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Soil microbial communities are important drivers of biogeochemical cycling of nutrients, organic matter decomposition, soil organic carbon, and Greenhouse gas emissions (GHGs: CO2, N2O, and CH4) and are influenced by crop and soil management practices. The knowledge on the impact of conservation agriculture (CA) on soil bacterial diversity, nutrient availability, and GHG emissions in semiarid regions under rainfed conditions is vital to develop sustainable agricultural practices, but such information has not been systemically documented. Hence, studies were conducted for 10 years in rainfed pigeonpea (Cajanus cajan L.)-- castor bean (Ricinus communis L.) cropping system under semi-arid conditions to assess the effects of tillage and crop residue levels on the soil bacterial diversity, enzyme activity (Dehydrogenase, urease, acid phosphatase, and alkaline phosphatase), GHG emissions, and soil available nutrients (Nitrogen, phosphorus, and potassium). Sequencing of soil DNA through Illumina HiSeqbased 16S rRNA amplicon sequencing technology has revealed that bacterial community responded to both tillage and residue levels. The relative abundance of Actinobacteria in terms of Operational Taxonomic Unit (OTUs) at phyla, class as well as genera level was higher in CA (NTR1: No Tillage + 10 cm anchored residue and NTR2 NT + 30 cm anchored residue) over CT (conventional tillage without crop residues). CA resulted in higher enzyme activities (dehydrogenase, urease, acid phosphatase, and alkaline phosphatase) and reduction in GHG emissions over CT. CA recorded 34% higher and 3% lower OC, as compared to CT, and CTR1, respectively. CA recorded 10, 34, and 26% higher available nitrogen, phosphorus, and potassium over CT and CTR1, respectively. NTR1 recorded 25 and 38% lower N2O emissions as compared to CTR1 and CTR2, respectively. Whereas only NT recorded 12% higher N2O emissions as compared to CT. Overall, the results of the study indicate that CA improves the relative abundance of soil bacterial communities, nutrient availability, and enzyme activities, and may help to contribute to the mitigation of climate change, and sustainability in rainfed areas. [ABSTRACT FROM AUTHOR]

Maintenance of soil physical health at its optimum level is essential for sustainable crop production and rational use of natural resources without jeopardizing their quality. The ongoing conventional tillage practices for crop production using intensive ploughing and removal of crop residue from the field have resulted in an increase in surface crusting, soil compaction, soil erosion, decrease in water infiltration and ultimately aggravation of the overall soil physical health deterioration. In recent years, many agricultural scientists across the world have recommended conservation agriculture as a solution to overcome the adverse effects of conventional tillage practices on soil physical health. Conservation agriculture is mainly an integration of three crop management practices, viz. minimum or no-tillage, permanent retention of crop residue and crop rotation. The present data indicates that conservation agriculture can improve soil physical properties and associated processes especially, soil water infiltration and storage, soil aeration, soil structure and soil porosity. It reduces soil erosion, soil compaction and crusting, and optimizes the soil temperatures for successful crop production. This article reviews the role of conservation agriculture in improving soil physical health and its associated processes. [ABSTRACT FROM AUTHOR]

