查看更多>>摘要：? 2022 Elsevier B.V.Replacing summer-fallow by growing cover crops (CC) in semi-arid regions might provide several soil health benefits. This study examined the effects of long-term CC management in place of fallow on soil properties in a no-till (NT) winter wheat (Triticum aestivum L.)-grain sorghum (Sorghum bicolor Moench)-fallow (WSF) cropping system. Fallow replacement treatments were spring-planted and included peas (Pisum sativum L.) for grain as well as one-, three-, and six-species CC mixtures compared with summer-fallow. Half of each CC treatment was harvested for forage and the other half remained standing after termination. Soil organic carbon (SOC) stocks within the 0- to 15-cm soil depth increased by 0.14 Mg ha-1 yr-1 for each Mg ha-1 CC residue added from 2008 to 2012 and were unaffected by CC diversity. However, SOC stocks were not different than fallow in 2018 likely because CC residue inputs declined due to a succession of drought years. Residue contribution from grain sorghum in the WSF rotation best predicted SOC in 2018 compared to 2012. Soil aggregation was greater with CCs compared to peas or fallow and was unaffected by CC diversity. Mean weight diameter (MWD) of water stable aggregates in 2018 was greater with standing CCs (1.11 mm) compared to peas (0.77 mm) but was similar to fallow (0.84 mm). The MWD of dry aggregates with standing (3.55 mm) and hayed (3.62 mm) CCs were greater compared to fallow (2.75 mm). Our findings suggest simple CC mixtures and CCs managed for hay provide similar soil benefits as diverse CC mixtures or CCs left standing in this semi-arid environment.
查看更多>>摘要：? 2022 Elsevier B.V.The fruit has become the third-largest agricultural planting industry after cereals and vegetables in China. Fertilization regimes (e.g., application rate and method) in fruit orchards typically differ from cereal croplands, which would incur a pronounced difference in fertilizer-induced nitrous oxide (N2O) emissions between them. However, fertilizer-induced direct N2O emissions from orchard fields remain poorly understood. We conducted a field experiment in a peach orchard and a global meta-analysis of N2O emissions from fruit orchards. The emission factor (EF) of fertilizer N for N2O averaged 0.81%, with a background N2O emission of 3.4 kg N ha–1 yr-1 in our field study. A global meta-analysis suggested that the linear regression model was the best to fit N2O emissions by fertilizer N input for most fruit types compared to the nonlinear models. When averaging all global data, the linear model projected the EF of N2O from orchards to be 0.84%, with the background emission of 1.96 kg N ha–1. The estimate of direct N2O derived from the orchard-specific nonlinear model was substantially lower than those from the nonlinear model with global cropland measurements. The fertilizer-induced direct N2O emission from Chinese orchards during the 2000s was estimated to be 32–49 Gg N yr–1, equivalent to about 14% of total direct N2O emissions from Chinese uplands. Therefore, orchard cultivation constitutes a hotspot of N2O emissions in the agricultural sector, and priority should be given to emissions reduction to achieve the transition to climate-smart agriculture.
查看更多>>摘要：? 2022Understanding drivers and monitoring changes of biodiversity forms the basis for evidence-based management and policy recommendations that aim to reduce biodiversity loss and to ensure the delivery of ecosystem services on which we rely. Ecoacoustic monitoring can be applied across large spatial and temporal scales, offering the potential for less resource-intensive ecosystem monitoring. Indices of acoustic diversity have been shown to correlate with species richness of various taxa, as well as vegetation and landscape structure. In order to apply ecoacoustic monitoring at large scales we need to improve our understanding of the effects of local and regional land-use on acoustic patterns, and assess how temporal aspects of acoustic patterns can be integrated in these analyses. We hypothesized that land-use intensity and landscape structure affect species richness and composition of birds and orthopteran, and therefore indirectly affect acoustic diversity and composition. To test this, we set up autonomous recording systems in grassland plots along land-use intensity gradients in three regions in Germany. We applied structural equation modelling to analyze the direct and indirect drivers of acoustic diversity and composition, including mowing and grazing intensities, landscape diversity, distance to the nearest road, vascular plant species richness as well as bird and orthopteran species richness and composition. Single indices of acoustic diversity did not reflect changes in bird or orthopteran species richness, making them poor predictors for local land-use related changes in species richness in grassland plots. Acoustic composition (non-metric multidimensional scaling combination of mean monthly acoustic indices at different day phases), however, did relate to differences in landscape structure, land-use intensity, vocalizing species composition and orthopteran species richness. We propose the developed acoustic composition metric as suitable proxy to detect ecosystem changes in grasslands.
