Field day

India's soils are in a bad shape. T V Jayan investigates

 
Last Updated: Sunday 07 June 2015 | 21:11:47 PM

Field day

-- (Credit: Angshuman De / CSE)What is soil? Nothing but simple clod, always taken for granted. But dig deeper, and you will find that this simple clod generates complex equations of survival and wealth, equity and polity. It is a big little ecological variable. Its influences remain hidden from us.

More and more urea

-- It is ironic that while India ranks third in fertiliser use worldwide, it ranks 14 and 16 respectively in the production of rice and wheat. It is even more ironic that India's fertiliser policy ensures precisely such a result.

Fertiliser use in India is dictated by the larger perceived need to increase foodgrain yield, itself a staple of post-independence agricultural policy. Foodgrain production has made a quantum jump from 50.8 mt in 1950-1951 to above 200 mt in 2000-2001. This is paralleled by an increase in fertiliser consumption, from 69,800 tonnes in 1950 to 16.7 mt in 2000-2001 (see graph: How it pans out).

The latter figure is a composite one; it points to the volume of use of 3 industrially produced fertilisers that mimic the properties of a soil's primary nutrients -- nitrogenous fertilisers (n), phosphatic fertilisers (p), and potassic fertilisers (k) -- and so are considered as absolute inputs for crop production. It is also a heavily skewed statistic: of the 16.7 mt pumped into the soil in 2000-2001, the amount of n used is by far the most (11.5 mt). There is nothing surprising about this skew. The form in which n is sold in the market is urea, and urea is the most preferred fertiliser. Above all, by those who make our fertiliser policy.

The main policy instrument to guide production and use of fertilisers is the retention price-cum-subsidy scheme, introduced in 1977. In theory, it is supposed to insulate farmers from rising prices, and ensure fertiliser consumption (itself an essential component of the green revolution strategy of agricultural growth) does not suffer. In practice, it has led to two terrible results: the government subsidises domestic private sector production of urea, and the balanced use of npk has gone completely awry.

The farm-gate price of urea is fixed at Rs 4,600 per tonne. For every tonne of urea sold to the farmer, the government bears a subsidy of more than Rs 4,100. As a consequence, the industry gets a free ride and farmers, seduced by the promise of lush fields and profits, prefer to dump urea on their fields.

Does this mean they don't want, or don't know about, balanced fertiliser use? Not at all. The fact is, they cannot afford p and k. Always more expensive than urea and less aggressively advertised, both these fertilisers were de-controlled (placed in the open market) on August 25, 1992. The government, then in a liberalising mood, did also talk about a concession scheme that would apply to p and k, but the harm was done. The rates of price concession (subsidy) have steadily increased. In 2001-2002, under the concession scheme, high-end fertilisers (n+p+k-based) such as di-ammonium phosphate sold for Rs 8,900 per tonne.

The effect of urea on a plant is immediate; it turns lush green. But the soil needs its other major nutrients, too, in order to remain healthy. The effect of skewed urea use has also unbalanced soils. While the ideal npk ratio is 4:2:1, in 2001 the ratio stood at 28:8:1 for north India, and the national average was 7:2.7:1 (see table: On edge).

Long-term fertiliser experiments conducted by the Indian Council for Agricultural Research (icar), New Delhi, in 17 soil-climatic conditions in the country turn these ratios into a worrying reality. For instance, it was found that in the alluvial soils of Barrackpore, Ludhiana and New Delhi, phosphate removal from the soil had more than doubled. While the mining of phosphate from soil in a control plot, where no fertiliser was applied, was 160 kg per ha, it shot up to 366 kg per ha when only nitrogenous fertilisers were used. It is the potassium reserves, though, that are the worst hit. Indian soils are considered rich in this nutrient, and farmers apply very little potash to crops. When they did use adequate amounts of potassium fertilisers, the yield and quality of crops improved dramatically.

