Restoring soil fertility: An urgent matter

Studies have shown that the decline in crops yields is associated with the loss of soil quality. Soil fertility is threatened by erosion – caused by water and wind – nutrient depletion and salinization, among other problems.

Although, on a global scale, soil fertility loss is unlikely to be a major threat to food security, the impacts are going to be felt more acutely at the local and regional levels, where farmers are too poor to overcome the damage. With mechanized agriculture billions of tons of carbon in the soils are released to the atmosphere as carbon dioxide and methane; lack of carbon in the soil makes productivity inefficient.

Global warming is bound to give the farmers more troubles. As the ground heats up, organic matters decompose more easily, reduce soil fertility, release carbon dioxide, further exacerbating the warming effect. Soil erosion has been contributing to global warming as some of the carbon in the soil-laden water running off fields escape into the atmosphere. Deserts are expected to expand as the interiors of continents become drier and erosion would worsen if soils dried out and violent storms became more frequent.

A warmer world is likely to have less organic matter in its soils giving tremendous problems for farmers in the marginal areas of developing countries where critical regions of soil degradation persists. Here high priority should be given to soil restoration and carbon sequestration (storing carbon in soil securely so it is not immediately re-emitted). These regions include sub-Saharan Africa, central and south Asia, China, the Andean region, the Caribbean, and the acid savannas of South America.

Fortunately, something can be done. Managing soil erosion and retaining more carbon can offset fossil fuel emissions by five to 15 percent each year will increase yields. Once sequestered, carbon can remain in the soil for the next 20-50 years so long as appropriate measures are used.

One proven method of resisting erosion, restoring soil fertility and boosting crop productivity is the use of organic compost which is a natural fertilizer supplying soils with vital plant nutrients and aiding soils to retain water and air. Too, it restores soil carbon, crucial in maintaining consisting productivity through improvements in water and nutrients holding capacity.

The materials for composting are mixed with soil and water, then left to decompose for some time. The heat generated during the process destroys weed seeds, fungul diseases, parasites and pests.

(Antonio M. Claparols is president of the Ecology Society of the Philippines and IUCN regional councilor)