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1.
In order to quantify the influence of land use systems on the level of soil organic matter (SOM) to develop recommendations, long-term field studies are essential. Based on a crop rotation experiment which commenced in 1970, this paper investigated the impact of crop rotations involving increased proportions of sugar beet on SOM content. To this end, soil samples were taken in 2010 and 2012 from the following crop rotation sequences: sugar beet–sugar beet–winter wheat–winter wheat (SB–SB–WW–WW = 50%), sugar beet–sugar beet–sugar beet–winter wheat (SB–SB–SB–WW = 75%), sugar beet–grain maize (SB–GM = 50%) and sugar beet-monoculture (SB = 100%); these were analysed in terms of total organic carbon (TOC) and microbial biomass carbon (MBC) content, MBC/TOC ratio and the TOC stocks per hectare. In addition, humus balances were created (using the software REPRO, reference period 12 years) in order to calculate how well the soil was supplied with organic matter. In the field experiment, harvest by-products (WW and GM straw as well as SB leaves) were removed. After 41 years, no statistically significant differences were measured between the crop rotations for the parameters TOC, MBC, MBC/TOC ratio and the TOC stock per hectare. However, the calculated humus balance was significantly affected by the crop rotation. The calculated humus balance became increasingly negative in the order SB–SB–WW–WW, SB–SB–SB–WW, SB monoculture and SB–GM, and correlated with the soil parameters. The calculated humus balances for the reference period did not reflect the actual demand for organic matter by the crop rotations, but instead overestimated it.  相似文献   
2.
Integrating biochar into cattle diets has recently emerged as a potential management practice for improving on-farm productivity.Yet,information concerning the cycling of biochar-manure mixtures is scarce.A 70-d incubation experiment was conducted within two surface(0–15 cm)Mollisols with contrasting textures,i.e.,sandy clay loam(Raymond)and clayey(Lethbridge),to evaluate the effects of biochar(3 Mg ha-1)on cumulative greenhouse gas(GHG)emissions and related fertility attributes in the presence or absence of cattle manure(120 Mg ha-1).Five treatments were included:i)non-amended soil(control,CK),ii)soil amended with pinewood biochar(B),iii)soil amended with beef cattle manure(M)(manure from cattle on a control diet),iv)soil amended with biochar-manure(BM)(manure from cattle on a control diet,with pinewood biochar added at 20 g kg-1of diet dry matter),and v)soil amended with B and M at the aforementioned rates(B+M).A total of 40 soil columns were prepared and incubated at 21℃and 60%–80%water-holding capacity.On average,total CO2fluxes increased by 2.2-and 3.8-fold under manure treatments(i.e.,M,BM,and B+M),within Raymond and Lethbridge soils,respectively,relative to CK and B.Similarly,total CH4 fluxes were the highest(P<0.05)in Raymond soil under B+M and BM relative to CK and B,and in Lethbridge soil under M and BM relative to CK and B.In Lethbridge soil,application of BM increased cumulative N2O emissions by 1.8-fold relative to CK.After 70-d incubation,amendment with BM increased(P<0.05)PO_4-P and NO_3-N+NH_4-N availability in Raymond and Lethbridge soils compared with B.A similar pattern was observed for water-extractable organic carbon in both soils,with BM augmenting(P<0.05)the occurrence of labile carbon over CK and B.It can be concluded that biochar,manure,and/or biochar-manure have contrasting short-term effects on the biogeochemistry of Mollisols.At relatively low application rates,biochar does not necessarily counterbalance manure-derived inputs.Although BM did not mitigate the flux of GHGs over M,biochar-manure has the potential to recycle soil nutrients in semiarid drylands.  相似文献   
3.
In North Kazakhstan there is concern about the degradation of Chernozem soil and agricultural sustainability by the inclusion and frequency of summer fallows in crop rotations in terms of their influence on the changes of soil organic matter (SOM) quality and quantity. We examined five fallow-wheat (Triticum aestivum L.) cropping systems with different frequencies of the fallow phase in Chernozem soil of North Kazakhstan; continuous wheat (CW), 6-y rotation (6R), 4-y rotation (4R), 2-y rotation (2R) and continuous fallow (CF). Soil samples were collected from the two phases of each rotation, pre- and post-fallow, and analyzed for potentially mineralizable C (PMC) and N (PMN), ‘light fraction’ organic matter (LF-OM), C (LF-C) and N (LF-N). Potentially mineralizable C was inversely proportional to the frequency of fallow and was highest in CW. Mineral N (min-N) and PMN were more responsive to rotation phase than other indices of SOM. Mineral N was higher in the post-fallow phase while PMN was higher in the pre-fallow phase. Light fraction organic matter was negatively correlated to the frequency of fallow and was higher in the pre-fallow than in the post-fallow phase in a rotation. The results suggested that the yearly input of plant residue in a less frequently fallowed system built up more PMC, whereas PMN was closely correlated to recent inputs of substrate added with plant residues. We conclude that a frequent fallow system may deplete SOM via accelerated mineralization. Also that LF-OM, PMC and PMN are more sensitive to detect subtle changes in SOM quality than total SOM. Our results may provide prediction of SOM response to fallow frequency in wheat-based rotation systems in Chernozem soils of semi-arid regions.  相似文献   
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Andosols are characterized by an abundance of black humic acids (HAs) belonging to Type A with a high content of aromatic carbon (C) in particular condensed aromatic C. Black HAs are also observed in other soils, such as Chernozems and the subsoil of paddy field, and extracted after washing with an acid or using chelating agent such as sodium pyrophosphate (Na4P2O7). However, contribution of condensed aromatic structures to those soil HAs are unknown. To obtain the information about C skeletal structures of black HAs in soils other than Andosols, HAs were obtained from 2 Chinese Chernozem samples, 2 subsoil samples from Japanese paddy fields (Fulvisols), and a Rendzina-like soil (Cambisols) as well as an Andosol sample (reference) by successive extraction with 0.1 M NaOH (HAs1) and 0.1 M Na4P2O7 (HAs2), and 13C nuclear magnetic resonance and X-ray diffraction 11-band profile analyses were applied. In the black HAs2 from the non-Andosol samples, the proportion of C present as aromatic C, size of C layer planes, and relative C layer plane content ranged from 52 to 59%, 0.48 to 1.92 nm (mean size, 0.76–0.91 nm), and 58 to 100 AU (arbitrary unit) mg?1, respectively, with a positive correlation between total C layer plane content and the degree of humification. Those ranges were similar to the distribution ranges of Andosols HAs1 reported by our previous study.  相似文献   
6.
