India is blessed with a wide array of soil types that would have developed in the subcontinent as a direct consequence varying climatic conditions and vegetations. According to the National Bureau of Soil Survey and Land Use Planning (NBSS & LUP), taxonomically eight out of twelve Soil Orders in the world exist in India. The Inceptisols (alluvial soils) cover nearly one-third of the geographical area of the country. The arable land available per head has been reduced by 50% in the past fifty years from 0.34 ha (1950) to 0.16 ha (1998-99). The land available for cultivation is shrinking at an alarming rate due to the exponential growth of urbanization that commensurate with increasing proportion of lands unsuitable for cultivation of crops (Yadav, ,2002). It is utmost essential to promote the soil productivity in order to maintain the achievement already made in realizing self-sufficiency in food grain production. India has been exposed to a very high degree of soil degradation within the club of developing countries. According to the latest estimate, 187.7 million hectares (57.1%) of the total geographical area (329 million hectares) is degraded. The degraded land encompasses water erosion (148.9 million ha), chemical hazard (13.8 m ha) wind erosion (13.5 m ha), water logging (11.6 m ha), salinization (10.1 m ha) and nutrient depletion (3.7 m ha). In this paper, various soil degradation hazards and their impacts on agro-ecosystems and suggested policies to be orchestrated in order to prevent further deterioration.1. SOIL EROSION
Soil erosion is the surface removal of productive soil by means of water, and wind that is the prime environmental costs in agriculture. Soil erosion alone constitutes 86.5% of land degradation that is considered the most serious hazard (Table 1). Approximately 5334 million tonnes of productive soil is being carried away by erosion that accounts for 16.4 t/ha/year. The eroded soils leaches out valuable plant nutrients to the tune of 5.0 to 8.4 million tonnes every year which accounts for Rs. 6,100 to 21, 600 crores of estimated loss of money. The removed soil gets accumulated in the reservoirs and thereby reducing their storage capacity by 1-2% every year. Erosion has been accelerated in recent times by vegetation removal, over exploitation of forest cover, excessive grazing and faulty agricultural practices.
Table 1: Soil degradation statistics (million hectares)
Types | 1994 | 1997 |
Soil erosion | 162.4 | 167.0 |
Salt affected soils | 10.1 | 11.0 |
Water logging | 11.6 | 13.0 |
Shifting cultivation | NA | 9.0 |
Total | 175.0 | 187.8 |
Sehgal and Abrol (1994)
Government programmes introduced for Soil Conservation
Year | Programme / Policies | Special features |
1978 | Desert Development Programme | Restoration of ecological balance by harnessing, conserving and developing natural resources |
1985 | National Land Use and Wasteland Development Council | Policy planning for the scientific management of the country's land resources |
1985 | National Land Use and Conservation Board | Review the implementation of ongoing schemes and programs connected with conservation and development of land resources and soils Formulate a national policy and perspective plan for conservation, management and development of land resources of the country |
1985 | National Wastelands Development Board | Formulate a perspective plan for the management and development of wastelands in the country Identify the waste land and assess the progress of programmes and schemes for the development of wasteland Create a reliable data base and documentation centre .for waste land development |
1988 | National Land Use Policy | To devise an effective administrative procedures for regulating land use for further deterioration Allocation of land for different uses based on land capability, productivity and goals in order to restore the productivity of degraded lands |
1989-90 | Integrated Wastelands Development Project | Adopt soil and moisture conservation measures such as terracing, bunding etc. Enhance people's participation in wasteland development programmes |
1992 | Constitution(74th Amendment ) Act, 1992 | Regulation of land use and urban planning brought under the domain of urban self-governing bodies |
1999 | Department of Land Resources | Formulation of Integrated Land Resource Management Policies Implementation of land based development programs |
Policy Suggestions to Prevent Soil Erosion
The erosion being the monstrous factor associated with soil degradation, it is appropriate to develop holistic strategies to minimize the erosion hazard and conserve soil productivity
· Well-defined database and mapping of various types of soil degradation hazard is very much required to develop strategies that maybe widely adoptable. This task can be accomplished using Geographical Information System (GIS) and Remote Sensing Techniques.
