Agriculture, Ecosystems & Environment最新文献

Crop rotation patterns have important effects on crop growth and disease occurrence, but there is a lack of understanding of how crop root systems and inter-root environments affect the bacterial communities involved in plant disease resistance under different crop rotation patterns. In this study, two crop rotation patterns, tobacco-rice (TR) and tobacco-maize (TM), were set up in a tobacco growing region of southern China, and the differences in soil bacterial communities and the mechanisms of their influence on the occurrence of tobacco diseases were investigated under the two rotation patterns. The results showed that the disease incidence rate of tobacco under TR crop rotation was low, only 4.92 %, while the incidence rate under TM crop rotation was as high as 34.44 %. The bacterial genera affecting the disease incidence of tobacco were identified through microbial network and correlation analysis, and a total of 12 genera were identified as significantly correlated with the disease incidence rate of tobacco in the soil layers of 0–10 cm and 10–20 cm. Of these, four genera (Acidothermus, Chujaibacter, Rhodanobacter, and Nitrospira) were significantly and negatively correlated with the incidence rate, and also more abundant in the bacterial community of TR. Soil nitrogen nutrients and pH were the main soil factors influencing the differences in bacterial communities between the two rotation patterns. Partial least squares path model (PLS-PM) analysis revealed that the key bacterial taxa directly influenced the disease incidence of tobacco in both the 0–10 cm and 10–20 cm soil layers. Interestingly, the key bacterial taxa were directly influenced by soil nutrients in the 0–10 cm soil layer and by the tobacco root system in the 10–20 cm soil layer. In summary, nitrogen-rich nutrients and well-developed plant root systems are conducive to shaping soil bacterial communities with disease-resistant properties, reducing the disease incidence of tobacco. This study also provides new research perspectives for sustainable agricultural development and crop disease control.

Aquaculture ponds are as hotspots for methane (CH₄) emissions of increased worldwide interest. However, management strategies and underlying mechanisms to mitigate CH₄ emissions from aquaculture ponds remain little explored. In this study, we constructed new rice-crab and rice-fish co-culture systems by planting rice in crab and fish ponds and conducted a 2-year field experiment to examine the effect of co-culture on CH₄ emissions and transport pathways. The results showed that compared with crab and fish monoculture, co-culturing with rice significantly reduced CH₄ emissions by 23.1 % and 23.7 % for crab and fish ponds over 2 years, respectively. Further analysis clarified that the mitigating effect of co-culturing with rice on CH₄ emissions resulted from the reduction of CH₄ ebullition from the stocking ditch, but not from the feeding platform. The effect of co-culturing with rice on CH₄ transport varied by functional areas. No significant effect of co-culture was found on diffusive CH₄ emission neither in the stocking ditch nor on the feeding platform. On the feeding platform, co-culture increased additional rice-mediated CH₄ emissions while it mitigated CH₄ ebullition under the combined effect of planting rice on CH₄ production and oxidation. In the stocking ditch, co-culture significantly reduced CH₄ ebullition by reducing sediment depth. Furthermore, co-culture obtained additional rice yields, leading to lower yield-scaled CH₄ and higher economic effects. These findings highlight that co-culturing with rice is a valuable solution for sustainable aquaculture development by reducing CH₄ emissions while increasing food production.

