Impact of Soil Chemical Properties on the Growth Promotion Ability of Trichoderma ghanense, T. tomentosum and Their Complex on Rye in Different Land-Use Systems

Microbial-based biostimulants that increase plant performance and ensure sustainable restoration of degraded soils are of great importance. The aim of the present study was to evaluate the growth promotion ability of indigenous Trichoderma ghanense, T. tomentosum and their complex on early rye seedlings in sustained grassland and arable soil. The impact of soil chemical properties on the ability of selected Trichoderma strains and their complex to promote plant growth was determined by the evaluation of the rye (Secale cereale L.) early seedling growth—measuring the length of shoots and roots as well as their dry weight. Trichoderma species were tested for their ability to produce extracellular degradative enzymes on solid media. Furthermore, the soil properties and CM-cellulase activity of soil were estimated. The indigenous Trichoderma strains possess the capacity to produce enzymes such as peroxidase, laccase, tyrosinase, and endoglucanase. The results indicated a significant (p < 0.05) increase in plant growth and the improvement of some soil chemical properties (total N, mobile humic and fulvic acids, exchangeable K2O, soil CM-cellulase activity) in inoculated soils when compared to the control. The growth of the roots of rye seedlings in sustained grassland was enhanced when T. tomentosum was applied (p = 0.005). There was an increase in total weight and shoot weight of rye seedlings when T. ghanense was used in the arable soil (p = 0.014 and p = 0.024). The expected beneficial effect of Trichoderma spp. complex on rye growth promotion was not observed in any tested soil. The results could find application in the development of new and efficient biostimulants, since not only do physiological characteristics of fungi play an important role but also the quality of the soil has an impact.

Biogas Generation from Maize and Cocksfoot Growing in Degraded Soil Enriched with New Zeolite Substrate

Degraded lands are potential areas for obtaining biomass which can serve as an energy source after its conversion into biogas. Thus, the studies on biogas production from maize and cocksfoot biomasses obtained from degraded soil supplemented with additions of new zeolite substrate (Z-ion as the nutrient carrier) and on arable soil (reference soil) were carried out during batch digestion tests. It was found that the biogas and biomethane potentials and specific energy of the test species growing in degraded soil enriched with Z-ion additions (1% and 5% v/v in the cases of cocksfoot and maize, respectively) did not differ significantly from the values of these parameters that were found for the plants growing in arable soil. The application of Z-ion to the degraded soil (especially in a dose of 5% v/v) resulted in an increase in the nitrogen content and decrease (below the lower optimum value) in the C/N ratio in the plant biomass. However, these changes did not negatively influence the final values of the biogas or methane potentials or the specific energy found for the maize biomass. Therefore, the study results indicated the usefulness of Z-ion substrate for improving the growth conditions for energy crops in degraded soils and, as a consequence, obtaining a plant feedstock suitable for the digestion process.

Organic matter of sod-podzolic soil after transition to a fallow state

Soil plays a crucial role in carbon sequestration in terrestrial ecosystems. It is known that the strengthening of carbon sequestration processes occurs with a decrease in the intensity of soil treatments. The study of changes in organic matter and physical properties of sod-podzolic soil 16 years after the transition from arable soils to a fallow state against the background of weak water erosion was carried out. A significant increase in the content and reserves of total carbon in fallow soil compared to arable soil was found, mainly due to carbon of the light fraction. On arable soil, the content of the light fraction in the lower part of the field was significantly higher than in the upper part, due to the washing away of light particles as a result of erosion, these differences were smoothed out on fallow soil. There are no significant changes in the density, density of the solid phase and total porosity in fallow soil at this stage of succession, compared with arable soil. In fallow soil, the content of macro-aggregates (including water-bearing ones) was noticeably higher, and the share of micro-aggregates was lower than in arable soil.

Nitrous Oxide Emission and Crop Yield in Arable Soil Amended with Bottom Ash

Bottom ash (BA), a byproduct of coal combustion from electric power plants with a porous surface texture and high pH, may influence the physical and chemical properties of upland arable soil associated with nitrous oxide (N2O) emission from upland soil. This study evaluated the use of BA in mitigating N2O emissions from upland arable soil and increasing the crop yield. In a field experiment, N2O emitted from the soil was monitored weekly in a closed chamber over a 2-year period (2018–2019). BA was applied to upland soil at the rates of 0, 200, and 400 Mg·ha−1. Cumulative N2O emission significantly decreased with increasing BA application rate; it decreased by 55% with a BA application rate of 400 Mg·ha−1 compared with the control. Yield-scaled N2O emission decreased with increasing BA application rates of up to 200 Mg·ha−1. Water-filled pore spaces (WFPS) were 70.2%, 52.9%, and 45.3% at the rates of 0, 200, and 400 Mg·ha−1, respectively, during the growing season. For economic viability and environmental conservation, we suggest that BA application at a rate of 200 Mg·ha−1 reduces N2O emissions per unit of crop production.

Metagenomic approaches reveal differences in genetic diversity and relative abundance of nitrifying bacteria and archaea in contrasting soils

The abundance and phylogenetic diversity of functional genes involved in nitrification were assessed in Rothamsted field plots under contrasting management regimes—permanent bare fallow, grassland, and arable (wheat) cultivation maintained for more than 50 years. Metagenome and metatranscriptome analysis indicated nitrite oxidizing bacteria (NOB) were more abundant than ammonia oxidizing archaea (AOA) and bacteria (AOB) in all soils. The most abundant AOA and AOB in the metagenomes were, respectively, Nitrososphaera and Ca. Nitrososcosmicus (family Nitrososphaeraceae) and Nitrosospira and Nitrosomonas (family Nitrosomonadaceae). The most abundant NOB were Nitrospira including the comammox species Nitrospira inopinata, Ca. N. nitrificans and Ca. N. nitrosa. Anammox bacteria were also detected. Nitrospira and the AOA Nitrososphaeraceae showed most transcriptional activity in arable soil. Similar numbers of sequences were assigned to the amoA genes of AOA and AOB, highest in the arable soil metagenome and metatranscriptome; AOB amoA reads included those from comammox Nitrospira clades A and B, in addition to Nitrosomonadaceae. Nitrification potential assessed in soil from the experimental sites (microcosms amended or not with DCD at concentrations inhibitory to AOB but not AOA), was highest in arable samples and lower in all assays containing DCD, indicating AOB were responsible for oxidizing ammonium fertilizer added to these soils.