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1.
Physical protection of mineralizable C in aggregates from long-term pasture and arable soil 总被引:4,自引:0,他引:4
Depending on agricultural management, soil aggregation can provide physical protection of organic matter against rapid decomposition. Within a given soil series, farm management affects the quality and quantity of organic inputs, soil disturbance and biological activity, and thereby the processes of aggregate formation (biogenic vs. physicogenic). We determined the physical protection of readily mineralizable organic matter against mineralization in undisturbed aggregates from a conventional arable field and a permanent pasture (>70 years). Soil samples from the two fields were incubated at constant temperature and moisture content, corresponding to field capacity. The increase in CO2 evolution due to crushing (<250 μm) of the aggregates was used to estimate the macroaggregate-protected C fraction. The fraction of C protected at the microstructural level was estimated from the increase in CO2 evolution after ball-mill grinding. In addition, aggregate size distribution and bulk density and porosity of undisturbed soil and macroaggregates were determined. Unprotected C fractions were not significantly different between the management systems and ranged from 1.9% to 2.4% of total organic C. In the arable soil, 1.4% of total soil organic C was physically protected in macroaggregates. Crushing of macroaggregates did not significantly increase C mineralization in the pasture soil. The results indicate that mineralization was considerably suppressed in the dominantly large and dense physicogenic macroaggregates from the arable field, but not in the dominantly porous, biogenic macroaggregates of the pasture soil. However, the protection in macroaggregates from the arable soil is not likely to be effective on the long-term because of the low water stability and the disrupting forces of cultivation under field conditions. A relatively high additional C mineralization from ground compared to crushed soil material, especially in the upper layer of the pasture soil, suggests a more important C protection at the microstructural level. Higher C protection in microaggregates from the pasture soil was supported by a previous micromorphological study of soil microstructures in thin sections of the considered management systems. 相似文献
2.
Organic carbon (C) was measured in the silt + clay fraction of 78 soils from agricultural areas in Tasmania, and the relationship between C in the silt + clay fraction and the percentage by weight of particles in this fraction was compared with similar data for soils from other regions and climates. Most of the cropping soils from Tasmania followed a previously published linear relationship, which is considered an indication of the capacity of soils to store C. The soils which fell the greatest distance below this relationship were sandy soils, consistent with previous evidence that these soils in Tasmania have been degraded. Soils which showed a major positive departure from the relationship were clay loams with >60% silt + clay. Most were also pasture soils. Tasmania's cool‐temperate climate would promote plant growth and C inputs and slow C breakdown, while the high clay content would help protect C. The results for the clay loam soils are consistent with earlier observations that these soils are generally in good health. 相似文献
3.
耕作年限对棉田土壤颗粒及矿物结合态有机碳的影响 总被引:5,自引:1,他引:5
研究耕作年限对棉田土壤颗粒及矿物结合态有机碳的影响.以相应荒地为对照,选取南北疆兰州湾、31团和普惠农场3个典型绿洲不同耕作年限土壤为研究对象,应用物理分组方法研究颗粒及矿物结合态有机碳的变化规律.结果表明:耕作有利于棉田土壤总有机碳的积累,耕作(0~5年)总有机碳增加迅速,年均增加在0.65 g/kg以上;颗粒有机物、有机碳和颗粒有机碳的分配比例在耕作0~10年间增加,较荒地分别增加50.12%,263.64%,79.79%,10年后下降.矿物结合态有机碳含量则随耕作年限的延长递增,矿物结合态有机物含量变化趋势与颗粒有机物相反.土壤有机碳在耕作1~10年增加,有利于土壤质量的提高,是荒漠区土壤碳汇,是合理的耕作年限. 相似文献
4.