查看更多>>摘要：? 2022 Elsevier B.V.Accurate estimation of maize (Zea mays L.) straw production and exploration of appropriate straw return rate have important reference for guiding the comprehensive utilization of crop straw. In this study, we estimated the maize straw production (including aboveground straw and root straw) in recent ten years (2009–2018) of the four largest maize growing regions across China using the latest obtained region-specific maize straw index and root-shoot ratio and then determined the appropriate straw return rate of different regions based on the carbon (C) balance between straw C input and the total C emissions generated in maize cultivation. Our results showed that there were significant differences in maize straw index (MSI) and root-shoot ratio between different maize growing regions in China with spatial distribution trends of Huanghuaihai (HM) > North (NM) > Southwest (SW) > Northwest (NW) maize regions and SW > NW > NM > HM, respectively. On average, in the recent ten years, the total maize straw production of the four major regions was 216.03 Mt yr?1, including 192.73 Mt yr?1 for the aboveground straw production and 23.30 Mt yr?1 for root straw production. Nationally, when the maize straw return rate was 70.4% (45.8%, 57.4%, 62.2% and 84.5% in SW, HM, NW and NM respectively), the straw C input into soil can theoretically counterbalance the total C emission generated in maize cultivation. Additionally, the total soil organic C sequestration increased from 11.26 to 18.88 Mt C yr?1 for the whole four regions under the scenarios of 0%, 25%, 50%, 75% and 100% maize straw return.
查看更多>>摘要：? 2022 The AuthorsWild ungulates are a major consumer of agricultural crops in human dominated landscapes. Across Europe, ungulate populations are leading to intensified human-wildlife conflicts. At the same time, ungulates play a vital role in the structuring and functioning of ecosystems, and are highly appreciated for recreational hunting. Thus, managers often face the challenge of maintaining the benefits of having thriving ungulate populations while simultaneously minimizing their negative impacts. Broadcasting playbacks of predator vocalizations (e.g. dogs barking, wolves howling or humans talking) could potentially be used to induce fear and thereby displace or steer behavior of ungulates from conflict-prone sites resulting in reduced visitation and foraging time and consumption. Predator playback experiments in wilderness areas have repeatedly demonstrated to reduce the preys′ resource use and impacts on the surrounding landscape, but this has not been tested in agricultural fields where human-ungulate conflicts are most pronounced. We responded to this need by conducting a predator playback experiment in multiple crop fields in southern Sweden, where multiple ungulate species (fallow deer, roe deer, red deer, moose, wild boar) coexist, using a novel integrated camera trap – speaker system (ABRs) that broadcasts sounds of choice when a camera is triggered by an ungulate. Predator playbacks (wolf, dog, human) reduced deer patch use and crop damage on wheat fields more than playbacks of control sounds (owl, goose, raven). Our results confirm findings from previous studies in wilderness areas, and demonstrate that broadcasting predator playbacks using ABRs may provide an effective tool to reduce crop damage at the scale and duration of our study.
查看更多>>摘要：? 2022 Elsevier B.V.Agricultural producers have many incentives to clear small natural areas from their fields, as this can expand their cultivated land base. However, natural areas can play a role in delivering ecosystem services that improve crop productivity (e.g., by providing habitat for beneficial arthropods, that deliver pollination or pest control). We assessed the impact of landscape complexity on adjacent canola (Brassica napus) yield at both the field- and subfield-level using remotely sensed products. Fields with higher landscape complexity generally had higher mean yields. However, fields surrounded mostly by either crop or non-crop covers had lower yields, possibly due to a lack of ecosystem services or a strong yield-reducing edge effect. At the subfield-level, we found evidence of a boost in yield between 30 and 100 m from the field edge towards its center, as well as a potential yield-stabilizing effect at the same range.
查看更多>>摘要：? 2022 The AuthorsThe melon/cowpea intercropping system can be a specific and efficient cropping pattern in a horticultural field. Intercropping systems contribute to the optimization of land use, fostering sustainable and efficient agriculture. This study entails a first-year comparative intercropping assay using cowpea (Vigna unguiculata) and melon (Cucumis melo) under organic management with different patterns and 30% less organic fertilization than usual in monocrops. We determined the soil nutrients, physicochemical properties, enzyme activities and microbes by high-throughput sequencing. We found that the intercropping system changed the bacterial community structure independently of the intercropping pattern. The bacterial community was characterized by a higher abundance of the phyla Proteobacteria and Bacteroidetes phyla and of the genus Pseudomonas, which are related to nutrient cycling, and by greater amounts of other beneficial microorganisms like Bacillus, Streptomyces and Sphingomonas. The intercropped systems significantly boosted the total nitrogen, available phosphorus and total organic carbon levels in addition to the melon yield. They also enhanced the acid phosphatase and β-glucosidase activity compared to the melon monocrop. Results from this study suggest that melon/cowpea intercropping, starting from the first year, not only provides a stable supply of food and income due to the diversified cropping systems, but is also beneficial for the soil microbial community and environment.
