Agriculture, Ecosystems & Environment最新文献

Photosynthesized carbon assimilation and allocation are crucial for plant responses to environmental changes, such as light. Intercropping typically enhances light interception. However, the effects on photosynthesized carbon allocation and microbial immobilization in intercropping systems remain unclear. We investigated light interception, photosynthetic rate, biomass, grain yield, soil organic carbon (SOC), and performed ¹³CO₂ pulse labeling to trace carbon footprints in the plant-soil system under long-term maize-soybean relay strip intercropping and maize monocropping systems. Results showed that, compared to monocropped maize, intercropped maize exhibited a 15.4 % increase in plant ¹³C fixation and significantly greater belowground carbon allocation, with increases of 52.7 % in roots, 64.1 % in rhizosphere soil, and 81.9 % in bulk soil. These outcomes were attributed to enhancements of 30.2 % in light interception and 16.5 % in photosynthetic rate during the post-silking period. At silking, increased light interception in intercropped maize directly contributed to belowground carbon allocation. During the filling period, the source-sink relationship between limited kernel sink capacity and sufficient source strength regulated belowground carbon allocation, resulting in no significant difference in grain yield between intercropping and monocropping. Additionally, the higher ¹³C content in microbial biomass (by 99.8 %) suggested increased microbial utilization of new carbon, potentially enhancing microbial carbon immobilization under intercropping. After 10 years of cultivation, intercropping resulted in a 13.9 % increase in SOC compared to monocropping. Overall, intercropped maize benefited from enhanced light interception, which facilitated plant carbon fixation and increased photosynthesized carbon sequestration in the soil through improved photosynthesized carbon allocation to the soil and microbial carbon immobilization. These findings demonstrate that strip intercropping cultivation can promote photosynthesized carbon sequestration in soil, thereby enhancing the carbon sink capacity of agroecosystems.

Agricultural intensification is debated as one of the major drivers for the decline of insect biodiversity. Agri-environmental schemes (AES) are a common measure to promote biodiversity in agriculture by granting compensational payments to farmers for environmentally friendly practices. In this study we examined the effect of buffer strips of at least 5 m width, adjacent to small watercourses and drainage ditches, on insect biomass and insect species richness in agricultural landscapes. We selected ten arable fields in each of four regions in lower and upper Bavaria, Southern Germany. 25 out of 40 sites had a buffer strip between arable crops and watercourse. Insects were sampled at three time periods (May/June, June/July and August/September) for two weeks each. In each period two samples were collected (one per week). On each site Malaise traps were set up in 5 and 80 m distance to the embankment of the watercourse. Half of the samples was then subjected to metabarcoding and the other half was classified into different insect groups by morphological identification and the number of the individuals for each group was counted. For hoverflies (Syrphidae), individuals were identified at species-level. Data on vegetation structure (cover of grasses and herbs) in the studied riparian buffer strips was collected and correlated with number of species, abundances and biomass of flying insects. The five taxonomic orders with the highest species richness and individual numbers were: Diptera, Hymenoptera, Coleoptera, Lepidoptera and Hemiptera. Diptera dominated hereby with 34% of all species and 81% of all individuals. On average, mixed models indicated 31% higher insect biomass, 15% higher species richness and 29% higher individual numbers of flying insects in buffer strips at 5 m distance to the watercourse compared to sites with no buffer strip. The effect was even stronger for butterflies (32% higher species species richness, 70% more individuals) and hoverflies (24% higher species richness, 51% more individuals). In the presence of a buffer strip significantly higher numbers were found for total individuals, Diptera, Hymenoptera and Coleoptera. In 80 m distance to the watercourse, the samples of flying insects were not significantly influenced by a riparian buffer strip. This study highlights the importance of buffer strips in agricultural regions and their multifunctional potential in fostering biodiversity additionally to their acknowledged use for water protection. Ideally, buffer strips are rich in herbs and inflorescences and are therefore beneficial for the insect fauna by serving as valuable habitat with high potential connectivity at landscape level.

