The present study was conducted to explore the role of different types of vermicomposts (VCs) prepared from different substrates to improve soil health (physical and chemical properties) and wheat plant growth under field conditions. Different combinations of vermicompost prepared from different substrates (cow dung, paper waste, and rice straw) and inorganic fertilizers were applied in soil using wheat as a test plant. The impact of three different VCs on physico-chemical characteristics and nutrient availability in soil was evaluated to examine their efficacy in combination with chemical fertilizers. Temporal trends in vermicomposting treatments at various stages showed significant improvement in physico-chemical attributes of the VCs substrates. All the plant physiological attributes showed significant response where N:P:K 100:50:50 kg ha⁻¹ + 10 t ha⁻¹ cow dung vermicompost was applied. In addition, post-harvest analysis of soil not only revealed that different combinations of the vermicomposting treatments improved the soil health by improving the physico-chemical attributes of the soil. Conclusively, application of cow dung vermicompost along with recommended NPK not only improved crop yield, soil health, reduced insect (aphid) infestation but also fortified grains with Zn and Fe.

Increasing cadmium (Cd) pollution in soil is of great concern. A pot experiment was conducted with the aim of assessing the effect of Cd on soil biological indices under potato cultivation. Cadmium was added to 10 kg soil in each pot (6 seeds pot–1) as Cd(NO3)2 at 0, 15, 30, 45 and 60 mg kg–1 with three replications. All soil and plant parameters decreased with all Cd treatments; however, high levels of Cd had a significant (P < 0.05) suppressive effect. The highest Cd level significantly (P < 0.05) decreased microbial biomass carbon (2.16-fold), nitrogen (11.37-fold) and phosphorus (10.3-fold), as well as enzyme activities of dehydrogenase (4.36-fold), phosphatase (9.23-fold), and urease (9.61-fold). The highest Cd level also decreased pH (1.46-fold), potato shoot (3.55-fold) and root (7.43-fold) length, root (10.9-fold) and shoot (6.04-fold) fresh weight, root (7.51-fold) and shoot (13.7-fold) dry weight, chlorophyll content (27.0-fold), carotenoid content (4.08-fold), and plant macronutrient and micronutrient uptake in potato root and shoots. Conversely, the highest level of Cd significantly (P < 0.05) increased the biomass C : N (5.27-fold) and C : P (4.77-fold) ratios, soil extractable Cd (5.38-fold), and Cd uptake in potato root (5.05-fold) and shoot (4.82-fold) at the end of the experiment (day 60). Cadmium contamination substantially affected soil biological indices and growth of potato, and the Cd threshold was strongly associated with the extent of Cd concentration and duration to accumulate. Soil microbial biomass, enzymatic activities, pH and potato physiological parameters could be used as a sensitive indicators to reflect environmental stresses in soil ecosystems.

A decrease in water resources around the globe in irrigated agriculture has resulted in a steep decline in irrigation water availability. Therefore, management options for efficient use of available irrigation water are inevitable. Deciding the critical time, frequency and amount of irrigation are compulsory to achieve higher crop outputs. Hence, this two-year field study was conducted to assess the role of different row spacings, i.e., 20, 25 and 30 cm, on growth, productivity, and water use efficiency (WUE) of wheat under deficit supplemental irrigation (DSI) at the vegetative and reproductive phase by using surplus supplemental irrigation (SSI) throughout the growing season as the control. DSI at both growth stages, and the reproductive stage in particular, changed the crop allometry, yield and net income of wheat. However, narrow spacing (20 cm) resulted in efficient use of available irrigation water (DSI and SSI) with higher yield, WUE and economic returns. Interestingly, wider spacing resulted in a higher number of grains per spike with higher 1000-grain weight under SSI and DSI, but final yield output remained poor due to a lower number of productive tillers. It was concluded that reducing irrigation during the vegetative stage is less damaging compared with the reproductive phase; therefore, sufficient supplemental irrigation must be added at the reproductive stage, particularly during grain-filling. Further, narrow spacing (20 cm) resulted in efficient utilization of available irrigation water; therefore, wheat must be grown at a narrow spacing to ensure the efficient utilization of available irrigation water.

Predicting carbon (C) and nitrogen (N) mineralization of plant residues returned to soils is vital for foreseeing carbon dioxide (CO₂) emissions into the atmosphere and soil nitrogen availability. Similarly, dissolved organic matter (DOM) is an important factor in forecasting microbial degradation of organic inputs as it represents the most active organic fraction, both biologically and chemically. In this study, an incubation experiment was conducted to investigate C and N mineralization and DOM potentials of residues of peanut (green manure, GM) and rice (rice straw, RS) at moisture regimes 50% (W1) and 100% (W2) of water holding capacity and temperature T1 (25°C) and T2 (35°C). The incorporation of plant residues significantly (P < 0.05) increased the mineralization and DOM, compared to controls. We observed that though GM residue had high carbon and nitrogen and DOM potential, but because of low C:N ratio and lignin, cellulose, and hemicelluloses compounds were vulnerable to easy decomposition with the increase in temperature, which led to more CO₂ emission, fast mineralization, and less net OM in the soil. Conversely, RS residue, due to high C:N ratio, lignin, cellulose, and hemicelluloses compounds was resistant to decompose with the increase in temperature and possessed slow mineralization and eventually low CO₂ emission. The moisture regimes (W1 and W2) and temperature (T1 and T2) had significant (P < 0.05) effect on mineralization and DOM potentials of both plant residues. The significant decrease and increase in the mineralization and DOM potential of both plant residues was observed with the increase in moisture and temperature. Our results suggest that plant residues with high C:N ratio, lignin, cellulose, and hemicelluloses compounds like RS are resistant to decompose with the increase in temperature, as a result possessed slow decomposition and mineralization, and can be used as an eco-friendly organic amendment, to get enduring benefits, and to mitigate the problem of carbon losses and CO₂ emission from soil to atmosphere.