Composting: let's give the soil something back

28 percent of the world's agricultural land grows crops that are wasted

One of the main goals of the International Year of Soils is to raise awareness about the importance of soils for food security and nutrition. But what actions can we carry out to safeguard our soils and guarantee a sustainable and food secure future?

Each year one third of food produced is wasted. Not only does this lead to major economic losses but the natural resources used for growing, processing, packaging, transporting and marketing our food are also wasted, with greenhouse gas emissions increased in vain.

How does food wastage impact on our soils and on sustainability?

With an expanding global population, increased food production, competition for land and water resources and the impact of climate change, our soils are under a lot of pressure.  Not using roughly one-third of the food produced globally means that our natural resources, including soils are unnecessarily misused. Decreased soil health leads to further use of synthetic inputs that, if overused, could cause pollution and eventually, loss of biodiversity and arable land.

It is estimated that 28 percent of the world's agricultural land grows crops that are wasted. In the process, 250 k of water goes to waste and the carbon footprint of food produced and not eaten is estimated at 3.3 gigatonnes of CO2 equivalent*. With 33 percent of the world's soil degraded, it's about time we stop food waste and start giving the soil something back.

How can we reduce food loss and waste?

Each actor along the food chain has an important role in reducing the food wastage footprint. Food producers can invest in better harvest and storage technology to avoid food loss. Food retailers can reduce prices of 'imperfectly' shaped vegetables and donate imperfect, yet edible groceries to those in need. Finally, policy makers can enhance the ability of producers, retailers and consumers to stop food waste. Investing in post-harvesting processing, revising laws around sell-by-dates and launching awareness campaigns to inspire consumers to pay more attention to waste are equally important.

Reducing landfills through investment in transforming suitable food waste into compost and biogas is also central to soil enhancement.

What is composting? Is composting of suitable food waste a viable action?

Perhaps, one of the most effective ways of using wasted food is recycling it through composting. By transforming food waste into compost we can give precious nutrients back to the soil, while reducing and reusing the waste produced at home and collectively in landfills. Composting is the natural process of 'rotting' or decomposition of organic matter such as residues, animal wastes and food garbage by microorganisms under controlled conditions. Compost is important because it enhances overall soil health and its resilience to shocks such as drought, including climate change adaptation.

Compost is a rich source of organic matter, a substance vital for air, moisture and nutrient retention. Soil organic matter plays an important role in sustaining soil fertility, and hence in sustainable agricultural production. In addition to being a source of plant nutrients such as nitrogen (N), phosphorus (P) and potassium (K), it improves the physico-chemical and biological properties of the soil. Advantages for the soil include:  

1. Improved physical properties

  • By facilitating farm management for seeding
  • By increasing moisture retention capacity
  • By reducing risk of erosion
  • By regulating soil temperature
  • By reducing water evaporation and regulating the moisture

2.  Improved chemical properties

  • By providing macronutrients such as N, P, K and micronutrients.
  • By improving cation exchange capacity

3.  Improved biological activity

  • By providing organisms (such as bacteria and fungi) which transform insoluble materials into soil nutrients for plants and degrade harmful substances
  • By improving soil conditions and adding carbon to maintain biodiversity, micro- and macrofauna (earthworms).

These advantages manifest themselves in reduced cropping risks, higher yields and lower dependence on inorganic fertilizers, supplemental water and pesticides for farmers. By strengthening and replenishing the soil, compost ultimately helps the soil resist erosion by wind and water by allowing water to enter the soil better which can stop showers building up into a flood. This also reduces soil erosion. Compost is economically viable and helps farmers improve the productivity of their soils and their income.

Everyone has a role to play

Composting is a simple, yet often overlooked method for tending to soil health. Farmers certainly play a central role in preserving soils but everyone can contribute in their own way. You too can make a difference by composting your organic residues and adding compost to your flower or vegetable garden, to your house plants or by getting involved in neighbourhood compost gardens.

Teach your children about reducing food waste and composting, saving our soil means the commitment of generations to come!

*FAO 2013 (Food Wastage footprint, Impact on Natural Resources)


Manual de Compostaje del Agricultor

On-farm composting methods

How to make and use compost

Food Wastage footprint, Impact on Natural Resources




Share this page