黑钙土自然肥力下重茬烤烟磷积累与分配规律研究   总被引:3,自引:0,他引:3  
在黑钙土自然肥力下,研究了重茬栽培对烤烟磷积累及分配的影响。结果表明:随着重茬年数的增加,收获时根系、下部叶、中部叶和上部叶内的磷积累量均呈下降趋势;重茬3年有利于磷在茎内的积累,但是重茬5年不利于磷在茎内的积累;重茬5年会使根系、中部叶内磷的分配比例增加,而使茎、下部叶和上部叶内磷的分配比例下降。综合分析认为,烤烟重茬栽培年限不宜超过5年。  相似文献   
7.
The effects of different land-use histories on contents of soil carbon (C) and nitrogen (N) and fluxes of greenhouse gases [carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)] measured using the closed chamber method were investigated in the Arkaim museum reserve located in the South Ural of Russia. A natural forest site (NF) and two grassland sites that had different land-use histories (CL: cropland until 1991; PST: pasture until 1991; both sites have been fallow for 18 years) were selected for soil sampling and gas flux measurements. The vegetation in NF was mainly Betula pendula Roth. with steppe cherry and grassy cover. Perennial grasses (Stipa spp., Festuca spp. and others) have been planted in CL and PST since 1991 to establish reserve mode, and the projective cover of these plants were?>?90% in both sites in 2009. Soil samples were taken from the A horizon in the three sites, and additionally samples of the O horizon were taken from NF. The contents of soil C and N [total C, total N, soluble organic C, soluble N and microbial biomass C (MBC)] in the O horizon of NF were the largest among all investigated soils (p?p?2 fluxes (i.e., CO2 efflux) in all three investigated sites were observed. The CO2 efflux in NF was significantly larger than in CL and PST (129, 30 and 25?mg C m?2 hour?1, respectively, p?2 efflux between CL and PST. There were no significant differences in the fluxes of CH4 and N2O among NF, CL and PST (p?>?0.05). Our current research indicated that, in soils of the Eurasian steppe zone of Russia, total C, total N and MBC were affected not only by current land-use (i.e., fallow grassland vs. natural forest) but also by past (until 18 years ago) land-use.  相似文献   
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9.
The proclamation of the “Soil of the Year” was made for the first time in Germany in 2005 on occasion of the World Soil Day. Chernozems were selected for this purpose. In this paper an overview of these groups of soils is given. Chernozems are concentrated in the drought region of Central Germany. A standard profile from the core area of Chernozems developed from loess is presented with comprehensive laboratory analysis. Chernozems developed primarily upon carbonatic loess substrates under summer‐dry climatic conditions in an open park‐like landscape with isolated forest stands. The development of Chernozems began as early as the late glacial period, and they were fully developed by the Atlantikum age. The far‐reaching, uniformly thick humus horizons indicate substrate differences in the loess cover, which are partly the result of bioturbation. Within Germany, Chernozems and Chernozem‐like soils make up approx. 3% of the surface area and 5% (approx. 11,000 km2) of the arable land. The results of the Static Fertilization Experiment in Bad Lauchstädt, founded in 1902, clarify the high value of Chernozem for biomass production and the environment. Each loss due to erosion or decrease in surface area reduces the fulfillment of soil ecological functions of the soils and is comparable to a loss of animal and plant species. Therefore, soil scientists and the results of soil research must be more comprehensively implemented for soil preservation, protection, and politics. For acceptance of these goals among the general public and the political‐decision makers, the campaign “Soil of the Year” should give some thought‐provoking impulses.  相似文献   
10.
青海省大通县脑山区退耕还林土壤质量演变评价   总被引:3,自引:1,他引:2  
选取青海省大通县脑山区退耕还林地典型土壤类型———黑钙土,进行标准地调查及标准剖面采样,以空间代替时间序列的方式,利用主成分分析(PCA)等多元统计方法来定量化比较不同退耕年限(0,5,10,15,20,25,30 a)的综合土壤质量指数,揭示不同退耕年限土壤质量演变规律。结果表明,退耕还林后的30 a中,随退耕年限的增长,土壤质量指数均呈增长趋势,其过程基本分为3个阶段:(1)退耕初期(退耕5a),林分幼林期,为土壤质量指数相对增长期;(2)退耕中期(退耕5~20 a),针阔叶林林分速生期,为土壤质量指数大幅度升高并达到峰值期;(3)退耕后期,退耕20 a后,林分相对稳定期,林分郁闭度增大,土壤质量指数随之下降;退耕25 a后,林分进入自疏期,土壤质量指数略有升高并趋于稳定。  相似文献   
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