Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources
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外来物种刺槐对土壤微生物功能多样性的影响
No full text以延河流域不同植被区内人工刺槐(Robinia pseudoacacia)群落和乡土植物群落的土壤微生物为研究对象，利用Biolog微平板技术对土壤微生物功能多样性进行测定，分析人工引种刺槐在不同环境梯度(三个植被区)下对土壤微生物功能多样性的影响。结果表明：刺槐对不同环境梯度下的土壤微生物的影响明显不同。从草原区到森林区，刺槐林之间土壤微生物群落的平均颜色变化率(AWCD)和土壤微生物功能多样性指数均没有显著变化；但与乡土植物群落比较，草原区、森林草原区和森林区土壤AWCD分别表现为刺槐>乡土植物、刺槐>乡土植物、刺槐<乡土植物；在草原区和森林草原区刺槐林土壤微生物群落的群落丰富度指数(S)、Shannon-Wiener指数(H)、Simpson指数(D)、McIntosh指数(U)均大于乡土植物，森林区刺槐林群落丰富度指数(S)、Shannon指数(H)、Simpson指数(D)均小于乡土植物；刺槐林和乡土植物群落下土壤微生物碳源利用存在差异，主要体现在对糖类、氨基酸类的利用上。PCA分析显示主成分1贡献较大的碳源有24种，在主成分分离中起主要贡献作用的是糖类、氨基酸类和羧酸类。土壤碳氮含量能影响土壤微生物功能多样性指数，土壤含水量和温湿度能够影响碳源的利用类型。刺槐对土壤微生物功能多样性的影响存在区域差异，在评价刺槐对土壤生态过程与功能的影响时必须要考虑这种空间差异性。</p
硫酸钾对浑水滴灌滴头堵塞的影响
No full text【Objective】 In order to provide reference for the implementation of water and fertilizer integrated drip irrigation, this study evaluated the effects of potassium sulfate on the clogging of the drip in fertigation with muddy water such as the Yellow River water. 【Method】Three kinds of sediment content（1.0，1.5 and 2.0 g/L） and three kinds of potassium sulfate mass concentration（10，20 and 30 g/L）were arranged. A kind of intermittent irrigation clogging experiment was designed, the changes of average relative flow rate and coefficient of uniformity of the drip were calculated. After that period, the siltation’s characteristics and structure of the runner block had been analyzed by field emission scanning electron microscopy. Lastly, the dripper output sediment and deposition sediment were collected and analyzed. 【Result】Adding potassium sulfate into muddy water accelerates the clogging of dripper, and the higher potassium sulfate mass concentration was, the more obvious the effect of accelerating the clogging was. When potassium sulfate mass concentration was 30 g/L, the effective irrigation times of different sediment content, which were 1.0, 1.5 and 2.0 g/L, reduced by 4 times, 9 times and 8 times respectively and the clogging rate increased by 30%—35%. Potassium sulfate increased the conductivity significantly, the conductivity of muddy water was 0.16 ms.cm-1 when there was no fertilization, and however the conductivity which potassium sulfate mass concentration of 30 g/L was about 25 ms/cm. The potassium sulfate mass concentration has a certain effect on the clogging position of the dripper, which has little effect on the inlet's clogging and has a great effect on the channel block. The potassium sulfate mass concentration was 10, 20and 30 g/L, and the total number of blocked flow blockage was increased by 7, 18 and 17 respectively than without fertilizer. Potassium sulfate changes the conductivity of irrigation water, affecting sulfate precipitation and resulting in dripper clogging. After the application of potassium sulfate, the sediment in the water is easy to adsorb K+, which increases the agglomeration between the sediment particles, resulting in the increase of the complexity of surface structure of the clogging and the compactness and stability of the clogging material. After applying potassium sulfate in muddy water, the proportion of silt and clay in the output sediment is larger than that in the capillary, and the proportion of sand is less than the deposition sediment in the pipe. The fractal dimension of siltation sediment was negatively correlated with the relative flow rate.【Conclusion】If using the potassium sulfate fertilizer for drip irrigation, people should reduce the potassium sulfate concentration below 10 g/L, in order to slow the dripper clogging.;【目的】分析引黄灌溉过程中肥料硫酸钾对滴头堵塞的影响，为水肥一体化滴灌的实施提供参考。【方法】分别配置了3种含沙量（1.0，1.5和2.0 g/L）和3种硫酸钾质量浓度（10，20和30 g/L）进行间歇灌水堵塞试验，计算滴头的平均相对流量和灌水均匀度，利用场发射扫描电镜分析流道堵塞物结构，收集并分析滴头输出泥沙和毛管淤积泥沙的机械组成。【结果】施加硫酸钾后浑水滴灌滴头堵塞出现加速现象，硫酸钾质量浓度越大，加速堵塞作用越明显。当硫酸钾质量浓度为30 g/L时，含沙量为1.0，1.5和2.0 g/L处理的有效灌水次数分别较未施肥处理减少4，9和8次，滴头堵塞率较未施肥处理增加30%~35%；施加硫酸钾显著增大了水的电导率，未施加硫酸钾的浑水电导率约为0.16 ms/cm，硫酸钾质量浓度为30 g/L时，含钾浑水的电导率为25.19 ms/cm。硫酸钾质量浓度对滴头堵塞的位置有一定影响，对滴头进水口堵塞影响较小，对滴头流道堵塞影响较大,当硫酸钾质量浓度为10，20和30 g/L时，流道堵塞滴头数比未施肥处理分别增加了7、18和17个。硫酸钾改变了灌溉水的电导率，易产生硫酸盐沉淀而造成滴头堵塞。施加硫酸钾肥后，浑水中泥沙颗粒易吸附K+，增加了泥沙颗粒之间的团聚，导致堵塞物表面结构复杂程度提高，堵塞物致密性和稳定性增强；浑水中施加硫酸钾肥后，输出泥沙中粉砂和黏粒比例较毛管淤积泥沙大，砂粒比例则较毛管淤积泥沙少，淤积泥沙的分形维数与平均相对流量呈显著负相关。【结论】选用硫酸钾滴灌时，硫酸钾质量浓度应小于10 g/L，以减缓其对滴头堵塞的影响。</p
