Influence of salinity and moisture on the threshold shear velocity of saline sand in the Qarhan Desert,Qaidam Basin of China: A wind tunnel experiment

Determination of the threshold shear velocity is essential for predicting sand transport, dust release and desertification. In this study, a wind tunnel experiment was conducted to evaluate the influence of salinity and moisture on the threshold shear velocity of saline sand. Saline sand samples (mean particle size of 164.50-186.08 μm and the total silt, clay and salt content of 0.80%-8.25%) were collected from three saline sand dunes (one barchan dune and two linear dunes) in the Qarhan Desert, Qaidam Basin of China. Original saline sand samples were placed in two experimental trays for wet and dry processing to simulate deliquescence and desiccation, respectively. Surface moisture content ranging from 0.30% to 1.90% was generated by the steam method so that the saline sand can absorb water in a saturated water vapor environment. The motion of sand particles was determined by the observers with a solid laser. The laser sheet (0.80 cm thick), which was emitted by the solid laser, horizontally covered the sand surface and was bound to the sand. Results show that the cohesion of saline sand results from a combination of salt and water. The threshold shear velocity increases exponentially with the increase in crust thickness for the linear sand dunes. There is a positive linear correlation between the original moisture content and relative threshold shear velocity. The threshold shear velocity of dewatered sand is greater than that of wet sand with the same original moisture content. Our results will provide valuable information about the sand transport of highly saline soil in the desert.     

基于变分法的FY-3C土壤水分产品适用性分析

FY-3C作为我国风云三号首颗业务卫星,其上搭载的微波成像仪(MWRI)可提供全天候土壤水分数据。【目的】获取高质量土壤水分数据可以对合理利用土壤水资源提供参考,为农田干旱监控和预报提供基础参数。【方法】选取山东省农业气象站土壤水分数据对FY-3C土壤水分产品进行检验,为获取更高质量FY-3C土壤水分产品,选用变分订正方法对FY-3C土壤水分产品进行偏差订正。【结果】FY-3C升降轨土壤水分产品与地面站土壤水分相关系数R分别为0.481 6和0.408 2,RMSE分别为0.099 6和0.091 0 cm~3/cm~3。订正后FY-3C升降轨土壤水分产品与地面站土壤水分R分别为0.701 4和0.892 4,RMSE分别为0.021 7和0.011 cm~3/cm~3。对2016年3—4月山东省干旱过程订正前、后FY-3C土壤水分变化情况进行对比,订正后FY-3C土壤水分更准确地反映出此次干旱过程。【结论】FY-3C土壤水分产品可以准确反映土壤水分随时间的变化趋势,订正后FY-3C土壤水分产品与地面站土壤水分间误差减小、相关性提高。     

不同裂解温度的污泥生物质炭理化特性分析

研究裂解温度对污泥生物质炭基础理化性质的影响,为安全、合理、高效处置污泥提供理论依据。将干燥污泥分别在200、300、500、700℃下进行热裂解处理(SBC200、SBC300、SBC500、SBC700),获得污泥生物质炭,测定其基础理化特性。结果表明：不同温度制备的污泥生物质炭表面颗粒结构完好,孔径范围均集中在10~50 μm,其中低温生物质炭SBC200表面较光滑,最可几孔径和中值孔径最大,分别为20.1 μm和14.8 μm,高温生物质炭SBC700表面较粗糙,比表面积最大,为5.98 m²/g。随裂解温度的提高,污泥生物质炭的产率、含水量、电导率、挥发分、阳离子交换量显著下降,全碳、氧、全氮、氢含量、有效磷和铵态氮均逐渐降低,pH和灰分含量显著增加。将污泥制备成生物质炭,是安全处置污泥的有效途径,低温制得的污泥生物质炭具有更大的提高土壤肥力的潜力,而高温制得的生物质炭在改良土壤酸性的应用上具有更大的潜力。     

Variations of SOC and MBC observed in an incubated brown loam soil managed under different tillage systems for 12 years

