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In intensive agriculture, integrated plant nutrient management takes care of both crop nutritional needs as well as soil fertility considerations leading to increased crop yields through judicious consumption of inorganic nutrients in cropping systems. There is an urgent need to reduce the usage of chemical fertilizers and in turn increase application of microbes along with organic manures, which are known to improve the physicochemical properties of the soil and supply of nutrients in an available form to plants. Therefore, integrated use of microbes for nutrient and disease management, along with organic manures and inorganic fertilizers simultaneously has been suggested as the most effective method to maintain a healthy and sustainable soil, while increasing crop productivity. Inoculation with these methods was found to increase crop yields by ~10–15% under farm conditions. In many situations, this association also leaves substantial amounts of residual nitrogen fixation for subsequent cropping systems. Use of biofertilizers requires special skills and therefore farmers need to be equipped with the knowledge and skills of using various biofertilizers in order to promote sustainability. Hence, this chapter enlightens the reader on the effect of different microbes [Rhizobium, phosphate solubilizing bacteria (PSB), and plant growth promoting Rhizobacteria (PGPR)] alone as well as in combinations with organic and inorganic additives on crop productivity and soil health.

Rice-wheat cropping system (RWCS), one of the prominent agricultural production systems, at an area of ~26 M ha is confined to the Indo-Gangetic Plains (IGPs) in South Asia and China. Crop residues obtained from field crops are essential sources of nutrition and organic carbon (40% of total dry biomass constituted by C) for the next crops, and hence they not only increase the agricultural productivity but also are responsible for the better quality of soil, water, and air. Perhaps the most important challenge facing exhaustive RWCS in all regions of the world is effective management of post-harvest crop residues. Disposal of wheat residue is easy as it can be used to feed animals. However, due to the presence of high silica content, rice residue is usually burned. Residue burning is the main method of disposal in areas under combined harvesting in the IGPs of eastern India as it reduces cost. However, burning of crop residue (CR) is not eco-friendly as it results in fast degradation of soil organic matter and nutrients and increased CO2 emission creating intense air pollution as well as global warming. Therefore, exploitation of CR is a crucial element for a sustainable production system, and it has generated much interest in the recent years by reducing the consequence of residue burning and increasing the soil organic matter (SOM) and the nutrient-supplying capacity. CR retention infield can be considered a key element in promoting soil health with increased physical, chemical, and biological properties. In RWCS, residue management can be done by (1) wheat residue retention in rice and its residual effect in succeeding wheat crop, (2) rice straw retention in wheat and its residual impact in following rice, and (3) wheat straw retention in rice and rice straw retention in wheat (cumulative effect). All these crop residue management systems depend on a systematic understanding of the factors that control residue decomposition and their careful application. Significant factors, such as tillage/CR management, influence soil microbial activity and biomass, bulk density, soil moisture content, porosity, soil structure stability, and nutrient-supplying capacity of the soil. Thus, the variations in soil properties consequently bring change in soil C and N dynamics and have an impact on plants’ nutrient uptake capacity.

Bread and rice basket of South Asia is feeding ~20% of the global population. The agricultural production system in South Asia is predominated by exhaustive cereal production system including rice, wheat, and maize. Thus, it greatly affects the livelihood and nutritional security of the rural and urban poor. Recently, cereal productivity had slowed down or stagnated. Present expansion rate in terms of yield of rice and wheat is ~2–3 times higher than in 1966–1994. During 1980s, the peak of “Green Revolution” in the agricultural production system helps in the reduction of rural and urban poverty by making food more affordable. During the 1990s, growth in yields slows down because of technological stagnation resulting in high food prices. Slow growth in yields mainly inflated on wheat and rice by ~1%. Therefore, agriculture in South Asia is presently in front of a major challenge of resource fatigue and declining crop productivity. In addition to that, a huge gap exists in yields mainly due to yield gap management, ranging from 14–47, 18–70, and 36–77% in wheat, rice, and maize, respectively. Crop residues are considered a vital natural resource for protecting and sustaining soil and crop productivity. Application of crop residues is useful for maintaining or enhancing soil organic matter (SOM). This chapter presents the perspectives on soil and environment through principles of conservation agriculture (CA) for sustainable cereal production system in Indo-Gangetic belts of South Asia.

Nowadays the land degradation, deteorating the soil health, is the major constraint, which led to the nutrient depletion and limited potential yield of crops toward the food security worldwide. To enhance the crop production, soil sustainability is one of the ideal and sustainable approaches to overcome depleting the soil fertility status and land degradation. The rhizospheric beneficial microorganisms (RBMs) may offers rate of plant growth, agronomically, pathogenically, and environmentally advantage for intensive agricultural production system. The nitrogen-fixing rhizobacteria (NFR) fix atmospheric nitrogen in the soil, while phosphate-solubilizing microorganisms solubilize the insoluble phosphorus (P) in the soil, potassium-solubilizing rhizobacteria (KSR) mobilizes the stable potassium in field, and similarly other microorganisms mobilize nutrients in soil and make it easily available to the crop plants. These NFR include symbiotic N2-fixing forms, in leguminous plants, viz., Rhizobium, and obligate symbionts in nonleguminous plant comprising species Alcaligenes, Azomonas, Beijerinckia, Achromobacter, Acetobacter, Arthrobacter, and Bacillus spp.; however, P is the primary essential macronutrient for vegetative and reproductive development of the plants. The majority of phosphorus in most soil is insoluble form and cannot be used by crops. Some important species are Aspergillus, Bacillus, Pseudomonas, Penicillium, etc., which secrete organic acids (products) that lower pH in their vicinity and help to bring the dissolution of fixed phosphates in soil. Additionally seed bio-priming can provide ~30 kg P2O5/ha. In soil system potassium (K) is associative to movement of water, nutrients, carbohydrates, and cellular and osmotic pressure in plant tissues. Supposing potassium is lacking or not provided in suitable amount, growth of the plants stunts and production reduces. Several bacterial species particularly rhizosphere-colonizing bacteria have been found, which solubilize insoluble inorganic phosphate like that tri-calcium phosphate (TCP), di-calcium phosphate (DCP), hydroxylapatite, and rock phosphate. It is already proved that application of Zn in the form of chemical fertilizer is inappropriate due to its unavailability to crop plants. In the recent past, rhizobacteria have exhibited terrific ability to improve zinc availability in root zone and enhance zinc in plants. In rice, silicate-solubilizing rhizobacteria (SSR) have gained importance in recent times because of their role in solubilization of silicate minerals, rendering potassium silicate (K2SiO3), and makes readily available potassium (K) and silicon (Si) for crop plants. Recent advancement in biotechnology and genetic engineering have provided new opportunity to find out the presence and abundance of particular microbes or to quantify the expression of target genes directly in soil or in rhizosphere with high levels of sensitivity. Genetically modified strains could be capable of solubilizing more available nutrient from the soil or rhizosphere. Development of genetically modified strains with enhanced mobilization by genetic engineering techniques and DNA technology is needed to maintain an eco-friendly and sustainable agriculture. This chapter focuses on diversifying of nutrient solubilizer/mobilizer microbes, mechanism of solubilization/mobilization, role of various enzymes/auxins/acids effect of various factors on nutrient solubilization, the present and future scenario of their utilization, and potential for application of this knowledge in managing a sustainable environmental ecosystem.