De Bernardi M.Priano M.E.Juliarena M.P.Fernandez M.E....
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查看更多>>摘要：? 2022 Elsevier B.V.Upland soils are the main methane (CH4) biological sink, and may be affected by land-use change. Changes in land uses and soil management affect soil properties that control diffusion of gases, which in combination with microbial activity, determine CH4 flux (fCH4) through the soil. Net CH4 fluxes and diffusivity -estimated by the CH4 diffusion coefficient- were measured in three common land uses typical from Pampean plains, South America (natural grassland NG; Eucalyptus globulus Labill. afforestation E; and agricultural land AL: oat, soybean and red clover in successive cultivation) during two years (March 2017–March 2019). Methane fluxes in the soil-atmosphere interface were measured using the static chamber technique, and a diffusion model was applied to estimate soil CH4 diffusivity from soil porosity. We aimed to quantify the effect of land use change (both E and AL vs. NG, the reference system) on fCH4 and gas diffusivity due to changes in the soil parameters. Soils were net sinks in the three land uses, with mean CH4 flux higher in the afforestation, intermediate in the natural grassland and lower in the agricultural land (? 10.99 ± 5.85, ? 8.9 ± 5.32 and ? 4.58 ± 4.19 ng CH4 m?2 s?1, respectively). CH4 fluxes varied significantly through seasons and space coinciding with variations in water-filled pore space and air-filled pore space variables (ρ > 0.7 and <?0.7 respectively; p < 0.05). Land-use change metric for methane flux ΔfCH4 was ? 2.1 ± 3.7 and 4.4 ± 2.5 for NG-E and NG-AL, respectively, indicating a significant increment in net CH4 uptake when the natural grassland is afforested and a decrease when it was converted to agricultural use. This change was mainly explained by changes in soil physical properties (bulk density, soil water content, WFPS and air filled porosity). In relation to this, soil CH4 diffusion coefficient followed the same pattern as fCH4 (0.024 ± 0.011; 0.015 ± 0.007 and 0.008 ± 0.007 cm2 s?1 for E, NG and AL respectively); and allowed us to recalculate mean CH4 fluxes. Theoretical and in situ measured CH4 fluxes were similar and followed the same patterns across land uses, suggesting the possibility to determine CH4 fluxes by means of simple measures of soil properties (bulk density and soil water content) and soil CH4 gradient concentration.
查看更多>>摘要：? 2022Atmospheric CO2 concentrations and water management practices both affect greenhouse gas (GHG) emissions from rice paddies, but interactive effects between these two factors are still unknown. Here, we show the ?rst study to compare the impact of elevated atmospheric CO2 (eCO2) on GHG emissions under continuously flooded irrigation (CF) and under intermittently flooded (IF) conditions. Elevated CO2 stimulated CH4 emissions under CF by 50% in a field experiment and by 46% in a pot experiment, but it had no effect under IF in both experiments. Elevated CO2 had no effect on N2O emissions in either the field or pot experiment. Rice root biomass, aboveground biomass and grain yield increased with eCO2, but were not affected by water management. Elevated CO2 only stimulated the abundance of methanogens under CF, suggesting that increased soil O2 availability with IF limited methanogenic activity under eCO2. Our findings suggest that estimates of CH4 emissions from global rice agriculture with eCO2 need to account for recent changes in water management.
查看更多>>摘要：? 2022 Elsevier B.V.Soil in agriculture systems is important for carbon sequestration. To explore the influence of rice-crayfish farming on soil organic carbon (SOC) content, 0–30 cm soil samples were collected from rice monoculture and rice-crayfish systems (1, 6, 10 and 15 years) scattered in Nanxian County, Hunan Province, China. Results showed that the SOC content in rice monoculture was approximately 22 g kg?1, while enhanced SOC content was observed in 6, 10 and 15-year rice-crayfish systems, around 27–33 g kg?1. The formation of water-stable aggregates mainly depends on the cementation of SOC. Meanwhile, the decomposition of organic matter may further lower the oxygen content and lead to accumulation of reduction substances in soil. Similar increasing trends also occurred in soil water-stable macro-aggregates (WR0.25) content (78–83%), mean weight diameter (MWD) (1.1–1.2 mm) and geometric mean diameter (GMD) (0.8–1.0 mm), whereas the aggregate fractal dimension (D) (2.58–2.44) decreased. Moreover, rice-crayfish farming over 6 years enhanced the content of total reducing matter (TRM), active reducing matter (ARM), Fe2+ and Mn2+ content by 1.7–3.4 cmol kg?1, 0.6–1.3 cmol kg?1, 0.5–1.2 cmol kg?1 and 0.2–0.6 cmol kg?1, respectively. However, the 1-year rice-crayfish system did not show significant changes after the conversion from rice monoculture systems. Overall, rice-crayfish farming has the capability to increase and preserve SOC, but it aggravates soil gleization.
