Applied Soil Ecology最新文献

Soil legacy phosphorus (P) activation is critical for enhancing P use efficiency, while how reduced P fertilization on legacy P recovery under intercropping soil remains elusive. This study investigated the impact of fertilizer P reduction on the fertilizer P use efficiency (PUE), crop biomass, legacy P recovery, transformation and the underlying biogeochemical driving mechanisms under the maize-soybean intercropping system using a combination of sequential fractionation (SF), solution ³¹P nuclear magnetic resonance (P-NMR) spectroscopy and Illumina MiSeq sequencing. Four P fertilizer application rates, including conventional fertilization rate (CF), P fertilization reduction by 15 % (P15), 25 % (P25) and 50 % (P50), were conducted in the pot experiment using an Ultisol with maize-soybean intercropping. The result showed that the P15 treatment significantly increased P uptake, biomass and PUE of the maize relative to the CF treatment, but insignificantly for the soybean. The SF and P-NMR analysis revealed the depletion of total organic P (P_o), while enrichment of liable P_o, i.e. orthophosphate diesters in the maize rhizosphere, which probably resulted from the rhizospheric enhancement of acid phosphomonoesterase and microbial activities, and enrichment of specific bacterial communities (Candidatus_Koribacter, Ramlibacter and Noviherbaspirillum). This study provides a theoretical basis for the P fertilization reduction to enhance PUE and legacy P recovery, thus facilitate pursuing soil health and green crop production under maize-soybean intercropping system.

Nitrogen (N) application provides an effective way to enhance the efficiency of phosphorus (P) -phytoextraction. However, it remains unknown how N application facilitates P accumulation of P-accumulating plant by regulating rhizosphere P fractions. We investigated the P accumulation, rhizosphere P fractions and phosphatase activities of Polygonum hydropiper (P. hydropiper), a P-accumulating herb, across four growth periods in high-P soil (800 mg P kg⁻¹) with different N applications (0 and 100 mg N kg⁻¹). N application increased shoot P accumulation of P. hydropiper compared with the control, with the greatest shoot P accumulation in mining ecotype (ME) of P. hydropiper at 12 weeks. Compared with bulk soil, the concentration of H₂O-Pi (Pi, inorganic P) and NaHCO₃-P increased but the concentration of H₂O-Po (Po, organic P) and NaOH-Po decreased in the rhizosphere after N application. Compared with the control, the stronger positive effects of NaHCO₃-Po and HCl-Po on H₂O-Pi and NaOH-Pi were observed after N application. The high activities of acid phosphomonoesterase (ACP) and alkaline phosphomonoesterase (ALP) in the rhizosphere of two ecotypes led to mineralization of Po. Overall, these results suggested that N application can enhance P-phytoextraction capability of P. hydropiper from high-P soil by increasing phosphatase activities and transforming P fractions. Our results also provided a practical optimization to extract excess P from high-P soil by P-accumulating plant.

Fusarium species are globally recognized as highly detrimental soil-borne plant pathogen, posing a significant threat to various crops. This study investigates the potential of biosynthesized selenium (Se) and TiO₂ nanoparticles (NPs), in conjunction with plant growth-promoting bacteria (Pseudomonas sp. and Enterobacter cloacae), to suppress the activity of F. culmorum and assess their impact on wheat growth and yield. Furthermore, the study evaluates the impact of these nanoparticles on selected soil chemical and biological properties. The experiment was conducted in a greenhouse using a completely randomized design. The application of nanoparticles and bacteria reduced the disease severity index and even yielded improvements in all measured properties, compared to uninfected plants. Notably, the combination of TiO₂NPs and a mixture of bacteria led to a substantial 33.13 % increase in the 1000-grain weight, while TiO₂NPs+ Pseudomonas and SeNPs+ Pseudomonas treatments enhanced the concentration of phosphorus in grains. The highest selenium content in grains was observed in the SeNPs+mixture of bacteria treatment. In addition, the application of TiO₂NPs + mixture of bacteria and SeNPs+mixture of bacteria treatments led to an increase in microbial biomass carbon and soil respiration compared to the control group. The utilization of a synergistic approach involving plant growth promoting bacteria and nanoparticles holds great promise for enhancing wheat growth and bolstering its resilience against biotic stress, with the added benefit of Se biofortification in grains. This research underscores the potential of such innovative strategies for sustainable agriculture in the face of plant pathogenic threats.

Soil acidification due to climate and anthropogenic changes persistently threatens biodiversity and biomass, the essential drivers of ecosystem multifunctionality. However, the influence of a sustained reduction in soil pH on the regulatory role of microbial communities in ecosystem multifunctionality has not yet been assessed. Here, we investigated the critical pH thresholds at which microbial biomass becomes a key determinant of soil multifunctionality (SMF) based on a large-scale paddy field study (n = 429) and a global dataset (n = 35,641). We found that when the soil pH was <5, microbial biomass (i.e., bacterial or fungal) was significantly positively correlated with the soil SMF, representing a critical threshold for microbial biomass regulation of ecosystem multifunctionality. We further predicted the global pattern of the microbial drivers of SMF under soil acidification scenarios over the next 50 years. Our results indicate that as soil acidification continues, the global area of biomass-mediated SMF will increase by approximately 14 % by 2070. Our results highlight that due to ongoing acidification, biomass reduction will cause accelerated losses in global SMF.