Intensifying agricultural landscapes by removing non-crop vegetation threatens ecosystem services like pest regulation. Non-crop areas may serve as overwintering habitat for natural enemy arthropods that disperse into and predate on insect pests in the adjacent field. However, managing this service requires greater understanding of the mechanisms driving this dispersal and the subsequent control of pests by arthropod predators. A functional trait framework, i.e., studying the traits of predators that influence their foraging behaviour and dispersal, supports generalization across cropping systems where conditions differ (e.g., which arthropod taxa are present). Predator body size, a trait known to influence both dispersal distance and prey consumption, is a plausible mechanism governing the supply and the effective delivery of pest control. We focused on ground beetles (Coleoptera: Carabidae), common insect predators found globally in agroecosystems. We measured 27,815 beetles collected in 20 crop fields from 180 sampling stations to examine how body size changes with distance from non-crop vegetation. We tested the effect of predator body size on foraging behaviour by exposing 77 Pterostichus melanarius ground beetles to different sizes of the model pest Trichoplusia ni (Lepidoptera: Noctuidae). The smallest six deciles of carabid body size increased in size with distance from non-crop vegetation, demonstrating that more smaller beetles are found closer to the field edge and that body size is a predator trait mediating the distance of dispersal. Larger P. melanarius show a trend towards predating larger prey than smaller prey, though we were unable to reject a null hypothesis of no effect (α=0.05; P=0.08). This affirms that body size is a plausible trait governing the effectiveness of pest control, and that size-based foraging behaviour requires in-field investigation. Our findings reinforce calls for more and better-protected non-crop vegetation areas in agroecosystems intended to control a diverse array of insect pests. Placing non-crop vegetation patches closer to crops (e.g., through restoration or reducing field size) is a critical lever for manipulating the body size distribution of predators in the crop, and subsequently may affect the prey that can be controlled without the use of pesticides.

Lack of floral resources is suspected to be one of the factors involved in flower-visiting insect declines. Because agricultural landscapes are often poor in flowers, it seems crucial to assess weeds as floral resources to feed flower-visiting insects and to identify the factors that drive floral productivity, defined as floral biomass produced by the weed community. We monitored floral presence, productivity and traits in 16 olive groves from September 2021 to June 2022. The objectives were to understand to which extinct abiotic factors, among agricultural practices, pedoclimate and weather, determine floral productivity and to analyse the relationships between floral traits, floral presence and productivity. We found mowing frequency (2–3 per year on average) increased mean floral area and height, advanced flowering onset, and increased floral functional diversity and flowering species richness, which in turn increased floral presence and productivity.

Existing studies have shown contradictory findings with respect to whether biosolids applications on agricultural lands lead to intensification of soil greenhouse gas (GHG) emissions. Here, we describe the results of deployment of the micrometeorological flux gradient method to quantify post-biosolid soil emissions of nitrous oxide (N₂O) and methane (CH₄) on a farm with drainage water management (DWM) on the Eastern Shore of Maryland. The fluxes following biosolid additions to cornfields in 2020 were compared with fluxes from the same farm in 2018, when no fertilizer was applied to soybeans, and in 2019, when urea ammonium nitrate (UAN) was applied to corn. Extractable soil nitrate was highest following biosolids application, contributing to the highest N₂O emissions in the growing season of 2020 compared to 2018 (no fertilizer) and 2019 (UAN). Other contributing factors include the low C:N ratio of the biosolids and the above average precipitation in 2020. In contrast, different fertilization regimes did not generate distinct differences for CH₄ fluxes, which were very low in all three years. No statistically significant treatment effect of DWM was found for either N₂O or CH₄ during the peak emission period after biosolids application, which aligns with the result of our earlier research. Annualized estimated N₂O emission factors (EFs) for biosolids addition were 5–6 % in the DWM and 3–4 % in the non-DWM fields, although this includes uncertainties associated with gap filling. These biosolids EFs are 2–3 times the N₂O EF for synthetic fertilizer application at this same farm in 2019 (1–2.5 %) and 2–4 times the IPCC Tier 1 EF (1.6 %) for synthetic fertilizer, demonstrating the intensification effect of biosolids addition on soil N₂O emissions for the cropland studied here.