Linkages of plant-soil interface habitat and grasshopper occurrence of typical grassland ecosystem
No full textHow to understand the interactive influence of environmental changes on the total grasshopper density (TGD) becomes an urgent issue in grassland ecosystems. Large-scale studies are ideal for assessing the relative contributions of multiple factors on grasshopper community dynamics. Using data from 634 sites, linkages of community habitats (plant functional groups (PFGs), vegetative litter (VT) and soil types (ST)) and grasshopper occurrence were studied in a farming-pastoral zone across Inner Mongolia. Each of the three primary grassland ecosystem drivers influenced total grasshopper density. The absence of VT (VTabsence) can decrease the total grasshopper density by degrading the habitat conditions. Similarly, grasshopper communities prefer to feed on legumes and forbs rather than grasses due to the plant-trait variance in PFGs. Moreover, total grasshopper density was driven by complex interactions, caused by PFGs, soil types and vegetation litter. Our results improve the understanding of where grasshoppers might occur and provide helpful strategies to prevent the outbreak of grasshoppers.</p
Controlled-release fertilizer with lignin used to trap urea/hydroxymethylurea/ urea-formaldehyde polymers
No full textTo improve nitrogen fertilizer efficiency and minimize the negative impact of nitrogen fertilizer on the environment, a novel three-dimensional network polymer material with slow release character was prepared based on hydroxymethylated lignin (HML) and urea/hydroxymethylurea/urea-formaldehyde polymers (U/HU/UF) through solution polymerization. The novel material (Lignin-U/HU/UF) was characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance spectra (1H NMR), and distortionless enhancement by polarization transfer analysis (DEPT 135). The N release characteristics of the material were determined by soil leaching experiments under laboratory conditions. On this basis, the release profiles of total nitrogen and other nitrogenous compounds (NH4+and NO3-) were investigated. The experimental data showed that lignin can be used as a majority component in material, which trapped polymers such as urea, hydroxymethylurea, and urea-formaldehyde to improve slow-release properties of fertilizer. The results indicated that the eco-friendly material (Lignin-U/HU/UF) with good controlled-release capacities potentially could be applied in agriculture and horticulture.</p
Correction of anisotropy effects on penta-needle heat-pulse probe sap-flux density and thermal property measurements
No full textGrowing interest in methods for estimating plant stem/trunk sap-flux density and thermal properties include the use of heated needles inserted into the plant. A penta-needle heat-pulse probe (PHPP) coupled with an on-chip integrated INV-WATFLX algorithm was newly developed for inverse estimation of isotropic porous media thermal-diffusivity, κ, -conductivity, λ, and heat velocity, Vh (converted to water-flux density, J), thus heat capacity, C(=λ/κ), and water content could also be derived. This integrated sensor, however, has yet to be applied in anisotropic sapwood sensing. Here, we conducted a numerical simulation of the PHPP heat pulse and a deviation analysis when using an INV-WATFLX code developed by Yang and Jones [Comput. Geosci.—UK. 35 (2009) 2250] in anisotropic porous media. Deviations in J were up to +40% and as low as -30%, and within 12% in κ, λ and C at static conditions for varied PHPP installation angles, α, in sapwood. We developed a correction of anisotropy effects, and followed up with a field test of the sensors installed on standing poplar (Populus simonii Carr.) trees using α = 0°, 15° and 30°. Field tests showed the corrected J estimated using PHPPs at α = 15° and 30° both agreed well with J from thermal dissipation probes (TDPs) in 1:1 line (R2 = 0.87 and 0.83, P < 0.01). The corrected J at α = 0° showed an apparent 30% underestimate (R2 = 0.87, P < 0.01), which was assumed to be due to wound effects. All PHPP estimates exhibited similar and stable κ, λ and C at night, but showed a diurnal fluctuation in J to varying extents likely due to the flow turbulence by inserted needles.</p