Coastal wetlands are vital carbon repositories with a substantial soil carbon storage potential; as such, they play a crucial role in global carbon sequestration and climate regulation. The most invasive species in the global coastal zone, Spartina alterniflora, has significantly affected the ecosystem functions and nutrient cycling of coastal wetlands. However, it is uncertain how S. alterniflora invasion affects the driving mechanism of greenhouse gas (GHG) emissions by causing changes in the soil labile organic carbon (LOC) pool. Therefore, we investigated the mediating role of soil LOC in influencing the impact of Spartina alterniflora invasion on soil GHG emissions. Our study was conducted in the coastal wetlands of the Dongtai Tiaozini Wetland Reserve in Yancheng, China. The relationship between variations in soil LOC components and GHG emissions in coastal wetlands was analyzed by measuring these variables across areas with high, moderate, and no invasion of S. alterniflora. The results showed that as the degree of invasion intensified, emissions of carbon dioxide (CO₂), nitrous oxide (N₂O), and the global warming potential (GWP) showed significant increasing trends, while methane (CH₄) emissions tended to increase first and then decrease. Compared with CO₂ emissions in the non-invasive plots of S. alterniflora, CO₂ emissions in moderately and highly invasive plots increased by 166.68 % and 403.35 %, respectively (P < 0.05). Similarly, N₂O emissions increased by 34.67 % and 303.03 %, respectively (P < 0.01), and the GWP increased by 683.87 % and 947.32 %, respectively (P < 0.01). For CH₄ emissions, moderate invasion represented a carbon source, and high invasion represented a carbon sink. The findings indicated that S. alterniflora invasion alters GHG emissions by modifying the soil LOC components and the ratio of LOC to soil organic carbon. These results provide a robust data foundation for understanding changes in carbon cycling and predicting feedback mechanisms on climate change in the context of S. alterniflora invasions in coastal wetlands.

Straw returning is one of the commonly used comprehensive utilization methods of straw, but the slow decomposition of straw could affect crop growth. Artificial humic acid (A-HA) can improve the physical and chemical properties of soil and facilitate the growth of soil microorganisms. In a 180-day incubation experiment, A-HA was used as a propulsive activator to study its effects on decomposition, soil carbon fixation and emission reduction of returning straw. The results showed that the decomposition rate of straw increased by 31 % in the presence of artificial humic acid after 180 days. Moreover, A-HA increases the diversity and abundance of soil microorganisms, especially those associated with carbon sequestration, thereby reducing the rate of CO₂ emissions. This study improves insights on the application of artificial humic acid in promoting straw decomposition, soil carbon sequestration and emission reduction.

With their various feeding types, soil nematodes play a crucial role in the soil food web. Here, we investigated if and how soil nematodes responded to a long-term irrigation in a drought-prone Scots pine (Pinus sylvestris) forest in southern Switzerland, applied to study whether greater soil water availability would improve tree health and reduce tree mortality. After 14 years of irrigation, tree vitality and soil development had improved significantly. However, morphological observations of the soil nematodes revealed a decrease in their total number in the irrigated plots. Overall, the irrigated plots had a lower nematode richness compared with the dry control plots, but the Shannon index did not differ between the two treatments. In addition, the nematode community shifted significantly as a result of the irrigation. Soil physical parameters, such as sand and silt contents and bulk density, were significantly positively correlated with the nematode community in the irrigation treatment. According to a DNA marker sequence analysis, a total of 43 genera of nematodes were assigned. Predatory nematodes were significantly less abundant in the irrigated plots than in the dry control plots, as the average number decreased to 74 in the irrigated plots compared to 3579 in the dry control plots, while non-predators were not significantly affected. A differential abundance analysis revealed that the genera Tripyla and Anatonchus were the predators that declined the most. Overall, marker sequence analysis of forest soil nematodes appears to be a suitable tool for assessing changes in nematode communities and taxa. The disappearance of predatory nematodes under irrigation, however, can perhaps only be explained if other predatory animal groups, such as predatory mites or millipedes, are also analyzed at the same time.

