A global meta-analysis of animal manure application and soil microbial ecology based on random control treatments

Impacts of farming activities on carbon deposition based on fine soil subtype classification

Introduction

Soil has the highest carbon sink storage in terrestrial ecosystems but human farming activities affect soil carbon deposition. In this study, land cultivated for 70 years was selected. The premise of the experiment was that the soil could be finely categorized by subtype classification. We consider that farming activities affect the soil bacterial community and soil organic carbon (SOC) deposition differently in the three subtypes of albic black soils.

Methods

Ninety soil samples were collected and the soil bacterial community structure was analysed by high-throughput sequencing. Relative changes in SOC were explored and SOC content was analysed in association with bacterial concentrations.

Results

The results showed that the effects of farming activities on SOC deposition and soil bacterial communities differed among the soil subtypes. Carbohydrate organic carbon (COC) concentrations were significantly higher in the gleying subtype than in the typical and meadow subtypes. RB41, Candidatus-Omnitrophus and Ahniella were positively correlated with total organic carbon (TOC) in gleying shallow albic black soil. Corn soybean rotation have a positive effect on the deposition of soil carbon sinks in terrestrial ecosystems.

Discussion

The results of the present study provide a reference for rational land use to maintain sustainable development and also for the carbon cycle of the earth.

Improving nitrogen retention of cattle slurry with oxidized biochar: An incubation study with three different soils

The application of livestock slurry in soils can lead to nitrogen (N) losses through ammonia (NH₃ ) emission or nitrate (NO₃ ^- ) leaching. Oxidized biochar has great potential to mitigate N losses due to its strong adsorption capacity; however, the effects of oxidized biochar in different soils treated with slurry are currently unclear. Here, we investigated the effect of untreated and oxidized biochar (applied at a rate of 50 kg C m^-3 slurry) on reducing N losses in a laboratory experiment with three different soils (loamy sand, sandy loam, loam) amended with cattle slurry at an application rate of 73 kg N ha^-1 . Oxidized biochar reduced NH₃ emissions by 64-75% in all soils, whereas untreated biochar reduced NH₃ emissions by 61% only in the loamy sand. Oxidized biochar significantly reduced the NO₃ ^- content in the soil solution of the loamy sand in the early phase of the incubation and led to a significantly higher NO₃ ^- concentration in the same soil compared with the slurry-only treatment at the end of the experiment, indicating a significant increase in NO₃ ^- retention in this organic C-poor soil. We conclude that oxidized biochar can reduce N losses, both in the form of NH₃ emission and NO₃ ^- leaching, from cattle slurry applied to soil, particularly in soil with soil organic carbon content <1% and pH <5 (i.e., oxidized biochar can serve as a means for improving the quality of marginal and acidic soils).

Perspectives on Converting Keratin-Containing Wastes Into Biofertilizers for Sustainable Agriculture

Keratin-containing wastes become pollution to the environment if they are not treated properly. On the other hand, these wastes can be converted into value-added products applicable to many fields. Organic fertilizers and biofertilizers are important for sustainable agriculture by providing nutrients to enhance the growth speed of the plant and production. Keratin-containing wastes, therefore, will be an important resource to produce organic fertilizers. Many microorganisms exhibit capabilities to degrade keratins making them attractive to convert keratin-containing wastes into valuable products. In this review, the progress in microbial degradation of keratins is summarized. In addition, perspectives in converting keratin into bio- and organic fertilizers for agriculture are described. With proper treatment, feather wastes which are rich in keratin can be converted into high-value fertilizers to serve as nutrients for plants, reduce environmental pressure and improve the quality of the soil for sustainable agriculture.