The message is clear: soils are suffering from major nutrient fatigue, and are hungry for p and k. But, says Veluthayam, "this situation will not change unless there is coherence between the price of fertilisers and the income farmers get from produce, so as to encourage farmers to use all fertilisers. This must be the cornerstone of fertiliser policies."

On edge
Precarious annual nutrient (im)balance
State N P2O5 K2O Total  
Maharashtra
Karnataka
Madhya Pradesh
-252.2
-92.3
-17.7
-1918.7
-224.8
-86.7
-367.2
-202.6
-824.7
-2538.1
-519.7
-929.1
Farmers in rainfed areas use very little fertilisers. So nutrient mining is very high
Punjab
Haryana
+497
-22.5
+9
-92.0
–673
-480.0
–167.0
-594.5
Rice and wheat corner over 90% fertilisers
Tamil Nadu
Andhra Pradesh
+78.0
+207.5
+35.0
-132.2
-236.0
-43.7
-123.0
+31.6
Somewhat balanced;
K levels inherently low
Gujarat +350.7 +146.6 -365.0 +132.3 High in K levels
Source: Souvenir, Second International Agronomy Congress on Balancing Food and Environmental Security — A Continuing Challenge, New Delhi, November 26-30, 2002

More yield per hectare

-- Agricultural growth in India has always laboured under the burden of producing more. The idea was: grow only foodgrains. That meant: not ecologically adapted cereals such as millets, but rice and wheat. The green revolution programme was single-minded: it came up with hyv (high-yielding variety) seeds for rice and wheat only. Dwarf wheats and rice were introduced, and the country was well on its way to prosperity.

Truly, it was. India became self-sufficient in foodgrains by the mid-1970s. But two other things happened. There began to emerge a regional imbalance in agricultural production. This can be gauged from another set of figures, that of irrigation. By 1996-1997, the state of Punjab had 92.9 per cent of its area under irrigation, followed by Haryana (76.2 per cent) and Uttar Pradesh (68.7 per cent). On the other hand, only 14.4 per cent of Maharashtra was irrigated, and 21.9 per cent of Karnataka. Secondly, and more importantly, the country's cropping patterns were completely transformed.

This transformation can be summarised thus: rice-wheat in the north, and rice-rice in the south and east. Among other effects (such as intensive water use, see next section), this led to the complete marginalisation of legume cultivation, even in traditional legume-growing areas. Even as the area under cereal cultivation in Punjab has increased from 50.9 per cent in 1966-1967 to 73.5 per cent in 1997-1998 (rice: 0.227 million ha to 2.278 million ha; wheat: 1.4 million ha to 3.3 million ha), leguminous crops such as pulses and oilseeds came to be grown far less widely (pulses: 13.47 per cent of cultivable area in 1966-1967 to 1.1 per cent in 1997-1998; oilseeds: 6.2 per cent to 1.8 per cent). Their B-grade status -- less profitable; less subsidy; less institutional support -- is reinforced by the manner in which they have been shunted to marginal lands.

Legumes naturally enrich soils (see box: Legume logic). "We have been pleading with farmers to go back to legumes. The government should come up with incentives for farmers who agree to grow legumes in place of paddy," says G S Hira, a soil physicist at the Punjab Agricultural University, Ludhiana, Punjab.

More and more water

-- A third factor has led to the current debility of soils in India: irrigation. That is to say, water over-use. To feed the rice-wheat mentality, net irrigated area rose from 20.8 million ha in 1950 to 53.5 million ha in 1995-1996. Fed on irrigation, the agricultural area grew from a mere 20.8 per cent in 1966-1967 to 42.4 per cent of the 120 million ha of cultivated land in the country by 1997-1998. Canals began to weave their way through the land, bringing subsidised water right up to the farm-gate. Farmers went on a flood; then began to suffer.

