Sustainable Agriculture Systems and Technologies. Группа авторов

agricultural intensification to ecological intensification.

      (See insert for color representation of the figure.)

      Even under stressed ecologies (poor soil fertility, dry land scenario, abiotic, and biotic stresses), the crop diversification and growing of large number of crops are widely recommended to reduce the risk factor of crop failures. For the majority of farmers in different parts of the country, the gains from application of scientific tools and technologies in agriculture are yet to be realized. On realization, it will help in greater expansion of crop diversification in many areas. It is hard fact that the productivity levels of many major crops in India do not match with the yields obtained in agriculturally advanced countries even under predominant rice–wheat system. On the other hand, as a result of growing few crops in large areas, many problems in the forms of increasing biotic and abiotic stresses are emerging. Therefore, diversification of predominant cropping system in India will bring the new dawn of prosperity and resilience in agricultural production system. Therefore, efficient and effective crop diversification is a crucial for the sustainability of Indian agriculture.

2.4 Reducing Emission of Greenhouse Gases

      The good agronomic practices (GAPs), such as, conservation tillage, organic nutrient sources along with inorganic nutrient sources, weeds, insect pest, and disease management along with adequate irrigation water management in diversified production system can greatly reduce greenhouse gases in the atmosphere. The selection of climate smart crops which require comparatively lesser nutrient, water from production system and have lesser impact of biotic and abiotic stresses are the essential components of the crop diversification. In this category, oilseeds, pulses are good examples; for these crops, the GHC emission is also less. Conservation tillage and deficit irrigation can also substantially minimize CO₂ and N₂O emission. Appropriate use of the crop residue and complete banning of its burning reduces the generation of CO₂, N₂O, and CH₄ to a significant extent. Crop diversification ensures greater functional biodiversity to cropping systems and it also regenerates biotic interactions underpinning yield‐supporting ecosystem services (Rathore and Shekhawat 2020). It embraces a variety of practices encompassing the management of crops, noncrop habitats, soil, and landscapes (Cardinale et al. 2012; Wagg et al. 2014; Renard and Tilman 2019; Tamburini et al. 2020).

2.5 Effect of Technology‐Induced Crop Diversification

      The advancement in technological development especially development of high yielding and biotic, abiotic resistant varieties, of wide window of growing period, CA‐based systems, land configuration, and other improved agronomic management, along with increasing value addition and better postharvest handling are the encouraging forces for promotion of crop diversification in different parts of the country. Green revolution technologies intensified cropping system in irrigated areas in favor of rice and wheat and other crops got less acreage due to low productivity and less profitability. This enhanced total output of cereals tremendously but also created second generation problems like intensive use of chemical fertilizers, pesticides, etc., led to pollution of resource base, overexploitation of groundwater resulted in depletion of ground water, salinization. This made urgent call for crop diversification to achieve sustainable high levels of productivity with conservation of natural resource base and to secure higher profitability to the farmers in the long run. Rice–wheat acreages increase substantially in Indo‐Gangetic plains (IGPs) zone due to better irrigation infrastructures and higher response to the applied inputs for long time. Also, the government support system was developed over the period to safeguards the interest of the cereal growers through better pricing, input supply, and other incentives like increased availability of quality seed of improved varieties to the farmers. Later the stockholders including the farmers realized the faults in the ongoing cereal‐based system and promoted crop diversification in originally green revolution areas.

      The technological development in all sectors of crop production also promoted farmers awareness to explore for crop diversification. High yielding varieties, suited to different ecologies, were developed in oilseeds, pulse crops, and millets and improved agronomic practices. These also helped in harnessing higher productivity from the diversified cropping system. The better minimum support price of the millets, oilseeds, and pulses also help in increasing the farmers’ awareness for bringing more and more area under crop diversification. The inclusion of leguminous crop not only helps in maintaining optimum soil fertility but also helps in minimizing the impact of biotic and abiotic stresses among the crop plants due to alteration in host–pathogen relationship. It helped in maintaining over all ecological balance in agriecosystem.

The date of sowing is considered as the simplest agronomic management to minimize the impact of climate change/variability on crop growth and productivity. It will be helpful to make contingency planning to fit proper variety to extreme weather conditions like raising and decreasing temperatures, varying rainfall and other weather components. The climate smart varieties would be used in large scale on farmers' field. The diversification of cereal‐based cropping systems with the crops such as oilseed, pulse, and forage crops, is another option for minimizing biotic and abiotic stresses. The pathogenic cycles could be broken up through crop substitution (Singh et al. 2002, 2020; Rathore and Bhatt 2008). Consistent practicing of monocropping resulted in loss of soil fertility, decline of soil health, factor productivity decline and lowering crop productivity even under high productivity areas (Saha et al. 2012). Conservation tillage also promotes greater soil biodiversity thereby leading to more biotic stresse suppression. Proper pest management is a permanent challenge to the farmers, and it is a very important ecosystem service, which can be restored through crop diversification. The erosion of genetic diversity led to an increase in crop disease occurrence. Greater varietal and species richness reduce the spread of disease in agricultural systems. Habitat management in agricultural systems is an effective means to enhance natural enemies. These have been developed for effective application in crop, at farm, and few of these are reported be very economically useful for the farmers. Gurr et al. (2003). The diversity of crop species within the agro ecosystem consequently offers long‐term pest suppression by building up potential natural enemies for any pest outbreaks.

2.6 Congenial Conditions for Crop Diversification

      India is a highly diversified country in terms of climatic conditions, soil types, topography, and other agro climatic conditions. Therefore, the ICAR has divided the whole country into 15 agroclimatic zones. This help for wider cultivation of number of crops in the country. India is also one of the mega biodiverse countries and many of the crops originated in India. Traditionally, the farmers were practicing a diversified cropping system by inclusion of many crops during different crop season. But over the period, after green revolution and increasing government efforts and food demand, lot of emphasis has been paid only to cereal‐based system. This resulted in growing of one or two crops only.

       Diverse agro‐climatic conditions

       Diverse weather within a year

       Huge market

       Great potential for processing and value addition

       Large number of crops, including underutilized

Figure 2.3 indicated that diverse bioclimatic zones of India along with different agroclimate favors for promotion of crop diversification. For achieving a very useful diversification plan, there is a need to develop intensive cropping systems with diverse crops. Furthermore, these agro ecological regional classifications indicate very systematically the existence of diverse soil, climatic, and growing conditions and based on these diverse conditions, across the country the suitable crop diversification plans have been developed by various experts. There is a need to popularize these time‐tested crop diversification plans vigorously in the country at farmers’ fields to get all the benefits to the small and marginal farmers in particular.

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