Sandy soil samples collected from under a woody/grass savanna in the Lamto experimental area (6°13N, 5°20W; Côte dIvoire, West Africa), were fractionated according to particle size with the aim of measuring the natural abundance of 15N and determining the contents and composition of hydrolysable carbohydrates of soil organo-mineral particles for a better understanding of the contribution of each individual fraction to the soil function. The contributions of the fractions <20 m to the total pool of organic matter were 77% for C and 84% for N. Larger amounts of carbohydrates were found in the clay and silt fractions (3,784–6,043 g g–1 soil). The carbohydrate composition indicated that microbe-derived carbohydrates [e.g. galactose (Gal) and mannose (Man)] accumulated preferentially in the fine fractions while plant-derived sugars [e.g. arabinose (Ara) and xylose (Xyl)] were dominant in coarse fractions. A negative relationship was observed between C:N ratio and 15N natural abundance on the one hand, and on the other hand between C:N and (Gal+Man):(Ara+Xyl), Man:(Ara+Xyl) and Man:Xyl ratios, clearly indicating that the chemistry of the organic materials of the particle-size fractions reflects a change from soil chemistry dominated by plant materials to that dominated by microbial biomass and metabolites. The contribution of a given fraction to soil microbial activity is controlled by the quality or quantity of associated soil organic matter, its microbial biomass and also by the accumulation of microbial-derived carbohydrates which can be resynthesized or recycled. 相似文献
5.
S. Hashimoto S. Ugawa K. Morisada M. Wattenbach P. Smith Y. Matsuura 《Soil Use and Management》2012,28(1):45-53
Forest management and climate change may have a substantial impact on future soil organic carbon (SOC) stocks at the country scale. Potential SOC in Japanese forest soils was regionally estimated under nine forest managements and a climate change scenario using the CENTURY ecosystem model. Three rotations (30, 50, 100 yr) and three thinning regimes were tested: no‐thinning; 30% of the trees cut in the middle of the rotation (e.g. 15 year in a 30‐yr rotation) and thinned trees all left as litter or slash (ThinLef) and the trees from thinning removed from the forest (ThinRem). A climate change scenario was tested (ca. 3 °C increase in air temperature and 9% increase in precipitation). The model was run at 1 km resolution using climate, vegetation and soil databases. The estimated SOC stock ranged from 1600 to 1830 TgC (from 6800 to 7800 gC/m2), and the SOC stock was largest with the longest rotation and was largest under ThinLef with all three rotations. Despite an increase in net primary production, the SOC stock decreased by 5% under the climate change scenario. 相似文献
6.
P. Falloon P. Smith R. I. Bradley R. Milne R. Tomlinson D. Viner M. Livermore & T. Brown 《Soil Use and Management》2006,22(3):274-288
We describe the development and application of an integrated data and modelling system for estimating soil carbon (C) fluxes from mineral soils caused by changes in climate, land use and land management at 1‐km resolution in the UK (RothCUK). The system was developed with the aim of improving methods for United Nations Framework Convention on Climate Change (UNFCCC) and Kyoto Protocol accounting and integrates national scale data sets of soil properties, land use and climate with the Rothamsted carbon model (RothC). A preliminary estimate of soil C fluxes because of land use change (LUC) over the period 1990–2000 is presented as an example application of the system. RothCUK shows LUC to be a net source of CO2 from 1990 to 2000 although the RothC estimate was smaller (6488 kt C) than the estimate from the single exponential model (SEM) method currently used to calculate C fluxes due to LUC for the UK National Greenhouse Gas Inventory (mean: 9412 kt C). Based on previous studies, an uncertainty range in our estimates of ±50–100% seems plausible. In agreement with the SEM, RothCUK suggests that the largest single contributor to soil C fluxes from LUC was conversion of grassland to arable land. Differences between the results may be attributed to differences in the two models and the assumptions and underlying data used in making the calculations. The RothCUK system provides a powerful method for estimating changes in soil C stocks, enabling areas and management systems with particularly large changes in soil C stocks to be located at fine resolution. 相似文献
7.
