Sustainable Agriculture:
The way towards conservation of natural resources, environment and crop diversity
-Dr. Arvind Singh
The modern agricultural practices which are heavily dependent on the use of chemical pesticides, inorganic fertilizers and growth regulators have raised the agricultural production manifold but at the cost of resource depletion, environmental deterioration and loss of crop diversity. Therefore it was realized that the modern agriculture is not sustainable in long run, hence the concept of sustainable agriculture emerged which not only emphasizes on the conservation of the natural resources but also maintains the quality of the environment. Often there is a misconception that sustainable agriculture and organic agriculture is the same thing.
However, it is not true, as both are different concepts. In sustainable agriculture chemical fertilizers and pesticides are often used in a limit that has no disruptive effect on the soil and the environment. However, organic agriculture strictly avoids the use of chemical fertilizers and pesticides. Therefore, sustainable agriculture is a broad term which includes organic agriculture as well. Sustainable agriculture is, in fact, the successful management of resources for agriculture to satisfy the changing human needs while maintaining or enhancing the quality of the environment and conserving natural resources.
( Read: Dryland Farming in India )
It is a balanced management system of renewable resources including soil, wildlife, forests, crops, fish, livestock, plant genetic resources and ecosystems without degradation and to provide food, livelihood for current and future generation maintaining and improving productivity and ecosystem services of these resources.
Sustainable agriculture systems are designed to use existing soil nutrient and water cycles, and naturally occurring energy flows for food production. Furthermore, such systems aim to produce food that is both nutritious and without products that harm human health. In practice, such systems have tended to avoid as far as possible the use of chemical fertilizers, pesticides, growth regulators, and livestock feed additives, instead of relying upon crop rotations, crop residues, animal manures, legumes, green manures, off-farm organic wastes, mechanical cultivation and mineral-bearing rocks to maintain soil fertility and productivity, and on natural biological and cultural controls for insects, weeds, and other pests. Why sustainable agriculture has become the need of the hour?
Chemical fertilizers and pesticides dependent on modern agricultural practices have caused several problems. In modern agriculture, there has been consistent use of few high yielding hybrid crop varieties which has resulted into the depletion of land varieties (desi varieties) that are not only nutritious but also possess several useful characters like drought, disease and pest resistance. The gradual loss of variability in the cultivated forms and in their wild relatives is referred to as genetic erosion. This variability arose in nature over a long period of time and if lost, would not be reproduced during a short period.
( Read: Agroforestry in India )
Therefore genetic erosion has emerged as a major problem of modern agriculture. Overuse of inorganic fertilizers has led to the problem of soil erosion. Fertilizers destroy the soil structure making the soil susceptible to erosive forces like water and wind. Overuse of nitrogenous fertilizer urea has caused the soil acidity. Excessive nitrogen suppresses biological activity including mycorrhizae (non-pathogenic association of fungi with roots of plants which helps in phosphorus uptake by plants), reduce nodulation in leguminous plants give a competitive advantage to the weed over the crop and increase pest incidence.
Mismanagement of surface and ground water resources has led to the problem of water logging, soil salinity and alkalinity. Moreover, the extraction of water for irrigation has caused the lowering of the ground water table. Deforestation has resulted in the problem of global warming, depletion of biological diversity, drought and the siltation of water reservoirs.
Modern agricultural practices have also enhanced ozone depletion. Nitrous oxide (N2O) produced by microbial action on the nitrogenous fertilizers is responsible for the thinning of the stratospheric ozone layer which provides protection against the harmful ultra violet radiation of the sun. Excessive use of pesticides to control pests in modern agriculture practices has led to the problem of pesticide resistance resulting in the rise of the pest population. In addition to this, pesticides are also responsible for environmental pollution which indirectly or directly affects human health.
( Read: Social Forestry in India )
Management practices in sustainable agriculture
The management practices for sustainable agriculture virtually differ from those of modern agriculture. The important steps in sustainable agriculture are conservation of crop diversity, conservational tillage, watershed management, efficient water management, integrated nutrient management, integrated weed management integrated pest management and crop diversification. Generally, the management practices in sustainable agriculture are aimed at achieving sustainable production with limited or no chemical inputs with priority to farm-grown inputs without pollution and minimum damage to the natural resource base.
Conservation of crop diversity:
Cultivation of high yielding fertilizer responsive hybrid varieties over large areas has resulted in the loss of land varieties (desi varieties) which need to be conserved not only for the maintenance of the crop diversity but also for their future use in crop improvement programme as these varieties have several useful traits like disease, pest and drought resistance, nutritive value etc. The priority to local or land varieties over hybrid varieties and simultaneously providing protection to wild relatives of crops will avoid the problem of genetic erosion. Oryza nivara a wild variety of rice found in Central India possess the resistant gene to grassy stunt disease of rice. The gene was incorporated in world-famous International Rice 8 (IR8) variety of rice through plant breeding at International Rice Research Institute (IRRI), Philippines.
Watershed management:
Watershed is an area of land and water bounded by a drainage divide within which the surface runoff collects and flows out of the area through a single outlet into a river or other body of water. Watershed management is a holistic approach to bring about the development of integrated farming systems on a watershed basis. It aims at optimizing the use of land, water and vegetation in an area to mitigate drought, moderate floods, prevent soil erosion, improve water availability and increase fuel, fodder and crop production on a sustainable basis.
( Read: What is Soil erosion )
Efficient water management:
Water management is key to the success of sustainable agriculture as water is an important natural resource. Water management can be divided into rain water management and irrigation water management. The important aspects of rain water management are water harvesting, supplemental irrigation and reduction of evapotranspiration. Irrigation water management involves scheduling irrigation at an appropriate time with adequate quantity of water without causing water logging, soil salinity and alkalinity.