· Encourage rural population and tribal communities to utilize the non-conventional energy sources such as biogas plants in order to prevent overexploitation of forest cover
· Provision of incentives may be a cost effective measure to encourage farmers to adopt soil conservation practices
· Research should focus on the sustainable farming practice "Integrated Crop Management " instead of looking at the crop production system multi-dimensionally
· Proposed land use policy should form a basis for integrated approach comprising different components such as land, soil and water
· Despite huge sum of money has been invested on watershed projects, the data generated from these programmes are considered deficient and requires clarity. A detailed database is required from each watersheds that enable the policy makers to relate money invested and productivity gains.
2. NUTRIENT IMBALANCE IN INDIAN SOILS
In the past fifty years, the fertilizer consumption has increased exponentially by 6 times from 3 (1950) to 18 million tonnes (2000) that commensurate with four-fold increase in food grain output. It has been observed that the indiscriminate use of nitrogenous fertilizers appears to affect the quality of crops through nitrate pollution in the groundwater. A holistic approach is to be adopted in order to maintain the balance between the crop removal and addition of fertilizers. Balanced fertilizer application is imperative for sustained productivity. In India, the problem is compounded by imbalanced fertilizer use, leading to widening of NPK ratio from 5.9: 2.4: 1 in 1991-92 to 10: 2.9: 1 in 1996-97 as against the optimum ratio of 4 : 2: 1 (Yadav, 2002). Most of Indian soils are deficient but excessive use of N alone fails to produce sustainable yields over a long period. Achieving balance between the nutrient requirements of crops and the nutrient reserves in the soils is essential for maintaining high yields and soil fertility, preventing environmental contaminations and sustaining agricultural productions over the long-term.
The deterioration in soil health caused by imbalanced fertilization has truly reflected on the annual yield growth rate of several field crops that begin to stagnate over the past few years (Table 2). The data have shown that the decrease is annual yield growth rate of food grains from 3.33 to 1.42%, from 2.47 to 1.28% in the case of non-food grains and from 2.99 to 1.34% in case of all crops. Cotton registered even a negative growth rate. Despite the use of improved crop varieties and production technologies, the declining trend is as a consequence of the deceleration in total factor productivity. This is a serious concern in achieving targeted productions.
Table. 2: Average annual growth rate (%) in yield of major crops of India
Crops | 1980 - 1990 | 1991 - 1999 |
Cereals | 3.43 | 1.63 |
Pulses | 2.63 | 0.65 |
Oilseeds | 2.73 | 1.62 |
Sugarcane | 1.81 | 1.08 |
Cotton | 3.56 | -0.47 |
All Crops | 2.99 | 1.34 |
(Swaminathan, 2000)
The statistics on soil deterioration in conjunction with stagnation in crop yields vividly suggest that there is an urgent need to bestow utmost importance to balanced fertilization to enable sustainable farm productivity. Plausible policies are to be orchestrated by both the Central and State governments to reduce further deterioration in soil quality.
Suggested Policies for the maintenance of soil nutrient balance
There are new developments in the mission to maintain soil nutrient balance that receive bountiful of appreciation from farmers, extension functionaries, scientists and students. The following technologies are to be popularized both by Central and State Governments.
· Fertilizer subsidy to a specific fertilizer may be avoided. Decontrol of nitrogenous fertilizers especially for urea has triggered its excessive use in crop production with consequential groundwater pollution.
· The organic status of most Indian soils has declined drastically due to continuous use of inorganic fertilizers. There is an urgent need to integrate nutrient supply with organic sources to restore the soil health. But the availability of organic manures (especially farm yard manure) is scarce in many pockets of the nation that can be fulfilled by alternate sources of organic manures such as vermicompost, composted coir wastes and farm wastes may be encouraged.
· Research on farm level nutrient balance studies has to undertaken in order to assess the emerging trends in nutrient deficiencies or toxicities in agro-ecosystems. The NUTMON tool box which is a computer software that can generate nutrient balance to determine the nutrient inflow and outflow in micro-level farming situations as well as regional and national scale. The outcome of this research programme will be useful for policy makers to plan for a sustainable nutrient management.
· Appropriate computer-aided decision support system can be lavishly used for scientific fertilizer prescription in the mission of soil fertility management. The Tamil Nadu Agricultural University, Department of Soil Science in Coimbatore, has developed a computer assisted Decision Support System for Integrated Fertilizer Management (DSSIFER). The DSSIFER is an effective tool to provide fertilizer prescription, ameliorative measures for problem soil management and other improved agronomic practices for cultivation of crops.
