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31621. 题目: Changes in soil enzymes, soil properties, and maize crop productivity under wheat straw mulching in Guanzhong, China
文章编号: N18062585
期刊: Soil and Tillage Research
作者: Kashif Akhtar, Weiyu Wang, Guangxin Ren, Ahmad Khan, Yongzhong Feng, Gaihe Yang
更新时间: 2018-06-25
摘要: Addition of organic material, such as crop straw mulch in most soils is considered a strategy for sustainable agricultural production. We conducted a two-year experiment in 2015 and 2016 to determine changes in soil biochemical properties and maize yield in response to treatment with wheat-straw mulch. The treatments consisted of the addition of different levels of wheat-straw mulch (S1: 0, S2: 2500, S3: 5000 kg ha 1). Soil samples from four depths (0.1, 0.2, 0.3, and 0.4 m) were collected and analyzed. Soil enzymes, such as invertase, phosphatase, urease, and catalase, were significantly higher in the S3 treatment than in the S1 treatment. Values were greater for the samples collected at 0.1 m soil depth than those collected from deeper soil layers. Regarding soil properties, soil organic carbon (SOC), available nitrogen (AN), available phosphorus (AP), total nitrogen (TN), total phosphorus (TP), and soil water content (SWC) were significantly higher in S3 at 0–0.1 m soil depth than in other treatments. Compared with the (S1), an average increase in SOC, AN, AP, TN, TP, and SWC in 0–0.4 m soil depth with full straw mulch (S3), were 32.4, 31.9, 32.0, 11.8, 16.7, and 18.5%, higher, respectively. On average, urease, phosphatase, invertase, and catalase increased by 15.1, 11.0, 88.4, and 24.0%, respectively in the S3 treatment compared with that in the S1 treatment at 0–0.1 m depth, and decreased with increasing soil depth. The S3 treatment had increased grain yield (7%), biomass yield (28%), and water use efficiency (8%), compared with the S1 treatment. Overall, our results suggested that the S3 straw mulch treatment (5000 kg ha 1) could be used to sustain maize productivity and promote a better relationship between soil enzymes and soil properties in the semi-arid conditions of the Guanzhong area.

31622. 题目: Characterization of the heavy, hydrolysable and non-hydrolysable fractions of soil organic carbon in conventional and no-tillage soils
文章编号: N18062584
期刊: Soil and Tillage Research
作者: Ravindra Ramnarine, Robert P. Voroney, Kari E. Dunfield, Claudia Wagner-Riddle
更新时间: 2018-06-25
摘要: Quantification of soil organic carbon (SOC) pool fractions under different tillage systems is important in understanding SOC dynamics and storage. Two major pools of SOC that can be isolated are the light (LF) and heavy fractions (HF). Few studies have quantified the effect of tillage systems on the hydrolysable (HYF) and non-hydrolysable fractions (NHF) which comprise the HF. The objective of this study was to evaluate if there were significant changes in the quantity and δ13C of the HF, HYF, and NHF fractions of SOC after six years of no-tillage (NT), on arable soils that were previously under conventional tillage (CT). Our study used 13C natural abundance (rotation of C3 and C4crops) on a calcareous Typic Hapludalf soil in southern Ontario, Canada. The HF (>1.7 g cm 3) was isolated using density fractionation and separated into its HYF and NHF using acid hydrolysis (6 M HCl) for three soil depths: 0–10, 10–20, and 20–30 cm. The HF pool (90–93% of SOC) was significantly greater (P < 0.05) in the NT (28.9) than the CT system (25.5 Mg C ha 1) only for the 0–10 cm depth. The dominant SOC fraction from the HF pool was the NHF (62–65% of SOC) for both tillage systems. However, the HYF (25–30% of SOC) was significantly greater in the NT (9.3) than the CT system (7.0 Mg C ha 1) only for the 0–10 cm depth. Additionally, there was a significantly higher proportion of C4-derived C in the HF only at the 0–10 cm depth of NT soils. Differences in the δ13C of the whole soil and SOC fractions show a preservation of newly derived C in the HF, HYF and NHF of NT soils. We conclude that the adoption of NT systems on arable soils increases the quantity of HF and HYF in the 0–10 cm depth only, but there is no difference in carbon sequestration potential when treatments are compared over the 0–30 cm depth in the short-term.

