Soil Conservation

It is easy to take soil for granted. But this priceless material is what sustains human civilisation by enabling the cultivation of crops. Only about 7.5 per cent of the earth’s surface is said to provide the topsoil we rely on for agriculture, and it is extremely fragile. And guess what? It is disappearing 10 times faster than it is being replaced, imperilling the food supply. It takes thousands of years to create an inch of fertile topsoil, but it can be destroyed in no time. 

According to a study, the world is ploughing through topsoil at an alarming rate as if there is no tomorrow. Making matters worse, around 12 million hectares of land is found to lost to desertification every year, putting about 20 million tonnes of grain out of the food supply. In addition, natural causes, such as soil erosion, flooding, climate change, soil acidity resulting from commercial and intensive farming systems, loss of organic matter and nutrients, and soil pollution caused by rapid urbanisation and industrialisation, have contributed to the continuous soil loss worldwide.  

What's more, soil quality is deteriorating due to the low adoption of healthy production techniques, unbalanced use of chemical fertilisers, limited use of organic fertilisers, and uncontrolled use of agrochemicals. Relentless tilling and disturbance from farm vehicles have paved the way for wind and water to whisk this invaluable resource away.  These factors have created serious challenges to food security as well as the ecosystem. 

It is to raise awareness about these critical issues and mobilise global efforts for the sustainable management of soil fertility that World Soil Day is observed annually on December 5. The nation is said to lose about 1.7 millimetres of topsoil annually. As per the Digital Soil Map (DSM) data, of the total soils tested, about 54 per cent were found to be acidic, 29 per cent neutral, and 17 per cent alkaline. The soil in eastern Nepal was found to be more acidic than that in western Nepal. This is a grave issue that must be addressed quickly. Acidic soil is toxic to plants, leading to their poor growth, nutrient deficiencies, and stunted root development. 

Most of the soils have low levels of organic matter. About 37 per cent of soils have low organic matter, 45 per cent have medium levels, and 18 per cent have high levels. Soil in the Tarai region, particularly, has lower organic matter content than that found in the hilly and mountainous region. Experts have cited the low use of cow dung or compost and green manure, unbalanced use of chemical fertilisers, increasing pesticide use, and a lack of crop rotation as the reasons for the deterioration of soil quality.

Also contributing to the degradation are intensive cultivation using unscientific methods, complete removal or burning of crop residues after harvesting, continuous soil erosion, and increasing industrial pollution. To mitigate these problems, it is necessary for farmers to test their soil periodically, use appropriate technologies, and apply compost fertilisers to preserve soil health.

As the layer of fertile topsoil thins, it gets increasingly difficult to grow plants. It is this thin layer of soil that is the difference between a thriving human civilisation and one going extinct. Only by urgently adopting sustainable agricultural practices as recommended can we preserve soil and ensure a robust food supply.