查看更多>>摘要：Different types of fertilizer can significantly change soil fertility. The response of soil bacterial communities to different fertilization regimes has been studied widely, but the inconsistent results urged us to systematically study the effect of multiple environmental factors on bacterial diversity and composition under different fertilization regimes. Here, we conduct a meta-analysis of a global dataset from 105 publications to explore the effect of mineral nitrogen, straw, and manure addition on soil bacterial alpha-diversity (Shannon and Chao1 indices) and community composition. Mineral nitrogen and straw addition decreased the Shannon (mineral nitrogen: -4.48%; straw: -11.83%) and Chaol (mineral nitrogen: -0.97%; straw: -11.57%) indices, while manure addition increased the Shannon (0.53%) and Chaol (5.64%) indices. The three types of fertilizer all favored the growth of Proteobacteria, Actinobacteria, and Bacteroidetes and inhibited the growth of Acidobacteria and Nitrospirae. Manure addition had the greatest increase in the abundance of Proteobacteria, Bacteroidetes, and the least decrease in abundance of Nitrospirae. Manure addition increased soil organic carbon, total soil nitrogen, and soil microbial biomass carbon more than mineral nitrogen and straw addition. Mineral nitrogen and straw addition decreased soil pH, while manure addition increased soil pH. Soil environmental and climate factors significantly drove changes in bacterial alpha-diversity and community, particularly soil pH. In conclusion, manure addition is the preferred fertilization management for most agricultural ecosystems. These results can be used as a valuable reference for agricultural management strategies to maintain belowground bacterial diversity and composition in agroecosystems across the globe.
查看更多>>摘要：Southern Africa is likely to be heavily affected by a changing climate and the brunt will have to be shouldered by smallholder farmers in rural areas. Long-term experiments on climate-smart sustainable intensification practices offer the opportunity to evaluate and assess the potential impact of a more variable climate on crop productivity. Here, we used meta-analytic and meta-regression approaches to assess the response of different Conservation Agriculture (CA) systems across experiments as compared to conventional practices (CP) of varying experimental duration, established in trial locations of Malawi, Mozambique, Zambia, and Zimbabwe under an increasingly variable climate. We assessed how different agro-environmental yield response moderators such as type of crop diversification and amount of rainfall affect maize yield responses. Smallholder farmers, often living below the poverty line, are primarily concerned about short-term gains from agriculture systems accepting loss in longer term sustainability. We therefore aim to identify cropping systems that may provide both short-term gains and longer-term sustainability. Results show that: a) long-term trends in yield performance are a result of many factors; b) the greatest yield gains between the best performing CA and least performing treatments at each location ranged between + 34% and + 117%; c) the greatest yields were found in direct seeded rotation systems; d) type of crop diversification and type of crop used in the diversification strategy affect yield response, with rotations involving legumes being more responsive than any practice without diversification; e) CA systems gains increase with time of practice as compared to CP and these responses are more pronounced under low to moderate rainfall, and in well drained soils. We therefore conclude that crop yield response under CA is determined by many yield defining agro-environmental factors and benefits of CA become more apparent with time.
Speir, Shannon L.Tank, Jennifer L.Trentman, Matt T.Mahl, Ursula H....
10页
查看更多>>摘要：Environmental impacts on freshwater ecosystems persist due to inputs of excess fertilizer to agricultural land-scapes. Conservation efforts, such as cover crops, are being encouraged to reduce nitrogen (N) and phosphorus (P) runoff from fields, but their effects on working lands are rarely documented. We quantified reductions of nitrate-N and soluble reactive phosphorus (SRP) losses from cropland in response to widespread planting of cover crops in two agricultural watersheds (Indiana, USA) over four water years (2016-2019). We collected water samples bimonthly from tile drains and stream sites to measure nitrate-N and SRP losses across scales. Cover crops consistently reduced tile drain nitrate-N loss by 27-72%, while SRP reductions were more variable, ranging from 7%-58%. Subwatershed nitrate-N yields were consistent across each watershed, while headwaters disproportionately contributed SRP to the stream, suggesting targeted cover crop implementation may be required to reduce SRP export. Finally, watershed-scale nitrate-N export was reduced by 2-67% (5/8 site-years) and SRP export by 31-88% (7/8 site-years) in spring. However, given the effect of interannual variability in runoff and spatial heterogeneity in N and P loading, regional-scale planting of cover crops may be needed to confer consistent reductions in annual export, with meaningful impacts on downstream water quality.
