Soil bacterial community structure and functioning in a long-term conservation agriculture experiment under semi-arid rainfed production system.

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 semi-arid 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 HiSeq-based 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.

Pest scenario of Helicoverpa armigera (Hub.) on pigeonpea during future climate change periods under RCP based projections in India.

Gram pod borer, Helicoverpa armigera (Hub.) is the major insect pest of pigeonpea and prediction of number of generations (no. of gen.) and generation time (gen. time) using growing degree days (GDD) approach during three future climate change periods viz., Near (NP), Distant (DP) and Far Distant (FDP) periods at eleven major pigeonpea growing locations of India was attempted. Multi-model ensemble of Maximum (Tmax) and Minimum (Tmin) temperature data of four Representative Concentration Pathways viz., RCP 2.6, 4.5, 6.0 and 8.5 of Coupled Model Inter comparison Project 5 (CMIP5) models was adopted here. The increase in projected Tmax and Tmin are significant during 3 climate change periods (CCPs) viz., the NP, DP and FDP over base line (BL) period under four RCP scenarios at all locations and would be higher (4.7-5.1 °C) in RCP 8.5 and in FDP. More number of annual (10-17) and seasonal (5-8) gens. are expected to occur with greater percent increase in FDP (8 to 38%) over base line followed by DP (7 to 22%) and NP (5to 10%) periods with shortened annual gen. time (4 to 27%) across 4 RCPs. The reduction of crop duration was substantial in short, medium and long duration pigeonpeas at all locations across 4 RCPs and 3 CCPs. The seasonal no.of gen. is expected to increase (5 to 35%) with shortened gen. time (4 to 26%) even with reduced crop duration across DP and FDP climate periods of 6.0 and 8.5 RCPs in LD pigeonpea. More no. of gen. of H. armigera with reduced gen. time are expected to occur at Ludhiana, Coimbatore, Mohanpur, Warangal and Akola locations over BL period in 4 RCPs when normal duration of pigeonpeas is considered. Geographical location (66 to 72%), climate period (11 to 19%), RCPs (5-7%) and their interaction (0.04-1%) is vital and together explained more than 90% of the total variation in future pest scenario. The findings indicate that the incidence of H. armigera would be higher on pigeonpea during ensuing CCPs in India under global warming context.

The food-energy-water-carbon nexus of the rice-wheat production system in the western Indo-Gangetic Plain of India: An impact of irrigation system, conservational tillage and residue management.

The conventional rice-wheat system in the western Indo-Gangetic plain of India is energy and water intensive with high carbon footprint. The transition towards resource-efficient eco-friendly production technologies with lower footprint is required for inclusive ecological sustenance. A five-year (2016-17 to 2020-21) field experiment was conducted in RWS with hypothesis that pressurized irrigation systems [drip (DRIP) and mini-sprinkler (MSIS)] in conservation tillage [reduced (RT)/zero (ZT)] and crop residue management [incorporation (RI)/mulch (RM)] might result in higher resource use efficiency with lesser carbon footprint compared to conventional system. Experiment consisted five treatments namely (1) puddled transplanted rice followed by conventionally tilled wheat (PTR/CTW), (2) DRIP irrigated reduced till direct seeded rice (RTDSR) followed by zero-till wheat with 100 % rice residue mulching (ZTW + RM) (DRIP-RTDSR/ZTW + RM), (3) surface irrigated RTDSR followed by ZTW + RM (SIS-RTDSR/ZTW + RM), (4) MSIS irrigated RTDSR followed by ZTW + RM (MSIS-RTDSR/ZTW + RM), and (5) MSIS irrigated RTDSR with 1/3rd wheat residue incorporation followed by ZTW + RM (MSIS-RTDSR + RI/ZTW + RM). The pressurized irrigation system in RWS established under conservational tillage and residue management (DRIP-RTDSR/ZTW + RM and MSIS-DSR + RI/ZTW + RM) produced at par system productivity compared to PTR/CTW. Substantial nitrogen (79-114 ka ha-1) and irrigation water (536-680 mm) savings under pressurized irrigation systems resulted in 41-64 % higher partial factor productivity of nitrogen with 48-61 % lower water footprint. These systems had lower energy consumption attaining 15-21 % higher net energy, 44-61 % higher energy use efficiency, and 31-38 % lower specific energy. Efficient utilization of farm inputs caused lower greenhouse gas emission (39-44 %) and enhanced carbon sequestration (35-62 %) resulting 63-76 % lower carbon footprint over PTR/CTW. The information generated here might useful in developing policies for resource and climate-smart food production system aiming livelihood security and ecological sustainability in the region. Further, trials are needed for wider adaptability under different climate, soil and agronomic practices to develop site-specific climate smart practices.

