Sustainable Agriculture Systems and Technologies. Группа авторов

which also produces diverse ecosystem services, such as regulation of soil and water quality, carbon sequestration, support for biodiversity, and cultural services, and these are well maintained under diverse production scenarios including well‐designed crop diversification (Polasky 2008). On the planet earth, there exist half a million‐plant species but we are depending only upon rice, wheat, maize, and soybean for food security, globally. Depending on fewer crops for our food and other needs may lead to serious ecological threats in terms of increasing biotic and abiotic stresses in crop production. In spite of the vast plant biodiversity across the world, unfortunately at present 150 crops species are being used widely as now commercially important crops. More worrisome is the fact that the cereals, rice, wheat, and maize account for 60% of the world's food supply. Over seven billion people depend on the productivity of these major crops and in the near future the global population will reach to 9.0 billion and meeting the food and nutritional requirement of burgeoning population is a daunting task. The mono‐cropping constraints the provisioning services of the ecosystem. Therefore, the major crops alone may not be able to meet the world's food and nutritional requirements. The higher crop productivity of food grain crops can meet the energy demands of a mounting population; they may not provide adequate nutrition. The double‐burden of over and under nutrition (Hidden Hunger) is a major challenge. Nutrient‐poor and energy‐rich diets are linked with lack of dietary diversity. In this context, it is very pertinent to mention the significance of the cropping systems diversification to promote ecosystem services, thereby reducing dependency on external inputs while sustaining the high crop productivity. Overall, diversification of cropping ensures diversity of beneficial organisms in the ecosystem, better pollination, pest management, nutrient cycling, and water regulation without compromising crop yields (Rathore et al. 2019). Hence, aboveground biodiversity reduces pest menace and helps in water regulation, while belowground biodiversity enhances nutrient cycling, soil resilience, and water regulation. It is very common that the diversification practices resulted in enhancing the support services of the ecosystem and enhances crop productivity (Tamburini et al. 2020).

2.2 The Need for Agricultural Diversification for Sustained Livelihood

      The size of holdings is declining across the world, more especially in developing countries. In India, almost 86% of the farmers are small and marginal (<1.0 ha) for whom agriculture has become cost‐intensive due to escalating prices of agro‐inputs, labor, and energy, etc. The decreasing landholding size and mono‐cropping types of crop cultivation poses grave challenges to the profitability and overall livelihood of the farmers. Achieving economic sustainability in such agricultural production system necessitates coherent linkage of climate‐smart agriculture with the farmer's needs. In this context, integration of cropping with other farming enterprises under agricultural diversification as integrated farming system (IFS) can ensure enhanced system productivity, resource‐use efficiency, and improved livelihood. Research evidences across the country clearly reveals that the complementary coexistence of diverse crops and other farm enterprises can provide an array of benefits in meeting out the growing demands for food and nutrition rich dietary, income stabilization, and livelihood upliftment while conserving ecological balance and environment, particularly for small holders with limited resources (Singh et al. 2020).

This is of utmost important to maintain ecosystem services adequately for ensuring sustainability in farming. The direct and indirect aids of ecosystems to plant–animal–human continuum are included mainly under the ecosystem services (TEEB 2010). Crop diversification, a type of cropping now has been widely recognized to maintain balance between human needs and ecosystem system services. It is a type of cropping with more number of the crop species. Agricultural diversification can safe guard greater food and nutritional security, minimizing environmental degradation, lessening poverty, higher use efficiency of land resources, and also preventing the impact of degradation forces and helping in contesting desertification. Diversification of agriculture opens new vistas for additional environmentally safe, sustainable systems, enhanced livelihood options for farmers. Some of the crops which are presently considered as underutilized can become a potential tool and hence will ensure more ecologically sustainable agricultural production systems and provide newer livelihood options for small holder farmers. As a matter of the fact global food supply relies on 150 crop species. And the most gruesome challenge is that out of the 150 crops, there are only 12 crops which provide around 75% of the world's food demand. This indicates toward one of the most unsustainable land use types for food production practices in the world. The simple fact that three cereal crops like rice, wheat, and maize are the principal source of more than half of the global food energy and that too from a limited number of varieties of the three “mega‐crops” made the agriecosystems very unsustainable. These cereal crops are also very exhaustive in their demand for nutrients and water, which further complicates the problem of resource degradation.

2.3 Crop Diversification and Ecosystem Services

Generally, crop diversification is perceived as a change from the regional supremacy of one crop to regional production of number of the crops to meet ever increasing demand of cereals, pulses, vegetables, fruits, oilseeds, fibers, fodder, grasses, etc., of the human and livestock population. Crop diversification also guarantees higher profits for the growers. It also aims to improve soil health and to maintain dynamic equilibrium of the agroecosystem. Furthermore, in India crop diversification is generally viewed as a shift from traditionally grown less remunerative crops to more remunerative crops. In the present context, the unsustainability of the modern agricultural system, there lies high stack on crop diversification mainly due to disturbance in the ecosystem. The sustainability of agricultural production system can be achieved by maintaining ecosystem services, with the design of appropriate crop diversification plans specific to agro climatic conditions. From Figure 2.1, it can be well understood that among all the agricultural operations/practices, the crop diversification including the agricultural diversification has a greater role to play in maintaining the ecosystem services.

The agroecosystems provide ecosystem services through improved human interventions which have no or very little pressure on environmental resources, ensure recycling of waste products and support large biodiversity as maintained under natural, unmanaged ecosystems. The ecosystems are vital for survival of all living beings. The genetic diversity of crops and livestock, soil health maintenance, and the provision of water sources are some of the very important supporting ecosystem services. Whereas, the regulating services of the ecosystems are in the form of pollinators, which ensures better seed setting, and the presence of the natural enemies control the crop pest within agro‐ecosystems. Natural ecosystems also filter water and normalize its flow into agricultural systems. Therefore, crop diversification create favourable conditions for smooth functioning of the ecosystem services. This ultimately improves the overall health of the ecosystem which are essential for survival and well‐being of mankind. It also ensures enhanced floral and faunal diversity, better pollination, natural pest management, efficient nutrient cycling, soil fertility, and water regulation without compromising on crop yields. Sustainable agronomic management targets above and below ground biodiversity, ensures better pest management, improved water regulation, enhanced nutrient cycling, and improved soil health.

Figure 2.1 Crop diversification maintains many of the ecosystem services and hence also maintains the resilience in the production systems.

Figure 2.2 (a) Functional biodiversity delivering ecosystem services (e.g. pollination, natural biocontrol) in support of crop yields along a gradient of crop diversification and ecological infrastructure and (b) alternative options (efficiency, substitution, redesign) for farm management systems