查看更多>>摘要：Intensification of agricultural production and simplification of landscape structure have negatively affected arthropod communities, in particular since the end of Second World War. Agri-environment schemes may partly compensate for these losses and enhance arthropod populations, but their effectiveness is higher in simple landscapes rather than complex landscapes, characterized by a large proportion and diversity of semi-natural areas. As the landscape-scale species pool is known to drive local species richness, we tested our hypothesis that landscape complexity determines local arthropod species richness, whereas local management affects only arthropod abundance. Here we undertake a meta-analysis as part of a wider systematic review of the effects of land use heterogeneity on arthropod species richness. We searched for studies quantifying the effects of agri-environment schemes (e.g. wildflower strips/areas, grassy field margins, organic farming) and landscape complexity on arthropod richness and abundance. We additionally separated vegetation-vs. ground-dwelling taxa, because the effects were hypothesized to be greater in the more mobile vegetation-dwelling taxa. As ex-pected, increasing landscape complexity enhanced arthropod richness, but not their abundance. Unexpectedly, agri-environment schemes did not only support the abundance of arthropods, but also their species richness. This pattern was driven by the vegetation-dwelling, not the ground-dwelling taxa, presumably because the higher mobility of vegetation-dwelling taxa allows faster responses to environmental changes. Our results show that agri-environment schemes in Europe benefit both arthropod abundance and species richness, whereas increasing landscape complexity primarily enhances species richness. This is why both local and landscape management need to be taken into account to halt current biodiversity losses in agricultural landscapes. Agri-environment schemes need to be implemented at a larger spatial and temporal scales to enhance landscape complexity, maintaining or restoring biodiversity sustainably.
Mitchell, Matthew G. E.Hartley, EmeryTsuruda, MattGonzalez, Andrew...
10页
查看更多>>摘要：Primary parasitoid species, usually Hymenopteran wasp species, contribute to pest regulation services in agro-ecosystems by parasitizing crop pests and reducing their abundance. However, this positive effect can be limited if primary parasitoids themselves are parasitized by secondary parasitoids, also known as hyperparasitoids. These trophic dynamics that influence pest regulation take place within the context of changes to agricultural landscape structure including loss of natural habitat and landscape simplification. Therefore, there is great interest in understanding how landscape structure influences pest, primary parasitoid, and hyperparasitoid dynamics. We investigated how the structure of agricultural landscapes in Southern Quebec affects primary and hyperpara-sitism rates of soybean aphid (Aphis glycines). We found that pests, primary parasitoids, and hyperparasitoids responded in contrasting ways to landscape structure. While aphid abundances and hyperparasitoid rates increased with increasing distance-from-forest in soybean fields and as the proportion of forest in the sur-rounding landscape decreased, primary parasitoid rates showed the opposite trends. Relationships with forest fragment size and isolation were complex, with contrasting positive, negative, and neutral effects across the three groups. Finally, wider fields consistently had lower aphid abundances, primary parasitoid rates, and hyper-parasitoid rates. Our results highlight the complexity of the trophic dynamics that underlie pest regulation and how changes to landscape structure can lead to conflicting and contradictory effects on pest regulation.
Ortner, Kaleb A.Tiemann, Lisa K.Renner, Karen A.Kravchenko, Alexandra N....
