长武塬区苹果园和农田相互转换的深层土壤水环境效应

研究长武塬区苹果园和农田相互转换后0~1 000 cm土壤含水量特征，分析了苹果园土壤干燥化和苹果园转换为农田后土壤水分的恢复效应。结果表明：2、7、17、23、29 a苹果园200~1 000 cm的平均土壤含水量分别为22.8%、21.4%、16.8%、15.4%、14.9%。500~1 000 cm土层中，29 a苹果园平均土壤含水量（14.5%）高于23 a的果园（13.3%）；17~29 a的苹果园均表现为轻度干燥化；基于苹果园和农田转换后土壤水分变化情况估算，苹果园最大种植年限为21 a。苹果园转换为农田1、5、10 a后，农田200~1 000 cm土层土壤含水量分别为：15.3%、15.7%和16.2%，恢复到土壤稳定湿度以上的土层厚度分别为140 cm（1 a）、220 cm（5 a）和400 cm（10 a）。     

黄土丘陵区流域主要植被类型养分循环特征

以黄土丘陵沟壑区典型小流域纸坊沟流域为例,系统研究流域在植被稳定恢复期1种乔木、4种灌木和9种草地植被类型的养分循环平衡特征。结果表明,乔灌植被类型的叶片养分含量明显高于当年的新生枝条,新生枝条则明显高于枝干;乔木植被类型的生物量、氮磷养分累积量明显高于灌木植被类型,灌木植被类型则高于草地植被类型;乔木的氮养分循环速率是0.789,灌木为0.742,草地为1.000;乔木P2O5循环速率是0.881,灌木为0.758,草地为1.000。乔木的氮养分年盈余量是333.0 kg/km2,灌木为508.5 kg/km2,草地为597.0 kg/km2;乔木的P2O5年盈余量是333.0 kg/km2,灌木为423.0 kg/km2,草地为531.0 kg/km2。     

Biochar but not earthworms enhances rice growth through increased protein turnover

The aim of this work was to compare the effects of biochar and earthworms on rice growth and to investigate the possible interactions between both. In addition to classic macroscopic variables we also monitored some leaf-level cellular processes involved in protein turnover. Both biochar and earthworms significantly increased shoot biomass production. However, biochar had a higher effect on the number of leaves (+87%) and earthworms on leaf area (+89%). Biochar also significantly increased the leaf turnover. At the cellular level, biochar but not earthworms enhanced protein catabolism by an increase in leaf proteolytic activities. This could be related to the increased expression of three of the six genes tested related to protein catabolism, one serine protease gene OsSP2 (+24%), one aspartic acid protease gene, Oryzasin (+162%) and one cysteine protease gene OsCatB (+257%). Furthermore, biochar also enhanced the expression level of two genes linked to protein anabolism, coding for the small and large subunits of rubisco (+33% and +30%, for rbcS and rbcL, respectively), the most abundant protein in leaves. In conclusion, our data gives evidence that biochar increased rice biomass production through increased leaf protein turnover (both catabolism and anabolism) whereas earthworms also increased rice biomass production but not through changes in the rate of protein turnover. We hypothesize that earthworms increase nitrogen uptake at a low cost for the plant through a simultaneous increase in mineralization rate and root biomass, probably through the release in the soil of plant growth factors. This could allow plants to accumulate more biomass without an increase in nitrogen metabolism at the leaf level, and without having to support the consecutive energy cost that must bear plants in the biochar treatment.     

Bacterial community structure and microbial activity in different soils amended with biogas residues and cattle slurry