查看更多>>摘要：? 2022 Elsevier B.V.Soil nutrient supply and resistance to pathogen invasion are critical to crop yield during agricultural production. Crop production is often hampered by co-occurring nutrient and pathogen stresses, but the relationship between soil nutrient status and disease suppression remains unclear. Here, we conducted a meta-analysis based on 406 observations from 55 studies to decipher the relationships between soil nutrient supply and disease suppression against bacterial wilt disease caused by R. solanacearum. We found that the contents of soil organic carbon (SOC), total nitrogen (TN), available potassium (AK) and available phosphorus (AP) were significantly higher in relatively disease suppressive soils than in conducive soils. Soil AP showed a significantly negative correlation with both crop disease incidence (DI) and disease severity (DSI). SOC was significantly and negatively correlated with DI and DSI in general, but a positive correlation with DI was found when SOC content was higher than 1.3%. Then for nutrient stoichiometry in soil, we found that the ratio of carbon to nitrogen (C/N), maximum to 22, was significantly and negatively correlated to the DI, but was positively correlated to DSI when C/N was higher than about 30. And the ratio of TN to AP (TN/AP) showed significantly positive correlations with both DI and DSI in soil. Further in applied organic fertilizer, the ratio of nitrogen to phosphorus (N/P) was significantly and negatively correlated with DI when N/P was lower than about 5, but was positively correlated with DI when higher than that. Our results demonstrated that the quantity and stoichiometry of phosphorus, organic carbon and nitrogen in soil and applied fertilizer, notably the prevention of nutrient deficiency and the balance of different nutrients, play an important role in supporting soil suppressiveness to R. solanacearum wilt disease, and this implied a possible trade-off between nutrient acquisition and pathogen defense in soil ecosystems.
查看更多>>摘要：? 2022 Elsevier B.V.Although rodents are recognized as pests, they are still an important part of agricultural ecosystems. In 2018–2020, we snap-trapped small mammals in Lithuania in 18 commercial orchards (apple and plum orchards, currant and raspberry plantations) and in adjacent control habitats. We aimed to discover whether the litter size of the six most abundant rodent species depended on season, on female body mass and/or on fitness. Litter size in common and root voles was smaller in habitats with a higher intensity of agricultural practices. Compared to summer, observed litter size in autumn significantly decreased in common voles (from 5.6 to 4.8) and yellow-necked mice (from 5.8 to 4.6). In autumn, litter size and female body mass was positively correlated in all rodent species, while in summer this was characteristic to root voles (r = 0.67, p < 0.05, 45% of variation of the litter size explained) and yellow-necked mice (r = 0.53, p < 0.005, 27% respectively) only. Female body condition index and litter size correlations were weak. Potential litter size exceeded the observed rate and breeding failures were observed in all species, with the highest percentage in root, bank and common voles.
查看更多>>摘要：? 2022 Elsevier B.V.Safeguarding crop pollination services requires the identification of the pollinator species involved and the provision of their ecological requirements at multiple spatial scales. However, the potential for agroecological intensification of pollinator-dependent crops by harnessing pollinator diversity is limited by our capacity to characterise the community of pollinator species for each crop, and to determine how it is influenced by the different survey methods used, as well as by climatic variables at larger geographic scales. Here, we surveyed wild bees using a standardised protocol at an unprecedented scale including 62 commercial apple orchards in Western and Central Europe (i) to validate recent findings on pollinator community divergence as measured by common survey methods (netting and pan trapping) using conventional and alternative biodiversity metrics (phylogenetic and functional diversity), and (ii) to investigate the impact of climatic variation on the patterns observed. Our results confirm the significant divergence in pollinator communities measured using the two common methods at the larger, sub-continental scale, and we provide evidence for a significant influence of climate on the magnitude of pollinator community divergence (beta diversity and its turnover component) between survey methods, particularly when comparing colder to warmer sites and regions. We also found that warmer sites are more dissimilar than colder sites in terms of species composition, functional traits, or phylogenetic affinities. This result probably stems from the comparatively larger species pool in Southern Europe and because apple flowers are accessible to a wide spectrum of pollinator species; hence, two distant survey localities in Southern Europe are more likely to differ significantly in their pollinator community. Collectively, our results demonstrate the spatially-varying patterns of pollinator communities associated with common survey methods along a climate gradient and at the sub-continental scale in Europe.
