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TiO2 nano particles (NPs) are one of the most produced nanoparticles in the world which are increasingly being released in to the soil. Soils are exposed to various level of concentration of TiO2 NPs, which has raised concern over the adverse influence on soil microbial community, in turn on ecosystem functions. Although, increasing number of studies on ecotoxicological effect of TiO2 NPs are coming up recently, however, a common conscience has yet to be reached regarding the impact of TiO2 NPs on soil microbial community and processes. Moreover, very few studies have targeted soil enzymes which are being considered as sensitive indicator of soil health. Therefore, the present study has been carried out to estimate the ecotoxicological effect of various doses of TiO2 NPs (5, 10, 20, 40, 80, 100 mg kg−1 soil) on different soil enzymes and microbial community structure. Results revealed that soil enzyme activities and microbial biomass had a uniform trend where the value increased up to the dose of 20 mg TiO2 NPs kg−1 soil and there onwards reduced drastically up to 100 mg TiO2 NPs kg−1 soil dose. On the contrary, soil respiration and metabolic quotient kept increasing up to 100 mg TiO2 NPs kg−1 soil dose indicating sub-lethal stress on microbial community. Nevertheless, the structure of microbial community had slightly different trend where the biomass of total phospho lipid fatty acid (PLFA), Gram positive, Gram negative bacteria, fungi, actinomyctetes and anaerobes were found to be increased up to dose of 80 mg TiO2 NPs kg−1 soil, but, significantly declined at 100 mg TiO2 NPs kg−1 soil dose. Furthermore, temperature effect on TiO2 NPs toxicity had exhibited a less negative impact at 40 °C rather than at 25 °C. In addition alteration index (AI3), an integrated indicator of C, N, P cycling of soils as well as a well-documented indicator of soil pollution, has been found to be regulated by soil respiration, clay content, anaerobe and eukaryote for AI3-Acid Phos. and by fungi to bacteria ratio, soil respiration, microbial biomass and Gram positive bacteria for AI3-Alk. Phos. Overall, the study provided valuable information regarding ecotoxicological impact of environmentally relevant concentrations of TiO2 NPs in clay loam soils as well as improved our perception regarding the impact of NPs on soil functioning.

Aim: To study the combined effect of tillage and manure addition on bulk soil and aggregate associated carbon and nitrogen in Vertisol. Methodology: The study was conducted in a long-term tillage experiment having two tillage treatments (reduced tillage and no-tillage) together with100% NPK fertilizer without (T1) and with addition of farm yard manure (T2) @ 2.0 ton C ha-1 to soybean in a soybean-wheat cropping system in a Vertisol of Central India, with three replicates in a split plot design. The parameters studied were aggregate size distribution, mean weight diameter, water stable aggregates, bulk soil and aggregate associated organic carbon, available nitrogen and rate of carbon mineralization. Results: The results indicated significantly higher SOC in reduced tillage (0.87%) than no-tillage (0.71%) under100% NPK fertilization in the bulk soil for 0-15 cm depth. However, 100% NPK + FYM showed a significant increase in the bulk soil organic carbon in the no-tillage treatment only. Available nitrogen content in the bulk soil and aggregate fractions were significantly lower under no-tillage than the corresponding reduced tillage treatments. Manure addition led to significantly higher available N content and proportion of WSA in both the tillage practices. The carbon mineralization was significantly higher by 1.4 to 1.6 times under reduced tillage than no-tillage. Interpretation: Long-term tillage study in Vertisol of Central India indicated reduced tillage to be a better option than no-tillage in maintaining organic carbon and nitrogen availability in soil.

