Soil Ecosystem Sustainability Research Articles

Research advances in trait-based approaches in soil animal community ecology

Functional traits are indicators of the responses and adaptation of organisms to environmental changes and cascade to a series of ecosystem functions. The functional traits of soil animals are sensitive to environmental factors and may characterize and predict the changes of ecosystem functions. Multiple dimensions of biodiversity that combing species, phylogenetic, and functional diversity improves the understanding of distribution patterns, community assembly mechanisms and ecosystem functions of soil animals. In this review, we listed the categories of soil animal functional traits and their ecological significance, and summarized current researches on the responses of soil animal communities to environmental changes and the community assembly processes based on trait-based approaches. We proposed to strengthen the study on the impacts of eco-evolution processes of biotic interactions to soil animal functional traits, establish the database of soil animal functional traits, and apply trait-based approaches in the ecological restoration in the future, which would benefit soil biodiversity conservation and sustainability of soil ecosystems.

Restoration of soils contaminated with PAHs by the mixture of zeolite composites mixed with exogenous organic matter and mineral salts

The major cause of soil degradation (contamination, erosion, compaction) is closely linked to agriculture, i.e., unsustainable agriculture practices, which are reflected in the depletion of the soil organic carbon pool, loss in soil biodiversity, and reduction of C sink capacity in soils. Therefore, the agricultural practice of applying carbon-rich materials into the soil is an attractive solution for climate change mitigation and soil ecosystem sustainability. The paper aimed to evaluate the effectiveness of the addition of organic-mineral mixtures to the mineral salts (NPK), including the exogenous organic matter (lignite) mixed with zeolite-carbon (NaX-C) or zeolite-vermiculite (NaX-Ver) composites in the restoration of soils contaminated with PAHs. The addition of zeolite composites to fertilizer resulted in a significant reduction in soil PAH levels and a corresponding reduction in plant tissue content, without compromising yields, compared to the control and separate application of NPK. A Significant correlation between PAHs and pHH2O, pHKCl, EC and dehydrogenase activity (DhA) was found in soils. The addition of zeolite composites with lignite significantly reduced the content of PAHs in straws, especially following the application of NaX-C. However, in the case of grains, the highest percentage reduction in comparison to NPK was observed for the highest dose of NaX-Ver.

Microplastic Pollution in Terrestrial Ecosystems and Its Interaction with Other Soil Pollutants: A Potential Threat to Soil Ecosystem Sustainability

The production and disposal of plastics have become significant concerns for the sustainability of the planet. During the past 75 years, around 80% of plastic waste has either ended up in landfills or been released into the environment. Plastic debris released into the environment breaks down into smaller particles through fragmentation, weathering, and other disintegration processes, generating microplastics (plastic particles ≤ 5 mm in size). Although marine and aquatic ecosystems have been the primary focus of microplastic pollution research, a growing body of evidence suggests that terrestrial ecosystems are equally at risk. Microplastic contamination has been reported in various terrestrial environments from several sources such as plastics mulch, pharmaceuticals and cosmetics, tire abrasions (tire wear particles), textiles industries (microfibers), sewage sludge, and plastic dumping. Recent studies suggest that the soil has become a significant sink for pollutants released into terrestrial ecosystems and is often contaminated with a mixture of organic and inorganic pollutants. This has gradually caused adverse impacts on soil health and fertility by affecting soil pH, porosity, water-holding capacity, and soil microbial enzymatic activities. Microplastics can interact with the co-existing pollutants of the environments by adsorbing the contaminants onto their surfaces through various intermolecular forces, including electrostatic, hydrophobic, non-covalent, partition effects, van der Waals forces, and microporous filling mechanisms. This subsequently delays the degradation process of existing contaminants, thereby affecting the soil and various ecological activities of the ecosystem. Thus, the present article aims to elucidate the deleterious impact of microplastics and their interactions with other pollutants in the terrestrial ecosystem. This review also addresses the impact of microplastics in disrupting the soil sustainability of the planet.