查看更多>>摘要：? 2022 The AuthorsMicroorganisms play a key role in nutrient cycling in agriculture and can contribute to improve soil quality and enhance crop production. Thus, there is a need to identify the most suitable management practices which foster increases in soil microbial biomass and diversity. A meta-analysis was performed to assess changes in microbial abundance in agricultural soils affected by: (i) management practices (tillage, fertilization and crop diversification); and (ii) environmental factors, including climate characteristics and soil properties. The scope of the meta-analysis was to evaluate whether microbial abundances are affected or not by organic fertilization or no fertilization, crop diversification (intercropping and crop rotations) and conservation tillage (reduced tillage/no-tillage) as an alternative to intensive conventional monocultures in agriculture. Only papers showing data on phospholipid fatty acids (PLFAs), providing indicators about soil microbial (total PLFA), fungal and bacterial biomass reached a critical mass to perform the meta-analysis. Therefore, soil microbial diversity could not be analyzed considering different management practices. Results showed that intercropping and crop rotations only significantly increased the abundance of fungi, with the corresponding increase in the fungal-to-bacterial ratio. Organic fertilization contributed to significant increases in bacterial and fungal abundance and total PLFA compared to mineral fertilization. Contrarily, the lack of fertilization negatively affected total PLFA, with no significant effect on bacterial and fungal abundances. Reduced tillage significantly increased total PLFA, fungal and bacterial abundances compared to conventional tillage, while no tillage had only a positive effect on fungi. Thus, as a general pattern, the adoption of sustainable management practices, mostly organic fertilization and reduced tillage, has overall positive effects on soil total microbial, fungal and bacterial abundance. These variables were not related to soil physicochemical properties and climatic factors, suggesting a positive global effect of sustainable management practices on soil microbial abundances. Thus, this study shows new insights by a meta-analysis of global studies about the effect of sustainable management practices on soil microbial abundances, needed for land-managers, policy-makers and farmers to select sustainable cropping systems that enhance microbial abundance.
查看更多>>摘要：? 2022 Elsevier B.V.Aboveground and belowground invertebrates play a key role in decomposition of organic matter in terrestrial ecosystems. Dung beetles are well known for their functions in breaking down and transporting ungulate dung into soils thus promoting dung decomposition. However, the effects of functionally different dung beetles on the decomposition processes of the dung from different ungulates remain less explored. We did an in situ experiment using the 'dung and soil' mesocosm to investigate the separate and combined effects of two functionally contrasting dung beetle species, a dweller Aphodius sordecens and a tunneler Onthophagus gibbulus, on the decomposition processes of the dung from horse and cattle. We determined the changes in dung mass, dung C and N contents, microbial respiration from the 'dung and soil' mesocosm or from the soil beneath the dung pats, and examined the amount of dung balls transferred by beetles into different soil layers, under five dung beetle treatments (C – soil, no dung nor beetles; D – dung on soil with no beetles; DB - dung on soil with dweller beetles; TB - dung on soil with tunneler beetles; DTB - dung on soil with dweller and tunneler beetles) were applied to the dung of two major grazers with different digestive systems in native steppes in northern China, over a two-month period following dung deposition. We found that (1) tunneler beetles (in TB and DTB) significantly enhanced the dry mass loss of cattle dung but not horse dung. (2) Dung C and N contents declined more rapidly with the presence of any dung beetle species (DB-DTB) than that without (D); and dung N content showed different decreasing rates between horse and cattle dung in different decomposition periods. (3) The presence of the two functionally contrasting dung beetle species together had a synergistic, positive effect on soil microbial respiration and thus on the decomposition rate of soil organic matter; however, no significant effects of beetles on net microbial respiration was detected in the 'dung + soil' mesocosm. (4) The direct effect of dung beetles on dung mass loss was stronger for cattle dung than for horse dung. In contrast, the decline in moisture content of horse dung with decomposition time affected the microbial respiration in dung, and thus indirectly affected the dry mass loss and the C and N contents. Our results suggest it critically important to incorporate the functions of soil invertebrates into nutrient cycling models to improve their accuracy, and to promote invertebrate diversity in grazed grassland to maintain ecosystem health and services.
