查看更多>>摘要：Intensification of agriculture, with landscape simplification and reduction of natural habitats, is known to contribute to the decline of arthropods. Implementation of agroecological practices and infrastructures in current cropping systems is expected to mitigate this biodiversity loss and provide pest regulation through natural enemies. The aim of this study was to assess the efficiency of an undestroyed strip of winter cover crop within maize fields to promote ground-dwelling arthropod spillover and their predation activity into fields. The field survey was carried out in 2019 and 2020 within 12 fields. Monitoring of ground-dwelling arthropod activity-density, richness, and predation rate, as well as slug activity-density, was conducted in the strip, in the cropped area and in a grassy field margin. The results show that activity-density of carabids, spiders, and slugs, and the predation rate were overall higher in the strip than in the cropped area or the field margin. No clear edge effect of the strip on arthropods in the cropped area was found, but predation rate was enhanced closer to the strip. We did not record a negative effect of the strip on the occurrence of slugs within the maize crop. The study shows that a mid-field strip of winter cover crops can be efficient for biodiversity conservation of ground-dwellings predators in agricultural landscapes and provide a potential pest control service in cropped fields.
查看更多>>摘要：Individuating strategies to reduce greenhouse gas (GHG) emissions from agricultural soil, while preserving crop yield and the quality of products is needed. The major GHG emitted from agricultural soils is nitrous oxide (N2O) and its production is largely influenced by the amount of nitrogen (N) fertilizers applied and by the soil con-ditions, such as water content and temperature. The cultivation of processing tomato may lead to high N losses because it is characterized by a high frequency of irrigation events and N fertilizer applications. In this study we assessed the effect of reducing water from reintegration of 100% of water missing to field capacity (Ir2) to 50% (Ir1) and N applied, by 30% from 170 kg N ha(-1) (N2) to 120 kg N ha(-1 )(N1) and 100% from N2 to 0 kg N ha(-1) (N0), on yield, fruit quality and GHG emissions from soil in tomato cultivated under fertigation for two growing seasons (2014, 2015). We highlighted a great variability of results, both on GHG emissions from soil and on tomato productivity, due to differences in meteorological conditions in the two growing seasons. Higher marketable yield of tomato was recorded in N2 than in N1 only in 2014 and in Ir2 than Ir1 only in 2015, while reducing the agricultural inputs did not reduce the fruit quality. Carbon dioxide and nitrous oxide emissions were higher in 2015, while soil was a sink for methane in both growing seasons. We highlighted a general trend in lower nitrous oxide emissions with reduced water and N fertilizer rate, even if these emissions were largely variable in time and space. In particular, yield-scaled N2O emissions were lower in Ir1 than in Ir2, suggesting that a reduction of the irrigation level may be a suitable strategy for mitigating N2O emissions from tomato cultivated under fertigation in a Mediterranean environment.
查看更多>>摘要：One challenge for modern agricultural management schemes is the reduction of harmful effects on the envi-ronment, e.g. in terms of the emission of nutrients. Sampling the effluent of tile drains is a very efficient way to sample seepage water from larger areas directly underneath the main rooting zone. Time series of solute con-centration in tile drains can be linked to agricultural management data and thus indicate the efficacy of individual management measures. To that end, the weekly runoff and solute concentration were determined in long-term measurement campaigns at 25 outlets of artificial tile drains at 19 various arable fields in the German federal state of Mecklenburg-Vorpommern. The study sites were distributed within a 23,000 km(2) region and were deemed representative of intense arable land use. In addition, comprehensive meteorological and man-agement data were provided. To disentangle the different effects, monitoring data were subjected to a principal component analysis. Loadings on the prevailing principal components and spatial and temporal patterns of the component scores were considered indicative of different processes. Principal component scores were then related to meteorological and management data via random forest modelling. Hydrological conditions and weather were identified as primary driving forces for the nutrient discharge behaviour of the drain plots, as well as the nitrogen balance. In contrast, direct effects of recent agricultural management could hardly be identified. Instead, we found clear evidence of the long-term and indirect effects of agriculture on nearly all solutes. We conclude that tile drain effluent quality primarily reflected the soil-internal mobilisation or de-mobilisation of nutrients and related solutes rather than allowing inferences to be drawn about recent individual agricultural management measures. On the other hand, principal component analysis revealed a variety of indirect and long-term effects of fertilisation on solutes other than nitrogen or phosphorus that are still widely overlooked in nutrient turnover studies.