31623. 题目: Consolidation and surface sealing of nine harrowed Swedish soils
文章编号: N18062583
期刊: Soil and Tillage Research
作者: Maria Sandin, Nicholas Jarvis, Mats Larsbo
更新时间: 2018-06-25
摘要: The structure of agricultural topsoils varies considerably throughout the year due to interactions between climatic and biological factors and agricultural management practices. Tillage generally decreases soil density and increases macroporosity, but the resulting arrangement of clods and aggregates is unstable and the soil eventually reverts back to its denser pre-tillage condition. Accounting for post-tillage changes in soil structure and related hydraulic properties could greatly improve model predictions of hydrological and transport processes. Model testing, development and parameterization is, however, currently hampered by a lack of direct measurements of the changes occurring in the structural pore system. We subjected repacked samples of soil collected from the harrowed layer of nine different fine- and medium-textured Swedish mineral soils to subsequent wetting and drying cycles in the laboratory. Initial wetting and equilibration at 30 cm pressure potential was followed by three cycles of simulated rainfall (5 mm h 1 for 4 h) and equilibration. X-ray tomography was used to quantify changes in surface and total porosity, pore size distribution (PSD) and connectivity of structural pores. Total porosity decreased (by 2–24%) in all soils except for two clay soils where in one case the porosity increased slightly (3%) and remained unchanged in the other. In six of the soils, the PSD shifted significantly towards smaller pore sizes, and in four of these soils the connectivity of the pore network decreased. Soil surface porosity decreased most markedly in two silt loam soils (by 73% and 75%). For the nine soils changes were strongly correlated with silt content. Only weak correlations were found between the changes in total porosity and soil texture and organic carbon content. Changes in the PSD appeared to be mainly controlled by the initial structure of the sample created at the time of tillage and sample preparation.

31624. 题目: Crop yield, weed infestation and soil fertility responses to contrasted ploughing intensity and manure additions in a Mediterranean organic crop rotation
文章编号: N18062582
期刊: Soil and Tillage Research
作者: Paola Baldivieso-Freitas, José M. Blanco-Moreno, Laura Armengot, Lourdes Chamorro, Joan Romanyà, Francisco Xavier Sans
更新时间: 2018-06-25
摘要: Conservation agriculture and organic farming are two alternative strategies that aim to improve soil quality and fertility in arable cropping systems through reducing tillage intensity, maintaining soil cover and increasing nutrient recycling, using farmyard and green manures. However, these practices can increase weed infestation or decrease nutrient availability. The objectives of this study were to evaluate the effects of tillage type (mouldboard vs. chisel ploughing), fertilization and green manure on soil parameters (SOC, N, bulk density, carbon stocks, and soil microbial biomass Cmic and Nmic), weed abundance and crop yields in a four-year rotation of spelt, chickpea, winter wheat and lentil in the Mediterranean region (Catalonia, Spain). Tillage and green manure did not affect crop yields or weed biomass, although during the last year of the experiment, plots with mouldboard ploughing had less weed biomass and higher lentil biomass. Fertilization was the most important factor, increasing the cereal yields, SOC, N and soil microbial biomass (Cmic and Nmic) content of the soil. However, fertilization did not favour chickpea and lentil crops because weed competition limited legume crop growth. Overall, there was a loss of SOC and a reduction of carbon stocks over the four years of the trial in the soil because of the deep soil tillage (25 cm) and low crop productivity irrespective of tillage type. In contrast, N content increased in all of the plots and was enhanced by fertilization. The use of chisel plough stratified the distribution of SOC and N in the surface layers (0–10 cm). Both Cmic and Cmic/SOC ratio increased in fertilized treatments, suggesting an increased lability of SOC. The application of more stabilized organic matter may be a better practice to build up soil organic matter and to maintain crop yields in organic farming systems.

31625. 题目: Effect of land use, time since deforestation and management on organic C and N in soil textural fractions
文章编号: N18062581
期刊: Soil and Tillage Research
作者: Alexandros Eleftheriadis, Francisco Lafuente, Maria-Belén Turrión
更新时间: 2018-06-25
摘要: Deforestation and subsequent cultivation practices often result in loss of soil organic matter, in a degree depending on time since deforestation and soil and crop management. A land in North Greece was studied in order to check the influence of land use and management on soil organic C (SOC) and N. Cultivated soils with three dates since deforestation (25, 34 and 72 years) were compared to adjacent undisturbed forest soils. Two management systems were used in the cultivated soils: not irrigated wheat with superficial ploughing and irrigated cotton crop with deeper ploughing alternated with wheat every two years. Soil samples were separated in textural size fractions and organic C and N were analysed. In terms of land use, the most distinctive differences between agricultural and forest plots were found in coarse particulate organic matter (2.8 g kg 1 soil in agricultural land vs 14.8 g kg 1 soil in forest sites), and in the fine sand fraction SOC (8.6 g kg 1 soil in agricultural land vs 40.6 g kg 1 soil in forest sites), and N (1 g kg 1 soil in agricultural land vs 2.4 g kg 1 soil in forest sites), with minimal differences in the clay fraction (15.5 g kg 1 soil in agricultural land vs 21.2 g kg 1 soil in forest sites for SOC, and 2.2 g kg 1 soil in agricultural land vs 2.4 g kg 1 soil in forest sites for N). Time as a factor was significant for all the studied properties regarding the first years following deforestation. Management practices had an effect on SOC and, more pronounced, on N, with the wheat plots showing higher contents. Clay particles present the most stable behavior in terms of SOC (especially regarding time and management as factors) and N (especially regarding land use and time as factors) protection and maintenance.