Anaerobic digestion of organic materials generates residues of differing chemical composition compared to undigested animal manures, which may affect the soil microbial ecosystem differently when used as fertilizers. This study investigated the effects of two biogas residues (BR-A and BR-B) and cattle slurry (CS) applied at rates corresponding to 70 kg NH₄⁺-N ha⁻¹ on bacterial community structure and microbial activity in three soils of different texture (a sandy, a clay and an organic clay soil). 16S rRNA genes were targeted in PCR reactions and bacterial community profiles visualized using terminal restriction fragment length polymorphism. General microbial activity was measured as basal respiration (B-resp), substrate-induced respiration (SIR), specific growth rate (μ_SIR), metabolic quotient (qCO₂) and nitrogen mineralization capacity (NMC). Non-metric multidimensional scaling analysis visualized shifts in bacterial community structure related to microbial functions. There were significant differences in bacterial community structure after 120 days of incubation (+20 °C at 70% of WHC) between non-amended (control) and amended soils, especially in the sandy soil, where CS caused a more pronounced shift than biogas residues. Terminal-restriction fragment (TRF) 307, the predominant peak in CS-amended sandy soil, was identified as possibly Bacillus or Streptococcus. TRF 226, the dominant peak in organic soil amended with BR-B, was classified as Rhodopseudomonas. B-resp significantly increased and SIR decreased in all amendments to organic soil compared with the control, potentially indicating decreased efficiency of heterotrophic microorganisms to convert organic carbon into microbial biomass. This was also reflected in an elevated qCO₂ in the organic soil. The μ_SIR level was higher in the sandy soil amended with BR-A than with BR-B or CS, indicating a shift toward species capable of rapidly utilizing glucose. NMC was significantly elevated in the clay and organic soils amended with BR-A and BR-B and in the sandy soil amended with BR-B and CS. Thus, biogas residues and cattle slurry had different effects on the bacterial community structure and microbial activity in the three soils. However, the effects of biogas residues on microbial activities were comparable in magnitude to those of cattle slurry and the bacterial community structure was less affected. Therefore, we do not see any reason not to recommend using biogas residues as fertilizers based on the results presented.     

Topography and land use effects on the spatial variation of soil organic carbon: A case study in a typical small watershed of the black soil region in northeast China

Soil organic carbon is a soil property of central importance for soil quality and the global carbon cycle. Studies specifically aimed at the relationship between the spatial variation of soil organic carbon and environmental factors are few. In this paper, a typical small watershed named Tongshuang in the black soil region of northeast China, which was subjected to drastic erosion before 1980 and was managed subtly after 1980, was chosen as a study area. Classical statistic and geostatistic analysis methods, in combination with a geographic information system (GIS), were used to quantitatively research the spatial variation characteristics of the soil organic carbon and their relation to the topographic factors and land use. The data on the soil organic carbon, topographic factors, and land use were obtained by soil sampling and measurements derived from DEM, remote sensing images, and field investigations, respectively. The classical statistics analysis results indicated that the variability of the soil organic carbon was moderate (C_v = 0.30). The slope position and land use types were the most discriminating factors. The soil organic carbon content was the highest in the grassland and lowest in the coniferous forest (P < 0.01). It increased gradually along the slope position gradients from the interfluve to the toe slope. The geostatistics analysis showed that the soil organic carbon had a strong spatial correlation. The C₀/(C₀ + C) was 0.1608, which was mainly induced by structural factors. The mean soil organic content is 2.27% in this watershed. It is on a very low level in the northern black soil of northeast China. In this small watershed of the eroded black soil region, the present soil and water conservation measures play an important role in controlling the soil loss. However, the soil organic carbon’s restoration is unsatisfactory. Nearly three-quarters of the land has worrisome productivity. How to improve the soil organic carbon content while targeting the soil fertility is a pressing need. Published in Russian in Pochvovedenie, 2008, No. 1, pp. 44–53. The text was submitted by the authors in English.     

植物介导金属纳米颗粒合成的研究进展

随着纳米科技的快速发展,人工合成的金属纳米颗粒已在农业生产、生物医药、个人消费品等领域广泛应用。同时,越来越多研究表明植物也能介导金属纳米颗粒的合成。这些研究为制备金属纳米颗粒提供了新思路,但是,多数研究只局限于植物合成方法的表观描述,缺乏对过程及机理的深入研究。这不仅阻碍了金属纳米颗粒与植物相互作用的理论认知,还限制了植物合成方法的大规模应用。本文总结了近年来植物体内金属纳米颗粒的鉴别与表征方法及植物合成纳米材料的应用,重点对植物合成纳米颗粒的过程进行了梳理,发现有机酸、还原性糖类、蛋白质等生物成分都会参与纳米颗粒的生成过程。今后需研发更多的表征手段,以原位技术全面揭示植物合成金属纳米颗粒的机制。     