查看更多>>摘要：The combination of forage-crop rotation with conservation tillage has long been known to result in proven productivity and sustainability, but less information is available on the influence of long-term conservation tillage practices on the movement of soil water and residual nitrate at deep soil depths in forage-crop rotation systems. In this study, we measured the changes in soil water storage, residual soil nitrate accumulation and their relationship to study the long-term effects of tillage and mulching practices on regional nitrogen management in maize (Zea mays L.)-wheat (Triticum aestivum L.)-common vetch (Vicia sativa L., annual legume forage) rotation system. Soils were collected from the 500-cm soil profile at the harvest stage of the maize and common vetch after 19 years of continuous conventional tillage (T), conventional tillage followed by straw mulching (TS), no tillage (NT), and no tillage followed by straw mulching (NTS) on the Loess Plateau, China. The results showed that the NT practices increased soil water storage by 3.07% compared with the T practices in the maize field, mulching practices increased soil water storage by 3.47% compared with no mulching practices in the common vetch field, and the improvement effect was mainly concentrated in the deep soil layer (150-500 cm). When compared with no mulching, straw mulching practices increased residual soil nitrate accumulation by 51.20 kg ha(-1) at shallow soil depths (0-120 cm) but decreased this accumulation by 206.09 kg ha(-& nbsp;1) at deep soil depths (120-500 cm) in the maize field; however, straw mulching decreased nitrate accumulation by 16.25 kg ha(-1) throughout the whole profile (0-500 cm) in the common vetch field. The NT practices decreased residual soil nitrate accumulation by 131.65 kg ha(-1) compared with the T practices in the maize field but had no effects on the common vetch field in the 0-500-cm soil profile. Greater changes in soil residual nitrate accumulation appeared at depths of 200-500 cm than at other depths. Moreover, according to structural equation model, nitrite accumulation was limited by soil water storage. Soil nitrate peaked at deeper soil depths in the NT (90-120 cm) and TS (250-300 cm) treatments than in the T treatment (60-90 cm), whereas the NTS treatment resulted in no nitrate accumulation peak across the whole soil profile. Soil water recharge and depletion were deeper in the NT and TS treatments than in the T treatment, and this effect could limit the further leaching of soil nitrate into deep soil. The depth of soil water recharge was deeper than the depth of nitrate accumulation, and the vertical movement speed of soil residual nitrate was slower than that of soil water. Therefore, the downward movement of soil nitrate lagged behind that of soil water. Together, these results demonstrated that the NTS treatment exerted the strongest effect on maintaining soil water and decreasing residual nitrate accumulation at deep soil depths, which will be favorable for improving regional N management and assessing N budgets in agroecological systems on the Loess Plateau.
Sarmiento-Soler, AlejandraRotter, Reimund P. P.Hoffmann, Munir P. P.Jassogne, Laurence...
16页
查看更多>>摘要：Increases in temperature and more erratic rainfall patterns due to climate change threaten the already fragile livelihood of smallholder coffee farmers. Shaded coffee in agroforestry systems appear to be a good alternative to protect coffee from extreme temperatures while providing additional ecosystem services, such as extra food and soil protection. However, excessive shade might reduce coffee yields. This study analyzed the effect of shade cover (shade type represented by cropping system (Coffee-Open (CO), Coffee-Banana (CB), Coffee-shade tree (CT))), and shade intensity (represented by leaf area index of the shade cover) along an altitude gradient on: (i) microclimate, (ii) soil water content and (iii) coffee reproductive and vegetative growth. Data was collected during two coffee fruit development cycles (2015 and 2016) in smallholder coffee farms (n = 27) on the west slopes of Mt. Elgon Uganda. Shade cover buffered coffee trees from microclimate extremes (maximum temperature (-3 C) and temperature amplitude -3 & nbsp;C). Fruit set decreased with shade cover increases. Leaf set was shown to be the most important variable for vegetative and reproductive growth along several production cycles, and fruit drop was determined mainly by fruit set. Intermediated shade cover (LAI ~ 1 m(2) m(-2)), as occurred in coffee intercropped with bananas, showed an optimal balance between microclimate regulations, fruit set, and fruit drop, and provided staple food and an extra source of income.