Fertility and biochemical activity in sodic soils 17 years after reclamation with flue gas desulfurization gypsum

Previous studies have mainly focused on changes in soil physical and chemical properties to evaluate the reclamation of sodic soils using flue gas desulfurization (FGD) gypsum. However, information on the effects of this reclamation method on microbial-based indicators of soil quality is limited, particularly after many years of FGD gypsum application. This study aimed to investigate the long-term effects of FGD gypsum on soil organic carbon (SOC), nutrients, microbial biomass and enzyme activity. Data were collected from soils of three exchangeable sodium percentage (ESP) classes (i.e., low-, middle- and high-ESP classes of 6.1–20, 20–30 and 30–78.4%, respectively) 17 years after FGD gypsum treatment in Inner Mongolia, China. Averaged across the three ESP classes, FGD gypsum application increased the SOC contents at the 0–20 and 20–40-cm soil depths by 18 and 35%, respectively, and increased available potassium at the 0–20-cm soil depth by 51% compared with the no-gypsum controls. The microbial biomass carbon and microbial biomass nitrogen contents at the 20–40-cm soil depth increased by 69 and 194%, respectively, under FGD gypsum. Except in the high-ESP class, urease activities in the 0–40 cm soil profile were significantly higher in the FGD gypsum treatments than in the controls. A significant increase in alkaline phosphatase activity was concentrated in the 20–40 cm soil layer; few classes showed significant increases in catalase and invertase activities in the 0–20 cm soil layer. Pearson correlation analysis showed that increases in soil fertility and biological activity could be attributed to reductions in electrical conductivity, pH and ESP caused by FGD gypsum application. These results confirm that FGD gypsum application is a viable strategy for reclaiming sodic soils due to its positive effects on soil fertility and biochemistry and that it may contribute to soil ecosystem sustainability.

Organic input practice alleviates the negative impacts of elevated ozone on soil microfood-web

Elevated ozone threatens the sustainability of soil ecosystems by negatively affecting underground ecological processes. Crop residue, as an energy source with a low risk of environmental influence, can alleviate the negative impacts caused by climate change. However, little knowledge is comprehended about the influences of crop residue input on soil nematode metabolic activities and microfood-web under elevated ozone. Soil microfood-web consisting of microorganisms and nematodes plays a significant role in the underground processes such as energy flow and nutrient turnover. Thus, the objectives of this study were to explore the responses of soil nematode metabolic activities and microfood-web to different elevated ozone levels and crop residue application managements. The pot experiment was a split-plot design with elevated ozone system as main plot and residue addition treatment as subplot utilizing the open-top chambers. Elevated ozone systems included three levels (control, 45 ± 5 ppb; lower elevated ozone level, 80 ± 10 ppb and higher elevated ozone level, 110 ± 10 ppb). Residue addition treatments were soil without residue addition and soil with residue addition. The results showed that elevated ozone generated negative influences on soil microorganisms and nematodes by decreasing their biomass carbon. Crop residue input practice increased the functional metabolic footprints of nematodes under elevated ozone. The carbon utilization of soil biological communities shifted from soil organic carbon to extractable organic carbon after crop residue incorporation. Soil nitrate-nitrogen was the main supplier to meet the nitrogen demand of soil biota. The analysis of structural equation modeling revealed that the system under elevated ozone without crop residue addition was predominated by a bacterial decomposition channel. While the application of crop residue into soils also made a contribution to the fungal decomposition pathway. Consequently, it can be concluded that organic input practice strengthens the cooperation of soil microfood-web channels, which plays an important role in alleviating the negative effects of elevated ozone on the stability of soil microfood-web.

Effects of Camellia oleifera clone selection on soil nutrient and microbial community structure

AbstractCamellia oleifera Abel. is an important woody oil plant that could solve the disparity between the supply and demand of edible oil in China. Although numerous excellent clones have been developed and introduced to enhance production, the interactions between high yield clones and soil ecosystem sustainability remains poorly understood. The high‐yielding period of a C. oleifera plant is approximately 100 yr; therefore, appropriate clone selection is crucial. We evaluated the differences between four major clones based on soil nutrient and microbial community structure, following cultivation for 10 yr to infer the influence of clone selection on soil sustainable utilization. The results showed significant differences in soil nutrient status and rhizosphere microorganism populations among clones. The bacterial communities in the XL1 plots had the highest species richness. According to the results, clone XL1 was found to be suitable for sustainable cultivation considering the high organic matter concentration and microbial diversity in the soil where it was cultivated. Although clone XL210 exhibited high yields and good economic benefits, it had a risk of inadequate production capacity in later periods, meaning that fertilization rates would have to be increased, and some annual plants with rich rhizosphere flora would need to be integrated in the farms to enhance microbial diversity in the soil to decelerate soil fertility decline.

