Recycling nutrients in soil
by Njoki Thuo, Agricultural Specialist – Kenya.
For most people, soil is just a medium which covers the ground and sometimes makes things dirty. My dictionary gives me two definitions of soil. The first is; ‘the upper layer of the earth in which plants grow, a black or dark brown material’. The second is; ‘make dirty’.
But, soil is much more than these definitions. For many people, it is their life.
One large group of people who depend on the soil are the world’s 500 million smallholder farmers. These small-scale farmers produce around 70% of the food consumed in the world. So this means that soil is important to us too!
But there is some bad news when it comes to soil. Soil degradation is ongoing with unprecedented speed of 12 million hectares per year. Despite this, small-scale farmers must produce to feed the ever increasing population. To make matters even worse, many farmers in the developing world lack information about soil degradation.
Recycling nutrients in soil
According to Fertile Ground Initiative and Wageningen University, soil degradation is often preceded by unbalanced nutrient management. Nutrients are the most manageable part of the soil, so there is potential to intervene and prevent degradation. Integrated soil fertility management aims to create a circular nutrient economy. This balances the supply and demand of nutrients.
In this situation, supply comes from the soil. This is supplemented by external products in the form of either chemical or inorganic manures. The demand is the demand for food from the world population, in the form of plants.
Cities and towns are quickly becoming vast nutrient sinks – food brought in and no waste out. We need ways of ensuring that the nutrients deposited in cities find their way back to the rural farms; recycling nutrients!
How do we recycle nutrients in soil? Well, organic waste in cities is both a bother and a resource. Organic food waste is a bother to the urban dweller because of the foul smell it gives off if left in the open unattended. But it can be a resource to the farmer when well decomposed.
Organic fertiliser vs. chemical fertiliser
Is organic fertiliser better than chemical inorganic fertiliser whose effect is seen fast? The answer is yes! Although organic fertiliser might not be fast acting as chemical fertiliser, manure generally improves the soil. Because of this, they have even been named ‘soil conditioners’ – in that they condition the soil overall.
In ‘DIRT! The Movie’, Vandana Shiva (PhD) says,’ In traditional agriculture, the soil is the mother who gives, to whom you must give back. To treat soil as the sacred mother is the best thing you could put in your relationship with the earth. Soil is recognized as the source of all fertility’.
With this, soil ought to be respected as much as one respect a mother. Continuous use of chemicals is not what one would do to a parent! Tremendous use of the chemical fertilisers on the soil causes various side effects to the environment.
Compost from food waste offers an opportunity to improve soil health in contrast to mineral fertilisers that only improve soil’s chemical properties. Compost improves all the three soil properties – physical, chemical and biological properties – thus offering the best way to make soil more climate change resilient.
Posted 19 October 2016 |