Objectives: This study addresses the critical issue of Cd contamination in agricultural soils, posing substantial risks to crop productivity and food safety. While prior pot experiment has undertook this issue on a small scale, this study aims to evaluate the efficacy of selected best soil amendments, at a large-scale field experiment. Methodology: Press mud and humic acid were applied at 0.5%, while gypsum and Fe2O3 were applied at 5 mg/kg alone and with foliar application of Fe nanoparticles at 5 mg/L. Analysis: Comparative analysis with control revealed the immobilization efficiency of all amendments in descending order of effectiveness as follows: 100, 102, 104, 104, 105, 102, 105, and 105% for PM, HA, GYP, Fe, PM + Fe Nps, HA + Fe Nps, GYP + Fe Nps, and Fe + Fe Nps. Additionally, reduced growth, photosynthetic activities, and elevated levels of malondialdehyde and hydrogen peroxide, indicative of oxidative damage in control plant. Findings: Application of these amendments with foliar spraying of Fe Nps effectively mitigates Cd toxicity in maize crops, leading to improved growth, biomass, photosynthetic pigments, and antioxidant enzyme activities. Novelty/Improvement: These findings highlight the significance of exploring innovative approach of combining different amendments with foliar application of nanoparticles to mitigate Cd contamination and enhance soil health, thereby contributing to global efforts in ensuring food safety and security.

One of the main abiotic stresses that affect plant development and lower agricultural productivity globally is salt in the soil. Organic amendments, such as compost and biochar can mitigate the opposing effects of soil salinity (SS) stress. The purpose of this experiment was to look at how tomato growth and yield on salty soil were affected by mineral fertilization and manure-biochar compost (MBC). Furthermore, the study looked at how biochar (organic amendments) work to help tomato plants that are stressed by salt and also a mechanism by which biochar addresses the salt stress on tomato plants. Tomato yield and vegetative growth were negatively impacted by untreated saline soil, indicating that tomatoes are salt-sensitive. MBC with mineral fertilization increased vegetative growth, biomass yield, fruit yield, chlorophyll, and nutrient contents, Na/K ratio of salt-stressed tomato plants signifies the ameliorating effects on tomato plant growth and yield, under salt stress. Furthermore, the application of MBC with mineral fertilizer decreased H2O2, but increased leaf relative water content (RWC), leaf proline, total soluble sugar, and ascorbic acid content and improved leaf membrane damage, in comparison with untreated plants, in response to salt stress. Among the composting substances, T-7 [poultry manure-biochar composting (PBC) (1:2) @ 3 t/ha + soil-based test fertilizer (SBTF)] dose exhibited better-improving effects on salt stress and had maintained an order of T-7 > T-9 > T-8 > T-6 in total biomass and fruit yield of tomato. These results suggested that MBC might mitigate the antagonistic effects of salt stress on plant growth and yield of tomatoes by improving osmotic adjustment, antioxidant capacity, nutrient accumulation, protecting photosynthetic pigments, and reducing ROS production and leaf damage in tomato plant leaves.

Biochar has been found to be an effective soil amendment in agriculture based upon its manifold functional groups as well as porous structure. However, the impacts of this material on soil mechanical properties are still poorly explored, especially under oscillatory shear conditions (as common due to traffic of agricultural machinery). Hence, our study investigates how short-term application of different rates and types of biochar in successive crops affects soil microstructural resistance, viscoelasticity, and resilience under oscillatory shear. In a completely randomized greenhouse pot experiment, wheat and soybean were grown successively in a sandy loam soil under single addition of two types of biochar (derived from either rice or soybean straw) at application rates (0 - control, 10 and 20 t ha-1). After crop harvesting, disturbed soil samples were collected in three layers to conduct amplitude sweep and thixotropy tests and analyze soil chemical properties. Biochar application resulted in extended elastic behavior, whereas soil strength decreased at low shear strain. Conversely, at high shear strain biochar had a destabilizing effect on soil microstructure, as indicated by the advancement of the flow point and lower overall viscoelasticity in biochar amended soils. Despite reduced microstructure stiffness exhibited in thixotropy tests, soil amended with biochar almost recovered completely its stiffness after high shear impact. However, significant effects were only noticed in topsoil layer independent of biochar type applied. Hence, accumulated biochar on soil surface layer had an overall negative impact on soil mechanical stability.