Basically, inappropriate management practices, poor irrigation water quality and climate change may increase the problem of soil salinity. For countries like Nepal, certain agricultural management practices can worsen soil salinisation, which include overgrazing of pasture lands, mono-cropping practices, inappropriate use of nitrogenous fertiliser and leaving farming lands barren
World Soil Day is held annually on December 5 to focus attention on the importance of healthy soil and to advocate for the sustainable management of soil resources. This year, it was marked with the slogan "Halt soil salinisation, boost soil productivity" to raise awareness of the importance of maintaining healthy ecosystems and human well-being by addressing the growing challenges in soil management.
While spreading awareness, the question arises, what is the importance of such events for the smallholder farmers, whose agricultural lands have been extensively cultivated? The poor socio-economic condition of the Nepali farmer is directly related to the degradation of natural resources, mainly soil, land and forest, which also eventually determine sustainability.
In addition, soil has been considered as an inferior resource, and negligence is shown by both the people and the government.
World Soil Day reminds us how our soil is under threat from deforestation, overgrazing, tillage and unsustainable agricultural practices.
Do we need to care about soil salinisation in agriculture? Salinisation of soil is an excessive accumulation of water-soluble salts. Because all irrigation waters contain water-soluble salts to some extent, the more irrigation water is used to increase food production, the more saline the soil becomes.
Most of the crop plants are sensitive to salinity caused by high concentrations of salts.
The book, "The Soils of Nepal", published in October 2021, reported that Nepal does not have a significant soil salinity problem.
It is because rainfall in most of the areas is about 1,000 mm per year, enough to leach the salts from the soil surface. Some arid and semiarid regions of Mustang and Manang districts can develop salinity problem, but the area is small, and melting of snow often leaches the salt. In addition, there is no direct problem of sea-level rise and possible saltwater overtopping and inundating agricultural lands.
Salinisation is a huge problem in arid and semi-arid regions, where irrigation is widely practised.
Due to poor drainage, it leads to water-logging and raises the water table. It brings the salts in the sub-surface nearer to the surface. When water evaporates, salt is left around the roots of plants, preventing them from absorbing water. Crops start wilting and die due to the inability to take up enough water. Similarly, sea level rise induces seepage into areas lying below the sea level. Due to high evapotranspiration and lack of rainfall to leach the soils in arid regions, winds in coastal areas can blow moderate amounts of salts inland. Accumulation of salts not only degrades the soil and crop productivity but also increases groundwater pollution.
Today 9 percent of the total land area worldwide is affected by salinity. In Bangladesh, there is a growing practice of converting farmland into shrimp farms as their land gets inundated due to rise in the sea level. Farmers in Israel share a similar problem of soil salinity because they are using the Mediterranean Sea as the main source of water for agriculture, although they are adopting desalinisation as well as recycling water technologies to meet agriculture's water requirement.
Basically, inappropriate management practices, poor irrigation water quality and climate change may increase the problem of soil salinity. For countries like Nepal, certain agricultural management practices can worsen soil salinisation, which include overgrazing of pasture lands, mono-cropping practices, inappropriate use of nitrogenous fertiliser and leaving farming lands barren.
Many farmers believe that increasing the amount of nitrogenous fertiliser will give a good yield. This is not true as it could lead to reduced crop yields and degraded soil and environmental quality from soil acidification, nutrient leaching and greenhouse gas emissions. Mono-cropping practices deplete the soil nutrients and enhance soil erosion over time. Barren fields must be covered with vegetation to protect it from erosion.
More importantly, we should avoid continuous livestock grazing on the same piece of land because such soil will have less tendency to hold water, which could lead to desertification.
We should plan rotational grazing, which can mimic nature and help in grassland restoration.
Many climate models project a decrease in rainfall in the dry season and an increase in rainfall during the monsoon in South Asia. Nepal has already seen an increased frequency of droughts in recent years. The drought of 1994 affected 35 districts of the western hilly and Tarai regions.
In 2008/2009, the drought affected 40 districts, where about 50 percent of the total precipitation got decreased.
Sometimes these droughts have been followed by floods and heavy rainfall, which not only reduce crop productivity, but also soil productivity.
Farmers cannot make rain or make it stop. But they can do things to make their land less vulnerable to the effects of extreme events.
We all are responsible for keeping the soil alive and healthy. A handful of healthy soil contains more living organisms than the current human population on the Earth. Imagine that soil to be like a giant stomach that can digest everything – woodlice and springtails break up larger pieces, round worms and single cell organisms take care of smaller ones, bacteria and fungi colonise the material, earthworms eat, dig tunnels, fertilise and aerate the soil – all these results produce fertile humus containing minerals.
Whenever you get a bunch of flowers from someone, the first thing you will do is put your face on the flowers and smell them. So, if you are showing love to the flower, why not take that further step and make sure that it is the healthiest thing that you could possibly have on Earth?
Panday is a soil scientist
A version of this article appears in the print on December 09, 2021, of The Himalayan Times.