Prof. (Dr) R.D. Gupta
Science and technology has made tremendous progress in various sectors including agriculture. Use of high yielding varieties of crops in agriculture, especially rice and wheat, which responded to high doses of chemical fertilisers, pesticides and require large quantities of water, brought about a Green Revolution during 1967-68. Though the Green Revolution brought a boost to India’s food grain production and pride in having achieved, self sufficiency. However, India’s agriculture has entered a post Green Revolution stage since 1998. Demands for agricultural technology are changing and diversifying. These demands can be broadly categorised as technologies to break the stagnation of yield growth in intensive irrigated agriculture as well as technologies for more sustainable use of natural resources stand discussed. Apart from this, how the country’s malnutrition crises, which persist even after Green Revolution in the country, can be lessened.
Impact of integrated nutrient management: Sustainability in crop production is not a viable proposition either through use of organic manures or chemical fertilisers alone (Yaduvanshi et al.2013). The use of organic manures including green manure was widely practised in number of Asian countries in irrigated rice in the past, but the yield declined with increasing crop intensity and ready availability of chemical fertilizers in the last few decades. However, owing to shortage of energy, increased cost of chemical fertilisers, deterioration of soil health, water and air, now the use of organic manures has become very important along with use of NPK fertilisers.
Recently the effect of inorganic fertilizer alone and in combination with organic manure stands evaluated for yields of rice and wheat grown on a reclaimed sodic soil after 12 years i.e; 1994-95 to 2005-06 as well as their effects on soil organic carbon, available NPK and bulk density. The results of this study has shown that the applicants of 100 per cent recommended doses of NPK (120+26+42 Kg ha-1) with organics (Green manure or farm yard manure) was the best INM combination because of improvement of soil organic carbon, bulk density and available N, P and K. It was also found that after 5-6 years, 50 per cent of recommended doses of inorganic fertilizers inorganic fertilizers(60 Kg N,13 Kg P and 21 Kg ha-1) with intergrated use of green manure of farm yard manure gave similar yield of 100 per cent recommended doses of N,P and K (120+260+42 Kg ha-1).
Application of FYM@10 tonnes ha-1 along with soil test based fertilizer recommendation can save 12.4, 11.6 and 6.5 Kg ha-1 of N, P2 O5 and K2O respectively in case of garlic grown under inceptisol soil conditions in Rahuri, District, Ahmednagar (Maharashtra). The continuous cropping under imbalanced use of chemical fertilizers for more than 22 years showed depletion of soil nutrients while they were enhanced due to intergrated use of nutrients (Kharche et al.2016). The available N,P and K status was significantly higher in intergrated treatment over rest of the treatments. Not only this, soil physical properties were improved due to continues application of chemical fertilisers in conjunction with organics over only chemical fertilisers. Soil organic carbon showed profound influence in increasing soil physical properties such as particle density, hydraulic conductivity and water retention characteristics indicating their characteristics indicating their dynamic nature and dependence on soil management practices.
Inclusion of legumes in cropping system
The contribution of leguminous crops or legumes in cropping systems to enhance crop yields and to ameliorate the soil fertility, has been reviewed from time to time. The effect of preceding crops on the succeeding non leguminous crops have been studied at a number of places in India and abroad. In India, major area is covered under food grains, rice being grown over the largest area. Generally, the prevailing stable cropping systems are as follows:
a) Mono cropping: It is broadly followed in semiarid and arid regions where mostly maize or pearl millet is grown.
b) Double cropping: It is such a cropping system, where mostly rice-wheat cropping system is mostly followed under irrigated conditions.
c) Intercropping: Intercropping system is generally chosen in dryland agriculture so as to have pulses (Legumes) associated with the cereal. The major emphasis in nitrogen management remains on the direct or current transfer of nitrogen from the legume component to the non-leguminous one. The roots of the leguminous plants contain symbiotic bacteria which are confined to nodules of legumes. Beijerinck was the first who isolated these bacteria and were named as Bacillus radicicola which are now called Rhizobium (Rhizobia). These bacteria fix the atmospheric nitrogen in nodules of the leguminous plants symbiotically. It is because these bacteria live in symbios is with the plants, derive the food, energy and minerals from the leguminous plants and in turn they supply nitrogen to the soils, which they obtained from the atmosphere and fixed in the nodules.
It is point to mention that an adequate supply of calcium, phosphorus and molybdenum are essential to enable the nodules to fix atmospheric nitrogen. Other soil conditions that influence the growth and longevity of Rhizobia are air supply, temperature and light. There are evidences that inclusion of legumes like green gram (Moong) and cowpea in the intercropping systems can lead to saving of N to the extent of 30 Kg N ha-1. In a five year rotation of castor with sorghum, sorghum + pigeonpea and green gram + pigonpea in a Alfisol of Hylerabad, it was found that green gram + pigeonpea intercrop (4:1) had a net positive balance of 97 Kg nitrogen ha-1 .
Adoption of agroforestry: Innovation in agroforestry systems can solve a number of problems presently being faced by the Indian farmers. Increasing human and livestock population and shrinking of agricultural land holdings are the main problems, causing a great concern to the planners. As agroforestry systems yield numerous products such as food, fodder, fuel, fruit and fertilizer and at the same time effectively conserve soil and moisture so it requires to be adopted fully wherever it is possible.
Use of biofertilizers: among various production factors to increase the productivity, use of biofertilizers like Azospirillum, and Azotobacter, Blue Green Algae, Rhizobium and Phosphated, Dissolving Bacteria play a keyrole. They economises the nitrogen use and phosphorus, and also improve the quality and yield of crops and fodders.
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