Processing technology and electrical decontamination of bedding manure and litter in ground trenches and bioreactors

The paper presents data on the effect of electric current on the quantitative index of Mucor and Bacillus fungal colonies in bedding litter. It was found that with an increase in direct current to 3A, the quantitative index (%) of Mucor fungal colonies sharply decreases from 45 to 3 (by 42%), and the quantitative index (%) of Bacillus fungal colonies decreases from 70 to 50 (by 20%). Fresh litter has high acidity, and it cannot be used without preliminary processing and electrical decontamination in ground trenches and bioreactors.

Fresh litter acts as a substantial phosphorus source of plant species appearing in primary succession on volcanic ash soil

Plants have difficulty absorbing phosphorus from volcanic ash soils owing to the adsorption of phosphorus by aluminum and iron in the soils. Thus, on volcanic ash soils, the phosphorus source for natural vegetation is expected to be organic matter, however, there is a lack of experimental evidence regarding this occurrence. Here, we studied the effect of organic matter on plant growth of some species that occur in primary successions of volcanic ash soil ecosystems, based on growth experiments and chemical analyses. We found that a large amount of inorganic phosphorus (but only a limited amount of inorganic nitrogen) is leached from fresh leaf litter of the pioneer spices Fallopia japonica at the initial stage of litter decomposition. Phosphorus from the fresh litter specifically activated the growth of subsequently invading nitrogen-fixing alder when immature volcanic soil was used for cultivation. In contrast, old organic matter in mature soil was merely a minor source of phosphorus. These results suggest that fresh litter of F. japonica is essential for growth of nitrogen-fixing alder because the litter supplies phosphorus. We consider that rapid phosphorus cycles in fresh litter-plant systems underlie the productivity of natural vegetation even in mature ecosystems established on volcanic ash soils.

Competition is a determinant of multidrug resistant plasmid acquisition in Salmonella

Host microbiome homeostasis ensures that gut conditions are unfavorable to an invading pathogen such as Salmonella enterica. Consequently, fostering a 'balanced' gut microbiome through the administration of microbes that can competitively exclude pathogens has gained a lot of attention and use in human and animal medicine. However, little is known on how competitive exclusion affects the transfer of antibiotic resistance. To shed more light on this question, we challenged neonatal broiler chicks raised on reused broiler chicken litter – a complex environment comprising of decomposing pine shavings, feces, uric acid, feathers, and feed, with Salmonella Heidelberg (S. Heidelberg), a model pathogen. We show that chicks raised on reused litter carried lower abundance of Salmonella and harbored a more uniform and diverse microbiome comprising of bacterial species that are known to provide colonization resistance towards Salmonella compared to chicks raised on fresh bedding composed of pine shavings. Additionally, these bacterial species were associated with a lower horizontal transfer of multidrug resistance genes to S. Heidelberg. Using in vitro competition experiments, we confirmed that conjugation between S. Heidelberg and E. coli strains from chicks raised on fresh litter resulted in the acquisition of multidrug resistant plasmids. Contrastingly, bacteriophage-mediated recombination between S. Heidelberg and E. coli strains made the acquisition of plasmid-mediated β-lactamase gene (blaCMY-2)possible. Collectively, this study demonstrates that competitive exclusion can reduce the transfer of antibiotic resistance and provides information on the bacterial species that can be explored for their benefits to reduce antibiotic resistance transfer.

Additional carbon stabilization in temperate subsoils impeded by biogeochemical and hydraulic constraints

