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The climate change and land degradation are both individually and in combination have profound influence on natural resource based livelihood systems and societal groups, but this land degradation is caused by land use changes and unsustainable management. The different land use systems practiced in southern agro-climatic zones of Karnataka have significant impact on soil carbon and fertility status of soils, a study was carried out to characterize and classify the soils of southern agro-climatic zones of Karnataka. Five pedons, one from each agro-climatic zone from cultivated land use were selected for the study. Soils of Hiriyur pedons were moderately shallow and rest were deep to very deep, red, well drained and appreciable amount of gravels were observed in all the pedons. Clay illuviation in sub-soil layers was observed hence sub-soil layer contained more clay than surface. The soil texture varied from sandy clay loam to sandy clay and clay. Bulk density of soil varied from 0.86 to 1.86 Mgm-3 in the surface. In all the profiles, bulk density increased with depth. Soil reaction varied from very strongly acidic to moderately acidic in Balehonnur and Brahmavara, moderately acidic to neutral in Hassan and Tiptur, neutral to moderately alkaline in Hiriyur. Cation exchange capacity was low and exchange complex was dominated by hydrogen and aluminum. Dominant cations were calcium and magnesium hence base saturation was high in the pedons due to leaching of bases and deposition in sub-surface horizons within the solum except in Brahmvara and Balehonnur was observed.

Microorganisms give life to the soil and provide a variety of ecosystem services to plants. Soil bacteria are the strongest candidates for determining soil health. Bacterial communities are important for the health and productivity of soil ecosystems. Therefore, we must have a thorough knowledge of the diversity, habitat, and ecosystem functioning of bacteria. In this chapter, we will discuss the functional, metabolic, and phylogenetic diversity of soil bacteria and highlight the role of bacteria in the cycling of major biological elements (C, N, P, and S), detoxification of common soil pollutants, disease suppression, and soil aggregation. This chapter also underlines the use of soil bacteria as indicators of soil health. We have concluded the chapter by taking note of the present agricultural practices that call for concern regarding the natural soil microflora and steps to return biological activity to the soil.

Highly weathered laterite soils are a characteristic feature of humid tropics with undulating topography and high rainfall. The crop of cashew (Anacardium occidentale L.) has been cultivated in such landscapes, mainly to prevent further degradation due to the drought hardiness of cashew and requirement of very limited soil disturbances for its cultivation. Providing proper nutrient management is important for balancing the nutrient removal by tree crops especially in poor fertile soils. A study was initiated, after 5 years of application of inorganic fertilisers and organic amendments to cashew in a weathered tropical soil, to evaluate the effects of organic and inorganic sources of nutrients on soil aggregation and biochemical characteristics. The experiment consisted of 11 treatments as Farm Yard Manure (FYM) alone; FYM + biofertiliser consortia; FYM, rock phosphate and wood ash; poultry manure; In situ composting using recyclable cashew biomass and weeds; In situ composting using recyclable cashew biomass and weeds + green manuring; vermicomposting of recyclable cashew biomass; FYM + organic cakes + recyclable cashew biomass + biofertiliser consortia; recommended dose of nitrogen, phosphorus and potassium fertiliser (NPK fertiliser); recommended NPK fertiliser + FYM; and control without nutrient application. Soil samples were collected from surface 0–30 cm layer. The soil samples were fractionated into three aggregate sizes, i.e., >2 mm (large macroaggregates), 0.25–2 mm (small macroaggregates), 0.053 to 0.25 mm (microaggregates) and

To assess the effect of planting density and irrigation in cashew (Anacardium occidentale L.) during its critical growth stages such as flowering and fruit set on, growth, yield, water-use efficiency and farm income, a field experiment was initiated in a split-plot design in 2011 at Puttur, Karnataka, India. The main plot consisted of three planting densities namely, 5 × 4 m, 6 × 4 m and 10 × 5 m. The irrigation treatments were imposed in subplots as, irrigation at 60% cumulative pan evaporation (CPE), at 40% CPE, at 20% CPE, irrigation once in 15 days, soil and water conservation technique, and control (without any irrigation or soil water conservation technique). The results indicated that the growth, raw cashew nut yield and net income during 5th and 6th year of plantation of cashew increased with increase in planting density per unit area. The average increase in nut yield under high density planting ranged from 75 to 81% compared to normal density planting. Irrigation using drip system from December to March at 20% CPE and 40% CPE was beneficial to increase the nut yield by 53.5% and 34.1% compared to control. The yield increase under soil and water conservation practice was 12.9%, and 59.7% under irrigation once in 15 days. The increased planting density was beneficial to increase the net income and benefit–cost ratio. The deficit irrigation practices were useful to increase the water-use efficiency in cashew. Widely spaced trees showed increased water-use efficiency compared to high-density planting. Overall, the study demonstrated the usefulness of increased planting density and appropriate irrigation practices to increase yield and net income from cashew orchards.

Rhizosphere, a zone of intense microbial activity is a hub of soil–plant–microbial interactions playing a vital role in the growth and yield of plants. Physical, chemical, and biological properties of rhizosphere are greatly influenced by root exudates, energy source for proliferation, and activity of microbes. Various microorganisms in rhizosphere greatly influence nutrient availability and play an important role in all aspects of nitrogen cycling. Nitrogen is one of the essential macronutrient elements considered critical in limiting plant growth and development. Majority of plant nitrogen uptake is accounted by organic nitrogen pool of soil; highlighting the role of plant roots and associated nitrogen transformation in the rhizosphere. In-depth understanding of various soil–plant–microbial interactions in rhizosphere governing nitrogen availability and uptake is essential for increasing plant nitrogen acquisition, thereby enhancing use efficiency.

The plant family Brassicaceae commonly known as the cabbage family or mustard family has several agriculturally important crops. The major vegetable crops include cauliflower, cabbage, broccoli, kale, Brussels sprouts, turnip, radish, etc., and major oilseed crops are mustard and canola. Every essential nutrient has an inevitable role to play in a plant’s growth and development; however some may be critical towards some crops such as in providing resistance to pests and diseases, or in terms of improving quality of the crop. Among macronutrients, S is one of them, very much essential to the plants of Brassicaceae family as it has got prominent effect on oilseed crops. Striking a perfect balance between N and S is important in growth and development of Brassicaceae plants. An understanding on the role of nutrients in the growth and development of plants belonging to Brassicaceae family is essential to identify their requirements for nutrients. This would provide an insight into identification of the symptoms exhibited as a result of nutrient deficiencies. The chapter deals with the nutrient deficiencies in Brassicaceae plants, and their responses and tolerance to stresses such as nutrient deficiencies. Hence, a better knowledge on these would aid in enhancing productivity of Brassicaceae plants by properly managing nutrient deficiencies and related abiotic stresses.