Evaluation of spatial spreading of phyto-available sulphur and micronutrients in cultivated coastal soils.

Understanding the spatial spreading patterns of plant-available sulphur (S) (AS) and plant-available micronutrients (available zinc (AZn), available iron (AFe), available copper (ACu), available manganese (AMn) and available boron (AB)) in soils, especially in coastal agricultural soils subjected to various natural and anthropogenic activities, is vital for sustainable crop production by adopting site-specific nutrient management (SSNM) strategies. We studied the spatial distribution patterns of AS, AZn, AFe, ACu, AMn, and AB in cultivated soils of coastal districts of India using geostatistical approaches. Altogether 39,097 soil samples from surface (0 to 15 cm depth) layers were gathered from farm lands of 68 coastal districts. The analysis of soil samples was carried out for soil pH, electrical conductivity (EC), soil organic carbon (SOC) and AS, AZn, AFe, ACu, AMn, and AB. Soil pH, EC and SOC varied from 3.70 to 9.90, 0.01 to 7.45 dS m-1 and 0.02 to 3.74%, respectively. The concentrations of AS, AZn, AFe, ACu, AMn, and AB varied widely in the study area with their corresponding mean values were 37.4±29.4, 1.50±1.53, 27.9±35.1, 2.14±1.74, 16.9±18.4 and 1.34±1.52 mg kg-1, respectively. The coefficient of variation values of analyzed soil parameters varied from 14.6 to 126%. The concentrations of AS, AZn, AFe, ACu, AMn, and AB were negatively and significantly correlated with soil pH and positively and significantly correlated with SOC. The geostatistical analysis indicated stable, Gaussian and exponential best-fit semivariogram models with moderate to strong spatial dependence for available nutrients. The generated spatial spreading maps revealed different distribution patterns for AS, AZn, AFe, ACu, AMn, and AB. There were variations in spatial spreading patterns of AS, AZn, AFe, ACu, AMn, and AB in east- and west-coastal area. About 62, 35, 12, 0.4, 23 and 45% of the study area had deficiency of AS, AZn, AFe, ACu, AMn, and AB, respectively. The spatial spreading maps will be highly useful for SSNM in the cultivated coastal soils of the country. This study could also be used as a base for assessing spatial spreading patterns of soil parameters in cultivated coastal areas of other parts of the world.

Disease-Suppressive Soils-Beyond Food Production: a Critical Review.