Autotrophic (AN) and heterotrophic (HN) nitrification pathways regulate soil nitrogen availability and are responsible for nitrate losses to the environment. It is often assumed that HN plays a more important role than AN in acidic soils. However, so far, no detailed study has attempted to identify how pH affects the relative importance of gross rates of AN (GAN) and HN (GHN) in acidic soils. Combining ¹⁵N dilution technique with acetylene inhibition along a natural soil pH gradient of 3.7–6.9, we revealed a negative exponential relationship between GHN/GAN ratio and soil pH, with a threshold of pH=4.5 and 4.7 with and without the addition of ammonium, respectively. Variations of fungal and ammonia-oxidizing archaea (AOA) abundances along the pH gradient further confirmed the existence of this threshold. Soil nitrification was predominantly fungi-driven HN below the threshold and AOA-driven AN above the threshold. Overall, we provide evidence that a pH threshold controls the dominant nitrification pathway in acidic soils by affecting specific microbes, which could be important for predicting soil nitrification patterns and developing effective mitigation techniques to promote nitrogen availability and decrease nitrogen loss risk.

Despite previous reports that autotrophic microorganisms have capable of absorbing atmospheric CO₂ and increasing soil organic carbon content, their specific pathways involved in carbon fixation have remained elusive. This study aimed to evaluate the differences of eight known carbon fixation pathways involving soil autotrophic microorganisms in vineyard soils with different planting years, and reveal the effects of soil physicochemical properties on the composition of carbon fixation microorganisms. Thus, we performed metagenomic sequencing on one uncultivated soil and four vineyard soils of different planting years. The results showed that autotrophic microorganisms harboring genes of eight konwn pathways related to carbon fixation were identified at each sampling site. The predominant phyla of autotrophic microorganisms were Actinomycetota, Pseudomonadota, and Acidobacteriota, respectively. The rTCA cycle was the most prominent carbon fixation pathway in this study. The relative abundance of genes related to rTCA cycle were increased by 11 %, 7 %, 4 %, and 8 % in the 5-year-old (C5), the 10-year-old (C10), the 15-year-old (C15), and the 20-year-old (C20) vineyard soils, respectively, compared to that in soil of uncultivated land (UL). The abundance of enzyme encoding genes involved in carbon fixation pathways varied significantly among soil samples, and the variation trend was consistent with the abundances of genes related to carbon fixation pathway, indicating their significant involvement in regulating carbon fixation. Moreover, environmental factors significantly impacted to the composition of autotrophic microbial, in particular, pH was primarily factor impacted on the composition of autotrophic microbial involved in carbon fixation. This study clarified the effects of vineyard planting years on the composition of soil autotrophic microbial and their carbon fixation pathway, which provides basic data for understanding the function of soil autotrophic microbial in orchards.

Good management practices (GMPs) on dairy farms have been shown to reduce contaminant losses and improve water quality. Few national long-term datasets exist globally on management practices on dairy farms over time and their effect on nutrient losses. Here, we examine 50 parameters across a 10-year period (from 2013 to 2022) thought to influence estimates of nitrogen (N) and phosphorus (P) losses (kg ha⁻¹ yr⁻¹) to water from dairy-farmed land in New Zealand. The number of farms in our database increased from 137 in 2013 to a total of 378 in 2022. The years from 2013 to 2017 were classed as ‘period 1’ and from 2018 to 2022 as ‘period 2’, which aligned with more intensive extension of GMPs. Nationally, there was a small increase in median N and P loss rates (38 – 40 kg N ha⁻¹ yr⁻¹ and 1.1 – 1.2 P kg ha⁻¹ yr⁻¹), fertiliser applied 140 – 141 kg N ha⁻¹ yr⁻¹ and total milk solids produced by 11 % between periods. However, between 1 – 42 % of farms exhibited decreasing N loss trends regionally, which were related to (in order of decreasing importance): N fertiliser applied, irrigation type, and forage establishment (cultivation) practice. Similarly, 1 – 25 % of farms with decreasing P trends regionally, trends were related to soil order, P fertiliser applied, and effluent storage method. We also found that these farms showed increased adoption of effluent and forage establishment method GMPs between periods, for example, the use of low-rate effluent application, direct drill, and minimum tillage, and increased effluent storage practice. These data suggest good management practices shown to decrease N and P losses from dairy-farmed land to water in New Zealand are being adopted; however, continued uptake on all farms will be required to achieve further improvement.