<p>Formation of mineral-associated organic matter (MAOM) is a decisive process in the stabilization of OM against rapid microbial decomposition and thus in the soils’ role as global carbon (C) sink. Sorption experiments of dissolved OM (DOM) repeatedly showed that particularly mineral subsoils have a large sorption capacity to retain more C. However, there is also an increasing body of literature, revealing an increasing output of dissolved organic C (DOC) from soils. Here, we investigated into this paradox in forest soil under beech by a combination of a field labelling experiment with <sup>13</sup>C-enriched litter with a unique DO<sup>13</sup>C and <sup>13</sup>CO<sub>2</sub> monitoring, an in-situ C exchange experiment with <sup>13</sup>C-coated minerals, and batch sorption experiments.</p><p>Within two years of <sup>13</sup>C monitoring, only 0.5% of litter-derived DO<sup>13</sup>C entered the subsoil, where it was only short-term stabilized by formation of MAOM but prone to fast microbial mineralization. The <sup>13</sup>C monitoring, sorption/desorption experiments in the laboratory, and also the in-situ C exchange on buried soil minerals revealed that there is a frequent exchange of DOM with native OM and a preferential desorption of recently retained OM. Hence, there appeared to be a steady-state equilibrium between C input and output, facilitated by exchange and microbial mineralization of an adopted microbial community. The remobilized OM was also richer in less sorptive carbohydrates. Along with transport of most of DOM along preferential paths, this further increased the discrepancy between laboratory-measured sorption capacities of subsoil and the actual C loading of minerals. Finally, the <sup>13</sup>C labeling experiments revealed that input of fresh litter-derived OM into subsoil may even mobilize old-soil derived OM. Hence, in the field different biogeochemical constraints are acting that prevent that the laboratory-based C sink can be reached in the field.  We conclude, that forest subsoils can hardly be considered as additional C sink, even at management options that increase DOC input to subsoil.</p>

Vertical partitioning of CO₂ production in a forest soil

Large amounts of total organic carbon are temporarily stored in soils, which makes soil respiration one of the major sources of terrestrial CO2 fluxes within the global carbon cycle. More than half of global soil organic carbon (SOC) is stored in subsoils (below 30 cm), which represent a significant carbon (C) pool. Although several studies and models have investigated soil respiration, little is known about the quantitative contribution of subsoils to total soil respiration or about the sources of CO2 production in subsoils. In a 2-year field study in a European beech forest in northern Germany, vertical CO2 concentration profiles were continuously measured at three locations, and CO2 production was quantified in the topsoil and the subsoil. To determine the contribution of fresh litter-derived C to CO2 production in the three soil profiles, an isotopic labelling experiment, using 13C-enriched leaf litter, was performed. Additionally, radiocarbon measurements of CO2 in the soil atmosphere were used to obtain information about the age of the C source in the CO2 production. At the study site, it was found that 90 % of total soil respiration was produced in the first 30 cm of the soil profile, where 53 % of the SOC stock is stored. Freshly labelled litter inputs in the form of dissolved organic matter were only a minor source for CO2 production below a depth of 10 cm. In the first 2 months after litter application, fresh litter-derived C contributed, on average, 1 % at 10 cm depth and 0.1 % at 150 cm depth to CO2 in the soil profile. Thereafter, its contribution was less than 0.3 % and 0.05 % at 10 and 150 cm depths, respectively. Furthermore CO2 in the soil profile had the same modern radiocarbon signature at all depths, indicating that CO2 in the subsoil originated from young C sources despite a radiocarbon age bulk SOC in the subsoil. This suggests that fresh C inputs in subsoils, in the form of roots and root exudates, are rapidly respired, and that other subsoil SOC seems to be relatively stable. The field labelling experiment also revealed a downward diffusion of 13CO2 in the soil profile against the total CO2 gradient. This isotopic dependency should be taken into account when using labelled 13C and 14C isotope data as an age proxy for CO2 sources in the soil.

INFLUENCE OF VARIOUS TYPES OF ORGANIC WASTE OF AGROINDUSTRIAL COMPLEX ON PRODUCTIVITY OF ROW CROPS IN THE CONDITIONS OF THE NIZHNY NOVGOROD REGION

The introduction of unprocessed organic waste into the soil leads to the accumulation of nutrition elements for their subsequent assimilation by plants in the land-use system from the organomineral complexes of the soil, which will significantly increase the yield of agricultural crops. However, for 2- 3 years with constant introduction of "raw" manure, soil degradation occurs. So, with the constant introduction of "fresh" litter will be the oppression of cultivated plants by "osmosis" and the subsequent destruction of their root rot due to its high content of raw litter of pathogenic organisms and high level of Pro-infectious potential, which reduces fungistasis soil, leading to lower yields. The cardinal way out of this situation is to add composted manure to the soil. In addition to increasing the content of organic matter in the soil, including humus. Due to this, there is a decrease in osmosis and phytopathogenic load. The biological activity of the soil when composting will be slightly lower than when applying " raw " manure. However, due to this fact, in the following years, when using complex compost, the soil will contain more organic matter compared to the control. In addition," full "composting reduces "osmosis", kills weed seeds and destroys potentially dangerous pathogens of agricultural crops. Based on the above, it can be assumed that the introduction of new organic fertilizers should have a multi-sided effect on the agronomic properties of the soil, which in the end, with the correct use of complex compost, dramatically increases the yield of crops, including cereals.