31626. 题目: Effects of biochar on spatial and temporal changes in soil temperature in cold waterlogged rice paddies
文章编号: N18062580
期刊: Soil and Tillage Research
作者: Yuxue Liu, Shengmao Yang, Haohao Lu, Yuying Wang
更新时间: 2018-06-25
摘要: Soil temperature is an important factor constraining plant growth, large fluctuations of which generally result in low crop yield. However, the investigation of the effect of biochar on soil temperature, especially in cold waterlogged paddies, has been limited. This study investigated the effect of bamboo biochar (BB), rice straw biochar (RB), and rice straw (RS) on temporal variations in soil temperature at different depths, compared with no exogenous organic matter amendment soil as control treatment (CK), in a cold waterlogged paddy in Zhejiang Province, China. A logger with probes was used to record soil temperatures at the depths of 5 cm, 10 cm, and 20 cm at 08:00 h, 14:00 h, and 22:00 h daily from July 1 to Oct 31, 2012. Soil physicochemical properties and rice yield were analyzed after the harvest. The results showed that the application of BB and RB significantly reduced the soil temperature at 5- and 10-cm depths by 0.11 °C–0.21 °C on average, whereas RS significantly reduced soil temperature at a 5-cm depth by 0.19 °C and increased the average temperature at a 20-cm depth by 0.06 °C. Moreover, the average soil temperature related to BB, RB, and RS treatment significantly increased at 08:00 h during the rice-growing season by 0.15 °C, 0.43 °C, and 0.52 °C and significantly decreased at 14:00 h by 0.51 °C, 0.73 °C, and 0.87 °C, respectively, as compared with that in CK. Overall, both biochar and RS reduced the differences between day and night soil temperatures by 0.66 °C–1.39 °C, thereby regulating diurnal soil-temperature fluctuations, especially at a 5-cm depth. The reduced differences were likely attributed to the relatively lower bulk density (8.87–17.1%) and higher water content (9.75–14.3%) in the biochar-amended soil as compared with that in control soil. Furthermore, RB had a significant stronger positive effect on grain yield than BB, because it regulated soil temperature more effectively. These results suggested the feasibility of applying RB to cold waterlogged paddies to improve soil properties and crop yield.

31627. 题目: Effects of biological soil crusts on some physicochemical characteristics of rangeland soils of Alagol, Turkmen Sahra, NE Iran
文章编号: N18062579
期刊: Soil and Tillage Research
作者: Jalil Kakeh, Manouchehr Gorji, Mohammad Sohrabi, Ali Tavili, Ahmad Ali Pourbabaee
更新时间: 2018-06-25
摘要: Salinity, water scarcity in the summer season, and grazing pressure are major problems in semi-arid ecosystems in the south-east region of the Caspian Sea where the Alagol rangelands of Turkmen Sahra (Golestan province) of North East Iran suffer from over-grazing and soil loss. This study investigated the influence of biological soil crusts (biocrusts) on soil physicochemical properties. Biocrusts create complex communities of specialized organisms composed of cyanobacteria, algae, microfungi, lichens, mosses and other microorganisms. Results have shown that bioencrusted soils increased levels of organic carbon, nitrogen, phosphorus, copper, and iron, and reduced pH, calcium carbonate, sodium, calcium, magnesium, sodium adsorption ratio and exchangeable sodium percentages compared to soils without biocrusts. Other positive influences of biocrusts on soil properties included increased infiltration (0.16 v. 0.081 cm min 1 for steady state rates), available water content, mean weight diameter of soil aggregates, geometric mean diameter and water stable aggregates. Bulk density was reduced under bioencrusted soils relative to non-biocrusts soils. In general, biocrusts had a positive effect on many soil properties and thus enhanced soil quality.

31628. 题目: Grass cultivation alters soil organic carbon fractions in a subtropical orchard of southern China
文章编号: N18062578
期刊: Soil and Tillage Research
作者: Hui Wei, Kun Zhang, Jiaen Zhang, Dengfeng Li, Yuan Zhang, Huimin Xiang
更新时间: 2018-06-25
摘要: Understory management is evidently important for improving the ecological and economic effects of orchards, and grass maintenance in orchards is a potentially preferable floor management measure relative to clean tillage. It is widely accepted that grass maintenance increases soil organic carbon (SOC) content, but whether different SOC fractions respond consistently is less understood. To clarify the potential effects of grass maintenance on SOC fractions, three grass species, including a leguminous species (Stylosanthes guianensis cv. Reyan) and two gramineous species (Paspalum notatum Alain ex Flugge. and Pennisetum americanum x P. purpureum), were planted under young Litchi trees in a subtropical orchard of southern China for eight months using clean tillage as a control. The labile and non-labile SOC fractions and microbial C mineralization were investigated. Relative to the control, grass cultivation significantly increased or trended to increase the SOC content and this was mainly due to increases in the labile SOC fractions. The increased C lability and substrate supply support higher soil microbial biomass C, consequently accelerating the soil C mineralization process and resulting in a greater biologically mineralizable C pool. However, grass cultivation significantly decreased the non-readily oxidizable OC content, although it was relatively more chemically recalcitrant. Our results suggest that grass cultivation may favorably accelerate nutrient cycling in orchards due to higher labile C substrate availability and soil microbial biomass and activity. Nevertheless, grass cultivation could decrease SOC stabilization as indicated by the increased SOC lability in the grass-planting systems.