Hoverflies (Diptera: Syrphidae) provide dual ecosystem services, as the adults act as pollinators and the larvae can be predators of crop pests. Because bloom time is limited in mass-flowering crops, resources within crops for hoverfly adults can also be limited and change temporally. Therefore, hoverflies need to move between crops and their borders. It may be that some field border vegetation types support the provision of hoverflies to crops better than other vegetation types. We sought to determine how field border type (herbaceous vs. treed), canola bloom, and border vegetation structure and composition (border width, canopy cover, grass height, grass cover, plant cover, flower availability, and density of trees, shrubs, snags, stumps, and downed woody debris) affect hoverfly movement into and out of crop fields from field borders. We placed bi-directional Malaise traps in herbaceous and treed field borders at 10 fields seeded with canola, and sampled continuously from May 17 to August 20, 2021 in central Alberta, Canada. We found that field border type affected hoverfly movement such that, across the whole summer, net-export of hoverflies into crops was over 33-times higher from treed field borders (an estimated 84,699 hoverflies per km per week) than from herbaceous field borders (an estimated 2515 hoverflies per km per week). We did not find any single component of the vegetation within treed field borders that explained the difference in movement. We found more hoverfly activity in herbaceous field borders than in treed field borders during and after canola bloom, but that overall activity was equal between field border types prior to canola bloom. Treed borders had greater Hill-Shannon and Hill-Simpson diversity and evenness than herbaceous borders. Throughout the growing season, the community became dominated by Toxomerus marginatus, which drove all temporal trends. We conclude that treed field borders act as net exporters of hoverflies to canola fields and are therefore important features for optimizing the magnitude of the ecosystem services provided by hoverflies in agricultural systems.

Transforming arid and semi-arid deserts into farmlands significantly alters soil moisture and fertility, affecting the trophic structure and functionality of soil fauna. Diversity and function of soil macrofaunal community can accurately reflect changes in soil quality and health during the succession of oasis farmlands. In this study, the assemblage of soil macrofauna and soil environmental factors in cultivated and abandoned croplands in the Zhangye Oasis of Gansu Province, were investigated using a hand-sorting method, and we analyzed the relationship between the trophic structure of soil macrofauna and the soil environment. Our results showed that: 1) Farmland cultivation increased the soil water content, soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP), while reducing pH. 2) The density, taxon richness, and Shannon-Wiener index of soil macrofauna in cultivated croplands were higher than in abandoned croplands, increasing with cultivation duration. The density of soil macrofauna in 100-year-old farmlands was 2.5, 1.5 and 1.4 times of that in 10-year-old, 30-year-old and 50-year-old farmlands; 3) the density and taxon richness of predatory, phytophagous, and other feeding types of soil macrofauna in cultivated croplands were higher than those of abandoned croplands. The observed increases in density and taxon richness are likely due to the improved soil conditions resulting from cultivation practices. The density-based ratio of predatory to phytophagous and other feeding types of soil macrofauna initially increases then decreases, inversely related to cultivation age. 4) changes in soil environment had little effect on the predatory soil macrofaunal community, and the explained variance by SOC, TP, and pH indicates the significant influence of these soil properties on the composition of the phytophagous soil macrofaunal community. SOC, TP, and pH explained 7.3 % of the variation in phytophagous soil macrofaunal community, while TN, TP, and pH explained 15.4 % of the variation in other feeding types of soil macrofauna. In conclusion, our findings highlight the positive impact of oasis farmland cultivation on soil quality and the enhancement of soil macrofauna diversity, which in turn could contribute to the resilience and productivity of these agricultural ecosystems.