Tianyun Wu Jeff J. Schoenau Fengmin Li Peiyuan Qian Sukhdev S. Malhi Yuanchun Shi 《Biology and Fertility of Soils》2006,42(4):338-344
The effects of several dominant tillage and rotation systems on soil organic C content of different particle-size fractions
were studied in Chernozemic soils from southwestern and east-central Saskatchewan, Canada. In an Orthic Brown Chernozem in
southwestern Saskatchewan, 7 years of no-till cereal–fallow, imposed on a long-term tillage fallow–wheat rotation soil, resulted
in 0.1 Mg C ha−1 more organic C mass in the sand + organic matter (OM) fraction of the 0- to 5-cm layer, whereas organic C associated with
coarse silt (CS), fine silt (FS), coarse clay, and fine clay of 0- to 5- and 5- to 10-cm layers was less than that of the
comparable tilled cereal–fallow system. Conversion of tilled fallow–wheat rotation soil to continuous cropping had a slight
effect, whereas the organic C mass in all the size fractions was significantly increased in both 0- to 5- and 5- to 10-cm
layers after alfalfa was introduced on tilled fallow–wheat as perennial forage for 10 years. In an Orthic Black Chernozem
in east-central Saskatchewan that was cultivated and tilled using a cereal–fallow rotation for 62 years, organic C mass decreased
in sand + OM, CS, and FS of 0- to 10-cm depth. Conversion of the tilled cereal–fallow cropland soil back to seeded grassland
resulted in significantly more soil organic C in sand + OM fraction after 12 years of grass seed-down. The sand + OM fraction
appears to be the size fraction pool initially most sensitive to adoption of management practices that are liable to sequester
carbon in the soil. 相似文献
8.
S. Covaleda J. F. Gallardo F. García‐Oliva H. Kirchmann C. Prat M. Bravo J. D. Etchevers 《Soil Use and Management》2011,27(2):186-194
The aim of this study was to determine the effect of land‐use and forest cover depletion on the distribution of soil organic carbon (SOC) within particle‐size fractions in a volcanic soil. Emphasis was given to the thermal properties of soils. Six representative sites in Mexico were selected in an area dominated by Andosols: a grassland site, four forested sites with different levels of degradation and an agricultural site. Soils were fractionated using ultrasonic energy until complete dispersion was achieved. The particle‐size fractions were coarse sand, fine sand, silt, clay and particulate organic matter from the coarse sand sized fraction (POM‐CS) and fine sand (POM‐FS). Soil organic carbon decreased by 70% after forest conversion to cropland and long‐term cultivation; forest cover loss resulted in a decrease in SOC of up to 60%. The grassland soil contained 45% more SOC than the cropland one. Soil organic carbon was mainly associated with the silt‐size fraction; the most sensitive fractions to land‐use change and forest cover depletion were POM followed by SOC associated with the silt and clay‐sized fractions. Particulate organic matter can be used as an early indicator of SOC loss. The C lost from the clay and silt‐sized fractions was thermally labile; therefore, the SOC stored in the more degraded forest soils was more recalcitrant (thermally resistant). Only the transformation of forest to agricultural land produced a similar loss of thermally stable C associated with the silt‐sized fraction. 相似文献
9.