Reducing tillage intensity and retaining residues are important components of conservation agriculture but in small holder systems in developing countries where crop residues have alternate uses such as fodder and fuelwood, recycling or external additions of organic matter may be a possible option. Information on impacts of long term reduced tillage on soil carbon, labile organic carbon fractions and their depth distribution is scant in drylands of semi arid regions. The effect of tillage intensity (CT—conventional tillage; RT—reduced tillage and MT—minimum tillage) and sources of nitrogen (100% OS: 100% of recommended N through organic source; 50% OS +50%IOS: 50% N through organic source and 50% N through inorganic source and 100% IOS: 100% N through inorganic source) on crop yields, soil organic carbon and C fractions in an Alfisol was assessed at the end of a 10 year long term experiment. Finger millet yields decreased significantly with reduction in tillage intensity (29%). Among N sources, highest yields were recorded with substitution of 50% of the N through organic source. After 10 years, the soil organic carbon (SOC) in 0–20 cm soil layer with MT was 11% higher than with CT. The labile fractions of carbon, viz. particulate organic carbon (POC), microbial biomass carbon (MBC) and permanganate oxidizable carbon (KMnO 4 -C) under MT were 47%, 16% and 43% higher, respectively, in comparison to CT in the 0–20 cm soil layer. The total carbon (TC) and total organic carbon (TOC) with MT were higher by 28% and 27% over CT and higher by 20% and 20% with 100%OS over 100% IOS. Labile carbon fractions revealed differential sensitivity and POC, MBC and KMnO 4 -C are sensitive indicators to detect short term management effects. Reducing tillage intensity and applying various N sources enhanced SOC marginally and the C sequestration rate varied from 62 to 186 kg ha −1 yr −1 . Based on the study it can be recommended for substitution of 50% of the recommended N with organic source as it increases crop yields and soil carbon and could be a potential alternative for residue retention for crops which have fodder value. Reducing the tillage intensity can enhance the SOC in semi arid rainfed systems but lower crop yields under MT is a concern which needs to be addressed in order to make these systems acceptable to the farming community. [ABSTRACT FROM AUTHOR]

Inceptisols in the submountainous region of Indo-Gangetic Plains in India are known as low productive areas due to several constraints like decline in soil organic matter and fertility, deterioration of soil physical and biological properties. The present study was conducted with tillage as main treatments and integrated nutrient management as subtreatments to improve soil quality and to identify the key indicators of soil quality after 5 years of experimentation in maize–wheat cropping system at Ballowal Saunkhri. Conventional tillage (CT) + interculture (IC) maintained significantly higher soil quality indices (SQI) of 1.12 which was at par with 50% CT + IC + chemical weed control (CWC) (1.08). Application of nitrogen (N) through 50% (organic) + 50% (inorganic) maintained higher soil quality with SQI of 1.10 followed by application of 100% N through organics (1.08). The results indicated that reduction in the intensity of tillage to 50% with interculture practices and combined use of organic and inorganic fertilizers maintained higher soil quality in these degraded Inceptisols. The methods of principal component analysis and computation of SQI adopted will be highly useful to future researchers, land managers, and students at locations across the world having similar climatic and edaphic conditions. [ABSTRACT FROM AUTHOR]

Rapid population increase, urbanization, soil degradation and inappropriate management practices have put tremendous pressure on natural resources, particularly on soil, water, and vegetation. Soil resource is vital for farming to provide food and nutritional security performing ecosystem functions and services and achieving Sustainable Developmental Goals (SDGs). Worldwide, ~33% soil resource has been adversely degraded by diverse processes. To protect soil resource from further degradation, there is a strong need of sustainable soil management practices for enhancing soil organic carbon (SOC), soil health, and crop production in a sustainable manner. "No-till farming (NT)/conservation agriculture (CA)" has been widely practiced worldwide on about 210 million ha. The long-term NT experiments play a significant role in improving soil health, SOC sequestration, and in-depth understanding of greenhouse gas (GHG) emission, climate change mitigation and optimizing resource use efficiency, to cater for the needs of the present- and future-generations. According to FAO, NT/CA is a farming system that promotes minimum soil disturbance (i.e., no tillage), maintenance of a permanent soil cover, and diversification of plant species. This system increases biodiversity and natural biological processes in above- and below-ground surface, which helps in enhanced water- and nutrient use-efficiency and sustained crop production. From the literature, it is evident that shift from traditional/conventional tillage (CT) with residue burning/removal to NT/CA farming has been recognized as an important soil management practice/strategy for sustaining soil health, reducing soil erosion and reversing soil degradation. This chapter deliberates the effect of NT/CA on soil health, nutrient stratification, SOC dynamics through modeling, SOC sequestration, GHG emissions, socio-economic condition in adoption and also suggesting the future perspectives on NT and CA. [ABSTRACT FROM AUTHOR]