Soil criteria for assessing the maximum permissible ground pressure of agricultural vehicles on Chernozem soils

The maximum permissible ground pressure of agricultural vehicles to permit satisfactory crop production on heavy loamy Chernozem soil was estimated from six criteria: (1) changes in soil water-physical properties; (2) crumbling characteristics; (3) depth of compaction; (4) rut depth; (5) soil strength potential; (6) self-loosening characteristics. Using these criteria it was possible to obtain reliable data for the maximum permissible ground pressure which was found to be correlated with the soil water content at the time of tillage.

At a water content equal to or somewhat lower than the water content at optimal soil crumbling (0.16–0.24 kg kg⁻¹), the permissible ground pressure was found to be within the range 80–120 kPa. At soil water contents slightly above the optimum soil crumbling (0.26–0.28 kg kg⁻¹), the permissible ground pressure was within the range 30–60 kPa.     

青海省大通县脑山区退耕还林土壤质量演变评价

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。     

Chernozem—Soil of the Year 2005

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.     

Carbon and nitrogen contents and greenhouse gas fluxes of the Eurasian steppe soils with different land-use histories located in the Arkaim museum reserve of South Ural,Russia

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.     

黑钙土自然肥力下重茬烤烟磷积累与分配规律研究

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。     

Comparison of carbon skeletal structures in black humic acids from different soil origins

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.     

Long-term corn grain and stover yields as a function of tillage and residue removal in east central Minnesota

Because the adoption of conservation tillage requires long-term evaluation, the effect of tillage and residue management on corn (Zea mays L.) grain and stover yields was studied for 13 seasons in east central Minnesota. Three primary tillage methods (no-till (NT), fall chisel plow (CH), fall moldboard plow (MB)) and two residue management schemes (residue removal versus residue returned) were combined in a factorial design experiment on a Haplic Chernozem silt loam soil in Minnesota. No significant effects on grain yield were seen due to tillage treatments in 9 out of 13 years. The NT treatment resulted in lower yields than CH and MB treatments in years 6 and 7, and lower than the MB in year 8, indicating a gradual decrease in yield over time with continuous use of NT. There were differences due to residue management in 8 out of 13 years. The residue-returned treatments contributed about 1 Mg ha⁻¹ greater yields in intermediate level dry years such as years 3 and 6, which had cumulative growing season precipitation 20 and 30% below the 9-year average, respectively. In excessively dry or long-term-average years, residues resulted in little yield difference between treatments. The most pronounced effects of residues were with the CH treatment for which yields were greater in 8 out of 13 years. The ratio of grain to total dry matter yield averaged 0.56 and did not vary with time or between treatments. These results apply primarily to soils wherein the total water storage capacity and accumulated rainfall are insufficient to supply optimum available water to the crop throughout the growing season. Under conditions with deeper soils or in either wetter or drier climates, the results may differ considerably.     

黑钙土中真菌的时空分布及其在贫营养条件下菌落特征研究

[目的]对黑钙土中真菌的时空分布及其在贫营养条件下菌落特征进行研究。[方法]采用稀释平板法对真菌进行分离,用单孢子分离法进行纯化,用不同稀释浓度的察贝克培养基进行培养计数。[结果]从供试黑钙土中分离出9种真菌菌属,并且确定了4种优势菌属,同时发现黑钙土中真菌数量分布呈现出明显的季节性,并且随采样深度增加其数量呈现减少的趋势,在贫营养条件下真菌种类和数量均明显减少。[结论]该研究可为黑钙土中微生物的相关研究提供理论依据。