Manuring and rotation effects on soil organic carbon concentration for different aggregate size fractions on two soils in northeastern Ohio, USA 总被引:5,自引:0,他引:5
Soil carbon (C) sequestration is important to the mitigation of increasing atmospheric concentration of CO2. This study was conducted to assess soil aggregation and C concentration under different management practices. The effects of crop rotation, manure application and tillage were investigated for 0–5 and 5–10 cm depths on two silt loam soils (fine-loamy, mixed, active, mesic Aquic Fragiudalfs and fine-loamy, mixed, active, mesic Aeric Fragiadalf) in Geauga and Stark Counties, respectively, in northeastern Ohio, USA. Wet sieve analysis and gravity fractionation techniques were used to separate samples in aggregate and particle size groups, respectively. In the Stark County farms water stable aggregate (WSA) is higher in wooded (W) controls (WSA = 94.8%) than in cultivated soils with poultry manure (PM, 78.7%) and with chemical fertilizers (CF, 79.0%). Manure applications did not increase aggregation compared to unmanured soils. The C concentrations (%) within aggregates (Cagg) are higher in W than in cultivated soils (W = 5.82, PM = 2.11, CF = 1.96). Soil C (%) is enriched in the clay (W = 9.87, PM = 4.17, CF = 4.21) compared to silt (4.26, 1.04 and 0.98, respectively) and sand (0.93, 0.14 and 0.32, respectively) fractions. In the Geauga County farm, continuous corn (CC) with conventional tillage has lower WSA (83.1%) than soils with rotations (R) (93.9%), dairy manure (DM) application (93.2%) and no-till (NT) (91.1%). The C concentrations within macroaggregates (Cagg) were higher in W soils (4.84%) than in cultivated soils (ranging from 2.65 to 1.75%). The C (%) is enriched in clay (W = 8.56, CC = 4.18, R = 5.17, DM = 5.73, NT = 4.67) compared to silt (W = 2.35, CC = 0.90, R = 0.96, DM = 1.57, NT = 1.06) and sand (W = 0.44, CC = 0.33, R = 0.13, DM = 0.41, NT = 0.18). Cultivation decreased C concentration whereas reduced tillage, rotation and manure enhanced C concentration in soil. 相似文献
10.
Using data from long-term experiments at the Loess-Chernozem site, Bad Lauchstädt und 12 other European sites, the carbon (C) and nitrogen (N) dynamics in soils, the determination of decomposable soil organic matter (SOM), the effect on yield of SOM as well as carbon and nitrogen balances are discussed. Both C and N in SOM have to be divided into an inert and a decomposable fraction. The inert C is strongly correlated with clay content, while most changes in both C and N occur in the readily decomposable fraction. In the experiments considered the latter ranges between 0.2 to 0.6% C and 0.02 to 0.06% N. The annual changes of the Corg content amount only to about 0.01% Corg corresponding to 500 kg/ha, even under extreme changes of the fertilizing system. Hot water extractable C (Chwe) has proved to be an appropriate criterion for the calculation of the decomposable C and thus for the N release from soil. Different methods to maintain a SOM balance are compared and first guideline values for an agronomically and ecologically justified SOM content of arable soils are recommended. In arable soils the exceeding of an upper Corg value influences neither crop yield nor the C and N balance in a positive way. In terms of ecology and environment, set-aside-programmes or fallows in a crop rotation affect the balances negatively. Atmospheric N deposition can amount to about 50 kg/ha·yr. 相似文献
11.
Rita KiemIngrid Kögel-Knabner 《Soil biology & biochemistry》2003,35(1):101-118
We assessed the contribution of polysaccharides and lignin, major components of plant residues, to the refractory pool of soil organic carbon (SOC) in arable soils. Soil samples from two contrasting treatment types of European long-term agroecosystem experiments, i.e. conventionally managed (fertilized) and C-depleted plots, enriched in refractory compounds, were compared. Bulk samples from eight experimental sites and particle-size fractions of two of the sites were investigated. The CuO oxidation technique was used as a relative measure of lignin and its degree of structural alteration. The contents and composition of polysaccharides were determined following hydrolysis with trifluoroacetic acid (TFA). For the bulk samples, the amount of lignin phenols declined more than the total OC in the course of C-depletion. The contribution of lignin phenols to total OC was thus lower in the C-depleted versus the fertilized plots. A greater lignin biodegradation was found in the bulk samples of the depleted plots compared with the fertilized plots. The analysis of size fractions revealed lower OC-normalized contents of lignin phenols and a higher degree of lignin alteration in fractions <63 μm of the depleted versus the fertilized plots. These findings indicate that lignin does not accumulate within the refractory C pool of arable soils. The refractory SOC pool shows a lower contribution of lignin as compared with more labile fractions of SOC. If lignin-derived carbon is present in the stable pool it has been extensively modified so that it can no longer be identified as phenolic CuO oxidation products. OC-normalized contents of polysaccharides (neutral sugars and galacturonic acid) were similar in bulk samples of the C-depleted and fertilized plots. The contrasting treatments showed similar polysaccharide contents especially in separates <6 μm. The separates <6 μm in the C-depleted plots retained between 50 and 100% of the polysaccharide amounts in the fertilized plots. The mass ratio of (galactose+mannose)-to-(arabinose+xylose) (GM/AX) was higher in bulk samples of the C-depleted versus the fertilized plots, indicating a higher relative contribution of microbial sugars. Within a particular soil, the fine separates were those with the highest GM/AX ratio. These results indicate that the refractory C pool has a similar proportion of polysaccharides as the labile C pool, but refractory polysaccharides are mainly associated with fine separates and show a dominant contribution of microbial sugars. Our results provide evidence that polysaccharides, mainly those of microbial origin, are stabilized over the long-term within fine separates of arable soils. In contrast, CuO lignin is associated mainly with the coarse fractions and does not contribute to the refractory C pool. 相似文献
12.