Peanuts are typically grown in continuous monoculture in China, leading to continuous cropping obstacles and reduced yields. Cover cropping is emerging as a pivotal strategy for enhancing soil quality and promoting sustainable agriculture. However, the effects of cover crops on the rhizosphere environment, and how they benefit subsequent crops, are not well understood. We hypothesize that planting cover crop ryegrass during the winter fallow period could alter peanut rhizosphere sediments, recruit plant growth-promoting microorganisms, and ultimately enhance peanut production. This study aims to fill this gap by investigating the impact of ryegrass cover cropping on rhizosphere sediments and peanut yield. Rhizosphere soil organic carbon, total nitrogen, pH, and soil enzymes, including sucrase, urease, N-acetyl-β-D-glucosaminidase, and β-glucosidase, were analyzed, along with metabolomics, 16S rRNA, and fungal ITS sequence analyses, under traditional planting management (TP) and long-term cover crop (CC) treatments. The results showed that CC treatment significantly increased rhizosphere pH, enhanced soil organic carbon and total nitrogen levels, and elevated soil enzyme activities compared to TP treatment. Metabolomic analysis revealed that CC treatment upregulated compounds such as D-pinitol, palmitoleic acid, fructose, sorbitol, and sucrose, while downregulated compounds including benzoic acid, dodecanoic acid, and carbamic acid. This alteration in metabolite composition influenced the recruitment and function of the microbial community. Specifically, CC treatment markedly enhanced the abundance of growth-promoting microbes such as Bacillus, Paenibacillus, Pseudomonas, Lysobacter, Bradyrhizobium, and Mortierell etc., which are involved in important functions such as chemoheterotrophy, nitrate reduction, and plant saprotroph. Simultaneously, there was a decrease in pathogenic microorganisms, such as Aspergillus flavus and Fusarium oxysporum. Moreover, CC treatment positively influenced peanut root growth, resulting in longer roots and ultimately increase pod yield by 21.15 % compared to traditional winter fallow practices. These findings underscore the potential of cover cropping with ryegrass to improve rhizosphere microecosystem components, and ultimately enhance peanut productivity, providing valuable insights for sustainable agricultural practices.

Intercropping with legumes can enhance crop productivity by increasing soil nutrient utilization efficiency and soil fertility. However, the influence of interspecific interactions on soil microbial community diversity and co-occurrence networks in different intercropping systems remain unclear. Here, an experiment was conducted on maize intercropping with soybean or peanut in a chernozem soil in northeast China to assess soil chemical properties, enzyme activities and the microbial community in both intercropping systems. Intercropping increased soil N_min contents over monoculture in the soybean/maize system with N fertilization but not in the peanut/maize system. Moreover, intercropping decreased the C-acquiring and N-acquiring enzyme activities by 55.1 % and 41.0 %, respectively, compared to monoculture maize in the peanut/maize system but not in the soybean/maize system. Nitrogen application and crop species affected the soil bacterial more than the fungal community β-diversity. Furthermore, intercropping had no effect on microbial community α-diversity but changed the bacterial community β-diversity in maize strips in the soybean/maize system and peanut strips in the peanut/maize system with N fertilization. Intercropping increased the complexity and stability of bacterial networks in both soybean/maize and peanut/maize systems with N application. However, the responses of bacterial networks to soybean and peanut intercropping with maize differed without N application. The complexity of microbial networks was driven largely by soil pH and enzyme activities, but the factors driving fungal taxa were more complex than those driving bacterial taxa. The effects of intercropping on soil biological properties (e.g. enzyme activities and microbial community β-diversity) were therefore greater than on chemical properties, and the responses of soil chemical properties, enzyme activities and microbial β-diversity and co-occurrence networks to intercropping systems were dependent on the neighboring crop species. The results have implications for the mechanisms of belowground interactions in legume-based intercropping systems.

Urea, one of the most widely used nitrogen fertilizers and known for its high nitrogen content, also contains 20 % carbon, which is often overlooked. The fate of urea-derived nitrogen (urea-N) in agricultural ecosystems is well-documented. However, little is known about the fate of the urea-derived carbon (urea-C) in the soil ecosystem, especially its utilization by soil microorganisms. To address these knowledge gaps, an experiment was conducted using ¹³C-labeled urea combined with ¹³C-PLFA-SIP to investigate which microorganisms benefit most from urea-C and how its utilization is affected by irrigation regimes (water-saving and flooded irrigation) and organic amendments (straw and biochar). Our results showed that both soil microbial biomass and community structure were strongly influenced by irrigation regimes and organic amendments, with microbial biomass significantly increased by straw application and/or water-saving irrigation. In water-saving irrigated soils, microbial biomass was higher, but the incorporation of urea-¹³C into PLFA was much lower compared to flooded conditions, indicating a higher potential for the assimilation of urea-C by microbes in flooded paddy fields. Some patterns in the partitioning of urea-C by microbial groups were similar across treatments: General and G- bacteria were the dominant groups assimilating urea-C, followed by fungi, G+ bacteria, and actinomycetes. Notably, the shifts in the pattern of ¹³C incorporation into PLFA induced by straw amendment were more pronounced in water-saving irrigation than in flooded irrigation, while shifts induced by biochar amendment were more pronounced in flooded irrigation than in water-saving irrigation. Similar patterns were also observed in their effects on soil microbial community structure, indicating that the effects of straw or biochar amendments on soil microbial community structure and their urea-C utilization patterns differed between irrigation regimes. These results provide valuable insights into the roles of different microbial functional groups in the competition for and processing of urea-derived C, enhancing our understanding of soil microbial communities and microbial-mediated carbon cycling under varying irrigation and soil amendment conditions.