· Suitable Government policies must be evolved to distribute Soil Health Card (SHC) nation-wide to the farmers for use. The SHC is similar to the ration card of a farm family who can make entries of the nutrient management practices in the card on a regular basis to enable them to identify the production constraints and take up suitable actions for sustainable farming.
· Encourage farmers to adopt Integrated Nutrient Management (INM) practices to the maintain soil fertility and plant nutrient supply to an optimum level for sustaining the desirable level of crop productivity through the concomitant use of inorganic, organic and biofertilizer inputs.
· Biofertilizers offer an economically attractive and ecologically sound means of reducing external inputs and improving the quality and quantity of internal resources. These are bioinputs that are mobilizing nutrients from non-usable to usable through biological processes. The beneficial microbes include N fixers, P solubilizers and mycorrhizas that could be able to save inorganic sources of nutrients by 25-30% with an additional benefit of environmental safety.
· Research priorities should include developing recommendations and technologies for fertilizer and organic matter management for specific soils, climate and crops as part of precision agriculture.
3. MICRONUTRIENT STATUS OF INDIAN SOILS
In India, the continuous cultivation of crops with high analysis straight fertilizers has pronounced a sharp decline in availability of micronutrients in soils and this associated with a reduction in nutritional qualities of agricultural produce and crop yields (Anon, 2003). It has been reported that the occurrence of micronutrients deficiencies in Indian soils to an extent of 46%, 9%, 5% and 4%, Zn, Fe, Cu and Mn, respectively (Singh and Saha, 1995). Consequently, both the production and consumption of micronutrients have increased by 30% in three years during 1999 - 2001. Correction of micronutrient disorders is gaining importance and of utmost need for sustainable farm production. Among the micronutrients, Zn appears to be deficient in most soils in India at varying intensities with the exception of acidic soil regions where the Zn status is at the moderate level. The inherent ability of the soil to supply boron and sulphur is at the declining trend and requires replenishment. Augmentation or restoration of lost soil fertility and productivity can be achieved only through addition of micronutrient fertilizers and mobilization of their residual effect through proper nutrient cycling. The applied micronutrient in the soil is often unavailable to the crop plants due heavy fixation in soils. Consequently, the micronutrient use efficiency by plants is extremely lower. To make the situation more complex, multiple micronutrient deficiencies are more prevalent than as a single nutrient deficiency.
The response to soil application of micronutrients is vividly indicated in field experiments conducted at the Tamil Nadu Agricultural University, Coimbatore Centre of the ICAR-Micronutrient Scheme in the past four decades. The data have shown that Zn application has enhanced the yield of rice, pulses, millets, oilseeds and turmeric to the tune of 25%, 20%, 16.7%, 17.3% and 14.4%, respectively. The response to added Zn is often associated with deficiencies below its critical levels in soils. Thus, addition of Zn is imperative in order to maintain crop yields in various production systems. Next to the Zn, Fe application appears to promote yields of millets and sugarcane by 30% and 40% respectively. The deficiency of Fe is often associated with lime status. As millets and sugarcane are quite sensitive to Fe, they exhibit interveinal chlorosis as a consequence of calcium induced Fe deficiency. In addition to the soil application, foliar sprays were found to correct nutrient disorders in crop plants. The response was more pronounced for pulses than other crops. In addition, pulses have responded favourably to foliar spray of Mn and Mo. On an out set , micronutrient fertilization contributes towards the crop yields to the tune of 10-20% depending on the severity of micronutrient deficiencies.
Suggested policies in micronutrient management
· Delineation of micronutrient deficiencies in India should be done to create a database as a reference tool for policy making. The ICAR has 15 micronutrient centres of which Tamil Nadu Agricultural University, Coimbatore, is one of the oldest Centres carrying out micronutrient research for the past 40 years. The data from various centres can be used to develop database on micronutrient status of Indian soils. The GIS technology may be employed to map the micronutrient deficient regions at the micro and macro levels.