A Well-Being Approach to Soil Health—Insights from Aotearoa New Zealand

This paper explores the concept of soil health from a human well-being perspective in Aotearoa New Zealand. Globally, soils play an integral role in wider society and the environment by maintaining a large range of ecosystem services and benefits. As populations and resource constraints increase and food production and food security become growing issues globally, there is a recognition of the importance of defining soil condition or soil health for sustaining all ecosystems, including services and benefits to humans, plants, animals, and micro-organisms. While the ecosystem services approach has helped to illuminate the varied services soils provide, an understanding of the complex human–soil relationships and values has been missing. Those seeking to understand and form concepts about soil health have concentrated on the more inherent biochemical, physical and economic (e.g., productivity) aspects of soils, but not on the human, social or cultural dimensions. It is argued in this paper that soils form an integral part of our social and cultural fabric and are fundamentally important to human and societal well-being. The way humans interact with, value and use soil is a critical part of determining the health and sustainability of soil ecosystems. We discuss how a well-being approach can improve understanding of soil health with respect to societal goals and needs. We believe this type of approach, which includes social and cultural dimensions, provides a more diverse and inclusive knowledge base and perspective to better inform the development of integrative policy. This would lead to improved management and decision-making of land resources and soils in Aotearoa New Zealand and globally.

Effects of maize pre-cultivation on soil deterioration indicated by the soil nematode community in replanted apple orchard

ABSTRACT Maize pre-cultivation was hypothesised to alleviate soil deterioration in replanted apple orchard, and this would be expected to be reflected in the nematode community in the soil. To test this hypothesis, soil parameters and nematode population composition were measured. Compared with replanted apple treatment, soil pH, soil organic matter, ammonium nitrogen and the available P and K content of the soil were enhanced after maize pre-planting cultivation. Maize pre-cultivation increased bacterivorous nematode populations and decreased herbivorous nematode populations, mainly Pratylenchus, Paratylenchus and Tylenchus spp. The Shannon-Weaver diversity index (H′) and the richness (SR) of the nematode population, the Wasilewska functional index (WI) (soil health index) and the maturity index (MI) were increased at the flowering stage after 2-year maize pre-planting treatment, and WI was increased at the maturity stage compared with replanted apple treatment. These results indicate that maize pre-cultivation can alleviate soil acidification and deterioration of the physicochemical properties of soil and improve soil health, food web stability and soil ecosystem sustainability in replanted apple orchard. These changes are accompanied by changes in the soil nematode communities.

Long-term fertilization alters soil properties and fungal community composition in fluvo-aquic soil of the North China Plain

Different fertilization regimes can substantially influence soil fungal community composition, yet fewer studies try to control for the effects of nitrogen input. Here, we investigated the impact of fertilization with equal nitrogen upon soil properties and soil fungal diversity and community composition in the North China Plain in a long-term field experiment. Long-term (32 years) fertilization regimes were applied with equal amounts of nitrogen: no chemical fertilizer or organic manure; chemical fertilization only; organic manure fertilization only, and; combination of 1/2 chemical fertilizer and 1/2 organic manure. Then we investigated the influence of these four fertilization regimes to soil properties, fungal diversity and community composition. The results showed that applying organic manure significantly influenced soil properties. Illumina MiSeq sequencing and its analysis revealed that organic manure fertilization significantly changed soil fungal alpha diversity, but chemical fertilization did not. Although soil fungal community composition did not differ significantly among all the fertilization regimes at the phylum and class levels, they did show differences in the abundance of dominant fungi. Yet at the genus level, soil fungal community composition, abundance, and beta diversity was affected by all fertilization regimes. Application of organic manure also reduced the abundance of soil-born fungal pathogens such as Fusarium. Our results suggest that long-term application of organic manure could markedly improve soil properties, altering soil fungal community composition and its diversity. Moreover, organic manure fertilization could limit soil-born fungal diseases, to further contribute to soil ecosystem sustainability.