31629. 题目: Impact of reduced tillage on CO2 emission from soil under maize cultivation
文章编号: N18062577
期刊: Soil and Tillage Research
作者: Beata Rutkowska, Wies?aw Szulc, Tomasz Sosulski, Monika Skowrońska, Jan Szczepaniak
更新时间: 2018-06-25
摘要: Carbon dioxide is an important greenhouse gas, which is released through human activities such as deforestation, burning fossil fuels, agriculture, and degradation of soil. The type of soil tillage systems has a very important impact on soil CO2 emissions. Usually higher soil CO2 emission have been observed under conventional tillage compared to reduced tillage. Maize is one of the main cereals grown around the world that reacts positively on conservation tillage. We hypothesized that reduced tillage with sub-soil fertilizer application could increase maize yield and reduce carbon emissions compared to conventional plowing. Therefore we studied CO2 emissions from soil under a conventional and innovative, environmentally safe, low-cost maize production system dedicated both to reduce time and resources and to manage the field sustainably with a lower CO2 footprint. We observed that the magnitude of grain yield depended on soil and climate conditions but not on the cultivation system. The CO2 emission level depended on the year of the study and the soil tillage method and was subject to considerable changes during the growing season. The use of reduced soil tillage significantly limited emissions of the analyzed gas into the atmosphere. Depending on the year of the study, CO2 emissions in the reduced tillage system were 7 to 35% lower than those in the conventional system. The extent of the reduction in CO2 emissions achieved under reduced tillage is very large relative to conventional tillage, which is probably due to the relatively low organic matter content of the both investigated soils in the conventional tillage. We could show that on sandy soils with a low organic matter content reduction in tillage is a factor significantly diminishing CO2 emissions.

31630. 题目: Irrigation induced surface carbon flow in a Vertisol under furrow irrigated cotton cropping systems
文章编号: N18062576
期刊: Soil and Tillage Research
作者: Gunasekhar Nachimuthu, Nilantha R. Hulugalle, Mark D. Watkins, Lloyd A. Finlay, Bruce McCorkell
更新时间: 2018-06-25
摘要: Pathways of sequestered carbon loss from cotton (Gossypium hirsutum L.) farming systems include the carbon transported off-site in runoff and erosion. There is a lack of field studies that quantify the carbon gains and losses in hydrological pathways in cotton and other irrigated row cropping systems A three-year field investigation was overlaid on a long-term experiment near Narrabri, New South Wales, Australia with the objective to evaluate the effect of tillage practices and crop rotations on carbon loads in irrigation and runoff waters, and their impact on soil carbon balance in an intensive cotton production system. The treatments included maximum or minimum tillage sown with cotton monoculture, cotton-wheat (Triticum aestivum L.) or cotton-maize (Zea mays L.) rotations. Maximum tillage consisted of slashing of cotton plants after harvest, followed by disc-ploughing to incorporate the cotton stalks to 0.2 m, followed by chisel ploughing to 0.3 m, then 1 m bed construction. For minimum tillage, slashing was followed by root cutting, then incorporation of cotton stalks into beds (0.1 m) and followed by bed renovation with a disc-hiller. The minimum-tilled cotton-wheat rotation included similar tillage operations after cotton, however maize or cotton was planted into standing wheat stubble with zero tillage. Irrigation volume, sediment, and total and dissolved organic carbon gains and losses during irrigation were monitored during the 2014–15, 2015–16 and 2016–17 cotton seasons. Runoff from maximum-tilled and minimum-tilled cotton monoculture systems averaged 32% and 40%, respectively, of applied irrigation. Irrigation-induced total organic carbon (TOC) losses in runoff from the cotton field were influenced by tillage during 2015–16 and ranged from 24 to 72 kg ha 1 year-1 across three years. Net TOC enrichment of cotton field soils by irrigation water ranged from 30 to 265 kg TOC ha-1. Overall, the average seasonal net carbon gains in irrigation water were equivalent to mitigating 4.7 to 24% of long term annual soil organic carbon (SOC) decline rate in the same experiment. Storm events intensified the movement of carbon and soil from bed to furrows. These sediments were prone to further erosion during subsequent irrigations. Minimum tillage can minimise carbon losses in runoff when combined with a crop sequence such as cotton-wheat-maize. Consequently, research on soil carbon sequestration in irrigated systems must account for carbon flow during irrigation because it is a significant factor in the carbon balance. Long term monitoring over several years is needed to quantify storm-induced carbon losses in semi-arid limited rainfall environments.

