Pedosphere最新文献

Soil multifunctionality represents a range of soil processes driven by the interactions between soil abiotic and biotic components. As a group of ubiquitous fungi that form mutualistic symbiotic associations with a vast array of terrestrial plants, arbuscular mycorrhizal (AM) fungi may play a critical role in maintaining soil multifunctionality, but the characteristics of their contributions remain to be unraveled. This mini review aims to disentangle the contributions of AM fungi to soil multifunctionality. We provide a framework of concepts about AM fungi making crucial contributions to maintaining multiple soil functions, including primary productivity, nutrient cycling, water regulation and purification, carbon and climate regulation, habitat for biodiversity, disease and pest control, and pollutant degradation and detoxification, via a variety of pathways, particularly contributing to soil and plant health. This review contends that AM fungi, as a keystone component of soil microbiome, can govern soil multifunctionality, ultimately promoting ecosystem services.

Plant roots and their associated mycorrhizal fungi critically mediate the decomposition of soil organic carbon (C), but the general patterns of their impacts over a broad geographical range and the primary mediating factors remain unclear. Based on a synthesis of 596 paired observations from both field and greenhouse experiments, we found that living roots and/or mycorrhizal fungi increased organic C decomposition by 30.9%, but low soil nitrogen (N) availability (i.e., high soil C:N ratio) critically mitigated this promotion effect. In addition, the positive effects of living roots and/or mycorrhizal fungi on organic C decomposition were higher under herbaceous and leguminous plants than under woody and non-leguminous plants, respectively. Surprisingly, there was no significant difference between arbuscular mycorrhizal fungi and ectomycorrhizal fungi in their effects on organic C decomposition. Furthermore, roots and/or mycorrhizal fungi significantly enhanced the decomposition of leaf litter but not root litter. These findings advance our understanding of how roots and their symbiotic fungi modulate soil C dynamics in the rhizosphere or mycorrhizosphere and may help improve predictions of soil global C balance under a changing climate.

Stoichiometry plays a crucial role in biogeochemical cycles and can modulate soil nutrient availability and functions. In agricultural ecosystems, phosphorus (P) fertilizers (organic or chemical) are often applied to achieve high crop yields. However, P is readily fixed by soil particles, leading to low P use efficiency. Therefore, understanding the role of carbon:nitrogen:P stoichiometries of soil and microorganisms in soil P transformation is of great significance for P management in agriculture. This paper provides a comprehensive review of the recent research on stoichiometry effect on soil P transformation in agricultural ecosystems. Soil microorganisms play an important role in the transformation of soil non-labile inorganic P to microbial biomass P by regulating microbial biomass stoichiometry. They also mobilize soil unavailable organic P into available P by changing ecoenzyme stoichiometry. Organic materials, such as manure and straw, play an important role in promoting the transformation of insoluble P into available P as well. Additionally, periphytic biofilms can reduce P loss from rice field ecosystems. Agricultural stoichiometries are different from those of natural ecosystems and thereby should receive more attention due to the influences of anthropogenic factors. Therefore, it is necessary to conduct further stoichiometry research on the soil biochemical mechanisms underlying P transformation in agricultural ecosystems. In conclusion, understanding stoichiometry impact on soil P transformation is crucial for P management in agricultural ecosystems.

Increasing global demand for food presents a significant challenge to maintaining soil health and sustainable production of agricultural crops. As plant root-associated microbial fitness is greatly impacted by community growth, development, and nutrient acquisition, the cultivation of functional assembly of root-associated microbes may provide solutions for achieving food security while maintaining healthy soils. Here, we propose a four-part strategy to promote soil health and agricultural productivity by partnering crops with root-associated microbes.

Methane (CH₄), a potent greenhouse gas, plays a pivotal role in the dynamics of climate change. While CH₄ emissions have been widely investigated, biological removal of CH₄ by upland soils has been less explored. Understanding the mechanisms and factors affecting CH₄ oxidation in soils is of paramount importance for devising successful mitigation strategies. This perspective paper discusses different types of aerobic methanotrophs and their activities under varying environmental conditions, highlighting the significant contribution of soil ecosystems to global CH₄ sinks. We emphasize the need for in-depth research on variables controlling CH₄ sinks on different spatiotemporal scales and the exploration of previously unidentified CH₄ sinks, such as deserts and areas of glacier retreat.