The intensification of agriculture has been identified as one of the main causes of arthropod declines. To halt the decline of arthropods, changes in farming practices and management of surrounding habitats may therefore be needed. A key challenge is to identify which changes in management approaches are most effective in restoring biodiversity. Therefore, this study examines arthropod abundance and diversity in different agricultural and semi-natural habitats, and among different management types. Arthropods were sampled three times in spring and summer of 2022 and 2023 with emergence traps in 128 unique sites in an intensively farmed area in Western Netherlands. These sites included a variety of crops as well as semi-natural habitats. Our study showed that on average the abundance and diversity of arthropods of several taxa was lower in crop habitats compared to semi-natural habitats. However, these effects strongly varied among crop species. For instance, alfalfa, spelt, spring and winter wheat fields (that often had a high plant cover) supported similar arthropod diversity and abundance levels as semi-natural habitats. Interestingly, in crop fields most variables related to field management, such as herbicide applications or amount of nitrogen fertilizers, did not show any significant relationship with arthropod abundances or diversity. The number of days after cultivation was an exception, and was positively related to total arthropod abundance, Hymenoptera and Collembola abundances, and Coleoptera family diversity. Within semi-natural habitats, number of days after mowing was positively related to total arthropod abundance, Diptera, Hemiptera and Hymenoptera abundances, and Hemiptera family diversity. Additionally, plant cover was positively related to total arthropod abundance. Overall, our findings suggest that crop species and management practices that increase plant cover in spring and early summer are increasing arthropod abundance and, to a lesser extent, higher-taxa diversity in intensively farmed agricultural landscapes.

Intensive, industrialized agriculture is considered a major driver of pollinator decline and viticulture may play a relevant role in this context. A global priority is to find ways to decrease the agricultural impact on biodiversity and to undertake an ecological intensification of farms, especially for maintaining pollinator biodiversity. To recommend practical ways to support pollinators, we explored if they react to the intensive vineyard production in a valley in Northern Italy: we tested if environmental, weather and management parameters could be responsible for shaping pollinator abundance, diversity and functional trait distribution across different wine farms, sampled with observation plots and transect walks. Results demonstrated both some effects shared across pollinator groups and some idiosyncratic responses. Generally, management factors including the herbaceous vegetation cover, weed height and its flower diversity showed strong and positive linear relationships with the abundance (+13 % by unit) and diversity of pollinators (+15 % by unit), while organic farming was associated with a slight decline in the abundance of the overall pollinators (-10 % by unit) and of hoverflies and butterflies. Regarding the temporal and weather factors, pollinators decreased with wind intensity and seasonal progression, while a positive effect was found for intermediate values of air temperature and sampling hour, thus affecting insect activity. The community composition analysis showed that environmental and management factors translated in specific distributions of bee and hoverfly functional traits across sites. Farming practices allowing herbaceous cover, weed height and flower diversity are overwhelmingly important for pollinators to assure shelter and nutritional resources and should be systematically incorporated to mitigate vineyard impact. Furthermore, measures that support pollinators should also consider pollinator phenological dynamics associated with temporal and environmental parameters to accordingly modulate the time of agricultural treatment application. Overall, our study provides a knowledge basis for the development of pollinator-friendly vineyard practices to foster the ecological value of farms.