12页
查看更多>>摘要：Planting cover crops within or following a cash crop may improve soil-based ecosystem services due to increased plant diversity and a longer duration of live vegetation coverage. We examined the effect of three different cover cropping systems on soil properties after one year of a three-year organic transition rotation at four agricultural field sites with contrasting topographical positions, namely depressions, slopes, and summits. The four studied systems were (1) cereal rye (Secale cereal L.) planted after corn (Zea mays L.) harvest (Rye); (2) a mixture of cold susceptible cover crop species, namely, oat (Avena sativa), winter pea (Pisum sativum), and radish (Raphanus sativus), interseeded into corn (WK); (3) a mixture of cold tolerant cover crop species, namely, annual ryegrass (Lolium multiflorum), Dwarf Essex rapeseed (Brassica napus), and crimson clover (Trifolium incarnatum), interseeded into corn (WH); and (4) a no-cover control (NC). While soil moisture was affected by topography, interseeding cover crops into corn did not influence soil moisture levels at the 0-10 cm depth for the studied year. Soil NO3- content was markedly higher in the WK system compared to cereal rye and WH cover crop treatments. The difference was especially pronounced in depressions and summits. Soil N mineralization rates followed the pattern WH>WK>Rye>NC and the effects were most pronounced in slopes. Soil microbial biomass C was the highest in depressions followed by summits and slopes, and in depressions the WH had higher microbial biomass than the other systems. There were no effects of cover crops and topography on soil C mineralization one year after the organic transition was initiated. The WH system increased the fraction of 0.053-2 mm aggregates and decreased > 2 mm aggregates in depressions. The results suggest that the effect of cover cropping can become evident already one year after the organic transition begins. The WH mixture interseeded into the cash crop was an optimal cover crop choice for improving soil characteristics as well as decreasing soil N leaching risks during organic transition in undulating agricultural terrain. However, the magnitude of the benefit provided by WH was mediated by topography.
查看更多>>摘要：Agricultural systems in Central Europe were redesigned during the last century to attain maximum yields. The results often lead to homogeneous landscapes with only few structures of ecological value and have concurrently exacerbated habitat fragmentation. Perennial wildflower strips have become a significant agri-environmental measure (AEM) to counteract the ecological consequences for wild bees and other pollinators in agricultural landscapes. The effectiveness of AEMs depends on the landscape context, but information about geodata sources and spatial scales relevant for the analysis of landscape effects on wild bees is lacking. This study uses data from various sources on land cover and agricultural practices to assess their applicability in an evaluation of perennial wildflower strips as AEM for wild bees in Saxony-Anhalt, Germany. We investigated the relationships of wild bee species diversity and abundance to the landscape context at spatial scales from 200 m to 10 km considering several factors: land cover/land use, protected areas, crop types, agri-environment schemes/greening, intensity of agriculture, and intensity of grassland farming. In general, our results revealed that landscape effects were more relevant for solitary than social wild bees on flower strips, pointing to a higher limitation of solitary wild bees in nesting resources as compared to social wild bees. Numbers of wild bee species and individuals benefitted from bare soil and ecological focus areas in the surroundings up to 3 km distance, whereas the share of Red List solitary bee species was positively influenced by a variety of factors (e.g., wood structures and grasslands) especially at large scales up to 10 km. The comparison of models based on different land cover data sources showed that the lack of geodata resolution can mask landscape effects on wild bees. Altogether, our results suggest a high potential of data from the Basic Digital Landscape Model (DLM), together with the Integrated Administration and Control System (IACS), to indicate effects of landscape structures and agricultural practices on the species composition and distribution of wild bee assemblages in Germany.