查看更多>>摘要：? 2022 Elsevier B.V.Increase in pesticide use and landscape homogenization are two key drivers of the decline in farmland biodiversity. The effects of these two drivers are often complex, interactive and vary among taxonomic groups. Our study tested the hypothesis that pesticide use influences the effect of different components of landscape complexity on different taxonomic groups. We sampled 32 rice paddy landscapes of 1 * 1 km in the Camargue (south of France), a wetland internationally recognized as an exceptional biodiversity hotspot. We assessed the abundance and diversity of 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders and birds) in 3 or 4 crop fields per landscape. For each landscape, we measured the length of different field margins (ditch, grass strip, hedgerow), the proportion of semi-natural areas and crop diversity. For each field, we measured management intensity by the treatment frequency index (TFI) of pesticides. We then tested our hypothesis across 118 fields. Our results show that different components of landscape complexity influence different taxonomic groups: crop diversity and the length of ditches influence bee abundance and species richness, the proportion of semi-natural areas influence spider abundance and species richness, and the length of grass strips influences bird abundance. Moreover, we show that local pesticide use modulates these effects, with more positive effects of landscape complexity in intensively-managed fields. However, we found no interactive effect between landscape complexity and field management for plants, butterflies, hoverflies and carabids. Our study therefore suggests that different components of landscape complexity need to be maintained in order to preserve multiple taxonomic groups. Moreover, it suggests that increasing landscape complexity is particularly relevant to restore biodiversity in intensively-managed fields. Agricultural policies should therefore support the simultaneous increase in semi-natural areas, field margins length and crop diversity to conserve a wide range of taxonomic groups in intensively-managed rice paddy landscapes.
查看更多>>摘要：? 2022 Elsevier B.V.The rehabilitation of disaster-prone areas can enhance the stability of soil structure and is a common way to increase organic carbon storage. The response of soil carbon sequestration pathways to different recovery modes is not clear, especially in mountain soils. After 11 years of recovery, we evaluated soil organic carbon (SOC) sequestration pathways in plantations (dominated by Olea europaea ‘Leccino’), croplands [Zea mays (L.)] natural shrublands (Lycium chinense Mill), and natural grasslands [Setaria viridis (L.) Beauv]. The physical and chemical properties of the soil and the 13C natural abundance of each aggregate and its density components were studied. The results showed that, during the restoration process, the soil organic carbon content of natural grassland increased the most, while the δ13C value of soil of natural shrubs was the highest. The natural abundance of 13C was used to reveal the pathway of C flow in soil organic matter (SOM), as follows: free light fractions (ρ < 1.6 g cm?3)→mineral fractions (ρ > 2.0 g cm?3)→dense occluded fractions (ρ from 1.6 to 2.0 g cm?3) (in plantation, natural shrubland, and grassland). However, in cropland soil, C flowed as follows: mineral fractions→free light fractions→dense occluded fractions. Specifically, the SOC content decreased with aggregate particle size, and after entering the soil, plant litter was first stored in large aggregates and then decomposed into the free light fraction. The study revealed the mechanism of organic carbon sequestration in the restoration area, emphasizing that artificial restoration treatment can change the carbon conversion pathway, and reduced the sequestration of organic carbon.
查看更多>>摘要：? 2022 Elsevier B.V.Biochar as a soil amendment is often described as a promising agricultural practice for climate change mitigation and adaptation. However, while recent research showed limited effects of biochar in temperate regions, its long-term impacts on nutrient management in-situ have been overlooked. Here we studied charcoal residues from pre-industrial kiln sites as a proxy to determine the effects of century-old biochar (~200 years old) on nutrient cycles of 3 land covers in a conventionally cropped field. We compared nutrient cycles of soil containing either century-old biochar (CoBC), recently pyrolyzed biochar (YBC) produced from similar feedstock (oak) and amended in similar amounts and a reference charcoal free soil (REF). For these three modalities, we characterized soil chemical properties, the pore water nutrient concentration evolution with time and depth using suction cups, and the crop nutrient uptakes. Our results revealed soil pore water nutrient concentrations strongly depended on biochar age. Indeed, YBC resulted in lower N-NO3- and K+ leaching but higher P-PO4– pore water concentrations in the topsoil Ap (0–30 cm) horizon. In CoBC higher K+ and Mg2+ concentrations occurred in the pore water than in REF for subsoil horizon E (30–60 cm) and Bt (60–100 cm). Beyond soil pore water, CoBC also strongly increased soil total N, available K+ and Ca2+ but decreased available P contents compared to REF and YBC. Finally, although no change in crop productivity occurred, lower N, K, Ca and higher Mg plant uptakes were observed for modalities with biochar. This resulted in no difference in terms of nutrient exports from the field in chicory but it significantly decreased N, K, Ca exports from biochar rich soil under winter wheat in straw. This study delivers the first field-based evidence that the effects of hardwood biochar on nutrient cycles change over its lifetime in a temperate Luvisol soil, whereby young biochar impacts mainly pore water nutrient concentrations and aged biochar mainly plant available contents. In such a strongly managed environment, no differences are noted in productivity despite strong changes in the nutrient cycle. Our study provides insights for addressing long-term effects of biochar in cultivated lands not only in terms of agronomic perspectives but through a biogeochemistry lens.
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