Take the case of Ram Pal, of village Kalwala in Bhatinda district, south Punjab. He has a family of three to feed and aRs 50,000 debt. His only asset -- 3.6 acres of land -- has turned saline. "What is the use of living when our only source of income is gone?" Ram Pal is just one of the many villagers in Punjab whose land is swamped with saline water. Waterlogging, caused by irrigation without drainage, leads to high rates of evaporation. With evaporation, salts in the water settle on the soil. This leads to salinity or alkalinity of the soil. (see map: A big pinch; also see table: A bigger pinch). As the salt content increases, the soil-plant system registers a reverse osmosis process. Due to osmotic pressure, plant roots tend to lose water and nutrients instead of absorbing them from the soil.

A classic example of this is the Kolhapur region in Maharashtra. Farmers took to cultivating sugarcane, a water-guzzling crop with many buyers in sugarmills around the area. About 65 per cent of the irrigation potential in the region is diverted to supporting sugarcane, which covers just three per cent of the cultivated area. The region's fine-grained black soil does not allow penetration of water, leading to salt build-up. Salt in the soil increases by 20 to 25 tonnes per ha after a single sugarcane crop. The result: lower yields of sugarcane on the same land.

A bigger pinch
Canal command areas display high salinity
Project Waterlogged
area
(1000 ha)
Percentage
of command
area
Saline area
(1000 ha)
Percentage
of command
area
Ramganga 195 10 352 18
Gandak 562 53 400 38
Nagarjuna 114 24 69 14
Sharda 260 7 253 7
Chambal 99 20 40 8
Mahi 89 39 61 29
Source: Singh, N T, Dryland Salinity in the Indo-Pakistan subcontinent, Universitat Bonn, 2000. Map source: Wastelands Atlas of India, ministry of rural development, 2000

More and more loss

-- (Credit: Angshuman De / CSE)The domino effect of bad policy-making and its fallout -- unsustainable practice -- has dwindled the nutrient quality of soils in more than the obvious ways. Apart from micronutrient loss, Indian soils already weak in carbon content are today even more incapable of acting as sequesters of carbon and so reducing global warming potential.

Agriculturists in India fully realised the extent of damage micronutrient deficiency could wreak only when the fertile terai region in Uttar Pradesh missed a couple of paddy crops in 1966. Studies pinned it down to zinc deficiency. Zinc is now considered the third-most limiting nutrient after nitrogen and potash. The very next year, an All-India Coordinated Project of Primary and Secondary Nutrients and Pollutant Elements in Soils and Plants was launched by icar. About 2.5 lakh soil samples collected from 20 states since then have shown that the practice of intensive agriculture depending on hyvs, extensive use of high analysis chemical fertilisers and reduced return of farm waste to soil is compounding nutrient deficiency in soils. Soils in many parts of Andhra Pradesh, Bihar, Karnataka, Maharashtra, Madhya Pradesh and Uttar Pradesh exhibited zinc deficiencies of over 60 per cent. Falling levels of other important micronutrients like boron, iron and molybdenum are also affecting yields.

Carbon content in soil is important to soil productivity. Indian soils are relatively low in carbon content: between 0.1 per cent in desert soils and 1 per cent in soils found in the humid and sub-humid climates of Kerala and some north-eastern states. A number of factors influence carbon content in soils. For instance, climate. Intensive cultivation in the Indo-Gangetic plains has led to deficiency in organic carbon.

Reclaiming Simple Clod

-- (Credit: N Thiagarajan)Soils are a very slow renewable resource. To reclaim them requires, above all, a long-term plan. With falling productivity, the realisation has sunk in that soils cannot be blindly mined, and that humans cannot just plough through the ecology they interact with.

apply gypsum: Seven lakh ha of land in Punjab and Haryana have been reclaimed using techniques such as applying gypsum or lime to salt-affected soils, or cultivating salt-tolerant crops along with nutrient and water management. But these technologies are expensive. And it takes a long time to make the soil fertile. Besides, salinisation is not always reversible, even with major investments in drainage facilities.