Soil water content and temporal stability in an arid area with natural and planted grasslands
No full textSoil water content (SWC) is a key factor for successful vegetation restoration in arid and semiarid regions, and vegetation has significant influences on the spatial patterns and temporal dynamics of SWC. The aim of this study was to investigate the temporal stability of SWC under different restored grasslands in an arid hilly area of Central China. SWC was measured in the 0- to 300-cm soil profile in the natural grassland (Stipa capillata) and three typical planted grasslands (Medicago sativa, Agropyron cristatum, and Caragana korshinskii) over two growing seasons (from June to October 2015 and 2016) under natural rainfall conditions. The results showed that the mean SWC in the natural grassland was approximately 30% higher than those in the planted grasslands. The SWC consumption of the planted legume grasslands in the deepest soil layers (below 200 cm) was higher than that of the natural grassland, owing to the deep root system of the legumes. Both natural and planted grasslands had low SWC temporal stability in the top soil layers (0-50 cm), whereas more stable conditions were gradually observed with increasing the soil depth. The mean value of the mean relative differences of SWC in natural grassland (ca. 15%) was lower than that in the planted grasslands (A. cristatum grasslands) and much lower than that in the scrubland, highlighting the stronger temporal stability of SWC in the natural grassland. In conclusion, natural grassland could maintain higher and stable SWC and is recommended to be used for achieving sustainable vegetation restoration in arid and semiarid regions.</p
人工模拟降雨条件下黄土坡面水-沙-氮磷流失特征
No full text黄土坡沟水沙及养分流失严重，不仅造成土地生产力下降，对水环境也存在潜在威胁． 为探索黄绵土坡面水沙氮磷流失相 关关系，采用人工模拟降雨试验，研究不同雨强( 45、 60、 75、 90、105、120 mmh) 、不同坡度( 5°、10°、15°、20°、25°) 下黄土裸地水沙 氮磷的流失规律． 结果表明: ①产流量可用坡度的二次多项式表达，确定系数( Ｒ2) 达 0. 83 以上，产沙量随雨强变化规律不明显， 但随坡度增加呈显著增加趋势． ②各雨强下，25°与5°坡面的ρ( TN) 比值范围为1. 63～5. 42，波动较大，而ρ( TP) 随坡度的增加基 本呈增加趋势，但整体数值低于ρ( TN) ． ③各雨强下ρ( 吸附态氮) 随降雨历时的延长呈剧烈起伏变化;大雨强( 105 和120 mmh) 下ρ( 吸附态磷) 随降雨历时的延长逐渐减少至稳定值，其他雨强下 ρ( 吸附态磷) 随降雨历时的延长呈现波动增加． 各雨强与坡度 下， ρ( 吸附态氮) 与 ρ( 吸附态磷) 分别占 ρ( TN) 、 ρ( TP) 的60. 66%、96. 62%，是黄土裸坡氮磷的主要流失形式． ④随水沙流失的氮 磷中，TN 占主要部分，其流失量是 TP 流失量的 1. 43～22. 46 倍，径流量增加时 TN 流失量显著增加，而产沙量增加时 TP 流失量 显著增加． 研究显示，雨强和坡度变化对水沙氮磷流失影响各异，吸附态氮磷是黄土养分流失的主要途径，可为黄土坡耕地水土 流失治理提供科学依据．</p
Spatial Patterns of Relationship Between Wheat Yield and Yield Components in China
No full textThe considerable plasticity of wheat (Triticum aestivum L.) in reaching final yield is dynamically determined by three yield components: spike number m(-2) (SN), kernel number spike(-1) (KN) and 1000-kernel weight (KW). Understanding the contribution of yield components to the variation of grain yield under different production environments is essential for designing breeding programs and increasing grain production. This study analyzed 2 years of experimental data from the Chinese Variety Evaluation Program to explore the relationship between grain yield and yield components in four main winter wheat production regions. Correlation and path analysis were the main methods used in this paper. Yield and yield components were restricted by high temperature and lower sunshine hours at southern regions (Upper Yangtze Valleys, UY and Middle and Lower Yangtze Valleys, MLY). No relationship between yield and climate elements was found at northern region (Yellow and Huai Valleys, YH and Northern Land, NL). Yield in the YH region was the greatest with both higher SN and KN, and SN had strong negative relationships with KN and KW. SN was the main factor correlated the variation of yield, especially in low yielding regions (UY and NL), suggesting breeding efforts should emphasize increasing SN in these environments. The role of KW and KN became increasingly important in high yielding region (YH), indicating that all yield components should be considered in breeding for high yielding environments