Van Syoc, EmilyAlbeke, Shannon E.Scasta, John Derekvan Diepen, Linda T. A....
11页
查看更多>>摘要：Grazing is known to affect soil microbial communities, nutrient cycling, and forage quantity and quality over time. However, a paucity of information exists for the immediate changes in the soil physicochemical and microbial environment in response to different grazing strategies. Soil microbes drive nutrient cycling and are involved in plant-soil-microbe relationships, making them potentially vulnerable to plant-driven changes in the soil environment caused by grazing. To test the hypothesis that variable grazing intensities modulate immediate effects on the soil microbial community, we conducted a grazing trial of three management approaches; high intensity, short-duration grazing (HDG), low-intensity, medium-duration grazing (LDG), and no grazing (NG). Soil and vegetation samples were collected before grazing and 24h, 1 week, and 4 weeks after HDG grazing ended. Soil labile carbon (C) and nitrogen (N) pools, vegetation biomass, and soil microbial diversity and functional traits were determined, including extracellular enzymatic assays and high-throughput sequencing of the bacterial 16S rRNA and fungal ITS2 regions. We found that labile soil C and inorganic N increased following LDG grazing while C-cycling extracellular enzymatic activities increased in response to HDG grazing but both total extracellular enzymatic activity profiles and soil abiotic profiles were mostly affected by temporal fluxes. The soil fungal community composition was strongly affected by the interaction of sampling time and grazing treatment, while the soil bacterial community composition was largely affected by sampling time with a lesser impact from grazing treatment. We identified several key fungal taxa that may influence immediate responses to grazing and modulate plant-soil-microbe interactions. There was strong evidence of temporal influences on soil biogeochemical variables and the soil microbiome, even within our narrow sampling scheme. Our results indicate that the soil ecosystem is dynamic and responsive to different grazing strategies within very short time scales, showing the need for further research to understand plant-soil-microbe interactions and how these feedback mechanisms can inform sustainable land management.
Kim, KeunbaeHernandez-Ramirez, GuillermoFlesch, ThomasDaly, Erin...
15页
查看更多>>摘要：Perennial grain crops represent a novel hybrid between annually harvested grain crops and perennial forage crops, which are seeded once and grow for multiple subsequent seasons. Previous research has shown comparatively reduced nitrous oxide (N2O) emissions from perennial forage crops relative to annual grain crops; however, the effect of perennial grain cropping on N2O emissions is unclear. We quantified field N2O emissions along an experimental continuum of perenniality (perennial forage, perennial grain, fall grain, spring grain and fallow) established at two sites within Alberta, Canada with contrasting soils: luvisolic at the Breton site and chernozemic at the Edmonton site. We used static chambers and a micrometeorological technique based on an open-path Fourier-transform infrared gas sensor (OP-FTIR). Perennial grain crops reduced cumulative N2O emissions at the Breton site by 60% and 94% in years two and three of the study, respectively (Ps < 0.0001). Conversely, no reduction in N2O emissions by the perennial grain crop relative to the annual crop was evident at the Edmonton site. Correlation analyses encompassing both sites revealed that the average root density from 0 to 60 cm was negatively correlated with soil available nitrogen (N) (0-15 cm depth) in years one (Ps < 0.01) and two (Ps < 0.05). Moreover, in year two, root density was negatively correlated with cumulative N2O emissions, specifically at the Breton site (P < 0.01). Results suggest that the enhanced root density of perennial crops reduced soil N availability at the Breton site, which translated into reduced cumulative N2O emissions in year two. Notably, increased root density did not correlate with reduced N2O emissions at the Edmonton site, suggesting that factors such as increased soil clay and carbon content in the Chernozemic soil overrode crop controls on N2O emission. Further, OP-FTIR measurements at the Breton site were in general agreement with static chamber measurements, which collectively informed that the bulk reduction in cumulative N2O emissions from the perennial grain plots occurred during spring thaw. Overall, the ability for perennial cereal grain crops to reduce N2O emissions relative to annual crops was site-specific.
