Response of Summer Mungbean [Vigna radiata (L.) wilczek] to Foliar Potash Fertilization under Different Moisture Regimes

Background: Scheduling of irrigation is the major factor in producing higher yields of summer crops. Water stress during the sensitive stages will cause significant reduction in yield. Potassium (K+) is reported as an important element in reducing the ill effects of crop water stress. Foliar application of potassium increases the drought tolerance in mungbean. Keeping this in view, a field experiment was conducted to study the response of summer mungbean to foliar potassic fertilization under different moisture regimes during 2018 at SVPUAT, Meerut (U.P). Methods: It included 12 treatment combinations comprised of 2 irrigation schedules (0.6 and 0.4 IW/CPE ratio) and 6 foliar potassium treatments (1% spray of K through KNO3 and/or KCl at flowering, flowering and pod development stage including control), replicated thrice and were tested under a split-plot design. Result: The results indicated that, the growth parameters, yield and yield attributes of mungbean were significantly higher under 0.6 IW/CPE ratio as compared to 0.4. The gross returns, net returns and B:C ratio were also found highest with 0.6 IW/CPE ratio. Among the foliar application of potassium treatments, the growth attributes, yield and yield attributes were significantly increased by foliar application of 1% K through KNO3/KCl at flowering and pod development stage. The foliar application of 1% K through KNO3 at flowering and pod development stage fetched significantly higher gross returns, net returns and B:C ratio, but remained on par with dual spray of 1% K through KCl. The interaction effect between irrigation regimes and potassium foliar levels was non-significant for most of the parameters.

Evaluation of CHIKPGRO model in semi arid and sub-humid climatic conditions of Madhya Pradesh

Based on field experiments conducted under different thermal and moisture regimes during rabi 2009-10 and 2010-11 at Jabalpur and Tikamgarh district of Madhya Pradesh, CHIKPGRO model was calibrated and validated for two popular and widely grown chickpea cultivars (JG 315 and JG11). Validations were done on the crop grown under the six dates of sowing in 2010-11 at Jabalpur (irrigated) and under two dates of sowing (2009-10 and 2010-11) at Tikamgarh (rainfed). The model overestimated the major phenological events under irrigated and underestimated in rainfed conditions, except the physiological maturity. The model also overestimated maximum LAI, biomass, seed yield and unit seed weight under irrigated conditions and underestimated in rainfed, conditions. The validation error was higher in rainfed conditions than irrigated conditions. The model simulated cultivars yield and biomass in irrigated and rainfed conditions differently with same genetic coefficients. The model simulated higher thermal and moisture stress than the actual field conditions under late sown conditions. The cultivar JG 11 had shown slightly more difference in simulation of yield and biomass as compared to JG 315. The model performance was tested with help CRM, RMSE and percentage difference between observed and simulated values.

Modelling soil organic carbon turnover with assimilation of satellite soil moisture data

The content of organic carbon is one of the essential factors that define soil quality. It is also notoriously challenging to model due to a multitude of biological and abiotic factors influencing the process. In this study, we investigate how decomposition of soil organic matter is affected by soil moisture and temperature. Soil organic carbon turnover is simulated by the CENTURY model. The accuracy of soil moisture data used is ensured by data assimilation approach, combing mathematical model and satellite retrievals. Numerical experiments demonstrate the influence of soil moisture regimes and climate on the quantity of soil humus stocks.

Effect of differential nitrogen management practices on growth, yield and water use efficiency of rice under varying moisture regimes