查看更多>>摘要：? 2022 Elsevier B.V.Shelterbelts are a popular form of agroforestry, providing a wide range of ecosystem services (e.g. wind speed reduction and wood production) which deliver farm-scale benefits. Variation in species composition and planting density drives structural differences in shelterbelts which directly influence the provision of ecosystem services and consequently the range of benefits received by farmers. Although specific structural characteristics of shelterbelts that determine provision of these services have been identified, little is known about how these characteristics vary with shelterbelt species composition and age, and how such variation may affect provision of a range of key services and benefits. This study explores the effects of shelterbelt composition and age on structural characteristics that determine ecosystem service provision. Structural characteristics (including vegetation height and porosity) were measured and compared across shelterbelts with three common species compositions (Eucalyptus nitens, Pinus radiata, mixed native) and three age classes (2–5 years, 6–14 years, 15–30 years) in the Midlands region of Tasmania, Australia. Species composition and age were key determinants of structural characteristics. For example, height, carbon sequestration, and stand basal area increased and porosity decreased with shelterbelt age, with rates of increase/decrease varying significantly between species compositions. We outlined how these structural characteristics affect provision of ecosystem services and showed that fine scale benefits are likely to be highly dependent on the species composition of the shelterbelt. These findings can assist agroforestry practitioners in designing shelterbelts that maximise benefits to their enterprise. There is value in expanding the approach used in this study to develop decision-making tools for practitioners, and to facilitate more meaningful application of natural capital accounting to agroforestry at the farm scale.
查看更多>>摘要：? 2022 Elsevier B.V.Genetically modified (GM) crops are considered a good way to reduce insecticide use and the presence of certain agricultural pests, thus improving food and environmental safety. Nevertheless, effects of GM plant residues on the soil food web are still poorly understood. Zea mays L., enriched with a gene from Bacillus thuringiensis Berliner subsp. kurstaki (Bt) as a defence against the maize borer, is widely cultivated. In this study, we explored the invertebrate food webs associated with residues of Bt and non-Bt maize, respectively represented by DKC6575, with a Cry1Ab transgene (event MON810), and its near-isogenic Tietar variety, in a five-month field experiment. C and N stable isotopes and Bayesian mixing models were used to assess trophic niche metrics and track nutrient flows from maize residues and weeds occurring in maize crops to invertebrate detritivores and predators. While there were no initial differences in the structural components of maize residues between varieties, after five months of exposure in the field, the lignin content was higher and the organic matter content was lower in non-Bt than in Bt maize. Organic matter depletion over time was associated with a decrease in primary consumer abundance and an increase in their trophic niche width in both Bt and non-Bt maize, but it was faster in the former. The abundance of primary consumers and predators was higher in non-Bt than in Bt maize, but the distribution of organisms across trophic levels differed between varieties, with prey availability being lower in non-Bt than in Bt maize. This allowed Bt-associated predators to maintain a diet based primarily on the maize food chain throughout the experimental period. In contrast, non-Bt-associated predators were more dependent on weed-feeding prey by the end of the experiment, increasing the coupling between the maize and weed energy channels in the soil food web. Some taxon-specific effects were evident. Less vagile organisms such as Diptera had a specific diet mostly related to maize regardless of variety and time, while the diets of more vagile organisms like Coleoptera and Opiliones changed the most over time. Overall, our results suggest that the attractiveness of non-Bt maize residues for invertebrate consumers is higher than the Bt variety, although the higher recalcitrant content following decomposition reduces it over time. The attractiveness also affects the movement of invertebrate predators (potentially including pest control agents) and thus nutrient flows in tri-trophic detritus-based food webs in cultivated and uncultivated plots.
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