查看更多>>摘要：Carbon (C) assimilation and allocation play a crucial role in determining plant responses to environmental stress such as herbivory. However, the pattern how these grasses allocate assimilated C under increasing herbivory intensity hasn't been fully understand. In this study, we quantified photosynthetic C assimilation and allocation of newly assimilated C among tissues and metabolic processes (structural growth, storage, and defense) under different grazing intensities using C-13 tracing of a dominant grass species, Leymus chinensis. Light grazing promoted utilization of newly-assimilated C-13 (more than 90% C-13 allocated to aboveground tissues on first day after labeling), photosynthetic rate, and reduced mean residence time of C-13 of L. chinensis . The photosynthetic capacity and regulation of chlorophyll fluorescence thereby C assimilation were constrained under medium and heavy grazing. Light grazing also increased accumulation of non-structural carbohydrates (NSC) in stems for energy supply to leaf regeneration. As herbivory pressure increased, C-13 tracing showed preferential allocation of newly assimilated C to belowground tissues (16-27% C-13 on first day after labeling), while upregulating leaf defenses by increasing secondary metabolites and in root storage by NSC accumulation. Although the significant changes showed in C allocation to storage and secondary metabolism of L. chinensis , there are no difference in structural growth (defined as structural biomass= biomass - NSC - secondary metabolites) among grazing intensities. Overall, L. chinensis adopted a conservative C-allocation strategy (upregulated C storage and secondary metabolism) that emphasized long-term survival under increasing herbivory. Light grazing was an optimal grazing intensity that promoted structural growth and C allocation of L. chinensis , which could sustain and even increase grassland productivity. These characteristics of the plant's C allocation strategy provide new insights into the C budget of grassland ecosystems and increase our understanding of the role of C fixation and partitioning when plants respond to environmental challenges.
查看更多>>摘要：Shifts in animal husbandry and landscape use have significantly changed ungulate grazing effects on ecosystem functioning. These changes are now the subject of extensive research with respect to plant and soil communities, but the results of these studies are highly varied and context dependent. The objective of this study is to address contextual variation by holding all sampling methods and analytical approaches constant and analyse the effect of the feral goat (Capra hircus) population of Mallorca Island, Spain, on soil physical, chemical and biological characteristics across five controlled sites. Specifically, vegetation cover and soil properties in fenced plots excluded from ungulates were compared with adjacent grazed plots in five independent mountain areas of Mallorca. Soil microbial activity measured as Community-Level Physiological Profiles (CLPP) using EcoPlate (TM) increased when ungulates were excluded. However, all other physical and chemical measures of the soils did not vary significantly when we considered ungulate exclusion across all plots, and this may be caused by a soil community that is simply robust to the effects of the herbivores. Or, it may be due to the high heterogeneity that was detected among pair plots comparisons within each of the five sites. Indeed, we find more variability within a site than among our independent sites leading us to hypothesize that grazing does influence biogeochemical cycles, but it does it by increasing variability of the system in general. Our well-controlled multilevel meta analysis confirms the notion that ungulate effects are highly context dependent, and soil heterogeneity makes resolving clear patterns very challenging. Apparently, context persistently drives the soil response more than the grazing itself, and this is seen even at very small scales.
查看更多>>摘要：China is the main global garlic and rice producer and garlic-rice (GR) therefore represents an important crop planting system. However, the relationship between the agricultural output and greenhouse gas emissions under the GR system remains unknown. In this study, we analyzed the greenhouse gas emissions, crop yield, net economic benefits, and other potential influencing factors of the GR system, to explore the impact of different crop systems on food output and the environment. We used a wheat-rice (WR) system as the control and collected data for two years (2017-2018). Net economic benefits of the GR system were 28670.2 and 35799.8 CNY ha-1 in the two years, respectively, much higher than corresponding values of 2718.4 and 1825.6 CNY ha-1 for the WR system. Global warming potential was 78.43% and 168.66% higher for the GR system in the same years. Compared to the WR system, the global warming potential of the GR system was concentrated in the dry season, with the main contributor being N2O emissions (57.62%). Two-year greenhouse gas emission intensities calculated using net economic benefits (0.11 and 0.08) were less than one-fifth of those of the WR system. The GR system could therefore be an effective option for generating high net economic benefits with a low greenhouse gas emission intensity.
NSTL
Elsevier