Mulching techniques can comprise a solution that better utilizes precipitation and irrigation water in such a manner that mitigates soil degradation and drought damage; however, there are still gaps in the literature with regard to the effect of the use of mulch materials on the development of plant–soil–microbe interactions. Waste fibers, as alternative biodegradable mulch materials, are becoming increasingly prominent. The effect of wool mulch (WM) on water use efficiency, with regard to pepper seedlings, was investigated in different soil types (sand, clay loam, peat) in a pot experiment. Two semi-field experiments were also set up to investigate the effect of WM–plant interactions on sweet pepper yields, as compared with agro textiles and straw mulches. Soil parameters (moisture, temperature, DHA, β-glucosidase enzymes, permanganate-oxidizable carbon) were measured during the growing season. The effect of WM on yield and biomass was more significant with the less frequent irrigation and the greater water-holding capacity of soils. Microbiological activity was significantly higher in the presence of plants, and because of the water retention of WM, the metabolic products of roots and the more balanced soil temperature were caused by plants. In the sandy soil, the straw mulch had a significantly better effect on microbiological parameters and yields than the agro textiles and WM. In soils with a higher water capacity, WM is a sustainable practice for improving the biological parameters and water use efficiency of soil. The effect of WM on yields cannot solely be explained by the water retention of the mulch; indeed, the development of biological activity and plant–soil–microbe interactions in the soil are also contributing factors.

In recent years, many alternative bio‐waste‐based fertilizers have been proven to have a beneficial effect on plant nutrition. These also include wool pellet, whose comprehensive evaluation of synergistic effects on plant development and soil biological activity is still a limited field of investigation. To address this, we explored the potential of combining soil inoculations and N‐rich wool pellet as ecologically sound alternatives to N fertilizers. In a pot experiment, we investigated the effect of Azotobacter vinelandii, the Trichoderma harzianum T34, and wool pellet, individually and in combination, on the growth and nitrate uptake of the test plants, as well as on the biological activity and permanganate‐oxidizable carbon of the sandy soil with low organic matter content. The combination of T. harzianum + wool pellet showed the highest biological activity and permanganate‐oxidizable carbon content, while the untreated control plants exhibited the lowest values. The treatment combination of wool pellet and A. vinelandii exhibited the highest nitrate uptake by plants. Measuring the concentration of photosynthetic pigments, net photosynthesis, transpiration rate, stomatal conductance, and total dry biomass, we found that the treatments led to a significant improvement in the photosynthetic intensity of lettuce plants. These results suggest that wool pellet served as a significant source of N and that their biological activity plays a key role in improving plant parameters. Moreover, the combination of microbial inoculants and wool pellet effectively increases N use efficiency in plant growth.

Soil organic matter is a biological system that functions as an integrated whole. These assemblies have different properties, functions, and decomposition times. SOM is one of the main determinants of soil productivity. Our studies were carried out in a temperate deciduous oak forest on Luvisols soil. In the DIRT Project (Detritus Input and Removal Treatments), the following treatments were applied: Double Litter, Double Wood, Control, No Litter, No Root and No Input. Our objective was to compare the effect of withdrawal or doubling of organic matter on the protein pattern of the soil and the biological activity and changes in labile C (permanganate-oxidizable carbon) content in a long-term organic matter manipulation experiment. Patterns of thermostable proteins, soil dehydrogenase enzyme activity, CO₂ emission, and POXC content were measured at the most biologically active soil depth of 0–5 cm after 23 years of treatment. Our results show that the enzyme activities of the litter removal treatments were significantly reduced compared to the doubling treatments, as were the values of soil respiration. The same significant difference was also detected in the C content of the soils of the treatments. Based on cluster analysis of the protein profile of the soil samples, the No Litter and No Input treatments were significantly different from the other treatments. This shows that specific organic matter is needed to enhance soil biological activity and the associated POXC content.

The various climate scenarios consistently predict warming and drying of forests in Hungary. Soils play a significant role in the long-term sequestration of atmospheric CO₂, while in other cases they can also become net carbon emitters. Therefore, it is important to know what can be expected regarding future changes in the carbon storage capacity of soils in forests. We used precipitation gradient studies to solve this problem, using a type of “space–time” substitution. In this research, we primarily examined the quality parameters of soil organic matter (SOM) to investigate how climate change transforms the ratio of the main SOM compound groups in soils. For our studies, we applied elemental and ¹³C and ¹⁵N isotopic ratio analysis, NMR analysis, FT-IR spectra analysis, thermogravimetric and differential thermal analyses to measure SOM chemistry in samples from different oak forests with contrasting mean annual precipitation from Central Europe. Our results showed that soil organic carbon (SOC) was lower in soils of humid forests due to the enhanced decomposition processes and the leaching of Ca, which stabilizes SOM; however, in particular, the amount of easily degradable SOM compounds (e.g., thermolabile SOM, O-alkyl carbon, carboxylic and carbonyl carbon) decreased. In dry forest soils, the amount of recalcitrant SOM (e.g., thermostable SOM, alkyl carbon, aromatic and phenolic carbon and organo–mineral complexes stabilized by Ca increased, but the amount of easily degradable SOM increased further. The main conclusion of our study is that SOC can increase in forests that become drier, compensating somewhat for the decrease in forest plant biomass.

Soil enzyme activity and labile carbon (LC) have long been used as soil health indicators. Soil health can be improved by molasses addition resulting in better plant growth and productivity. The effect of molasses on soil biological activity and plant growth under different tillage soil has not been discussed in many studies in Hungary. We assessed two soil types under different long-term tillage practices: conservation tillage (CT), which leaves 30% or more residue on the soil surface, and conventional-ploughing tillage (PT). A pot experiment with maize as the crop was carried out using the composite soil (0-20 cm) of CT and PT; a randomized block design with four replications was employed. Three levels of molasses concentration, 0 g L-1, 0.05 g L-1, and 0.2 g L-1 were applied. LC, dehydrogenase (DHA), β-glucosidase activity, plant height, and dry weight biomass were measured at the end of the experiment (after eight weeks). The results indicated that LC in CT increased by 7.61-21.23% over the increase in molasses concentration. LC concentration was significantly higher in the CT than in the PT soil. β-glucosidase activity increased along with the increase of molasses concentration by 11.42-30.43% in CT and 16.03-56.67% in PT; however, the significantly different appeared only in PT soil. The molasses application affected the DHA as well. The activity of dehydrogenase increases by 39.49-80.76% and 30.43-50.59%, respectively, in CT and PT. Nevertheless, no significance occurred in the tillage system or the molasses concentration. Our study also found that the different molasses concentrations did not affect the plant height and dry weight biomass in CT and PT. However, applying each molasses concentration in CT markedly escalated the plant height and dry weight biomass compared to PT. The enhancement of soil biological activity and plant growth by the molasses application allows a promising strategy for maintaining the soil health of agricultural land.