查看更多>>摘要：Farming intensity and landscape heterogeneity influence agrobiodiversity and associated ecological functions. The relative contributions of these agroecosystem components to agricultural production remain unclear because of inter-relations and weather-dependant variations. Using a structural equation modelling approach, we estimated direct and indirect contributions of farming intensity (soil management, pesticide use and fertilisation) and landscape heterogeneity (of semi-natural covers and crop mosaic) to cereal crop production, in 54 fields (mostly wheat), in two years (24 and 30 fields). Indirect effects were evaluated through agrobiodiversity (carabid and plant communities) and ecological functions (pollination and pest control). In 2016, farming intensity had the largest direct positive effect on cereal crop yield, followed by agrobiodiversity (74% of the farming intensity impact) and ecological functions. However, the direct benefits of farming intensity were halved due to negative indirect effects, as farming intensity negatively affected within-field biodiversity and ecological functions. Overall, agrobiodiversity and farming intensity had equal net contributions to cereal crop yields, while heterogeneity of the crop mosaic enhanced biodiversity. In 2017, neither higher farming intensity nor agrobiodiversity and ecological functions could lift cereal production, which suffered from unfavourable meteorological conditions. Semi-natural habitats supported agrobiodiversity. Our study suggests that a reduction of farming intensity combined with higher heterogeneity of crop mosaic can enhance the benefits of ecological functions towards crop production. Semi-natural covers seem to play an essential role in the face of climatic events, by supporting agrobiodiversity and the potential resilience of the agroecosystem functioning.
De Heij, Stefanie E.Benaragama, DilshanWillenborg, Christian J.
13页
查看更多>>摘要：Reduced use of chemicals in weed management has been identified as a key strategy to increase overall agricultural sustainability. Carabid (Coleoptera: Carabidae) and cricket (Orthoptera:Gryllidae) weed seed predation has shown promise, but also variability, as an additional weed management tool. Therefore, it is important that carabid activity-density and weed seed predation is further explored in a wide variety of crops and cropping systems, including large conventional systems where sustainability gains may be the largest. Here we explored carabid and cricket activity-density, community, and weed seed consumption in commercial conventional pulse crop fields. Pulse crops are increasingly being incorporated in cropping rotations but weed seed predation is hardly explored in this group of crops. We sampled twenty-four large commercial lentil, pea, faba bean, and soybean fields, and found that crop type did not affect levels of seed predation or carabid activity-density but was a factor in shaping the carabid + cricket community. Crop history had an unexpectedly large impact on the community, fields previously planted to canola had relatively high Amara activity-densities. The carabid genera Amara and Pterostichus, as well as crickets were associated with volunteer canola seed predation. None of the studied carabid taxa, nor crickets, were a significant factor explaining kochia seed predation. We also explored the effects of crop canopy-driven microclimate factors on carabid and cricket activity-density and weed seed predation. The Amara, the most abundant granivorous taxon in this study, were positively related to soil temperatures but not to soil light intensity. Our study highlights the importance of cropping history on the community of beneficial insects in crop fields and indicates a taxon specific relationship with soil temperature and weed seed predation.
查看更多>>摘要：Cover crop (CC) residue decomposition influences the provisioning of agroecosystem services. While several laboratory and field studies have investigated processes and mechanisms of CC residue decomposition at specific point or plot scales, regional assessment of factors controlling decomposition rates (i.e., k-values) in no-till corn (Zea mays L.) systems are currently lacking. Here, we conducted the first multi-state on-farm litter bag studies over 105 site-years in the mid-Atlantic and Southeastern US states to determine the independent and combined effect of factors intrinsic to the field (soil and weather) and extrinsic or management factors (CC quantity and quality) on k-values. In the coastal plain regions, the k-values decreased as the underlying soils became sandier. Among weather variables, mean daily air relative humidity (RH) and number of rainy days showed stronger control on k-values than cumulative rainfall. This suggests faster decomposition of CC residues in humid envi-ronments and in site-years with frequent rain-events. Among extrinsic factors, the k-values decreased with higher CC biomass, C:N, residue holo-cellulose concentrations, and lignin:N, but increased with higher residue carbo-hydrate concentrations. The combination of CC residue quality (C:N and holo-cellulose) and weather (RH and rainy days) variables accounted in total for 69% of the variability in k-values with CC residue quality having a greater control over k-values than does weather in the mid-Atlantic and Southeastern US states. Therefore, our study emphasizes the necessity to update current process-based decomposition models to explicitly consider both CC residue quality (C:N, holo-cellulose) and weather factors (RH, rainy days), when predicting CC residue decomposition in no-till cropping systems.
NSTL
Elsevier