Sustainable agriculture requires the formation of new humus from the crops. We utilized 13C and 15N signatures of soil organic matter to assess how rapidly wheat/maize cropping contributed to the humus formation in coarse-textured savanna soils of the South African Highveld. Composite samples were taken from the top 20 cm of soils (Plinthustalfs) cropped for lengths of time varying from 0 to 98 years, after conversion from native grassland savanna (C4). We performed natural 13C and 15N abundance measurements on bulk and particle-size fractions. The bulk soil δ13C values steadily decreased from −14.6 in (C4 dominated) grassland to −16.5‰ after 90 years of arable cropping. This δ13C shift was attributable to increasing replacement of savanna-derived C by wheat crop (C3) C which dominated over maize (C4) inputs. After calculating the annual C input from the crop yields and the output from literature data, by using a stepwise C replacement model, we were able to correct the soil δ13C data for the irregular maize inputs for a period of about one century. Within 90 years of cropping 41-89% of the remaining soil organic matter was crop-derived in the three studied agroecosystems. The surface soil C stocks after 90 years of the wheat/maize crop rotation could accurately be described with the Rothamsted Carbon Model, but modelled C inputs to the soil were very low. The coarse sand fraction reflected temporal fluctuations in 13C of the last C3 or C4 cropping and the silt fraction evidenced selective erosion loss of old savanna-derived C. Bulk soil 15N did not change with increasing cropping length. Decreasing δ15N values caused by fertilizer N inputs with prolonged arable cropping were only detected for the coarse sand fraction. This indicated that the present N fertilization was not retained in stable soil C pool. Clearly, conventional cropping practices on the South African highlands neither contribute to the preservation of old savanna C and N, nor the effective humus reformation by the crops. 相似文献
13.
A.J.N. Silva M.R. Ribeiro F.G. Carvalho V.N. Silva L.E.S.F. Silva 《Soil & Tillage Research》2007,94(2):420-424
The effects of continuous sugarcane (Saccharum officinarum) cropping on the properties of a cohesive Yellow Latosol were studied in the region of the Coastal Tablelands, Northeast Brazil. Four areas were studied at Caeté mill, municipality of São Miguel dos Campos, Alagoas State, involving a native forest (Tn), and sugarcane fields cultivated for periods of 2 years (T2), 18 years (T18) and 25 years (T25). Samples were collected from each area at 0–0.2 and 0.2–0.4 m depth, to determine total organic C, physical fractionation of soil organic matter and consistence limits. Undisturbed samples were collected to determine wet aggregate mean weight–diameter, dry mean weight diameter and aggregate stability. In relation to the soil under native forest, total organic C and particulate organic matter contents were reduced after 2 years of cultivation. Sugarcane cropping for a longer period promoted a recuperation of soil organic matter content. The decrease of total organic C and reduction in aggregate stability and plastic limit after 2 years of sugarcane cultivation rendered the soil more susceptible to compaction. 相似文献
14.