Intensive agriculture in the Upper Mississippi River Basin contributes nitrogen and phosphorus loads to the Gulf of Mexico. Increases in nitrogen and phosphorus loads from basin states such as Illinois despite an increasing implementation of best management practices suggest overlooked sources of nutrient losses. Nitrogen co-applied with phosphorus fertilizer as monoammonium and diammonium phosphates is one such overlooked loss source. We conducted field experiments on Mollisols and Alfisols, two dominant soil types in Illinois and the greater Upper Mississippi River Basin, to quantify hypothesized losses of nitrogen from ammonium phosphate fertilizers. The inorganic nitrogen and phosphate leaching loss potential of mono- and diammonium phosphates compared to nitrogen-free triple superphosphate were evaluated under representative soybean production systems at two application rates and three timing-placement combinations, for two years at two sites. Though high non-fertilizer nitrate leaching loads generally outstripped the effect of nitrogen co-applied with monoammonium and diammonium phosphates, off-season nitrate leaching loads relative to triple superphosphate were greater for monoammonium phosphate by +30.0 kg NO₃-N ha^-1 and for diammonium phosphate by +49.9 kg NO₃-N ha^-1 in the first year under fall application on Mollisols, supporting the hypothesized water quality co-benefit of using triple superphosphate instead of ammonium phosphates as a phosphorus source. Additionally, relatively high non-fertilizer nitrate leaching loads regardless of fertilization point to the high nitrogen loss potential of soybean production, likely driven by mineralization of nitrogen-rich soybean residues following harvest. Our results suggest that targeting non-fertilizer nitrate leaching by cover cropping, and secondarily eliminating nitrogen co-applied with monoammonium and diammonium phosphate fertilizers by switching to triple superphosphate, could substantially mitigate nitrogen loading to surface waters in this region.

Grasslands support multiple ecosystem functions and services, and diverse biota, and are critical for human well-being. Grazing is the most pervasive land use in grasslands, but can have damaging effects when poorly managed. How grazing management and the environment interact to affect ecosystem functions globally is less well understood. Addressing this knowledge gap is important if we are to evaluate where (climate region, soil texture, and grassland type), what (livestock type), and how (grazing intensity, grazing regime, and duration) grazing might minimize grassland degradation and sustain healthy grassland functions. We used a systematic meta-analysis to explore the effects of grazing on ecosystem functions (primary production, carbon sequestration, water conservation, nutrient cycle, and decomposition) based on 3917 paired data from 148 studies across the globe. We found that grazing substantially reduced plant productivity (-26 %), followed by water conservation (-18 %) and carbon sequestration (-19 %). The value of most ecosystem functions declined with increasing grazing intensity, and more pronounced negative effects of grazing with mixed-herbivore than single species grazing. Grazing impacts also varied with environmental conditions, with light grazing increasing carbon sequestration in arid regions, but reducing it in semi-arid regions. Further, increasing aridity indirectly weakened the positive impacts of light grazing on ecosystem functions by suppressing grazing effects. Our study suggests that the interactions between grazing management and environmental conditions are critical when assessing the effects of grazing on grassland functions, and this will likely be more important as climates become hotter and drier.

The anaerobic digestion industry, which is still developing, generates biogas from organic waste products. A co-product of this process, digestate, is increasingly produced and can be recycled on agricultural land as an alternative to mineral fertilizers. Biogas digestate is a recent product whose chemical composition differs from that of its source material, and additional data still need to be acquired on its effects on dissolved carbon fluxes. The objectives of this study were to assess (i) the effects of applying biogas digestate on dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) fluxes with different winter crops, (ii) the dynamics of DOC and DIC concentrations during the drainage season, and (iii) the annual dynamics of DOC and DIC fluxes along the soil profile. The study examined effects of applying biogas digestate, pig slurry, or a mineral fertilizer to winter wheat and two catch crops (mustard and a multispecies crop) on DOC and DIC fluxes in the soil. Lysimeters at 40 cm (topsoil) and 90 cm (subsoil) depths were monitored from 2014 to 2023, from November to March (i.e., 9 winter drainage seasons). During the drainage season, the DOC concentration was highest with digestate, and its timing depended on development of the cover crop: from the beginning of the drainage season for mustard and the multispecies crop and around February for wheat. Applying digestate increased the topsoil DOC fluxes (mean of 35.7 ± 13.7 kg.ha⁻¹ with digestate vs. 21.0 ± 6.7 kg.ha⁻¹ with the other treatments), particularly under mustard. Topsoil DIC fluxes were highest with pig slurry due to higher mineralization than that with digestate (mean of 59.1 ± 22.8 kg.ha⁻¹ with pig slurry vs. 46.2 ± 16.3 kg.ha⁻¹ with the other treatments). In the subsoil, DOC fluxes were low (6.2 ± 4.1 kg.ha⁻¹) and DIC fluxes were high (80.0 ± 45.7 kg.ha⁻¹), with no difference among treatments.