黄土高原地区林地枯枝落叶层水土保持效应研究进展

枯枝落叶层是林地垂直结构中参与水文循环过程的重要作用层,在涵养水源和保持水土中发挥着重要作用。黄土高原经过20年植被快速恢复,枯落物覆盖使近地表植被特征和生态过程变化明显,这必将影响地表土壤水分入渗、产汇流等水文和土壤侵蚀过程。为全面掌握黄土高原地区林地枯枝落叶层的水土保持效应研究动态,系统回顾了林地枯枝落叶层在凋落动态、蓄积量变化、截留降雨、阻延地表径流、提高土壤抗蚀抗冲能力和增加土壤入渗等方面的研究历史。分析了目前林地枯枝落叶层研究中存在的若干问题,提出未来黄土高原地区应加强野外坡面枯落物原位长期监测和降雨试验研究,开展多地貌、多尺度研究,关注天然林和人工林枯枝落叶层水土保持功能的对比研究,以及水文物理过程模型建立和参数确定,并重视林地枯枝落叶层的保护和监管。     

Soil acidification induced by intensive agricultural use depending on climate

Journal of Soils and Sediments - Soil acidification is a major issue in agricultural ecosystems. However, how agricultural land uses shape the soil pH pattern and affect soil acidification on a...     

Do model choice and sample ratios separately or simultaneously influence soil organic matter prediction?

This study was performed to examine the separate and simultaneous influence of predictive models’ choice alongside sample ratios selection in soil organic matter (SOM). The research was carried out in northern Morocco, characterized by relatively cold weather and diverse geological conditions. The dataset herein used accounted for 1591 soil samples, which were randomly split into the following ratios: 10% (～150 sample ratio), 20% (～250 sample ratio), 35% (～450 sample ratio), 50% (～600 sample ratio) and 95% (～1200 sample ratio). Models herein involved were ordinary kriging (OK), regression kriging (RK), multiple linear regression (MLR), random forest (RF), quantile regression forest (QRF), Gaussian process regression (GPR) and an ensemble model. The findings in the study showed that the accuracy of SOM prediction is sensitive to both predictive models and sample ratios. OK combined with 95% sample ratio performed equally to RF in conjunction with all the sample ratios, as the latter did not show much sensitivity to sample ratios. ANOVA results revealed that RF with a ～10% sample ratio could also be optimum for predicting SOM in the study area. In conclusion, the findings herein reported could be instrumental for producing cost-effective detailed and accurate spatial estimation of SOM in other sites. Furthermore, they could serve as a baseline study for future research in the region or elsewhere. Therefore, we recommend conducting series of simulation of all possible combinations between various predictive models and sample ratios as a preliminary step in soil organic matter prediction.     

淡水入渗模型对咸水入渗过程的适用性

由于咸水中含有各种盐分离子,当咸水进入土壤后,会引起土壤物理特性改变,从而影响土壤的入渗特性.为了分析单因素对土壤入渗能力的影响,在中国科学院南皮生态农业试验站进行了不同矿化度和钠吸附比(SAR)的咸水一维垂直积水入渗试验.结果表明:咸水的土壤表征饱和导水率在2.99 g/L时存在突变现象,并达到最大值;当矿化度为3 g/L,而SAR不同的水入渗时,SAR在8.15(mmol/L)1/2时,饱和导水率达到最大值;当SAR大于8.15(mmol/L)1/2时,饱和导水率呈下降趋势.利用Green-Ampt模型及一维代数入渗模型,对试验结果进行对比分析,结果表明两种模型都可以描述咸水入渗特征,但相关参数具有不同于淡水的变化特征.通过对累积入渗量的理论值与实测值的分析得知,长历时入渗的情况下,Green-Ampt模型较精确;在短历时入渗情况下,一维代数入渗模型较精确.