To accelerate the process of decomposition using consortia of thermophilic ligno-cellulolytic fungi, different crop residues viz. sorghum (SG), soybean (SS), maize (MS), sugarcane (SC), cotton (CS) and pigeon pea (PS) with a varied C:N ratio and sawdust (SD) having high lignin content were collected and used for decomposition process. Compost quality assessed by evaluating different maturity and stability indices at five succeeding stages [first mesophilic (M1), thermophilic (T), second mesophilic (M2), cooling (C) and humification (H)]. A significant reduction was observed in the C:N ratio, biodegradability index, nitrification index, ratio of water-soluble carbon to organic nitrogen (WSC/Org.N) with an increase in concomitant over time while Ash (%), organic matter loss (%), CEC/TOC ratio, cellulose biodegradation ratio (BR) and lignin/cellulose ratio were significantly increased with time. By correlation study, biodegradability index (BI) and fluorescein diacetate (FDA) hydrolysis emerged as the most suitable compost maturity and stability parameters, respectively. Principal component analysis (PCA) results confirmed that BI, BR, WSC/Org. N and FDA can be regarded as key indicators for assessing compost quality. Our findings conclude that fungal consortia of Tricoderma viride, Rhizomucor pusillus, Aspergillus awamori and Aspergillus flavus can accelerate decomposition time from 8 to 12 months (which is normal farming practice) to 120 days.

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Although industrialization has been a boon to our economy and self-sufficiency, yet it accompanies a major drawback of generation of a huge amount of wastes as well as pollutants that accumulate in soil and aquatic systems, eventually contaminating and degrading the ecosystem. Moreover, the ever-increasing human population is making the situation worse. It is therefore a great challenge to manage the rapidly generating enormous amount of organic wastes and the accompanying pollutants. In this respect, biodegradation and decontamination of organic waste by employing microbial inoculants is an eco-friendly and cost-effective sustainable solution. Although the concept of biodegradation and decontamination by microbes is not new, however, it is yet to reach its full application potential. In spite of the promising response of microbial inoculants under laboratory/controlled conditions, a large field-scale application has shown limited efficacy, possibly due to the complex nature and nonsegregation of wastes. Both the waste decomposition through composting and waste decontamination through bioremediation rely on active microbial participation where they perform complex multistep pathways to achieve the final product. Henceforth, improving our perception of the microbial mechanisms and their interactions with organic waste material is the key requirement for harnessing the full potential of microbial technology in maintaining sustainability of the environment. This chapter presents an overview of the current researches on microbial inoculation as a way forward to achieve sustainability in managing overwhelming quantity of organic wastes and to achieve clean environments heavily affected by pollution. Furthermore, the potential of vital processes employed by the microorganisms for sustainable development and environmental management are also discussed, followed by their future prospects.

Open field burning of crop residue causes severe air pollution and greenhouse gas emission contributing to global warming. In order to seek an alternative, the current study was initiated to explore the prospective of lignocellulolytic microbes to expedite in situ decomposition of crop residues. Field trials on farmers’ field were conducted in the state of Haryana and Maharashtra, to target the burning of rice and wheat residue and sugarcane trash, respectively. A comparative study among crop residue removal (CRR), crop residue burning (CRB) and in situ decomposition of crop residues (IND) revealed that IND of rice and wheat residues took 30 days whereas IND of sugarcane trash took 45 days. The decomposition status was assessed by determining the initial and final lignin to cellulose ratio which increased significantly from 0.23 to 0.25, 0.21 to 0.23 and 0.24 to 0.27 for rice, wheat residues and sugarcane trash, respectively. No yield loss was noticed in IND for both rice-wheat system and sugarcane-based system; rather IND showed relatively better crop yield as well as soil health parameters than CRB and CRR. Furthermore, the environmental impact assessment of residue burning indicated a substantial loss of nutrients (28–31, 23–25 and 51–77 kg ha−1 of N+P2O5+K2O for rice, wheat and sugarcane residue) as well as the emission of pollutants to the atmosphere. However, more field trials, as well as refinement of the technology, are warranted to validate and establish the positive potential of in situ decomposition of crop residue to make it a successful solution against the crop residue burning.

