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.
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.
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.