Compost tea is widely recognized for its beneficial effects on crop growth and soil health. However, its efficacy varies depending on the composition of the feedstock and brewing conditions. This study investigates the chemical composition and agronomic impact of compost tea prepared from a commercial mixture of plant residues and animal manure. Standard chemical analyses, combined with solid-state 13C CPMAS NMR spectroscopy, were employed to characterize the organic chemistry of the feedstock. High-throughput sequencing of bacterial and eukaryotic rRNA gene markers was used to profile the microbiota. Compost tea was applied to three crops, Allium cepa, Beta vulgaris, and Lactuca sativa, grown in protected Mediterranean environments on volcanic soils. The 13C CPMAS NMR analysis revealed that the feedstock is predominantly composed of plant-derived tissues, including grass straw, nitrogen-fixing hay, and animal manure, with a significant presence of O-alkyl-C and di-O-alkyl-C regions typical of sugars and polysaccharides. Additionally, the chemical profile indicated the presence of an aliphatic fraction (alkyl-C), characteristic of lipids such as waxes and cutins. The compost tea microbiome was dominated by Pseudomonadota, with Pseudomonas, Massilia, and Sphingomonas being the most prevalent genera. Compost tea application resulted in significant yield increases, ranging from +21% for lettuce to +58% for onion and +110% for chard. Furthermore, compost tea application reduced slug damage and enhanced the shelf life of lettuce. These findings highlight the bio-stimulant potential of this standardized compost tea mixture across different vegetable crops.

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.

Salinity and sodicity greatly influences ongoing physical processes in soils. Organic matter may rehabilitate physical and mechanical properties of soils. Vermicompost as an amendment influences moisture-related parameters including consistency (plastic - PL and liquid limit - LL) and compaction. This study was conducted on soils (sandy-clay-loam) treated with different salinity levels (0.58 (control - irrigation water quality, tap water), 4 and 8 dS m(-1)) to investigate the effects of different vermicompost doses (0% (control), 2.5% and 5% w/w) on soil consistency limits and compaction. The pot experiment was carried out in a total of 27 pots, i.e. 3 (vermicompost doses) x 3 (salinity levels) x 3 (number of replicates). For Proctor compaction properties, maximum dry bulk density (MDD) reduced and optimum water contents (OWC) increased with increasing vermicompost doses under different salinity levels (p < .01). Increasing vermicompost doses under the lowest salinity level (0.58 dS m(-1)) yielded increasing optimum water contents for control (LL = 35.93% and PL = 25.85%). Optimum water contents were determined as 42.19% (LL) and 29.93% (PL) for 2.5% vermicompost dose and as 47.33% (LL) and 36.01% (PL) for 5% vermicompost dose under the lowest salinity level. LL, PL, OWC and MDD were significantly affected by vermicompost x salinity interactions. The highest maximum dry bulk density (1.92 g cm(3)) and the lowest optimum water contents (13.50%) were obtained from 0% vermicompost under the 8 dS m(-1) NaCl level. Mean weight diameter (MWD) values ranged from 0.690 mm for 0% VC treatment under high Na salt level (8 dS m(-1) NaCl) to 0.821 mm for 5% VC treatment under lowest Na salt level (0.58 dS m(-1) NaCl). The correlations between aggregate stability (particle size group 1-2 mm) and optimum water content were 0.647*, 0.587* and 0.598* as compared to correlations of -0.512*, -0.470*, and -0.617** between aggregate stability (particle size group 1-2 mm) and maximum dry bulk density for the 0, 4 and 8 dS m(-1) NaCl levels, respectively. MWD was positively correlated with OWC (0.386*) and negatively correlated with MDD (-0.385*). The greatest (2.39%) and the lowest (0.32%) soil organic matter values were respectively observed in 5% VC under the lowest salinity level (0.58 dS m(-1)) and 0% VC with at high Na salt level (8 dS m(-1) NaCl). It was concluded that vermicompost reduced compaction-induced damage in soils.

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.