The present investigation was aimed to identify the most ecologically viable agroecosystem among the three dominant, differently managed land use systems which were, agriculture (Long Term Fertilizer Experiment – LTFE, continuous pulse and organic system), horticulture (mango: Mangifera indica and guava: Psidium guajava) and agroforestry (bamboo: Bambusa sp., Dendrocalamus sp., poplar: Populus deltoides, and Dalbergia sissoo) on the basis of selected soil carbon fractions, microbial (microbial biomass carbon, basal soil respiration), biochemical parameters (dehydrogenase activity, easily extractable glomalin related soil protein, total extractable glomalin related soil protein) and microbial indices. The study area targeted the Mollisol of Uttarakhand which typifies the typical fragile ecosystem of Terai region of North-Western Himalayan region. Results indicated that LTFE, mango and Dalbergia system appeared as the most sustainable based on soil carbon, biochemical and microbiological attributes among their own agro-ecosystem. Our study also revealed guava system to be the most stressed as shown by the highest value of metabolic quotient. We further attempted to enumerate the sensitivity of a set of soil quality indicators controlling soil ecological process. In discriminant function analysis, a composite of indicators (inorganic carbon, dehydrogenase activity, easily extractable and total extractable glomalin related soil protein) discriminated well in the three studied agro-ecosystems. Furthermore, this study highlighted the necessity of inclusion of soil inorganic carbon and glomalin fractions for generating soil quality indicators.

Expeditious growth of population and urbanization has led the global challenge for Municipal Solid Waste (MSW) management. An investigation on rapid composting of biodegradable city waste was carried out with three treatments, two on a rapo-composter with and without consortia of thermophilic ligno-cellulolytic microbes and third is the common practice of compost producer. The quality of compost i.e. the maturity and stability index was tested at four different stages of decomposition. After 30 days of decomposition it was elucidated that rapo-composter with consortia (Bacillus sps., Streptomyces sps., Rhizomucor pusillus and Aspergillus flavus) fasten the decomposition time. This paper finds uniqueness in deriving 10 maturity parameters, 6 stability parameters with one parameter as confirmatory test of compost toxicity. It was concluded from the study that the Water Soluble Carbon (WSC) and Organic Nitrogen (Org. N) ratio is the key regulator of maturity parameter and the dehydrogenase (DHA) activity is important factor for compost stability.

In the recent past, biochar and crop residues have attracted lots of attention as a viable strategy for maintaining soil health. This paper evaluates the comparative effect of two different doses (equivalent to 2 and 5 t C ha−1) of each of pine needle and Lantana biochar (PBC and LBC), wheat residue and lentil residue (WR and LR) on soil biological properties, nutrient availability and yield of rice and wheat in pot culture. Energy-dispersive X-ray spectroscopy (EDS) revealed higher C content of biochar than crop residues. Evaluation of biochemical quality reflected high recalcitrance indices of C and N for both PBC and LBC. Application of LBC and PBC increased the wheat grain yield significantly by 6.2%–24.2% over control. Both PBC and LBC significantly increased N and P uptakes in grain over the control and crop residues. Both biochars recorded a significant decrease of 33.9 and 71,7% in β-glucosidase activity in comparison to control at termination of study. PBC and LBC also resulted in more so...

Biochar amendment to soil is a proposed strategy to enhance soil C sequestration and soil fertility. However, to date, knowledge about the specific effects of biochar on soil microbial community, instrumental for soil C dynamics and nutrient cycling is poorly explored. This study evaluates the comparative effect of two doses (equivalent to 2 and 5 t C ha−1) of each of pine needle biochar, Lantana biochar, wheat residue and lentil residue on soil microbial community in a pot culture study at Pantnagar, India. Energy dispersive X-ray spectroscopy revealed higher C content of biochar than that of crop residues. Evaluation of biochemical quality of the biochars and crop residues through acid hydrolysis reflected high recalcitrance indices of C and N of both pine needle biochar and Lantana biochar. Phospholipid fatty acid (PLFA) analysis indicated that PBC at 5 t C ha−1 recorded the highest Gram-positive bacteria and fungi whereas the highest fungi/bacteria ratio was found with the same dose of Lantana biochar. Lentil residue at 5 t C ha−1 recorded the highest Gram-negative bacteria. Principal component analysis of PLFA also distinctly separated biochar and crop residue treatments. Pearson correlation coefficients indicated that particulate organic carbon served as the carbon and energy sources for Gram-negative bacteria, whereas the Gram-positive bacteria and fungi utilized the more recalcitrant fraction of total organic carbon of soil. Pine needle biochar at 5 t C ha−1 reflected the best sustainable co-existence of bacteria and fungi as compared to other treatments.