Pot experiments were conducted during 2018and 2019 at the College of Agriculture, Central Agricultural University, Imphal, Manipur, India to investigate the effect of different nitrogen management practices on growth, yield and water use efficiency of rice variety “CAU R1” under varying moisture regimes. Keeping this rationale, three nitrogen management practices {60 kg N/ha (Urea), 40 kg N/ha (Urea) + 20 kg N/ha equivalent FYM, 30 kg N/ha (Urea) + 15 kg N/ha equivalent FYM + 15 kg N/ha equivalent Azolla and three levels of moisture regime {continuous flooding (5 cm depth), no standing water (wetting soil just after hairy cracks appear), 5 cm water depth at tillering, panicle initiation and flowering stage} were tested in a Factorial Randomized Block Design and replicated thrice. Overall, the results of investigational findings indicated that the integrated approach of nitrogen management viz. 50% RDN through Urea + 25% RDN through FYM + 25% through Azolla with maintenance of 5 cm water depth at tillering, panicle initiation and flowering stage markedly improved growth and yield attributes and subsequently yield and water use efficiency of rice as compared to conventional method of nitrogen supplementation through fertilizer. Multivariate principal component analysis and stepwise regression showed that number of tillers/hill is the most important yield attributing characters implicated in augmenting the rice yield significantly.

Volatile and Dissolved Organic Carbon Sources Have Distinct Effects on Microbial Activity, Nitrogen Content, and Bacterial Communities in Soil.

Variation in microbial use of soil carbon compounds is a major driver of biogeochemical processes and microbial community composition. Available carbon substrates in soil include both low molecular weight dissolved organic carbon (LMW-DOC), and volatile organic compounds (VOCs). To compare the effects of LMW-DOC and VOCs on soil chemistry and microbial communities under different moisture regimes, we performed a microcosm experiment with five levels of soil water content (ranging from 25-70% water-holding capacity) and five levels of carbon amendment: a no carbon control, two dissolved compounds (glucose and oxalate), and two volatile compounds (methanol and α-pinene). Microbial activity was measured throughout as soil respiration; at the end of the experiment, we measured extractable soil organic carbon and total extractable nitrogen and characterized prokaryotic communities using amplicon sequencing. All C amendments increased microbial activity, and all except oxalate decreased total extractable nitrogen. Likewise, individual phyla responded to specific C amendments – e.g., Proteobacteria increased under addition of glucose, and both VOCs. Further, we observed an interaction between moisture and C amendment, where both VOC treatments had higher microbial activity than LMW-DOC treatments and controls at low moisture. Across moisture and C treatments, we identified that Chloroflexi, Nitrospirae, Proteobacteria, and Verrucomicrobia were strong predictors of microbial activity, while Actinobacteria, Bacteroidetes, and Thaumarcheota strongly predicted soil extractable nitrogen. These results indicate that the type of labile C source available to soil prokaryotes can influence both microbial diversity and ecosystem function and that VOCs may drive microbial functions and composition under low moisture conditions.

After the Storm: Fate and Leaching of Particulate Nitrogen (PN) in the Fluvial Network and the Influence of Watershed Sources and Moisture Conditions

Large storms can erode, transport, and deposit substantial amounts of particulate nitrogen (PN) in the fluvial network. The fate of this input and its consequence for water quality is poorly understood. This study investigated the transformation and leaching of PN using a 56-day incubation experiment with five PN sources: forest floor humus, upland mineral A horizon, stream bank, storm deposits, and stream bed. Experiments were subjected to two moisture regimes: continuously moist and dry–wet cycles. Sediment and porewater samples were collected through the incubation and analyzed for N and C species, as well as the quantification of nitrifying and denitrifying genes (amoA, nirS, nirK). C- and N-rich watershed sources experienced decomposition, mineralization, and nitrification and released large amounts of dissolved N, but the amount of N released varied depending on the PN source and moisture regime. Drying and rewetting stimulated nitrification and suppressed denitrification in most PN sources. Storm deposits released large amounts of porewater N regardless of the moisture conditions, indicating that they could readily act as N sources under a variety of conditions. The inputs, processing, and leaching of large, storm-driven PN inputs become increasingly important as the frequency and intensity of large storms is predicted to increase with global climate change.

DNA Viral Diversity, Abundance, and Functional Potential Vary across Grassland Soils with a Range of Historical Moisture Regimes

Soil viruses are abundant, but the influence of the environment and climate on soil viruses remains poorly understood. Here, we addressed this gap by comparing the diversity, abundance, lifestyle, and metabolic potential of DNA viruses in three grassland soils with historical differences in average annual precipitation, low in eastern Washington (WA), high in Iowa (IA), and intermediate in Kansas (KS).