Like humans, soil is a living system. Breathes like us. Soil also needs nutrients. Soil is healthy and fertile if there is a balanced availability of air, water and nutrients. It is from the soil that we get food.

Soils purify water, store carbon and protect biodiversity. In addition, the necessary vegetable food for animals and birds also takes nutrients from the soil. 

Soils of such importance are being neglected at the policy and program level, which is putting them at risk of erosion, pollution and unbalanced farming systems day by day. According to the Food and Agriculture Organization of the United Nations, about 33 percent of the world's soil has been degraded, which is projected to have negative consequences for food security and environmental balance.

In the case of Nepal, if there is only a few hours of heavy rain (about 50 mm) in the Terai region, about 300 grams of soil per parcel will be washed away from the exposed soil at one time. Such damage should be considered extremely devastating. Because it takes hundreds of years for nature to restore the soil fertility equal to the same damage. The theme of World Soil Day 2024, 'Soil Improvement: Testing, Monitoring and Remediation', also conveys the message that soil should be healthy for a sustainable future. This brief article mentions the current soil challenges in Nepal and the necessary solutions to restore and protect this living system. 

Soil in health perspective

When you go to the hospital for a health check-up, various indicators like temperature, blood pressure and pulse rate are measured. These measurements help you understand your overall health status. Similarly, soil health is also measured by various indicators. Just as early resolution of health problems is important to staying healthy, the principle that 'prevention is better than cure' applies to soil health. Proactive measures are needed to prevent further soil erosion. For example, in Nepal, challenges such as soil erosion, nutrient imbalance and pollution are increasing rapidly, which shows the need to take immediate steps to protect and restore soil health. 

Soil degradation can be considered as one of the main reasons for reducing soil fertility or land productivity. This erosion process is aggravated by activities such as slope erosion, landslides, bank erosion, and deforestation. Erosion removes the top layer of soil (called topsoil) from one place and transfers it to another. It takes about 30 years to re-establish the top layer of this fertile soil. Such erosion of soil from arable land leads to problems such as reduction in crop production, damage to drainage systems, deterioration of water quality, and eutrophication of water sources (a gradual increase in the amount of phosphorus, nitrogen and other plant nutrients in the reservoir).

When soil erosion increases, it degrades faster than the soil formation process. In Nepal, 369 million metric tons of soil is lost annually, with 34 percent of arable land being affected by water erosion. For example, in the barren lands of the Koshi basin, up to 22 tonnes per hectare of soil has been found to run off annually.

Although the average usage rate of chemical fertilizers in Nepal has increased from 16.7 kg per hectare in 2002 to 97.8 kg per hectare by 2021, farmers are still facing challenges in proper management of fertilizers. These challenges are particularly related to the four basic principles of food management (right source, right amount, right time, right place). The main reason for not adopting these principles is lack of awareness and reliance on traditional farming systems. Apart from this, neglecting the various sources of organic fertilizers that are used traditionally is another major factor that leads to imbalance of the nutrient cycle in the agricultural system.

Excessive use of urea as a nitrogenous fertilizer is increasing soil acidity. Due to acidity alone, about 40 percent of Nepal's arable land has been affected and crop productivity has decreased. Along with this, the use and management of balanced nutrients has not been possible due to the fact that various aspects related to agriculture are not included in Nepal's fertilizer recommendation system. Although the need for site-specific, balanced fertilizer application based on soil testing has been realized, there is a lack of establishment and management of a soil health card system in agricultural extension and related public bodies.

The impact of microplastics

Microplastics are tiny pieces of plastic, less than 5 millimeters in size, or about the size of a pencil eraser. Microplastics also play a major role in soil pollution. According to previous studies, around 2.1 kg of microplastics are found in fertile soil of Pratikatha. Major sources of microplastics are broken down plastic mulch, sewage sludge and irrigation water. These plastics reduce the activity of soil microbes and microbes by 30 to 50 percent and mix with harmful chemicals to make them more toxic.

According to a study conducted in Fewatal in 2021, the amount of microplastics in surface water was found to be about 3 particles per liter in winter and about 1.5 particles per liter in rainy season. Microplastics also increase exposure to pesticides and metals, which directly impact crop production and food security. What is even more alarming is that by eating food contaminated with such plastics, people are consuming about 50,000 particles annually. For all these reasons, the United Nations Environment Program has listed microplastic pollution as one of the world's top 10 environmental risks.

There are not only microplastics in the soil of Nepal, but also other problems such as nutrient runoff, loss of organic matter and soil compaction, which are known regionally or globally. The Intergovernmental Technical Soil Panel of the Food and Agriculture Organization of the United Nations has identified ten major soil challenges globally. Its challenges include soil erosion, depletion of soil organic carbon and nutrient imbalances. Continuing to ignore these problems will have a negative impact on food security and environmental balance. On the positive side, it is possible to reverse soil degradation. The soil can be returned to a healthy state if the principles of continuous soil inspection, maintenance and proper management are followed. 

The way forward

Soil degradation is a problem that challenges not only the balance of environmental resources but also human existence. In a country like Nepal where most of the population depends on agriculture, an integrated effort at the scientific, policy and social levels is necessary to find a long-term solution to soil degradation.

Basic and ongoing efforts can include soil degradation control, balanced fertilizer use, improvement of biological and organic elements in soil, public awareness campaigns and literacy programs for farmers on soil management. To ensure the sustainability of these efforts, it is important to use soil health indicators as a guide, just as indicators are used to measure human health. 

It is a need of today and a sustainable solution to bring the farmers to a state where they are ready to use the recommended fertilizers by testing the soil of their fields to understand the actual nutritional status. It is necessary to expand research and dissemination services to make Malkhad recommendation system location-specific and timely. Integrated management of soil fertility through balanced use of natural and non-natural resources is essential to keep the nutrient cycle in a functional/active condition.