In the pursuit of higher food production and economic growth and increasing population, we have often jeopardized natural resources such as soil, water, vegetation, and biodiversity at an alarming rate. In this process, wider adoption of intensive farming practices, namely changes in land use, imbalanced fertilizer application, minimum addition of organic residue/manure, and non-adoption of site-specific conservation measures, has led to declining in soil health and land degradation in an irreversible manner. In addition, increasing use of pesticides, coupled with soil and water pollution, has led the researchers to search for an environmental-friendly and cost-effective alternatives to controlling soil-borne diseases that are difficult to control, and which significantly limit agricultural productivity. Since the 1960s, disease-suppressive soils (DSS) have been identified and studied around the world. Soil disease suppression is the reduction in the incidence of soil-borne diseases even in the presence of a host plant and inoculum in the soil. The disease-suppressive capacity is mainly attributed to diverse microbial communities present in the soil that could act against soil-borne pathogens in multifaceted ways. The beneficial microorganisms employ some specific functions such as antibiosis, parasitism, competition for resources, and predation. However, there has been increasing evidence on the role of soil abiotic factors that largely influence the disease suppression. The intricate interactions of the soil, plant, and environmental components in a disease triangle make this process complex yet crucial to study to reduce disease incidence. Increasing resistance of the pathogen to presently available chemicals has led to the shift from culturable microbes to unexplored and unculturable microbes. Agricultural management practices such as tillage, fertilization, manures, irrigation, and amendment applications significantly alter the soil physicochemical environment and influence the growth and behaviour of antagonistic microbes. Plant factors such as age, type of crop, and root behaviour of the plant could stimulate or limit the diversity and structure of soil microorganisms in the rhizosphere. Further, identification and in-depth of disease-suppressive soils could lead to the discovery of more beneficial microorganisms with novel anti-microbial and plant promoting traits. To date, several microbial species have been isolated and proposed as key contributors in disease suppression, but the complexities as well as the mechanisms of the microbial and abiotic interactions remain elusive for most of the disease-suppressive soils. Thus, this review critically explores disease-suppressive attributes in soils, mechanisms involved, and biotic and abiotic factors affecting DSS and also briefly reviewing soil microbiome for anti-microbial drugs, in fact, a consequence of DSS phenomenon.

Agricultural labor, COVID-19, and potential implications for food security and air quality in the breadbasket of India.

To contain the COVID-19 pandemic, India imposed a national lockdown at the end of March 2020, a decision that resulted in a massive reverse migration as many workers across economic sectors returned to their home regions. Migrants provide the foundations of the agricultural workforce in the 'breadbasket' states of Punjab and Haryana in Northwest India.There are mounting concerns that near and potentially longer-term reductions in labor availability may jeopardize agricultural production and consequently national food security. The timing of rice transplanting at the beginning of the summer monsoon season has a cascading influence on productivity of the entire rice-wheat cropping system. To assess the potential for COVID-related reductions in the agriculture workforce to disrupt production of the dominant rice-wheat cropping pattern in these states, we use a spatial ex ante modelling framework to evaluate four scenarios representing a range of plausible labor constraints on the timing of rice transplanting. Averaged over both states, results suggest that rice productivity losses under all delay scenarios would be low as compare to those for wheat, with total system productivity loss estimates ranging from 9%, to 21%, equivalent to economic losses of USD $674 m to $1.48 billion. Late rice transplanting and harvesting can also aggravate winter air pollution with concomitant health risks. Technological options such as direct seeded rice, staggered nursery transplanting, and crop diversification away from rice can help address these challenges but require new approaches to policy and incentives for change.

Thermophilic ligno-cellulolytic fungi: The future of efficient and rapid bio-waste management.

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.

Effect of nutrient management on soil organic carbon sequestration, fertility, and productivity under rice-wheat cropping system in semi-reclaimed sodic soils of North India.

