It remains unclear whether biodiversity buffers ecosystems against climate extremes, which are becoming increasingly frequent worldwide. Early results suggested that the ecosystem productivity of diverse grassland plant communities was more resistant, changing less during drought, and more resilient, recovering more quickly after drought, than that of depauperate communities. However, subsequent experimental tests produced mixed results. Here we use data from 46 experiments that manipulated grassland plant diversity to test whether biodiversity provides resistance during and resilience after climate events. We show that biodiversity increased ecosystem resistance for a broad range of climate events, including wet or dry, moderate or extreme, and brief or prolonged events. Across all studies and climate events, the productivity of low-diversity communities with one or two species changed by approximately 50% during climate events, whereas that of high-diversity communities with 16–32 species was more resistant, changing by only approximately 25%. By a year after each climate event, ecosystem productivity had often fully recovered, or overshot, normal levels of productivity in both high- and low-diversity communities, leading to no detectable dependence of ecosystem resilience on biodiversity. Our results suggest that biodiversity mainly stabilizes ecosystem productivity, and productivity-dependent ecosystem services, by increasing resistance to climate events. Anthropogenic environmental changes that drive biodiversity loss thus seem likely to decrease ecosystem stability, and restoration of biodiversity to increase it, mainly by changing the resistance of ecosystem productivity to climate events.

Biodiversity increases the resistance of ecosystem productivity to climate extremes

Composting is the controlled conversion of degradable organic products and wastes into stable products with the aid of microorganisms. Composting is a long-used technology, though it has some shortcomings that have reduced its extensive usage and efficiency. The shortcomings include pathogen detection, low nutrient status, long duration of composting, long mineralization duration, and odor production. These challenges have publicized the use of chemical fertilizers produced through the Haber–Bosch process as an alternative to compost over time. Chemical fertilizers make nutrients readily available to plants, but their disadvantages outweigh their advantages. For example, chemical fertilizers contribute to greenhouse effects, environmental pollution, death of soil organisms and marine inhabitants, ozone layer depletion, and human diseases. These have resulted in farmers reverting to the application of composts as a means of restoring soil fertility. Composting is a fundamental process in agriculture and helps in the recycling of farm wastes. The long duration of composting is a challenge; this is due to the presence of materials that take a longer time to compost, especially during co-composting. This review discusses the proper management of wastes through composting, different composting methods, the factors affecting composting, long-duration composting, the mechanism behind it, the present trends in composting and prospects. The extraction of mono-fertilizers from compost, development of strips to test for the availability of heavy metals and pathogens as well as an odor-trapping technique can go a long way in enhancing composting techniques. The addition of activators to raw materials can help to improve the nutritional quality of compost. This review further recommends that degradable organic material in which composts slowly should be assessed for their ability to mineralize slowly, which could make them advantageous to perennial or biennial crops. Viricides, fungicides, anti-nematodes, and anti-bacterial of plant or organic sources could as well be added to improve compost quality. The enhancement of composting duration will also be useful.

Waste Management through Composting: Challenges and Potentials

Reports of the Technical Working Groups Established under the Thematic Strategy for Soil Protection.Vol. I. Introduction and Executive Summary.

Agricultural waste recycling in horticultural intensive farming systems by on-farm composting and compost-based tea application improves soil quality and plant health: A review under the perspective of a circular economy.

Degradation of norfloxacin with peroxymonosulfate activated by nanoconfinement Co3O4@CNT nanocomposite

Application of sewage sludge to agricultural soil increases the abundance of antibiotic resistance genes without altering the composition of prokaryotic communities.

The use of organic amendments in agriculture is a common practice due to their potential to increase crop productivity and enhance soil health. Indeed, organic amendments of different origin and composition (e.g., animal slurry, manure, compost, sewage sludge, etc.) can supply valuable nutrients to the soil, as well as increase its organic matter content, with concomitant benefits for soil health. However, the application of organic amendments to agricultural soil entails a variety of risks for environmental and human health. Organic amendments often contain a range of pollutants, including heavy metals, persistent organic pollutants, potential human pathogens, and emerging pollutants. Regarding emerging pollutants, the presence of antibiotic residues, antibiotic-resistant bacteria, and antibiotic-resistance genes in agricultural amendments is currently a matter of much concern, due to the concomitant risks for human health. Similarly, currently, the introduction of microplastics to agricultural soil, via the application of organic amendments (mainly, sewage sludge), is a topic of much relevance, owing to its magnitude and potential adverse effects for environmental health. There is, currently, much interest in the development of efficient strategies to mitigate the risks associated to the application of organic amendments to agricultural soil, while benefiting from their numerous advantages.

https://www.mdpi.com/2073-4395/9/9/542/pdf

Potential Benefits and Risks for Soil Health Derived From the Use of Organic Amendments in Agriculture

The application of fresh and composted horse and chicken manure affects soil quality, microbial composition and antibiotic resistance

The impact of nanoscale zero-valent iron particles on soil microbial communities is soil dependent

The application of organic amendments to agricultural soil provides organic matter and valuable nutrients, improves soil structure, increases its water holding capacity and stimulates soil microbial communities. However, when using organic amendments of animal and/or anthropogenic origin, the risk of contamination with organic and/or inorganic compounds, as well as the risk of dissemination of potential human pathogens and antibiotic resistance genes, must be taken into account. Here, we characterized seven amendments used in organic farming, in order to evaluate the agro-environmental consequences of their utilization. Amendments (vermicompost, bokashi, municipal solid waste, compost in pellet form, composted cow manure from intensive farms, composted cow manure from organic farms, composted sheep manure from organic farms) were sampled for the determination of (i) the presence of chemical (metals, aromatics, halogenated hydrocarbons, pesticides, phthalates and total petroleum hydrocarbons) and biological (Escherichia coli, Salmonella, relative abundance of the integrase intl1 gene) contaminants; and (ii) their quality, in terms of physicochemical (moisture, organic matter, nutrients, C/N ratio) and microbial (potentially mineralizable nitrogen, microbial biomass carbon, bacterial and fungal abundance by real-time PCR, community-level physiological profiles through Biolog EcoPlates™) properties. Regarding metal concentrations, the only amendments that met the Spanish legal requirements for “Class A” fertilizers were composted intensive and organic cow manure. Zinc was the most limiting metal for the use of these amendments. None of the amendments showed high concentrations of organic contaminants. Bokashi was the only amendment in which Salmonella was detected. Besides, bokashi showed a high abundance of the integrase intl1 gene associated with class 1 integrons. Composted organic sheep manure showed the highest content of organic matter, total nitrogen and extractable humic acids. Composted intensive cow manure showed highest values of microbial activity (potentially mineralizable N) and biomass (microbial biomass C, total bacteria). Owing to its low content of potentially health-threatening contaminants and its highest quality, as reflected by the Amendment Quality Index, composted intensive cow manure was concluded to be the most suitable amendment for agricultural use.

/pdf/characterization-of-composted-organic-amendments-for-1rav6gbik1.pdf

Julen Urra

Papers

Application of sewage sludge to agricultural soil increases the abundance of antibiotic resistance genes without altering the composition of prokaryotic communities.

Potential Benefits and Risks for Soil Health Derived From the Use of Organic Amendments in Agriculture

The application of fresh and composted horse and chicken manure affects soil quality, microbial composition and antibiotic resistance

The impact of nanoscale zero-valent iron particles on soil microbial communities is soil dependent

Characterization of Composted Organic Amendments for Agricultural Use