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Eroding Soil Fertility


According to American agricultural scientist John Melar, who has been working in agricultural planning in Nepal since the 1950s, Nepali soil was the most  fertile in South Asia until just twenty five years ago. But it has now become the poorest quality in the entire region.


The fertility of Nepalese soil is fast being eroded by the excessive use of chemical fertilizers and the adoption of unscientific agricultural methods at a time when the deteriorating quality of foodgrains and vegetables is posing a grave problem for the health of human beings. 

Increased use of chemical fertilizers in agriculture has brought about a decrease in the numbers of beneficial life forms available in the soil, leading to an increase in the resistance capability of harmful insects, making them more hazardous than before. 

Since continuous crop cultivation results in a progressive decline in soil fertility, sustainable agricultural productivity requires sustained measures to improve fertility.  This means that chemical fertilizers used should be tailored to the soil and the crops being grown, and special attention should be paid to the use of organic fertilizers.

No doubt, the production and use of chemical fertilizers were a great help in bringing about a green revolution against the backdrop of burgeoning human population in South Asia.  This resulted in favorable publicity for the use of chemical fertilizers in agriculture.  Farmers looked upon fertilizer as a boon, because even limited quantities were enough to meet the nutrient requirements of crops and plants; it was easy to transport and handle and it produced quick results.   But the flip side is that the levels of productivity have not been sustained even though progressively large quantities of chemical fertilizer were used, and the soil has become more hardened and sterile, say farmers. 

Apart from market forces, Melar says that science and technology will be the main engine for the 20-year long agricultural perspective plan announced by HMG two years ago; and that although agricultural planning did take place in the decade from 1950 to 1960, all the foreign aid resources were used up in the hiring of foreign technicians and putting in chemical fertilizer. For these reasons, agriculture could not gather the expected momentum. 

Even though the government has spent a great deal of money every year on the import of chemical fertilizers, and has gone to a great deal of trouble to take fertilizers to farmers in every nook and cranny of the country from the hilly areas to the Terai, fertilizers have still not been available to farmers when they need it, and they have had to wander from pillar to post in search of it, even though per hectare use of fertilizer was minimal compared to other South Asian countries.  As a consequence, a tendency has arisen among farmers of using whatever chemical fertilizers they can lay their hands on, with scant regard for the recommended quantities for different crops, the time, the type of crop nutrients needed, and other factors.

Fertilizers rich in the main crop nutrients like nitrogen, phosphorous and potash should be used on crops in the recommended quantities  But farmers generally end up using urea fertilizer as it is more easily available in the market.  Thus, while chemical fertilizers are not properly utilized on the one hand, organic fertilizer, which is readily available in one's own village, is not made use of at all.  This has serious implication from the economic and environmental points of view.  

According to statistics from the Nepal Agricultural Research Council, the use of chemical fertilizers in Nepal has grown by 100 percent in the past twenty five years.  Some three decades ago, 494 metric tones of chemical fertilizer was used in the country annually.  In recent years, this figure has risen to over 50,000 metric tones

According to Bhola Man Singh Basnet, an official at the Agricultural Research Council, an unchanging cropping pattern based on chemical fertilizer use instead of the use of organic fertilizer leads to the deterioration of the physical and chemical properties of the soil; plants will not be able to draw the elements they need from it; the resulting destruction of beneficial microorganisms results in a loss of the soil's ability to retain water and the soil begins to harden and crack. 

Brown plant hoppers (BPH) have destroyed some 9910 metric tones of foodgrain in a total of 25, 600 ha. of land in ten districts of the Terai recently.  The main reason for this is unscientific use of chemical fertilizers and pesticides which has brought about an imbalance in nature, thus giving the BPH a chance to peroliferate, says head of the Crop Division Bharat Prasad Upadhyaya.  

Before the widespread use of chemical fertilizers, BPH was food for spiders, cicadas, and other predator insects.  But these natural predators have been decimated by the careless use of chemical fertilizers and pesticides, and as a result, the BPH population has shot up. 

In the face of this development, farmers should remedy the situation by using  organic fertilizer,says Upadhyaya.   While most farmers are ignorant about microscopic nutrients, not enough research has taken place in the country on the availability of such nutrients in the soil either.   Continuous use of organic fertilizers builds up reserves of nutrients in the soil, and makes possible a scaling down of chemical fertilizer use. 

Cow dung is a main source of organic fertilizer and can play a big role in sustaining soil fertility.  But dung is now used as an alternative to fuelwood.  At the same time, because of problems with fodder and pasturage, farmers in the Terai, the bread basket of the country, have become more and more discouraged from the animal husbandry that provides the dung. 

The use of draught animals is also slowly giving way to tractors and mechanical threshers, and has brought about a reduction in the organic matter available to the soil in the form of cow dung.

Adapted from:  "Unscientific Agricultural Methods Eroding Soil Fertility" By, Shital Prasad Mahato.  In The Kathmandu Post, November 24th, 1998