Spatial and depth variability of streambed vertical hydraulic conductivity under the regional flow regimes
No full textThis study investigated the influence of the regional flow on the streambed vertical hydraulic conductivity (K-v) within the hyporheic zone in three stream reaches of the Weihe River in July 2016. The streambed K-v with two connected depths was investigated at each test reach. Based on the sediment characteristics, the three test reaches could be divided into three categories: a sandy streambed without continuous silt and clay layer, a sandy streambed with continuous silt and clay layer, and a silt-clay streambed. The results demonstrate that the streambed K-v mainly decreases with the depth at the sandy streambed (without continuous silt and clay layer) and increases with the depth at the other two test reaches. At the sandy streambed (with continuous silt and clay layer) where streambed K-v mainly decreases with the depth, the regional upward flux can suspend fine particles and enhance the pore spacing, resulting in the elevated K-v in the upper sediment layers. At another sandy streambed, the continuous silt and clay layer is the main factor that influences the vertical distribution of fine particles and streambed K-v. An increase in streambed K-v with the depth at the silt/clay streambed is attributed to the regional downward movement of water within the sediments that may lead to more fine particles deposited in the pores in the upper sediment layers. The streambed K-v is very close to the bank in the sandy streambed without continuous silt and clay layer and the channel centre in the other two test reaches. Differences in grain size distribution of the sediments at each test reach exercise a strong controlling influence on the streambed K-v. This study promotes the understanding of dynamics influencing the interactions between groundwater and surface water and provides guidelines to scientific water resources management for rivers
Nitrogen addition increases the contents of glomalin-related soil protein and soil organic carbon but retains aggregate stability in a Pinus tabulaeformis forest
No full textBackground: Glomalin-related soil protein (GRSP) and soil organic carbon (SOC) contribute to the formation and stability of soil aggregates, but the mechanism by which global atmospheric nitrogen (N) deposition changes soil aggregate stability by altering the distribution of GRSP and SOC in different aggregate fractions remains unknown. Methods: We used a gradient N addition (0-9 g N m(-2) y(-1) ) in Pinus tabulaeformis forest for two years in northeast China and then examined the changes in SOC contents, total GRSP (T-GRSP), and easily extractable GRSP (EE-GRSP) contents in three soil aggregate fractions (macro-aggregate: >250 mu m, micro-aggregate: 250-53 mu m, and fine material: <53 mu m) and their relationship with aggregate stability. Results: (1) The soil was dominated by macro-aggregates. Short term N addition had no significant effect on mean weight diameter (MWD) and geometric mean diameter (GMD). (2) GRSP varied among aggregate fractions, and N addition had different effects on the distribution of GRSP in aggregate fractions. The EE-GRSP content in the macro-aggregates increased initially and then decreased with increasing N addition levels, having a peak value of 0.480 mg g(-1) at 6 g N m(-2)y(-1) The micro-aggregates had the lowest EE-GRSP content (0.148 mg g(-1) ) at 6 g N m(-2)y(-1) . Furthermore, the T-GRSP content significantly increased in the aggregate fractions with the N addition levels. (3) The macro-aggregate had the highest SOC content, followed by the micro-aggregate and the fine material had the lowest SOC content. N addition significantly increased the SOC content in all the aggregate fractions. (4) GRSP and SOC contents were not significantly correlated with MWD. Conclusion: Glomalin-related soil protein and SOC contents increased by N addition, but this increase did not enhance aggregate stability in short term, and the improvement of stability might depend on binding agents and incubation time