31631. 题目: Microaggregate stability and storage of organic carbon is affected by clay content in arable Luvisols
文章编号: N18062575
期刊: Soil and Tillage Research
作者: Lars Krause, Andrei Rodionov, Steffen A. Schweizer, Nina Siebers, Eva Lehndorff, Erwin Klumpp, Wulf Amelung
更新时间: 2018-06-25
摘要: As soil microaggregates (<250 μm, SMA) usually withstand long-term tillage, we hypothesized that i) elevated clay contents in arable soil support aggregation already at microaggregate level, leading to ii) increasing organic carbon (SOC) enrichment in smaller SMA size fractions. To test these hypotheses we sampled the topsoil (5–20 cm) of Luvisols with a long history of agricultural management at the Scheyern experiment station (Germany) in quintuplicates from each of five subsites with different clay contents (19–34%). The field-fresh topsoil was fractionated into macroaggregates (8000–250 μm), large SMA (250–20 μm), and small SMA (<20 μm) and the mass distribution was recorded. In addition, the water stable macroaggregates (>250 μm) were dispersed ultrasonically to study occluded SMA and single building units. Finally, we analyzed the size distribution of the small SMA by laser diffraction analysis. The total mass distribution of free and occluded SMA grouped soils into those with small (19, 22, and 24%) and large (32 and 34%) clay contents. The finer textured soils exhibited larger portions of occluded SMA, with a gamma size distribution of small SMA peaking at 6 μm. Yet the occluded small SMA in the finer textured soils showed an additional enrichment of colloids <1 μm. The SOC was indeed enriched in finer fractions, but more in the small SMA of the coarse textured sites than in the finer textured ones, whereas the opposite was true for the large SMA. We conclude, therefore, that elevated contents of clay-sized particles promote SMA formation and stabilization, therewith shifting SOC enrichment from small to larger SMA.

31632. 题目: Mid-long term effects of no tillage and Ca-amendment on degraded acid soils under contrasting weather conditions
文章编号: N18062574
期刊: Soil and Tillage Research
作者: Chiquinquirá Hontoria, Clara Gómez-Paccard, Eduardo Vázquez, Ignacio Mariscal-Sancho, Rafaela Ordónez-Fernández, Rosa Carbonell-Bojollo, Rafael Espejo
更新时间: 2018-06-25
摘要: Inadequate soil management such as excessive ploughing is one of the main problems affecting the sustainability of agroecosystems and may exacerbate problems in acid soils. The application of Ca-amendments to ameliorate acid soils and no tillage practices to recover degraded soils are common management strategies. However, few studies have focused on their interactive effects under conditions of variable rainfall. In this study, we assessed the changes in soil properties over a period of seven years in response to no tillage (NT) and tillage, with or without the application of a Ca-amendment (sugar beet foam and red gypsum). Our split-plot experiment, which started in 2005 was carried out in a degraded Palexerult in Southwestern Spain with an annual rainfed forage crop. The Ca-amendment increased soil pH, Ca content and ameliorated Al-toxicity down to a depth of 50 cm, even under NT, due to the relatively high solubility of the amendment. However, after seven years of experiment, soil organic matter variables were enhanced only to a soil depth of 0–5 cm: NT and the Ca-amendment increased total organic carbon by 31% and 25%, respectively, whereas particulate organic carbon was increased to a larger extent (by a factor of 2.5 and 2, respectively). The positive effect of NT on organic matter variables increased with time, whereas the beneficial effect of the Ca-amendment was stronger in the early years of the experiment. Adverse weather conditions, with either excessive precipitation in autumn-winter or scarce precipitation in spring, favoured biomass production under NT. Given that NT mitigated the adverse effects of both water excess and deficit on biomass, it constitutes a valuable tool to combine with Ca-amendment to maintain crop productivity and recover degraded acid soils. This is especially the case under the changing weather conditions of a Mediterranean climate or other climates with increasing occurrences of periods of drought and/or water excess.

31633. 题目: Modeling soil organic carbon and carbon dioxide emissions in different tillage systems supported by precision agriculture technologies under current climatic conditions
文章编号: N18062573
期刊: Soil and Tillage Research
作者: Donato Cillis, Bernardo Maestrini, Andrea Pezzuolo, Francesco Marinello, Luigi Sartori
更新时间: 2018-06-25
摘要: Soil organic matter (SOM) represents the biggest pool of carbon within the biosphere and influences the flux of greenhouse gases between land surface and atmosphere. In this regard, conservation tillage systems have been adopted to reduce negative impacts of conventional tillage practices on greenhouse gases (GHG) emissions. However, the role of these techniques to increase carbon sequestration also depends upon soil features and climatic conditions, which is studied and managed by precision agriculture (PA) principles and technologies. Simulation models have shown to be useful tools to understand the interaction between soil, climate, genotypes and management practices to simulate the long-term effects of management approaches of different soils on crop yield, soil organic carbon (SOC) storage, and GHG emissions. The research goals of this study are (1) to examine the mid-term (15 years) trajectory of SOC in the upper 0.4 m of the soil profile under different tillage systems using the SALUS model; (2) determine the impact of PA on the inputs to the crop and CO2 emissions; (3) identify the strategies, derived from the synergy between conservation agriculture and PA, so as to decrease the CO2 emissions of agricultural systems. The validated SALUS simulation showed a significant reduction in SOC losses in minimum tillage (MT) and no-tillage (NT), 17% and 63% respectively, compared to conventional tillage (CT). Furthermore, the adoption of conservation tillage techniques decreased carbon emissions related to farming operations, while PA technologies led to an optimization of the exhaustible sources such as fossil fuels and fertilizers. Finally, the synergy between conservation tillage systems, especially NT, and PA strategies represents a useful tool in terms of carbon emissions mitigation with a reduction of 56% of total CO2 as compared to CT.