The ever shrinking agricultural land availability and the swelling demand of food for the growing population fetch our attention towards utilizing partially reclaimed sodic soils for cultivation. In the present investigation, we compared six treatments, like control (T1), existing farmers' practice (T2), balanced inorganic fertilization (T3) and combined application of green gram (Vigna radiate) with inorganic NPK (T4), green manure (Sesbania aculeate) with inorganic NPK (T5), and farmyard manure with inorganic NPK (T6), to study the influence of nutrient management on soil organic carbon sequestration and soil fertility under long-term rice-wheat cropping system along with its productivity in gypsum-amended partially reclaimed sodic soils of semi-arid sub-tropical Indian climate. On an average, combined application of organics along with fertilizer NPK (T4, T5, and T6) decreased soil pH, ESP, and BD by 3.5, 13.0, and 6.7% than FP (T2) and 3.7, 12.5, and 6.7%, than balanced inorganic fertilizer application (T3), respectively, in surface (0-20 cm). These treatments (T4, T5, and T6) also increased 14.1% N and 19.5% P availability in soil over the usual farmers' practice (FP) with an additional saving of 44.4 and 27.3% fertilizer N and P, respectively. Long-term (6 years) incorporation of organics (T4, T5, and T6) sequestered 1.5 and 2.0 times higher soil organic carbon as compared to the balanced inorganic (T3) and FP (T2) treatments, respectively. The allocation of soil organic carbon into active and passive pools determines its relative susceptibility towards oxidation. The lower active to passive ratio (1.63) in FYM-treated plots along with its potentiality of higher soil organic carbon (SOC) sequestration compared to the initial stock proved its acceptability for long-term sustenance under intensive cropping even in partially reclaimed sodic soils. Among all the treatments, T4 yielded the maximum from second year onwards. Moreover, after 6 years of continuous cultivation, the observed EWY (2011-2012) was found to be 41.9 and 33.1% higher in T4 as compared to FP (T2) and T3, respectively. Thus, for maintaining higher yield coupled with improved SOC sequestration and nutrient availability, T4 followed by T6 treatments would be the suitable options for long-term intensive rice-wheat system in partially reclaimed sodic soils of northern India.

Fulminant hepatic failure due to dengue.

Dengue Fever (DF) is only rarely considered as a cause of acute liver failure even globally and only a few case reports of acute hepatic failure and encephalopathy occurring in DF in adults are available. We report a case of Acute Liver Failure due to Dengue during a major outbreak in 2010 in Chitwan. A 20 year old previously healthy female presented to the emergency department of Chitwan Medical College with fever, jaundice and altered sensorium. She was tested positive for Dengue IgM. Her biochemical and clinical parameters were suggestive of acute liver failure with total billirubin of 10.1 mg/dL, direct billirubin of 5.2 mg/dL, ALT 5760 IU, AST 14100 IU, alkaline phosphatase of 1250 IU, PT INR of 1.76 and platelet count of 30,000/mm3. Other causes for acute hepatic failure like acute viral hepatitis, leptospirosis, malaria, Reyes syndrome were ruled out. The patient was admitted and managed in the ICU with supportive care and platelet transfusion. With treatment she made a significant clinical and biochemical improvement with AST of 105 IU, ALT of 120 IU and platelet count of 150,000/mm3. She was discharged after 11 days of hospital stay.

Substituted thiazolidones: selective inhibition of nicotinamide adenine dinucleotide-dependent oxidations and evaluation of their CNS activity.

Eight 2-arylimino-3-(3-N-morpholinopropyl) thiazolid-4-ones were synthesized from the corresponding 1-aryl-3-(3-N-morpholinopropyl) thiocarbamides, characterized, and tested for their effects on the cellular respiratory activity of rat brain homogenates. All substituted 4-thiazolidones selectively inhibited nicotinamide adenine dinucleotide (NAD)-dependent oxidations of pyruvate, citrate, DL-isocitrate, alpha-ketoglutarate, malate, beta-hydroxybutyrate, L-glutamate, and NADH, while the NAD-independent oxidation of succinate remained unaltered. All thiazolidones possessed some degree of anticonvulsant activity against pentylenetetrazol-induced convulsions, and the protection afforded by these compounds at a dose of 100 mg/kg ranged from 30 to 80%. The low toxicity possessed by most of these thiazolidones was reflected by their approximate LD-50 values from 300 mg/kg to greater than 1000 mg/kg. In the present study, the anticonvulsant activity possessed by these substituted 4-thiazolidones was unrelated to their ability to inhibit selectively the NAD-dependent oxidations by rat brain homogenates. These thiazolidones exhibited depression of the CNS activity which, in some cases, was associated with the increase in respiration. All thiazolidones potentiated pentobarbital (sodium) sleeping time in mice when administered in a dose of 100 mg/kg.