Effect of conservation tillage on crop performance and soil properties has been studied extensively under different agro-climatic situations. However, the impact of reversal from conservation tillage to conventional tillage on crop growth and soil nutrient release is rarely addressed. Thus, this study was conducted by converting half of the eight years old conservation tillage experiment to the conventional one with a similar level of residue return to compare the effect on soil nutrient availability and nutrient uptake in soybean crops in the Vertisols of Central India. The conservation tillage treatments included no-tillage (NT) and reduced tillage (RT) with 100% NPK (T1), 100% NPK + farmyard manure (FYM) at 1.0 Mg-carbon (C)/ha (T2), and 100% NPK + FYM at 2.0 Mg-C/ha (T3). After eight years of the experiment, the RT and NT treatments were subjected to conventional tillage, and thus the tillage treatments were RT-CT, RT, NT, and NT-CT. After tillage reversal for three growing seasons, soybean yield and nutrient uptake (N, P, K) got significantly influenced by the tillage and nutrient management. Averaged across nutrient treatments, NT showed highest soil organic carbon (SOC) content (8.4 g/kg) in the surface 0&ndash, 5 cm layer. However, at 5&ndash, 15 cm depth, the SOC was greater in the RT-CT treatment by 14% over RT and by 5% in the NT-CT treatment over NT. The soil nutrient availability (N and P) was not significantly (p &gt, 0.05) affected by the interaction effect of tillage and nutrient on the surface soil layer (0&ndash, 5 cm). Interaction effect of tillage and nutrient was significant on available P content at 5&ndash, 15 cm soil depth. In contrast to N, soil available P relatively increased with reversal of tillage in both NT and RT. Tillage reversal (NT-CT, RT-CT) and RT had significantly higher available potassium than NT in 0&ndash, 5 and 5&ndash, 15 cm soil layers. Among the treatments, NT-CT-T3 showed significantly higher seed N (85.49 kg/ha), P (10.05 kg/ha), and K (24.51 kg/ha) uptake in soybean. The study indicates conventional tillage with residue returns and integrated nutrient management could be a feasible alternative to overcome the limitations of no-till farming in the deep black Vertisols of Central India.

Fast urbanization, and agricultural escalation produce a lot of municipal solid wastes (MSW). There is need to recognize economically practical innovations to debase substantial metals to an innocuous state. The present investigation aimed to recognize proficient fungi and develop bio-filtration strategy utilizing them for expulsion of substantial heavy metals (HMs) from tainted MSW compost (MSWC). Six fungi were isolated from sewage sludge, namely, Trichoderma viride, Aspergillus heteromorphus, Rhizomucor pusillus, Aspergillus flavus, Aspergillus terreus, and Aspergillus awamori. Growths of all these fungi were highly susceptible to Cd at 5 ppm. Trichoderma viride, Aspergillus awamori, and Rhizomucor pusillus were highly susceptible to Cu at 50 ppm. Aspergillus flavus and Aspergillus heteromorphus could tolerate Cr below 50 ppm. The varying degree of HM tolerance by different fungi may be due to diverse strategies to dodge HM toxicity. Functional groups like amide (-NH2), hydroxyl (-OH), carboxylate anions (-COO), carbonyl groups (-CO), C-F and C-Br were responsible for bio-sorption of heavy metals by fungi through chelation with HMs. We found Trichoderma viride and Aspergillus flavus based bio-filters were capable to remove the highest amount of Pb (>40%) and Cd (>20%). Aspergillus heteromorphus based bio-filters was the most efficient to remove Cu and Cr from MSWC ( ∼ 20%). Trichoderma viride, Aspergillus heteromorphus, Rhizomucor pusillus and Aspergillus flavus based bio-filters were equally effective for elicitation of Zn ( ∼ 30%) and Ni (>30%) toxicity. Differential minimum inhibitory concentration, uptake of HMs, bio-sorption capacity of HMs by fungi resulted in unequal efficacy of fungal bio-filters.

