement farmer income:

  1. Using as animal feed
  2. Accelerating decomposition on fields
  3. Convert to bio-char
  4. Use for mulching
  5. Cultivate mushrooms

We encourage urban farmers to also explore the ways of nourishing their kitchen gardens using harvest waste.