The remarkable increases in agricultural production have been achieved in past decades with practices that are more dependent on external inputs and improved crop varieties. The energy intensive agricultural practices using fertilizers for nutrition, agrochemicals for plant protection and mechanization for farm operations, may yield short term economic gains, but lack long term ecological sustainability. Integration of crop species and animals in production systems lead to interaction among production components, which is essential for attaining sustainability. Furthermore, in recent times, the approach has been enlarged to combine trees, annual crops, perennial herbs and animals (Agro forestry). Sustainable agriculture or sustainable farming has many definitions, depending upon various aspects on which individuals place emphasis.
Nutritional requirement of crop plants can also be met out by recycling and use of biological inputs. Replenishment of nutrients is a critical need of present age. Due to bulkiness, transport and cost per unit nutrient and high cost of incorporation, sudden and total shift to organic manures is impractical. Gradually, proportion of organic manures can be increased in plant nutrient management system, to attain nutritional sustainability. Dependence on forests for biomass may prove nonsustainable practice in long run. For maximizing biomass content, we need to consider trees, herbs, perennial vines and species requiring very less moisture and producing biomass, even in dry season. Symbiotic (legume-rhizobia) and asymbiotic (Azotobacter, Azospirillum) associations lead to enhanced nutrient availability. Micro organisms play important role in breakdown of organic matter (composting). Nowadays, earthworms and microbial cultures are used to accelerate the process of bio mass break down. Phosphate Solubilising Bacteria (PSB) and Vescicular Arbuscular Mycorrhiza (VAM) play important role in enhancing nutrient and water uptake by plant.
As far as the resource utilization is concerned, there is need to design farming systems in the most appropriate manner. Over exploitation of natural resources also lead to loss of sustainability. The water depletion must be matched by annual recharge during the rainy season. Incorporation of trees in the production system, may lead to enhanced nutrient and water use efficiency. With respect to water requirement, farm sustainability would be high if it meets its water requirement internally through rain water harvesting and saving of water in water bodies. Water use efficiency can also be improved by providing irrigation at critical stages of crop growth.
Germplasm conservation is another aspect in achieving sustainability. Following traditional agriculture, every year some seeds of native varieties must be kept for sowing next year, so as to conserve native germplasm. In some adverse conditions, local/native varieties perform much better than the improved varieties. Therefore it is better to have a mix of native and improved varieties. Improved varieties mainly aim at high yields, irrespective of high disease and insect pests incidence. Among control measures first preference is given to chemical control, while for the sustainability aspect, large farm community efforts should be made on adopting biological and cultural control of disease and insect-pests.
Agriculture is said to be sustainable, when it is in harmony with natural cycles, especially those of carbon, nitrogen, water and energy. The most widely known sustainable agricultural practices include permaculture, nature farming, biodynamic farming and ecological agriculture. Sustainability in farming cannot be achieved through short-term measures or within a short period of time. To attain this sustainability, first we need to sustain our interest and determination through experiences, which may not always be pleasant. But a resourceful farm is an eventual reward, with the capacity to withstand environmental stresses and meet not only the current needs but also serve the future generations.