Effect of Alum (Aluminum Sulfate) Addition to Poultry Litter on Layer Performance, Litter pH and Litter Composition

The current experiment was conducted to assess the effect of using different litter types with or without alum on performance and litter quality of the hen layers. A total number of 120 Inshas layer hens of 24 weeks of age were randomly distributed into 4 groups (3 replicates each 10 hens) of floor litter: T1 birds were raised on wood shaving litter, T2 birds were raised on wheat straw litter, T3 birds were raised wood shaving with 100 g of alum / kg of bedding, and T4 birds were raised on wheat straw litter with 100 g of alum / kg of bedding. Topping of fresh litter with acidifier amendment improved body weight, egg weight, egg number, egg mass, feed intake and feed conversion ratio of layers compared to chickens in the untreated litter group. In comparison with the control group, alum treatment reduced the pH level of the litter. Regarding the NH4+-N content, alum-treated litter showed a higher value than the untreated litter. On average, alum-treated litter had lower P content than the untreated litter. Alum treated group showed a significant increase in dry matter and total nitrogen content when compared with the untreated group. The study results showed significant variability (p < .05) in the moisture content and pH of the control and treated litter. This clearly shows the effectiveness of litter treatment products enhancing litter quality and therefore the bird’s environmental climate. Thus it can be decided that litter modification with alum treatment had a significant impact on litter quality and in turn enhanced the productive performance of layer chickens without any adverse effect.

Effects of initial microbial biomass abundance on respiration during pine litter decomposition

Microbial biomass is increasingly used to predict respiration in soil organic carbon (SOC) models. Its increased use combined with the difficulty of accurately measuring this variable points a need to directly assess the importance of microbial biomass abundance for carbon (C) cycling. To test the hypothesis that the initial microbial biomass abundance (i.e. biomass abundance on new plant litter) is a strong driver of plant litter C cycling, we manipulated biomass abundance by 10 and 100-fold dilution and composition using 12 source communities on sterile pine litter and measured respiration in microcosms for 30 days. In the first two days of microbial growth on fresh litter, a 100-fold difference in initial biomass abundance caused an average difference in respiration of nearly 300%, but the effect rapidly declined to less than 30% in 10 days and to 14% in 30 days. Parallel simulations with a soil carbon model, SOMIC 1.0, also predicted a 14% difference over 30 days, consistent with the experimental results. Model simulations predicted convergence of cumulative CO2 to within 10% in three months and within 4% in three years. Rapid microbial growth likely attenuates the effects of large initial differences in biomass abundance. In contrast, the persistence of source community as an explanatory factor in driving differences in respiration across microcosms supports the importance of microbial composition in C cycling. Overall, the results suggest that the initial abundance of microbial biomass on litter is a weak driver of C flux from litter decomposition over long timescales (months to years) when litter communities have equal nutrient availability. By extension, slight variation in the timing of microbial dispersal to fresh litter is likely to be a minor factor in long-term C flux.ImportanceMicrobial biomass is one of the most common microbial parameters used in land carbon (C) cycle models, however, it is notoriously difficult to measure accurately. To understand the consequences of mismeasurement, as well as the broader importance of microbial biomass abundance as a direct driver of ecological phenomena, greater quantitative understanding of the role of microbial biomass abundance in environmental processes is needed. Using microcosms, we manipulated the initial biomass of numerous microbial communities across a 100-fold range and measured effects on CO2 production during plant litter decomposition. We found that the effects of initial biomass abundance on CO2 production was largely attenuated within a week, while the effects of community type remained significant over the course of the experiment. Overall, our results suggest that initial microbial biomass abundance in litter decomposition within an ecosystem is a weak driver of long-term C cycling dynamics.