manage nutrients: Scientists believe integrated nutrient management (farmyard organic manure used in combination with chemical fertilisers) is the best way to tackle micronutrient deficiency in soils (see diagram: Go with the flow). Experiments conducted by icar proved that use of npk fertilisers (in recommended quantities) combined with 10 to 15 tonnes of farmyard manure per ha could as much as triple yields obtained from nitrogenous fertilisers alone. The potential for rural compost alone is 600 million tonnes. Urban compost adds up to another 15 million tonnes and green manure about 30 million tonnes. Less than 50 per cent of this potential has been harnessed so far.

microbes and earthworms: There is a teeming, if invisible, army of microbes in the soil and subsoil that support plant growth and recycle nutrients; an estimated 100 million bacteria, and 10,000 different species, in every gram of arable soil. The top 15 centimetres may contain as much as 4,000 kg of live microorganisms. These process organic manure twice their weight, making nutrients available to plants in readily usable form. However, their contribution has not received the kind of attention it ought to have.

There are also other organisms that help improve soil quality. Earthworms, for instance, function as 'underground farmers', turning the soil over. Just one acre of land could be home to over a million earthworms, eating about 10 tonnes of leaves, stems and dead roots a year and ploughing 40-odd tonnes of soil. This is also the basis of a process called vermiculture, where worms are used to decompose organic waste into nutrient-rich vermicompost. Vermicompost improves soil structure, texture and aeration, as well as its water-holding capacity.

what about sludge? In India, farmers in and around cities and towns apply sewage sludge to agricultural land, especially for growing vegetables and other horticultural crops. However, there has been some controversy surrounding the use of sludge, especially in the us. (see: 'Fresh evidence', Down To Earth; Vol 11, No 16; January 15, 2003) Waste materials from households and industrial units have heavy metals -- such as lead, chromium, cadmium and arsenic -- in toxic levels. There could also be pharmaceutical wastes, or pathogens. There's a long way to go before this application finds use as a source of organic manure. As Dilip K Biswas, chairperson, Central Pollution Control Board, puts it dryly, "We do not have any standards for sewage sludge for land application."

or sequestration? The spectre of climate change, and global warming, has brought to the fore the issue of soil carbon sequestration. It is now touted as a two-pronged solution: it could make up for loss of soil carbon over years of land degradation; and help reduce greenhouse gases. Soils, through inorganic chemical reactions, convert atmospheric carbon dioxide into soil inorganic compounds such as calcium and magnesium carbonates. Plants also absorb carbon directly from the atmosphere through photosynthesis. Subsequently, some of this plant biomass is indirectly sequestered as soil organic carbon when the plant decomposes.

biggest hope: Perhaps the biggest hope is a re-recognition of the value of traditional farming systems, and creating what may be called farming eco-technologies that combine modern methods with traditional practices (see box: B Vishwanath's dream come true?).

but then... It is intriguing that the hundreds of scientific conferences and fora, which have discussed eroding soil fertility in India, have had little influence on government policies. Part of the problem is that scientists are not involved in the fertiliser or agriculture policy-making process in India. These policies are influenced by various pressure groups, such as the fertiliser industry and groupings of big farmers.

Soil scientists unanimously aver that if soil health, and by implication crop yield, has to improve, the focus has to shift from crops to soil. But who will make the bureaucrats understand this? Much research is available, and even more data. But not a single figure can match the intentions of politicians, who only like short-term experiments with soiling democracy. Isn't it execrable that scientists have not been involved in any serious macro-level planning to restore depleted soil fertility?

Recently, the nbss-lup has come out with a soil map of India, the first-ever. It took 1,500 personnel over 10 years to prepare; and samples were taken every 10 km. The survey accounts for diverse factors, such as physical, chemical and biological properties, soil depth, particle size, soil temperature, and climate. Is the Union Cabinet aware of this? Does it plan to use it for the country's better future?

But then, B Vishwanath no longer delivers the presidential address at the Indian Science Congress.

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