15.
The knowledge about the relevance of physical and chemical fractionation methods to soil organic carbon (SOC) stabilization
mechanisms is fragmentary but needed to manage the SOC pool. Therefore, our objective was to compare the C contents of the
particle size fractions coarse and fine sand, silt, and clay of the two uppermost horizons of a soil under three different
management systems (meadow; no-till corn, NT; no-till corn with manure, NTm). The mineral composition was dominated by silt
(48–60%). However, coarse sand and clay showed the highest enrichment of C compared to the bulk soil. In spite of an enrichment
factor below 1, the high proportion of silt made this fraction the main C store. In the upper 30 cm, this fraction amounted
to 27.1 Mg C ha−1 in NTm and progressively less in NT (15.5 Mg C ha−1), and meadow (14.9 Mg C ha−1), representing 44%, 39%, and 39% of the total SOC pool, respectively. The C in the isolated particle size fractions was further
investigated by an oxidizing treatment with Na2S2O8 and a treatment with HF to solubilize the mineral phases. The pools of oxidizable C were comparable among particle size fractions
and pedons, as indicated by Na2S2O8 treatment. The pools of C preferentially associated with soil minerals were also comparable among pedons, as indicated by
HF treatment. However, NTm stored the largest pool (12.6 Mg ha−1) of mineral-associated C in 0–30 cm depth. The silt-associated and mineral-bound SOC pool in NTm was greater compared to
NT due to increased organic matter (OM) input. Thus, the silt particle size fraction at the North Appalachian Experimental
Watershed (NAEW) has the potential for SOC sequestration by stabilizing OM inputs. Mineralogical and molecular level analyses
on a larger set of fractions obtained from entire rooted soil profiles are required, however, to compare the SOC sequestration
capacity of the land uses. 相似文献
16.
洞庭湖区不同耕种方式下水稻土壤有机碳、全氮和全磷含量状况 总被引:16,自引:1,他引:16
在洞庭湖区的2km2典型样区内,按3个/hm2的密度采集土样,分析不同耕种方式下(水稻、水旱轮作油菜、水改旱种苎麻1~5年)水稻土壤的有机碳、全氮和全磷含量状况。结果表明,水稻田土壤有机碳、全氮和全磷含量水平均较高,水田改为旱地后土壤有机碳、全氮含量及C/N比值有较大幅度的下降,但全磷含量变化不大。土壤有机碳、全氮及C/N比值均以水稻田土壤>油菜地土壤>苎麻地土壤,与水稻田相比,油菜土壤有机碳平均下降了11.19%、全氮下降了10.33%,而苎麻土壤有机碳平均下降了35.57%、全氮下降了31.61%。土壤有机碳与全氮之间呈线性关系,相关性均达极显著水平(P<0.01)。 相似文献
17.
During the last three decades, large amounts of soil organic matter (SOM) and associated nutrients have been accumulated in arable soils of Western Germany (former FRG) due to deepening of the plough layers (from < 25 to > 35 cm) and to fertilizer application rates which have exceeded the amounts of nutrients removed in harvested crops. Organic carbon and total nitrogen balances (1970—1998) on 120 plots from 16 farms in southern Lower Saxony yielded a cumulative increase of up to 16 t C ha−1 and 1 t N ha−1 in loess soils used for cash crop production and up to 26 t C ha−1 and 2.4 t N ha−1 in sandy soils under livestock production. The buffering capacity for reactive compounds, particularly of C, N, S and P and of other (organic or inorganic) pollutants will reach its limits in the near future, after organic matter ”︁equilibria” have been re‐established. An immediate adaptation of the current fertilizer application rates to the nutrient export by field crops is therefore urgently needed. 相似文献
18.