31634. 题目: Seasonal dynamics of the physical quality of volcanic ash soils under different land uses in southern Chile
文章编号: N18062572
期刊: Soil and Tillage Research
作者: Susana R. Valle, José D?rner, Felipe Zú?iga, Dorota Dec
更新时间: 2018-06-25
摘要: In Chile, volcanic soils were developed under almost all of the diverse rain and temperature regimes, from the Arid Mediterranean to the Wet Zone of the South. Due to their andic properties, volcanic soils exhibit characteristics that are entirely different from other soil types around the world. The soil physical quality (SPQ) is strongly related to the functions of the soil pore system. Thus, soils characterized by a good SPQ have the ability to store and conduct water, air and nutrients promoting both: maximum crop yield and minimum environmental degradation. Many studies and much scientific progress have been made concerning the storing and conducting of water and air functions in volcanic soils. However, soil physical quality indicators and their temporal changes have been less studied. Thus, the objectives of this study were: i) to assess the impact of land use changes on the physical quality of three main volcanic soil groups in Chile, ii) to quantify the magnitude of their temporal changes and iii) to compare these results with threshold values found in the literature. Three soils derived from volcanic materials formed under different conditions and with different degrees of development were sampled (with different intrinsic properties), on five sampling dates, under three land uses (intensities): native forest (NF), prairie (P) and crops (C). Undisturbed samples were taken at two soil depths: 0–15 cm and 15–30 cm, in 230 cm3 metallic cylinders, and then covered with caps and plastic film to prevent mechanical disturbance and evaporation. We measured and /or calculated from these samples: air capacity (AC), plant available water capacity (PAWC), relative field capacity (RFC), bulk density (dB), air conductivity (kl), pore connectivity indexes (C2 and C3), the coefficient of linear extensibility (COLE) and saturated hydraulic conductivity (Ks). Undisturbed soil blocks were collected to evaluate aggregate stability. To assess differences among land uses and seasons in the SPQ indicators, analyses of variance (ANOVA) were used and an LSD test (p ≤ 0.05) was conducted to separate the means. A principal component analysis (PCA) was performed to associate the SPQ indicators. The results of this study allow us to conclude that the impact on SPQ indicators depended on the soil type, considering their degrees of development, clay content and type, as well as the organic carbon content and the season in which the soil functions were determined. When values of the SPQ indicators were compared with critical and/or threshold values of the mineral soils found in the literature, the indicators of dB and RFC fell completely out of the range considered typical for mineral soils. Thus, several questions remain regarding the real critical values of these soil properties in volcanic soils. More work is necessary to establish the critical value of volcanic soil’s bulk density, since this is a widely used soil property that serves as an estimator of other functional soil quality indicators.

31635. 题目: Soil organic carbon, macro- and micronutrient changes in soil fractions with different lability in response to crop intensification
文章编号: N18062571
期刊: Soil and Tillage Research
作者: R. Romaniuk, M. Beltrán, L. Brutti, A. Costantini, S. Bacigaluppo, H. Sainz-Rozas, F. Salvagiotti
更新时间: 2018-06-25
摘要: Soils under no tillage have experienced unfavorable changes, mainly due to current agricultural practices that consist in monocultures that leave little residue cover. The inclusion of grass as cover crops during the winter season could be a sustainable strategy to increase crop intensification in sequences where soybean predominates, helping to maintain soil fertility, organic matter levels and enhance soil physical properties. The aim of this research was to evaluate the effects of 8 years of sustainable crop intensification (by increasing the proportion of cereals in crop rotations) on soil organic carbon, macro- and micronutrients associated with granulometric fractions of different lability in a Typic Argiudoll of the Rolling Pampa, Argentina. The experiment included two crop sequences commonly used in this area: soybean-soybean (S-S) and maize-soybean-wheat/soybean (M-S-W/S) combined with the inclusion of wheat (Triticum aestivum L.) as cover crop (CC) in winter. The intensification sequence indices (ISI) were 0.39, 0.69, 0.55 and 0.64 for S-S, S-CC-S, M-S-W/S and M-CC-S-W/S, respectively. The carbon measured in the coarse particulate fraction (Pcf) in the 0–5 cm soil depth was 3 times larger in S-CC-S than in S-S. Cropping intensity also modified N, S, P, Ca and Mn in the Pcf with no changes in Mg, K, Zn, Fe and Cu contents. Among the carbon fractions studied, only the carbon measured in the Pcf and the easy mineralizable carbon estimated by the soil respiration in the first soil layer (0–5 cm), were positively correlated with the ISI. In the present study, 8 years under sustainable crop intensification were sufficient to show changes in the mineral associated fraction (Maf). Increases in the C in the Maf in maize legume-based rotation, suggest SOC accumulation in more stable carbon pools.