The rapid growth in population, food production, urbanization, and industrialization has accelerated the generation of bio-waste material such as crop residues, animal waste, and municipal solid waste. They wield tremendous impacts on soil health, climate change, and overall environment with pronounced ramifications for developing countries like India. In addition to the previously mentioned challenges, overexploitation of soil is causing the second-generation problems of nutritional disorders, decline in productivity, global warming–driven climate change, pollution, and so on. Therefore scientific and logical recycling of organics is of prime importance to eradicate the huge piles of bio-waste material in agriculture. It will, firstly, be of benefit to minimizing environmental pollution and, secondly, improve crop productivity, soil carbon status, and soil health in general. Contrary to this, unscientific management of organic waste hold disadvantages such as losses of essential plant nutrients, greenhouse gas emissions (GHG), heavy metal contamination and development of sporadic pathogens harmful to animals and plants. The prime focus of this review is to signify the current prospects of organic waste management in India and their potential in agriculture. The article has comprehensively elaborated on GHG, fertilizer consumption, food grain production, nutrient removal by crops, and constraints of waste recycling. This review further emphasizes through future research needs the need to advance our knowledge regarding bio-waste management, so that we better understand and implement efficient waste management. It is also pertinent to develop a sustainable and eco-friendly agricultural practices so that organic resources mainly in the form of crop residues, animal waste, and municipal solid waste are utilized.

The soil scientists along with microbiologists had a big responsibility to come forward with a sustainable solution to enhance soil nutrient supplying capacity, without applying the agrochemical and mineral fertilizers. The only way out to this problem is through the use of efficient microbes which plays a vital role as organic or biological agents in facilitating uptake of many primary and secondary nutrients. Moreover, the fertility of any soil is directly proportional to the microbial biomass and its potential of functional activity and diversity. Billions of microbes which are present in soil are major key players of nutrient cycling and their solubilization and mineralization. This fact has been known and scientifically reported for a number of decades, but still its significance has not yet channelized into the mainstream of intensive agriculture. Thus, in this chapter, exhaustive overview of the different groups of agriculturally important microbes has been given which are responsible for enhancing nutrient availability particularly nitrogen, phosphorus, potassium, sulphur, iron and zinc in agricultural soils.

The diversity of microbes present in the rhizosphere plays a significant role in nutrient cycling and soil sustainability. Plant–microbe-modulated phytoremediation is a viable technology for the cleanup of contaminated environments. Several plants that were identified have various degrees of capacity to eliminate, degrade or detoxify, metabolize, or immobilize a wide range of soil contaminants. Plant-based remediation technologies are not yet commercialized because of its major limitation of slow process and restricted bioavailability of the contaminants, and it is greatly influenced by the climatic factors. The extensive use of plants can overcome most of the limitations by exploring the potential of microbe–plant–metal interaction. The biogeochemical process occurring in the root zone can influence on several rhizobacteria and mycorrhizae directly linked with microbial metabolite synthesis. Thus, a holistic approach of novel remediation technologies and understanding of plant–microbe–contaminant interaction would help for customizing phytoremediation process in relation to site-specific contamination. There is a huge challenge to remediation of contaminated sites by long-term accumulation of heavy metal. Unlike organic contaminants, metals are very much resistant to degradation, and in the long run, continuous accumulation may cause food chain contamination. It is very important to decontaminate the polluted sites in order to reach safe level of metal concentration below the threshold limit of toxicity. Recent studies revealed that phytoextraction, mainly the use of hyperaccumulator plants to extract toxic metals from the contaminated sites, has emerged as a cost-effective, eco-friendly cleanup technology. Novel, efficient microbes and their potential use in the plant rhizosphere could further enhance the phytoremediation for wider range of soil contaminants.