Little is known about the nature of organic sulfur (S) in soils of the Marsh in Schleswig‐Holstein, Northern Germany. In addition to total and inorganic S, we determined two organic S fractions (ester sulfate‐sulfur and carbon‐bonded sulfur) in 14 aerated mineral top horizons of two salt marshes and ten dyked polder soils of different age. All soils developed from marine sediments. Total S concen‐trations ranged from 153 to 950 mg kg—1. Organic S was the main S constituent (range from 53 to 99% with a median of 97%). Higher inorganic S levels were found only in the salt marshes due to soluble sulfate (15 to 47%). The younger marsh soils (salt marshes and soils of a polder dyked in 1978) had unique high S contents of 0.9 to 2.4% in their organic matter, whereas the S contents of the organic matter in older marsh soils were at only 0.6%. This S‐rich organic matter is a heritage of a former anoxic marine environment. In most horizons the carbon‐bonded S was the dominant sulfur form. However, both carbon‐bonded S and ester sulfate‐S did not relate to soil age. This limits the benefit of the wet chemical fractionation procedure used for studying the fate of organic S in marsh soils. 相似文献
19.
Impacts of 22-year organic and inorganic N managements on soil organic C fractions in a maize field,northeast China 总被引:1,自引:0,他引:1
Impacts of 22-year organic and inorganic N managements on total organic carbon (TOC), water-soluble organic C (WSOC), microbial biomass C (MBC), particulate organic C (POC) and KMnO4 oxidized organic C (KMnO4-C) concentrations, C management index (CMI), and C storage in surface soil (0–20 cm) were investigated in a maize (Zea may L.) field experiment, Northeast China. The treatments included, CK: unfertilized control, M: organic manure (135 kg N ha− 1 year− 1), N: inorganic N fertilizer (135 kg N ha− 1 year− 1) and MN: combination of organic manure (67.5 kg N ha− 1 year− 1) and inorganic N fertilizer (67.5 kg N ha− 1 year− 1). TOC concentration and C storage were significantly increased under the M and MN treatments, but not under the inorganic N treatment. The organic treatments of M and MN were more effective in increasing WSOC, MBC, POC and KMnO4-C concentrations and CMI than the N treatment. The M treatment was most effective for sequestrating SOC (10.6 Mg ha− 1) and showed similar increase in degree of grain yield to the N and MN treatments, therefore it could be the best option for improving soil productivity and C storage in the maize cropping system. 相似文献
20.
Henry Neufeldt 《植物养料与土壤学杂志》2005,168(2):202-211
Soil organic carbon (SOC) inventories are important tools for studying the effects of land‐use and climate change and evaluating climate‐change policies. A detailed inventory of SOC in the agricultural soils of the federal state of Baden‐Württemberg was therefore prepared based on the highest‐resolution geo‐referenced soil, land‐use, and climate data (BÜK200 inventory). In order to estimate the quality of different approaches, C inventories of the region were also prepared based on data from the National Inventory Report (UBA, 2003) and by applying the IPCC (1997) method to the two data sets. Finally, the BÜK200 inventory was used to estimate potentials of no‐tillage agriculture (NT) and peatland restoration to contribute to C sequestration and greenhouse‐gas (GHG)‐emission mitigation since both measures are discussed in this context. Scenario assumptions were change to NT on 40% of the cropland and restoration of 50% of cultivated peatlands within 20 years. On average, grasslands contained 9.5 kg C m–2 to 0.3 m depth as compared to only 6.0 kg C m–2 under cropland, indicating strong land‐use effects. The SOC content depended strongly on waterlogging and elevation, thus reflecting reduced C mineralization under aquic moisture regimes and low temperatures. Comparison of the BÜK200 inventory with the approach used for UBA (2003) showed high inconsistencies due to map resolution and SOC contents, whereas the IPCC method led to fairly good agreements. Results on the simulated effects of NT and peatland restoration suggested that 5%–14% of total agricultural GHG emissions could be abated with NT whereas peat restoration appeared to have a minor mitigation potential (0.2%–2.7%) because the total area of cultivated organic soils was too small to have larger impact. 相似文献