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31.
32.
Soil carbon sequestration with continuous no-till management of grain cropping systems in the Virginia coastal plain 总被引:2,自引:1,他引:2
John T. Spargo Marcus M. Alley Ronald F. Follett James V. Wallace 《Soil & Tillage Research》2008,100(1-2):133-140
Carbon sequestration in agroecosystems represents a significant opportunity to offset a portion of anthropogenic CO2 emissions. Climatic conditions in the Virginia coastal plain and modern production practices make it possible for high annual photosynthetic CO2 fixation. There is potential to sequester a substantial amount of C, and concomitantly improve soil quality, with the elimination of tillage for crop production in this region. The objectives of our research were to: (1) measure C sequestration rate with continuous no-till management of grain cropping systems of the Virginia middle coastal plain; (2) determine the influence of biosolids application history on C content and its interaction with tillage management; and (3) evaluate the impact of continuous no-till C stratification as an indicator of soil quality. Samples were collected from 63 sites in production fields using a rotation of corn (Zea mays L.)–wheat (Triticum aestivum L.) or barley (Hordeum vulgare L.)/soybean double-crop (Glysine max L.) across three soil series [Bojac (coarse-loamy, mixed, semiactive, thermic Typic Hapludults), Altavista (fine-loamy, mixed semiactive, thermic Aquic Hapludults), and Kempsville (fine-loamy, siliceous, subactive, thermic Typic Hapludults)] with a history of continuous no-till management ranging from 0 to 14 years. Thirty-two of the sites had a history of biosolids application. Five soil cores were collected at each site from 0–2.5, 2.5–7.5 and 7.5–15 cm and analyzed for bulk density and soil C. Bulk density in the 0–2.5 cm layer decreased and C stratification ratio (0–2.5 cm:7.5–15 cm) increased with increasing duration of continuous no-till due to the accumulation of organic matter at the soil surface. A history of biosolids application resulted in an increase of 4.19 ± 1.93 Mg C ha−1 (0–15 cm). Continuous no-till resulted in the sequestration of 0.308 ± 0.280 Mg C ha−1 yr−1 (0–15 cm). Our results provide quantitative validation of the C sequestration rate and improved soil quality with continuous no-till management in the region using on-farm observations. 相似文献
33.
Yuk HJ Curtis-Long MJ Ryu HW Jang KC Seo WD Kim JY Kang KY Park KH 《Journal of agricultural and food chemistry》2011,59(23):12683-12690
Soybean leaves are eaten as seasonal edible greens in Korea. Analysis of the ethyl acetate extract of these leaves showed that it exhibited potent and selective neuraminidase inhibition, which began at the R3 stage and peaked at R7. Ten pterocarpans, including the new 6a-hydroxypterocarpan 10, were isolated from soybean leaves and their inhibition activities tested against a range of glycosidases. The relationship between structure and enzyme inhibition was investigated: 6a-hydroxypterocarpans exhibited much higher inhibition against neuraminidase (IC(50) = 2.4-89.4 μM) than α-glucosidase (IC(50) = 90.4-?>100 μM). Glyceollin VII (7) displayed 40-fold greater activity (IC(50) = 2.4 μM) against neuraminidase than α-glucosidase (IC(50) = 90.4 μM). On the other hand, coumestanes (1-3) were good α-glucosidase inhibitors (IC(50) = 6.0-42.6 μM). In kinetic analysis, the most potent neuraminidase inhibitors (5-10) were noncompetitive. HPLC analysis indicated that most pterocarpan synthesis began from the R3 stage, and a rapid change of pterocarpan concentrations was observed between the R4 and R7 stages. 相似文献
34.
Many threatened primates now exist in fragmented forest habitats. The survival of these populations may depend on their ability to utilise agricultural or other matrix habitats between forest fragments, but this is poorly known. Here, we systematically investigate an arboreal primate’s use of a heterogeneous matrix in a fragmented forest landscape: the Angola black-and-white colobus (Colobus angolensis palliatus) in southern Kenya. We used a novel technique, based on semi-structured interviews with local informants, to address the difficulty of sampling relatively rare but important events, such as dispersal between fragments. We found that colobus frequently travelled and foraged in indigenous matrix vegetation (such as mangrove, wooded shrubland and shrubland) up to 4 km from the nearest forest fragments. Agricultural habitats, such as perennial plantation (coconut, mango and cashew nut) were also used by colobus for travelling and foraging (in remnant indigenous trees). The probability of sighting colobus in the matrix increased with the proportion of both tall (>6 m) vegetation cover and food tree cover, but declined with distance from forest habitat. Our findings suggest that certain matrix habitats are important for C. a. palliatus, and that future primate conservation initiatives might benefit from adopting a ‘landscape-level’ approach to habitat management, particularly in fragmented forest systems. 相似文献
35.