Elevated evapotranspiration due to warmer air temperature could raise salinity and nutrient levels of some inland wetlands, potentially impacting nitrogen cycling. To characterize the impact of high evapotranspiration on soil microbial nitrogen cycling in inland wetlands, we compared freshwater and brackish marsh (or non-marsh) wetlands in terms of sediment ammonia-oxidizing rate (AOR), denitrifying rate (DR), and related microbial communities in a typical inland basin, the Hulun Lake basin, in China. Results showed that marsh ecosystems (ME) exhibited 31% higher AOR and 65% higher DR than non-marsh ecosystems (NE). For NE, freshwater non-marsh wetland exhibited 12% higher AOR than brackish non-marsh wetland. This was probably due to the inhibitory effects of high NH₄⁺ and salinity levels on ammonia-oxidizing archaea in brackish non-marsh wetland. Conversely, DR in brackish non-marsh wetland was 23% higher than that in freshwater non-marsh wetland, with total organic carbon (TOC) significantly influencing this difference, suggesting that the higher DR in brackish non-marsh wetland was mainly due to its higher TOC level. For ME, due to the direct and indirect interference of salinity, brackish marsh wetland displayed 26% lower AOR and 19% lower DR than freshwater marsh wetland. Besides, brackish wetlands harbored distinct ammonia-oxidizing and denitrifying microbial communities compared to freshwater wetlands. The assembly of these communities was dominated by stochastic processes, while brackish wetlands exhibited more prominent deterministic processes than freshwater wetlands. Overall, high evapotranspiration altered activities and community characteristics of ammonia oxidizers and denitrifiers in inland brackish wetlands by enhancing salinity and nutrient levels, while emergent plants occurring in ME could mitigate the adverse effects of salt stress of inland brackish wetlands on nitrogen cycling.

The introduction of cover crops into monoculture systems to improve soil health has been widely adopted worldwide. However, little is known about the environmental risks and application prospects of different cover crops in spring maize (Zea mays L.) monocultures proposed in the North China Plain. A pot experiment was conducted to evaluate the effects of different winter cover crops on subsequent maize yield, soil fertility, and environmental risks of nitrogen (N) loss, and a questionnaire survey was conducted to examine factors influencing farmers' willingness to adopt cover crops in the North China Plain. Based on the same fertilization regime during the maize growing period, four winter cover crop treatments were set up, including bare fallow, hairy vetch (Vicia villosa Roth.), February orchid (Orychophragmus violaceus), and winter oilseed rape (Brassica campestris L.). The results indicated that winter cover crops significantly increased subsequent maize yield and soil organic carbon, total N, and microbial biomass carbon and N compared with the bare fallow treatment. The incorporation of cover crops led to a negligible increase in nitrous oxide (N₂O) emissions and had a very limited effect on ammonia (NH₃) emissions. The incorporation of February orchid and winter oilseed rape decreased nitrate leaching compared with the hairy vetch treatment in the maize growing season. The N losses via N₂O and NH₃ emissions and N leaching accounted for 71%–84% of the N surplus. However, yield increase and environmental benefits were not the main positive factors for farmers to accept cover crops. Financial incentive was rated by 83.9% of farmers as an “extremely important” factor, followed by other costs, when considering winter cover cropping. These results indicate that the environmental benefits depend on the type of cover crop. Maintaining high levels of soil fertility and maize yield, providing sufficient subsidies, and encouraging large-area cultivation of cover crops are critical measures to promote winter cover cropping in the North China Plain.

Ammonia (NH₃) volatilization from rice fields contributes to poor air quality and indicates low nitrogen use efficiency. Although organic fertilizers can meet the nitrogen requirement for rice growth, the simultaneous effects of organic fertilizers on NH₃ volatilization and rice yield in paddy fields are poorly understood and quantified. To address this gap in our knowledge, experimental field plots were established in a conventional double-cropping paddy field in the Pearl River Delta region, southern China. Five fertilizer treatments were used besides the control with no fertilizer: fresh organic fertilizer, successively composted organic fertilizer, chemically composted organic fertilizer, mixture of chemically composted organic fertilizer with inorganic fertilizer, and chemical fertilizer. Ammonia volatilization was measured using a batch-type airflow enclosure method. No significant differences in grain yield were observed among organic and chemical fertilizer treatments. However, compared with chemical fertilizer, chemically composted organic fertilizer and successively composted organic fertilizer significantly decreased total NH₃ volatilization by 70% and 68%, respectively. The ammonium-nitrogen concentration in field surface water correlated strongly (P < 0.01) and positively with NH₃ volatilization across fertilization treatments. Our findings demonstrate that chemically composted organic fertilizer can sustain rice yield while reducing NH₃ volatilization. An important future step is to promote these field measurements to similar rice cultivation areas to quantify the regional- and national-scale impact on air quality and nitrogen deposition in sensitive areas, and to design and implement better fertilizer management practices

With the increased interest of plants in space, gravity cannot be ignored when studying soil-plant-water relations. Therefore, it is important to understand the water relations of soils under zero gravity in space or under reduced gravity on the Moon or Mars. This paper outlines the problems of moving water in soils under zero gravity or microgravity, as well as growing plants in these soils. It is suggested that microgravity experiments could be done on Earth using both soils and plants. Results from such experiments could be used to grow plants when mankind establishes bases on the Moon and Mars.