Agricultural waste

Burning of rice residues in southeast Punjab, India, prior to wheat season

Agricultural waste consists mainly of cellulose, hemicellulose and lignin.[7] Agricultural waste is poorly digestible and in unprocessed form not widely suitable as animal feed.[8]

Sometimes, agricultural waste is burnt, either as biomass in power plants or simply on land.[9] Burning agricultural waste on land is called stubble burning and is still common in countries like China and India where a third of the world's population lives.[10][11] Then, instead of being reused to make new products, valuable substances in agricultural waste are turned into CO₂, smog, particulate matter and ash.[12]

Today, burning of agricultural waste is increasingly banned and pruning biomass is used for applications, including woodchipper for bedding soils. Three categories of substances are mainly extracted from agricultural waste: proteins, materials containing cellulose and bioactive substances such as essential oils and carotenoids.[13][14] The increasing ability to isolate such valuable substances in a pure form increases the economic value of agricultural waste.[15]

Farmer burning, on a large scale, pruning and agricultural waste, leading to smog and loss of organic matter, among other things

The world's population and livestock size is growing and that is where the rising demand for food comes from. The average European is expected to consume 165 grams of meat per person daily.[16] People around the world consume an average of 75 pounds of meat per person per year.[17] Global meat consumption has more than doubled since 1990.[18] Producing 1 kg (2.2 lb) of beef requires an average of 25 kg (55 lb) of crop.[19] The production of all this food also results in more and more agricultural waste.

In large quantities, agricultural waste can have a negative impact on the environment and habitat, for example through greenhouse gas emissions, the creation of unpleasant odours, and toxic liquids that can infiltrate water sources.[20][21]

The frequent and large-scale burning of agricultural waste also has negative health impacts on people who are exposed to toxic smog through the fires. Particularly in early autumn, large-scale burning of agricultural wastes worldwide results in frequent smog.[22]

The World Health Organisation (WHO) identifies smog due to agricultural waste burning as one of the largest sources of ambient air pollution. All forms of air pollution combined cause 7 million deaths annually, including 650,000 children.[23]

Schematic representation of the waste hierarchy, a waste management standard

Besides the impact on air quality, burning of agricultural waste in fields also has a negative impact on soil fertility, economic development and climate.[24] The absence of environmentally friendly agricultural waste management further leads to animal suffering, water pollution, fertilisation, and decline in biodiversity, among others.[25]

According to the waste hierarchy, burning agricultural waste for the sake of energy generation is a less environmentally friendly treatment method than recycling or reusing it. Moreover, incineration for energy generation can be done once, while consumer goods (such as paper made from agricultural waste) can be recycled another seven times.[26] After this, it can possibly still be burned for energy, or even converted into biogas or compost through fermentation.[27]

In an effort to reduce the negative impact of agricultural waste on earth, some companies have focused on developing new technologies that allow agricultural waste to be put to meaningful use and returning to traditional non-combustion use.

California accepts burning as a tool to remove weeds, prevent disease and control pests, especially for rice and pears. Burning is allowed in Permissive Burn Days.[28]

Several companies worldwide use leftover agricultural waste to make new products.[29] Reusing agricultural waste is in line with the desired circular economy. In today's economy, primary raw materials are mostly used.[30] Agricultural waste, on the other hand, is a secondary raw material. They are residual (waste) streams from an existing industry that can serve as raw materials for new applications. Increasingly reusing materials as raw materials for the production process contributes to the EU goal of achieving a circular economy by 2050.[31]

Most farmers in developing countries are not aware of the alternative applications and therefore consider burning as the best option.[38] Therefore, large-scale awareness programmes are needed to;

• Recognise agricultural waste as a waste stream.
• Educate on the adverse effects of low-grade waste treatment methods such as incineration and landfill.
• Educate farmers on the availability of economically viable options higher up the waste hierarchy and their benefits to themselves and the environment.

• Environmental monitoring
• Eutrophication
• Plasticulture
• Plastic pollution
• Pruning