Root development of winter wheat in erosion‐affected soils depending on the position in a hummocky ground moraine soil landscape
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Agricultural soil landscapes of hummocky ground moraines are characterized by 3D spatial patterns of soil types that result from profile modifications due to the combined effect of water and tillage erosion. We hypothesize that crops reflect such soil landscape patterns by increased or reduced plant and root growth. Root development may depend on the thickness and vertical sequence of soil horizons as well as on the structural development state of these horizons at different landscape positions. The hypotheses were tested using field data of the root density (RD) and the root lengths (RL) of winter wheat using the minirhizotron technique. We compared data from plots at the CarboZALF‐D site (NE Germany) that are representing a non‐eroded reference soil profile (Albic Luvisol) at a plateau position, a strongly eroded profile at steep slope (Calcaric Regosol), and a depositional profile at the footslope (Anocolluvic Regosol). At each of these plots, three Plexiglas access tubes were installed down to approx. 1.5 m soil depth. Root measurements were carried out during the growing season of winter wheat (September 2014–August 2015) on six dates. The root length density (RLD) and the root biomass density were derived from RD values assuming a mean specific root length of 100 m g?1. Values of RD and RLD were highest for the Anocolluvic Regosol and lowest for the Calcaric Regosol. The maximum root penetration depth was lower in the Anocolluvic Regosol because of a relatively high and fluctuating water table at this landscape position. Results revealed positive relations between below‐ground (root) and above‐ground crop parameters (i.e., leaf area index, plant height, biomass, and yield) for the three soil types. Observed root densities and root lengths in soils at the three landscape positions corroborated the hypothesis that the root system was reflecting erosion‐induced soil profile modifications. Soil landscape position dependent root growth should be considered when attempting to quantify landscape scale water and element balances as well as agricultural productivity. 相似文献
36.
Double-stranded ribonuclease coinduced with interferon 总被引:5,自引:0,他引:5
Double-stranded (ds) RNA and many viruses are inducers of interferon (IFN), the latter presumably because they contain, or can form, dsRNA. Concomitant with the induction of IFN in chicken embryo cells was the induction of a novel double-stranded ribonuclease (dsRNase), which was released into the medium and continued to accumulate long after IFN production ceased. Only avian cells (chicken, quail, turkey, or duck) expressed high levels of this dsRNase; mammalian, turtle, or fish cells did not. Production of the nuclease was inducer dose-dependent. Optimum pH and cation requirements distinguished it from other dsRNase activities. Degradation of dsRNA was endonucleolytic. Activity resided in a molecule of an Mr of approximately 34,500. Low levels of a single-stranded (ss) RNase activity were inseparable from the dsRNase. The role for a dsRNA-inducible dsRNase released from cells is unknown. 相似文献
37.
Marcus André Ribeiro Correia Renato de Mello Prado Willian Natale Danilo Eduardo Rozane Diego Wyllyam do Vale 《Communications in Soil Science and Plant Analysis》2018,49(8):903-912
Soil acidity is one of the most important factors limiting crop production. The objective of this work was to evaluate the effects of limestone application on the soil chemical properties, nutrition and yield of mango plants in an orchard under implementation. The design was randomized blocks, with five limestone doses (0; 2; 4; 6 and 8 t ha?1) and four replications. Soil chemical analyses were performed (at 12, 24, 36 and 48 months after the experiment implementation) in the layers 0–20; 20–40 and 40–60 cm deep. Nutrition status and yield were assessed during the first and second crop seasons. The highest fruit yield was associated with the application of 3.9 and 3.8 t ha?1 of limestone in the 2008/09 and 2009/10 seasons, respectively, that is, the dose recommended by the literature for raising base saturation to 80%, as a function of the fertility conditions of the soil initially obtained. 相似文献
38.
Marcus Gumpert 《Growth and change》2019,50(2):775-802
Desmet, Gumpert, and Ort?n have analyzed regional development using the Ricardian model or the Heckscher–Ohlin theorem. However, aspects such as consideration of combined wages, substitution elasticities, marginal costs, fixed costs, and number of companies were completely ignored. This study investigates the underdevelopment of regions in light of Krugman`s core–peripheral model. The extension of the model is intended to analyze the aspects that have so far been ignored and their influence on the benefits of the two regions. The following aspects characterize the model. Two regions with two sectors are considered for the model. The regions are characterized by different technological equipment. The first region is industrial. The second region has an agricultural character. When a new technology is available, both regions can benefit under certain conditions. The financial transfers lead to a convergence of wages. 相似文献
39.
Marcus J. Collier 《Landscape Ecology》2015,30(8):1363-1369
40.
Temporal development and actual assessment of a lead soil contamination in the surroundings of a glass factory in Thuringia In this study the lead content in the area around a source of emission was investigated. The lead pollution of the soil originates in lead containing dust from glass production. The overall contamination of the considered area was found out using the geostatistical method of kriging. The measurement included 34 samples taken at different spots around the source of emission. A similar study as this was made in the beginning of the eighties. In comparison to the latter the recent results show lower values of lead contamination of the soil, but at the same time the area of pollution enlarges. At a high polluted point a profile of the soil was investigated. It showed that the lead content decreases rapidly with increasing depth. A contamination by lead can be detected down to a depth of 20 cm. The lead values show a significant correlation with the carbon contents of the soil. An estimation of the amount of lead stored in the investigated area indicates an obvious reduction from 2.1 t in 1985 to 1 t in 1994. This can be explained by a secondary transfer of the dust from the considered to adjoining areas. 相似文献