Frequency of stover mulching but not amount regulates the decomposition pathways of soil micro-foodwebs in a no-tillage system

In soil micro-foodwebs, resource-transfer links between bacteria, fungi and microbivorous nematodes govern the transformation and cycling of soil organic carbon and for the quality, productivity and sustainability of soil ecosystems. However, changing the amount and frequency of stover mulching affects the resources available for the bacterial versus fungal decomposition pathways of soil micro-foodwebs. Therefore, we investigated the responses of the soil micro-foodweb to maize stover mulching amounts (33% and 67% of the stover remaining at harvest) and frequencies (high frequency had continuous mulching every year; low frequency had mulch applied once every three years) during a 10-year mulching experiment in a no-tillage system. Soil microorganism and nematode communities were affected significantly by the frequency, but not the amount of stover mulching. Greater abundance of bacterial PLFAs that were correlated with bacterivores occurred in the high frequency mulching treatments. In the low frequency mulching treatments, the abundance of fungal PLFAs and their correlations with fungivores were higher. Greater nematode enrichment index in the high frequency mulching indicated more carbon flow from mulch into the soil micro-foodweb, whereas low frequency mulching tended to develop a relatively stable soil micro-foodweb. We conclude that trophic interactions regulate the binary coupling between bacteria and bacteriovores with high frequency mulching and between fungi and fungivores with low frequency mulching. Consequently, the structure and activity of decomposition pathways in these soil micro-foodwebs are determined by the bottom-up effect of stover mulching.

Resilience of soil functions to transient and persistent stresses is improved more by residue incorporation than the activity of earthworms

The development of soil sustainability is linked to the improved management of soil biota, such as earthworms, and crop residues to improve soil physical structure, enhance microbial activities, and increase nutrient cycling. This study examined the impacts of maize residue (65.8C/N ratio, dry biomass 0.75 kg m−2) incorporation and earthworms (70 g Metaphire guillelmi m−2) on the resistance and resilience of soil C and N cycling to experimentally applied stresses. Field treatments were maize residue incorporation, maize residue incorporation with earthworm addition, and an unamended control. Resistance and resilience of C mineralization, ammonia oxidation, and potential denitrification were investigated over 28 days following a persistent stress of Cu (1 mg Cu soil g−1) or a transient heat stress (50 °C for 16 h). The results indicated that C mineralization was more resistant and resilient than ammonia oxidation and denitrification to either a persistent Cu or a transient heat stress. The application of maize residues significantly increased soil microbial biomass, C mineralization, ammonia oxidation and potential denitrification compared with the unamended control. Maize residues significantly improved the resistance and resilience of N processes to Cu and heat stress. The presence of earthworms significantly increased potential denitrification but had limited positive effect on functional resistance and resilience. This study suggested crop residue incorporation would strongly increase soil functional resistance and resilience to persistent and transient stresses, and thus could be a useful agricultural practice to improve soil ecosystem sustainability.

Caenorhabditis elegans as a Test Organism for Detecting Soil Toxicity in Saudi Arabia

The extensive and intensive use of many pesticides in agriculture has caused environmental pollution. Chemicals directly added to the soil, whether in greenhouses or in open fields can reach ground water, rivers and lakes by run off, where significant amounts may directly or indirectly affect human health. Therefore, interest has grown to establish appropriate, fast and inexpensive methods to assess the environmental impacts of chemicals, including pesticides, in soil. Soil organisms are important for soil fertility, and sustainability of soil ecosystems can be disrupted by soil toxicity. The main aim of this study is to establish a novel and convenient assay to investigate and quantify soil toxicity.

Soil fungal dynamics: Parameterisation and sensitivity analysis of modelled physiological processes, soil architecture and carbon distribution

The role of fungi in soil ecosystem sustainability is poorly understood, as is the extent to which it is affected by the microscale heterogeneity of soils with respect to structure, chemistry and biology. This is due to the complexity of soil ecosystems, presenting significant challenges to their study in situ. Many theoretical and simulation models have been developed to link nutrient levels to colony dynamics. Unfortunately, there is currently no model that can take both structural and nutritional microscale heterogeneity into account, and is parameterised for the soil environment. In this context, the objective of this article is to develop such a 3D spatially explicit model of fungal dynamics, and to calibrate it for a soil system using data from the literature. A sensitivity analysis is carried out to better understand the uncertainties in the input parameters and their effect on colony dynamics in terms of biomass yield and respiration rates. The results highlight simulation outcomes that are most suited to validation by experimentation. The results also indicate that predictions in biomass yield are sensitive to uncertainties in model parameters relative to the soil–fungal complex that at this point are insufficiently understood experimentally and still have to be estimated by model fitting. The latter parameters, which influence biomass yield and respiration, are associated with biomass recycling processes such as adsorption (,αni) desorption (βni, βi), insulation (ζni) and biomass yield efficiency (ɛ1), and translocation (Dv). The model now opens up great opportunities for hypothesis-driven research, combining theoretical models and novel types of experimentation, especially given the recently acquired ability to generate artificial, replicable soil-like microcosms on which to test model predictions.