31636. 题目: Soil organic matter widens the range of water contents for tillage
文章编号: N18062570
期刊: Soil and Tillage Research
作者: Peter Bilson Obour, Johannes L. Jensen, Mathieu Lamandé, Christopher W. Watts, Lars J. Munkholm
更新时间: 2018-06-25
摘要: The effects of soil organic matter on the water contents for tillage were investigated by sampling soils with a uniform texture, but a range of soil organic carbon (SOC) from two long-term field experiments at Highfield in Rothamsted Research, UK and Askov Experimental Station, Denmark. The treatments studied in Highfield were Bare fallow (BF), Continuous arable rotation (A), Ley-arable (LA) and Grass (G); and in Askov: unfertilized (UNF), mineral fertilizer ( NPK), 1 mineral fertilizer (1NPK), and 1 animal manure (1 AM). Minimally disturbed soil cores (100 cm3) were sampled per plot in both locations from 6 to 10 cm depth to generate water retention data. Soil blocks were also sampled at 6–15 cm depth to determine basic soil properties and to measure soil aggregate strength parameters. The range of soil water contents appropriate for tillage were determined using the water retention and the consistency approaches. SOC content in Highfield was in the order: G > LA = A > BF, and in Askov: 1 AM > 1NPK = NPK > UNF. Results showed that different long-term management of the silt loam Highfield soil, and fertilization of the sandy loam Askov soil affected the mechanical properties of the soils— for Highfield soil, aggregates from the G treatment were stronger in terms of rupture energy when wet ( 100 hPa matric potential) than the BF treatment. As the soil dried ( 300 and 1000 hPa matric potentials), soil aggregates from the G treatment were relatively weaker and more elastic than the BF soil. Our study showed, for both Highfield and Askov soils, a strong positive linear increase in the range of water contents for tillage with increasing contents of SOC. This suggests that management practices leading to increased SOC can improve soil workability by increasing the range of water contents for tillage. We recommended using the consistency approach over the water retention approach for determining the range of water contents for tillage because it seems to give realistic estimates of the water contents for tillage.

31637. 题目: Soils response to the land use and soil climatic gradients at ecosystem scale: Mineralogical and geochemical data
文章编号: N18062569
期刊: Soil and Tillage Research
作者: Andrey Alekseev, Tatiana Alekseeva, Pavel Kalinin, Mieczys?aw Hajnos
更新时间: 2018-06-25
摘要: Ecosystem in responses to land use change create feedbacks in soils and ecological processes in Critical Zone (CZ). The identification and quantification of such changes is needed as a part of understanding the relationship between climate, CO2 emission, humidity, biological activity, soil carbon, surface redox, and plant nutrient cycling and lithology, mineralogy, biogeochemistry of bedrocks. The CZ observation as complex investigation of three Luvic Phaezoem soils under secondary deciduous forest, grassland and cropland from Moscow region, Russia, was fulfilled with the main goal to study weathering processes in soils along global gradients of environmental change. Detailed study of mineralogy and chemistry (XRD, XRF), surface area, porosity, organic matter, carbon/microbial biomass, moisture content, monitoring of total soil respiration was performed. Ecosystem in responses to land use change the parameters of CZ (CO2 emission, humidity, biological activity). Land use change result in climate parameter on a local scale (soil climatic gradients) and formed feedback in weathering intensity and basic soil properties-organic matter, acidity, bulk density, WHC, surface properties and porosity, mineralogy and geochemical changes. The decreasing of smectites in the upper parts of the profile and the increasing of illite and vermiculite content was observed. Montmorillonite into vermiculite transformation, which took place only under the forest, which caused the decreasing of pH, soil vermiculite may also derive from muscovite. The intensity of the given process increases as the following: forest soil <grassland <cropland. The given tendency was explained by both the mineral transformations and redistribution of mineral components within the soil profile. The redistribution of chemical elements between the different sub-fractions of silt and clay is in relationship to the land use. As a general trend, we can conclude that clay fractions in a comparison with bulk soil samples are enriched in both OC and N. Mineralogical and chemical changes influenced the surface properties and porosity. The 50–150 years of different land use resulted in these feedbacks with maximum in aboveground zone and soils as main point of surface of a given CZ.

