Prof. (Dr) R.D. Gupta
In the name of Green Revolution during 1967-68, the chemical farm inputs like fertilizers and pesticides were introduced for high yielding varieties of rice and wheat, with the focus of having a single benefit of increasing their yields to solve insufficient food supply problem of those days. However, continuous use of these technologies even after attaining the purpose, threatened our land and water resources in many ways like land degradation and decline in soil fertility, desertification, ground water depletion and water contamination, eutropohication etc.
Land degradation and decline in soil fertility
The overall land degradation figures given by various agencies are variable due to differences in their approaches, methodologies and criteria used for its assessment. But the fact is true that large land area remains under degradation due to various factors. Out of the total area of 328.60 million hectares (Mha), 120.80 to 146.83 Mha, constituting 36.5 to 44.2% has been categorized recently as degraded land due to soil erosion salinity/alkalinity and acidity, water logging and other problems (Minhas, 2012; Rajput and Prabhakar, 2012). Land degradation is a severe problem in the intensively cultivated soils of North West indogangtic plains with mining of soil fertility through continuous cultivation with limited use of organic plant nutrients sources.
Key factor causing low soil fertility and productivity is the soil erosion. The north western Himalayan and north east hill states are in the grip of severe soil erosion. The entire kandi belt of Jammu, Punjab, Haryana, Himachal Pradesh and Uttrakhand are now a vast eroded areas. About 8 million tonnes of plant nutrients are washed away along with eroded soils and sediments.
With the use of chemical fertilizers, the loss of soil fertility is taken to mean multiple nutrients deficiency and loss of organic matter. Nutrient mining has increased with intensive cultivation during post Green Revolution period. The situation has now been compounded with low soil fertility status both of major and micro plant nutrients. Nearly 89, 80 and 50% of the Indian soils have been found to fall under low to medium categories in case of N,P and K (Sharma and Singh, 2012). Now a days, S-deficiency has become wide spread (About 41% soil samples being deficient). The micronutrients deficiencies are found to the tune of 49,33,13,12,5 and 3% of the soils for Zn, B, Mo, Fe, Mn and Cu, respectively. The productivity of intensive rice-wheat cropping system of Punjab, Haryana, Himachal Pradesh and Jammu and Kashmir has already shown signs of serious decline in their productivity which is associated with soil quality. In Gujarat known as the chemical capital of India, the continous use of chemical fertilizers has resulted in loss of soil fertility greatly and decrease in farm output to the extent of 60-80% over the past few decades.
Desertification
Desertification refers to the formation and expansion of degraded land/soil. Although desertification is found on every continent to some extent yet it has now been recognized as a global problem. Infact desertification occurs on land under agriculture (both irrigated and unirrigated), grassland as well as forests. Loss of soil and deterioration in its fertility and loss of natural vegetation all lead to desertification. Drought, a period of unusually dry weather, can cause loss of vegetation which in turn leads to desertification.
Poor land management and increasing population are the factors that promote increased irrigation, improve cultivation and increased number of livestock. All these alter the land and the soil, diminish the resources and increase the chances of desertification. Arid and semiarid lands can be degraded even if there is no adjacent desert. Desertification can take place without drought and drought can occur without resulting in desertification.
As droughts are short term and cyclical so by themselves, they do not degrade the land. However, they intensify the pressures which lead to mismanagement of land, soil and water resources ultimately leading to desertification. The availability of water for irrigation can cause desertification. It is attributed to all irrigation waters contain some salts and if irrigation systems lack of a good drainage system then the salts accumulate on the soils. Eventually the salt reaches toxic levels to most plants leading to the desertification. Such events have occurred in India and Pakistan.
Ground water depletion
Expansion of agriculture has totally changed the world’s water flow scenario. The high water requirement for high yielding varieties of rice and wheat has made it essential to create more irrigation facilities through surface and to draw ground water by sinking wells/ tube wells. Since the main feature of Green Revolution was to grow rice and wheat year after year in the same field, so area under irrigation had to increase tremendously, which has now become almost double. As a result, the water table declined and some of the dug wells dried up. There was lowering of water by 0.6m a year. Due to this some of the farmers having shallow wells in states like Punjab, Haryana, parts of Himachal Pradesh and Jammu region of Jammu and Kashmir were forced to drill tube wells. In Uttar Pradesh the Central Ground Water Board has identified 22 over exploited and critical blocks in the state, of which 19 blocks were present in western Uttar Pradesh. The water table has already been plummeted to a level that is becoming an unviable proposition. Similar is the condition in certain parts of Punjab and Haryana. Falling of water table in some parts of Fategarh district, Punjab has made tube wells useless. In other parts, a few years ago, a centrifugal pump could be installed at 3m, but these days one had to go as deep as 10m. For supply of clean water submersible pump at a depth of 18m is required.
The water table has also gone down in some parts of Jammu region like RamGarh area of Samba district and that of Chatha of Jammu. A number of areas also fall in the same category of R.S.Pura and Bishnah tehsils of Jammu district.
On interaction with farmers, it was found that level of dug well water in Saror area is decreasing year after year. Similarly farmers of Tanda Burj, Samba district reported that hitherto, the underground water could be available at 4.5m depth. But now one has to go deeper up to 7.5m. Thus, if over exploitation of water mining is not stopped immediately, the aforesaid areas may be turned into deserts.
Water contamination
The soils are being polluted in some areas with toxic elements from geogenic sources or from sewage water, industrial effluents, urban solid wastes and fertilizers. For example, about 30 million people inhabiting 8 districts of West Bengal are exposed to arsenic poisoning through intake of contaminated water and food. Studies in India have also shown contamination of package drinking water with significantly high levels of organo-chlorine and organophosphates, and heavy metals (Pb,Cr.Cd, Cr).
Eutrophication
Eutrophication is a common phenomenon in fresh water ecosystems and is really a part of the normal aging process of many lakes and ponds. However, accelerated human activities like breaking of grassy slopes and clearing of forests for cultivation, application of fertilizers for agriculture and horticulture production, runoff loss through soil erosion and release of human waste, have resulted in the mobilization of nutrients such as N and P into aquatic ecosystems. Accumulation of these nutrients perturbs the aquatic ecosystem by increasing the growth of unwanted algae and weeds. The decomposition of the algae fuels bacterial growth whose metabolism consumes oxygen. This unnatural high rate of oxygen consumption decreases the dissolved oxygen on which aquatic organisms are dependent upon. Thus oxygen depletion in water and with high CO2 content the aquatic organisms start dying i.e; killing of fish, loss of biodiversity and renders water unfit for drinking and industrial uses.
Climate change
( The author is Ex Associate Dean Cum Chief Scientist KVK, SKUAST, Jammu)
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