Conservation tillage:
Tillage practices in sustainable agriculture aim at reducing soil degradation and losses by erosion. A common way is to provide an optimal condition for beneficial soil organisms, thereby enhancing organic matter decomposition and nutrient cycling. Managing the top 8 cm of soil is vital because most of the biological activity, micro-organisms and organic matter are found in this soil layer.
Therefore, conservation tillage is adopted in place of conventional tillage. Conservation tillage is disturbing the soil to the minimum extent necessary and leaving crop residues on the soil. Minimum tillage and Zero tillage are the types of conservation tillage which reduce soil loss up to 99% over convention tillage. In minimum tillage, the tillage practices are reduced to a minimum extent for ensuring (improved soil condition due to decomposition of plant residues in situ) a good seed bed, rapid germination and favourable growing condition, whereas the zero tillage is an extreme form of minimum tillage where primary tillage (opening of the compact soil with the help of different ploughs) is completely avoided and secondary tillage (lighter or finer operations performed a soil after primary tillage) is confined to seed bed preparation in the row zone only.
( Read: Land Degradation in India )
Zero tilled soils are homogenous in structure with more number of earthworms. There is an increase in organic matter content due to less mineralization. Surface runoff is reduced owing to the presence of mulch. In most cases, conservation tillage reduces soil loss by 50% over conventional tillage. Moreover, conservation tillage maintains the organic matter content of the soil and prevents the removal of nutrients from the soil through rainwater. Conservation tillage also causes an increase in microbial and earthworms population in the soil.
Nutrient management:
Indiscriminate use of chemical fertilizers in modern agriculture to enhance the crop yield has abused the land resources resulting in stagnation in food grain production. Therefore Integrated Nutrient Management (INM) is key to the success of sustainable agriculture. Integrated nutrient management which emphasizes on the use of renewable sources of nutrients ameliorates the soil health in the long run. Therefore, it ensures the concept of sustainability in agriculture. In integrated nutrient management all the possible sources of nutrients are applied based on economic consideration and the balance required for the crop is supplemented with chemical fertilizers. The sources include manures, green manures, compost, vermin-compost, bio-fertilizers and concentrated organic manures.
Organic fertilizers have a slower action but they supply available nitrogen over a longer period of time. Moreover, they protect useful flora and fauna of the soil, ameliorate yields and quality of products. Since there is an increase in soil fertility the biological activity is maintained intact.
Weed management:
Weed control includes cultural, physical, biological and chemical methods. In sustainable agriculture, cultural, physical and biological methods are at priority. Weeds are generally controlled by rotation, tillage and hand-weeding. Chemical weedicides are also used to control the weeds if the above methods fail to overcome the problem of weeds. However, in sustainable agriculture weeds are often tolerated and encouraged up to some extent as weeds play valuable function like nutrient cycling, disease and pest control, soil and moisture conservation and organic matter improvement as green manure.
( Read: Green Revolution in India )
Pest management:
In modern agriculture practices, the over the use of chemical pesticides has led to the problem of pesticide resistance and pest resurgence. Besides this, many of the pesticides are non-biodegradable causing the problem of environmental pollution. This has led to the emergence of the concept of Integrated Pest Management (IPM). It refers to an ecological approach of pest management in which all available necessary techniques are practised in a unified programme so that pest population can be managed in such a manner that economic damage is averted and adverse effects are minimized. It includes mechanical, physical, cultural, biological and chemical methods. In addition to these methods, sometimes friendly insects and spiders are also encouraged.
Spiders are farmer-friendly as they destroy pests in many crops especially rice. Most common of them are wolf spider, sack spider, diver spider, orb spider and the jumping spider. Besides these, botanical pesticides (derived from plants) are used to control the pests and diseases.
Crop diversification:
Crop diversification is an important factor for enhancing crop production and maintaining sustainability. Crop rotation, mixed cropping and intensive cropping are the methods of crop diversification which not only enhances yield but also reduce the erosion.
Crop rotation which refers to the alternate growing of crops is important for successful sustainable farming. Crop rotation practices are not only important for soil fertility management but are also helpful in weed, pest and disease control. In any rotation, leguminous crops are essential for nitrogen supplement to the soil.
( Read: Floods in India )
Mixed cropping is the practice of growing two or more crops together in the same piece of land. The major advantage of this type of cropping is that even under adverse conditions all crops are not destroyed. Mixed cropping with leguminous crops increases the yield of non-leguminous crop therefore it is necessary for the success of sustainable agriculture.
In intensive cropping, a number of crops are grown simultaneously in the same piece of land in one agricultural year. Multiple cropping and relay cropping are examples of intensive cropping. Multiple cropping aims at maximizing production per unit of land and per unit of time by taking three or four crops from the same piece of land in a year. Relay cropping is a system of cropping where one crop hands over the land to the next crop in quick succession.
Conclusion:
Sustainable agriculture has several benefits over modern agriculture as it is cheap, conserves water, soil and environment, maintain crop diversity and the food grains produced are nutritious and free from pesticide residues. Therefore shift from modern agriculture to sustainable agriculture is the need of the hour for the conservation of natural resources, environment, crop diversity and production of nutritious food grains.
Author Bio:
Dr. Arvind Singh is M. Sc. and Ph. D. in Botany with an area of specialization in Ecology. He is a dedicated Researcher having more than four dozen published Research Papers in the Journals of National and International repute. His main area of Research is Restoration of Mined Lands. However, he has also conducted Research on the Vascular Flora of Banaras Hindu University-Main Campus, India.
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