31638. 题目: Stimulation of N2O emission by conservation tillage management in agricultural lands: A meta-analysis
文章编号: N18062568
期刊: Soil and Tillage Research
作者: Kun Mei, Zhenfeng Wang, Hong Huang, Chi Zhang, Xu Shang, Randy A. Dahlgren, Minghua Zhang, Fang Xia
更新时间: 2018-06-25
摘要: Conservation tillage has been widely adopted in agricultural lands worldwide and is considered a potential strategy for climate change mitigation through enhanced carbon sequestration. However, conservation tillage may alter soil N2O emissions, which may diminish the potential climate change mitigation benefits. Based on 212 observations from 40 publications, a meta-analysis was conducted to quantitatively assess the effects of climate regimes, initial soil properties, and type/duration of agricultural practices on soil N2O emission following application of conservation tillage. Overall, conservation tillage significantly increased soil N2O emission by 17.8% compared to conventional tillage. The greatest increase in N2O emission was observed from soils in tropical climates (70.1%) experiencing short-term (29.3%) application of conservation tillage. Soil pH and clay content significantly influenced N2O emission, while overall soil texture and soil organic carbon (SOC) were not effective predictors of soil N2O emission following conservation tillage. According to the categorical meta-analysis, agricultural practices, including water, residue, and rotation managements and crop types, significantly affected soil N2O emission following conservation tillage. Conservation tillage induced N2O emissions were mitigated with rain-fed cropping systems, residue removal, crop rotation and cultivation of beans and some vegetables. Significant categorical variables affecting N2O emission were mainly attributed to soil aeration and substrate availability, which were important factors affecting nitrification and denitrification processes. Overall, the conservation tillage induced N2O emission factor (EFad ) increased by 0.40%, suggesting an attenuation of climate change benefits from increased N2O emission. Our meta-analysis provides a scientific basis for assessing the effects of conservation tillage on N2O emissions and provides site-specific information to mitigate N2O emissions associated with conservation tillage practices.

31639. 题目: Strength and hydraulics characteristics variations within a tropical Alfisol in Southwestern Nigeria under different land use management
文章编号: N18062567
期刊: Soil and Tillage Research
作者: Johnson Toyin Fasinmirin, Idowu Ezekiel Olorunfemi, Fasilat Olakuleyin
更新时间: 2018-06-25
摘要: This study investigated the hydraulics and strength characteristics of an Alfisol under long-term land use in Akure, southwestern Nigeria. The three agricultural land uses under study are Cropland, Grazing land, and Oil palm plantation. Hydraulic conductivity tests were randomly conducted at 60 sampling points per location (10 m apart), to make a total of 180 samples from the three land uses, while the unconfined compressive strength (qu f) and vane shear strength measurement were conducted in the laboratory and insitu, respectively on soil at depths up to 45 cm (i.e. 0–15, 15 – 30, and 30 – 45 cm). The hydraulic conductivity and soil water sorptivity were determined using mini disk infiltrometer at a steady-state flow of – 0.5, – 1 and – 2 cm water suction rates. Land use and land cover change significantly affected the hydraulic and mechanical properties of the soil (p ≤ 0.001, p ≤ 0.01 and p ≤ 0.05). The hydraulic conductivity value showed an increasing trend from the grazing land to cropland and oil palm plantation in the order: grazing land (4.72 cm h 1) < cropland (10.80 cm h 1) < oil palm plantation (13.21 cm h 1). Grazing land recorded the highest mean soil water sorptivity value, while oil palm plantation had the least value. Grazing land had the highest average qu f and shear strength among the land use types at depths 0–15 cm, 15–30 cm and 30–45 cm of soil. Depth – wise consideration showed that in all the land uses, unconfined compression strength (qu f), shear strength and vane shear strength significantly increased with depth. Soil properties such as organic matter content, bulk density, and aggregate sizes influence the infiltration and strength characteristics of soils of the study area. Land uses influenced the hydraulic properties and strength characteristics of agricultural soils and therefore, assessment of changes in soil properties under land use types should be conducted periodically to effectively monitor the soil status over time. This will guide decisions on measures adoptable to ensure the sustainability of soil structure and texture for optimum crop productivity.

31640. 题目: The benefits of conservation agriculture on soil organic carbon and yield in southern Africa are site-specific
文章编号: N18062566
期刊: Soil and Tillage Research
作者: C.M. Swanepoel, R.P. R?tter, M. van der Laan, J.G. Annandale, D.J. Beukes, C.C. du Preez, L.H. Swanepoel, A. van der Merwe, M.P. Hoffmann
更新时间: 2018-06-25
摘要: Conservation agriculture (CA), with reduced tillage, permanent soil cover and diversified cropping systems, is advocated in southern Africa to improve soil quality, reduce input costs and mitigate climate-induced risks. However, improvements in terms of yield and soil organic carbon (SOC) under CA are slow and variable and many small-scale farmers are unable to buffer themselves against potential short-term financial losses. In this study we examined the effects of CA-related management practices on SOC sequestration and productivity at two medium-term sites on a sandy soil (eight year trial) and clay soil (six years) in maize producing areas of South Africa. Using field data, current input costs and market prices for crops, we calculated the gross margin for each system. Treatments compared conventional ploughing under maize monoculture with reduced tillage, intercropping and crop rotation. On the clay soil, SOC was increased under reduced tillage (57.6 t C ha 1) compared to conventional tillage (54.9 t C ha 1) while there was no difference for the sandy soil (19.7 t C ha 1 average across treatments). Profitability was most strongly influenced by seasonal rainfall, but was higher on the sandy soil than the clay soil, with an average gross margin of R11,344 ha 1 and R5,686 ha 1, respectively. This study has demonstrated that while certain CA practices can create site-specific benefits for farmers, it is highly dependent on local weather and soil conditions. For the clay soil an additional payment scheme would be required to reward farmers in southern Africa for C-sequestration to make CA profitable and achieve increased C-mitigation through soil sequestration.