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Compost: A two-way solution for climate change and managing food waste

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Compost: A two-way solution for climate change and managing food waste

Food loss is exacerbating hunger and food insecurity globally.


According to the United Nations Environmental Programme (UNEP) Food Waste Index, 1.3 billion tonnes of food is either lost or wasted yearly, across the world.


Also, a report published in July 2021 by the Food and Agriculture Organization, the World Food Programme, the World Health Organisation, and other UN agencies, revealed that one-tenth of the global population was undernourished in 2020 (up 118 million from 2019).


With world hunger on the rise, it is becoming imperative to reduce food waste and this is not only because of hunger. It is also because food loss and waste contribute to climate change, biodiversity loss, and pollution.


Food loss and waste generate an estimated 8-10 percent of global greenhouse gas emissions, especially methane (a more potent greenhouse gas) which exacerbates the climate change crisis. Also, they use land and water resources which increasingly put pressure on biodiversity.


No doubt, food loss and waste occur across the entire food system. However, individuals and households are complacent (almost 570 million tonnes of food loss and waste produced are from homes. This means households play a critical role in the food waste-induced climate crisis.


In order to reduce the organic waste we generate in our daily lives and mitigate the effects of this waste on the environment, we need to properly compost inedible or unused food.


According to guidelines issued by UNEP and the Institute for Global Environmental Strategies (IGES), the practice of composting is one of the best options for reducing food waste, managing organic waste, and reducing greenhouse gas emissions that affect climate change.


What makes a good compost?


People have different ideas about what makes good compost and what does not. For example, some people keep meat scraps or paper out. Many people agree that manure from horses and cattle is good for compost, but feces from dogs and cats are not.


As a general rule, plastic, metal, glass, and anything else that is not directly from the earth is not good for compost as it will not break down. Plants that poison people or other plants, like castor beans and eucalyptus, will not make good fertilizer.


Also, large branches or very thick leaves will break down too slowly. If paper or cardboard is added, it is best if it is shredded and kept damp so it can break down more easily. Meat, bones, and greasy kitchen waste attract pests and break down very slowly.


How to make compost


There are two ways to make compost: slow compost and fast compost. They depend on the amount of compost you want to make in a given period and the amount of space you have.


Making slow compost


This way of making compost requires little space and little work and produces compost in about 6 months.


Dig a hole in the ground 60 cm by 60 cm wide and 1 meter deep. Put a mix of dry and wet organic waste in the hole.


Cover every 20 cm depth of organic material with 3 cm soil and add water to keep it damp (just moist, not soaked).


Cover the hole to keep the rain out. After a week, the compost should start to break down. The pile of waste will heat up and shrink as it breaks down.


Making fast compost


This is a way to produce a lot of compost in 1 to 4 months if you have a large open space.


Choose a flat area 1½ meters wide by 4 meters long. Mark the area with stakes. Loosen the soil to a depth of 30 cm. This will help the compost pile drain, and help worms enter the pile and break down wastes. If the soil is very dry, water it.


Find 2 big sticks about as tall as a tall man. Put them upright in the middle of the loosened earth. Do not sink them too far down, because later you will take them out.


Mark lines on the posts at 20 cm from the ground, then 5 cm above that, then 2 cm above that. Repeat these marks 7 or 8 times until the whole post is marked with measuring lines.


Make a pile of food and plant wastes (a mix of dry and wet materials is best) up to the 20 cm mark on the sticks. The pile should cover the entire area of loosened earth and be of an even height. If it is very dry add water until it is moist, but not soaked.


Put a layer of animal manure up to the next line (5 cm). Fresh manure is best because it is hot and will help the compost break down quickly. On top of the manure, add a layer of soil up to the next mark (2 cm).


Continue building up layers in this order as organic material becomes available. Add a little water to each layer so the entire pile will be damp. Over time you can build the pile up to a height of 2 meters or so. Then cover the entire pile with a layer of soil, and wet it more.


After 2 days, remove the sticks. This will leave wide holes for air to enter the pile and help it break down. After 3 weeks, turn and mix the pile with a shovel. Do this again every week or so. The more you turn it, the faster it will break down.


The pile will heat up and shrink as it breaks down. After 1 to 4 months, the pile should turn into sweet-smelling, dark, fertile soil.


How do you know your compost is working?


No matter which method you use, there are ways to know if your waste is becoming good compost and not just a big, stinky mess.


To break down, compost needs both wet wastes like food scraps and dry wastes like straw, brown leaves, husks, or shredded paper.


A working compost pile heats up as the waste breaks down. If the pile remains a pile of rotting food rather than heating up and turning to soil, it may need more dry, brown plant matter.


In some instances when a pile does not heat up, it could be from too much or too little water. Turn the pile with a shovel. If it is very dry, add more water. If it is very wet, add less water. Covering the pile with a black plastic sheet will also help it stay warm.


If the pile smells bad or does not shrink, it needs more air. Turn the pile with a shovel or open holes by poking sticks into it.


If the compost has ants, add water. If it attracts flies, it needs to be covered better with soil. After a while, the compost should turn into sweet-smelling, rich black soil.

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