· Popularization of computer-assisted software for the identification nutrient disorders in crop plants should be taken up all levels. The Tamil Nadu Agricultural University, Department of Soil Science, Coimbatore, has developed an innovative computer aided Visual Diagnostic Kit (VDK) that can be used for the identification of nutrient deficiencies and to derive suitable remedial measures. Besides it is a user-friendly tool for the farmers, students, researchers and extension workers to precisely identify nutrient disorders in crop plants.
· Research on multi-micronutrient product formulations including chelating compounds has to be carried out in various cropping situations. This may be an effective technology to ameliorate multi-micronutrient deficiencies and sustain farm production.
· Studies on economizing micronutrient use through seed pelleting and foliar sprays may be taken. As the utilization of micronutrients by plants is relatively smaller these agro-techniques may be useful in curtailing costs with an added benefit of highest rate of use efficiency.
4. ORGANIC FARMING
In India, there are also efforts to return back to the organic agriculture in order to improve the quality of food production and to promote nutritional security and ensure sustainability. It’s the concept of “Merry Go Around”. Organic production system largely excludes the use of synthetically compound fertilizers, pesticides, growth regulators and livestock feed additives. To the extent possible, organic farming rely on crop rotation, crop residues, animal manures, biofertilizers, botanicals and biopesticides to maintain soil productivity and tilth, to supply plant nutrients and to control weeds and pests. The organic agricultural products fetched US $ 17 billion in the global market in the year 2000 that is likely to double in five years reaching a figure of US $ 31 billion in 2005. Over 50% of the global share comes from the USA that gains $ 8 billion through the sale of organic produce. Inside this market place, India’s share is meager 0.001%. India is ranking 75th position in the global organic agriculture scenario. Why there is a vertical shift required from inorganic to organic? The Indian agriculture is beginning to show a sign of yield stabilization, imbalance in soil nutrient status, loss of nutritional security and livelihood of people. India’s organic production has touched 14,000 tonnes in 2002, of which 11,000 tonnes had been exported. The exported organic produce includes coffee, tea, rice, wheat, pulses, oilseeds, fruits, vegetables, cotton and herbal extracts. India is a highly bidiversified country producing a wide array of oriental vegetables and fruits that has greater export market potential. Organic farming is essential to promote export-oriented agriculture and stimulate livelihood of the farming communities.
The organic farming in relation of food security of India is yet to be established. The primary concern for any Government is to meet the food requirement of the people and to ensure hunger free situation in any nation. To maintain current rate of food grain production in India without chemical fertilizer input, additional area has to be brought under cultivation that is hardly possible to achieve (Chhonkar, 2003). Almost all long-term fertilizer experiments conducted by ICAR centres in the country have vividly demonstrated that the integration of organics and inorganics can produce reasonably higher yields and maintain soil fertility. Despite organics are indispensable in agricultural production system, the realization of its fullest potential is yet to be seen in sustainable grain productivity.
Suggested policies in organic farming
· Policy initiatives are required to demonstrate at the commercial scale that how best the organic agriculture can minimize or eliminate usage of chemicals and costs involved in agricultural production systems.
· Efforts are to be geared up to enhance the availability of non-conventional (coir waste compost and vermicompost) and conventional (green manure) sources of organics.
· Intense research is necessary to unequivocally prove the nutrient utilization pattern and quality improvement in organically grown agricultural produce.
· Research on organic production package for exportable crops such as sugarcane, fruits, vegetables and medicinal plants is very much required
· Organic certification centres have to be established in various export zones with a complete set of administrative and analytical facilities as is the one in Tamil Nadu Agricultural University, Coimbatore.
· Laws and legislation should be in place to monitor the organic production and marketing of agricultural produce
CONCLUSIONS
The soil degradation is increasing at the alarming proportion and needs to be circumvented to sustain agricultural production in India. Among various factors responsible for soil degradation, erosion appears to be the first and deserves governmental and non-governmental agencies to take immediate steps to minimize the hazard. Currently, several policies are in place without much impact at the large scale. Maintenance of soil nutrient status may be possible by adopting recently developed innovative site-specific nutrient management approaches. Micronutrient fertilization seems to contribute one-fifth of the total agricultural output deserves much more significance in the years to come. Timely identification and ameliorative measures are required to minimize the loss in crop productivity. Organic movement is gaining momentum in India and its applicability is more rationale and reasonable for export oriented agriculture. Sustainability in food security in relation to organic farming is yet to be established.
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