To assess changes in organic carbon pools, an incubation experiment was conducted under different temperatures and field moisture capacity (FMC) on a brown loam soil from three tillage practices used for 12 years: no‐till (NT), subsoiling (ST) and conventional tillage (CT). Total microbial respiration was measured for incubated soil with and without the input of straw. Results indicated that soil organic carbon (SOC) and microbial biomass carbon (MBC) under ST, NT and CT was higher in soil with straw input than that without, while the microbial quotient (MQ or MBC: SOC) and metabolic quotient (qCO₂) content under CT followed the opposite trend. Lower temperature, lower moisture and with straw input contributed to the increases in SOC concentration, especially under NT and ST systems. The SOC concentrations under ST, with temperatures of 30 and 35°C after incubation at 55% FMC, were greater than those under CT by 28.4% and 30.6%, respectively. The increase in MBC was highest at 35°C for 55%, 65% and 75% FMC; in soil under ST, MBC was greater than that under CT by 199.3%, 50.7% and 23.8%, respectively. At 30°C, the lower qCO₂ was obtained in soil incubated under NT and ST. The highest MQ among three tillage practices was measured under ST at 55% FMC, NT at 65% FMC and CT at 75% FMC with straw input. These data indicate the benefits of enhancing the MQ; the low FMC was beneficial to ST treatment. Under higher temperature and drought stress conditions, the adaptive capacity of ST and NT is better than that of CT.     

广西钦州市菠萝山不同朝向土壤理化性状比较分析

以钦州市钦南区菠萝山为研究对象，采用环刀取土烘干法及混合土样法对不同区域（东南、西南、西北）土壤的理化性状进行分析。结果表明：不同采样区域（东南、西南、西北）土壤含水量和物理性粘粒（＜0.01 mm）差异显著，东南朝向含水量及粘粒含量最高，其次是西南朝向，西北朝向最低；不同采样区域（东南、西南、西北）土壤容重、孔隙度及 pH 值差异不显著。通过该研究表明，山体的不同方向对土壤发育及水土保持有显著影响，人为干扰影响山体土壤良性发展。     

竹柳等4个柳树无性系造纸材性测定分析

对3年生竹柳、苏柳172、苏柳795、苏柳799进行造纸材性测定,结果表明:4个柳树无性系的木材基本密度在0.324~0.368 g/cm3之间,纤维长度在0.866 9~0.928 8 mm之间,纤维宽度在21.349~22.683μm之间。4个柳树无性系木材纤维的长宽比、壁腔比及腔径比等指标均符合造纸原料要求,而且纤维长度、宽度均分布比较均匀。     

基于PLC与组态王的实木板材双面检测装置的总体设计

选用S7-200 PLC,结合组态王人机交互界面,运用激光轮廓和色泽集成扫描技术设计了一种实木板材双面检测系统。主要介绍了该检测系统的工作原理和工作流程,简述了检测装置的整体结构及其传动、升降、检测、行程控制等主要模块的设计及电气控制系统总体设计。试运行表明,该装置集合PLC和组态王的优势,利用激光扫描技术,可实现对板材双面检测过程的实时控制;板材检测运用色泽与轮廓相结合,有效地解决了现有实木板材单面检测系统不能全面地反映实木板材表面缺陷状况的难题。该设计可为实木板材表面缺陷检测中三维轮廓检测技术的进一步应用提供有益参考。     

饲草作物对土壤健康与农业可持续发展的作用

饲草作物是指为增加土壤肥力,防止土壤侵蚀,累积和保护土层,增加土壤养分和含水率以及提高土壤质量而种植的植物。饲草作物为农田土壤提供了诸多益处,其还有助于增加和维持土壤中的微生物多样性。本文对多种饲草作物对土壤特性的作用,如土壤含水量、土壤微生物的活动、土壤碳固存、土壤硝态氮淋失、土壤水分和土壤健康等进行综述。饲草作物的选择通常取决于其自身对土壤的作用,其他考虑因素还包括天气条件,播种时间,是否为豆科植物以及杀灭饲草作物的时间和方法。研究表明,饲草作物也可用于减缓气候变化,抑制作物中的杂草,增加可交换的营养物质如Mg2+和K+,具有一定的经济性。另外,覆盖作物也会存在一些问题,包括杀灭覆盖作物的方法,其可能成为病原体的寄主,饲草作物的再生性以及短期收益不明显。尽管有一些局限,饲草作物仍被认为可以明显改善土壤整体健康状况,为主栽作物提供可持续的生态环境。     

不同沟垄覆盖下土壤水热效应对旱作马铃薯生长及产量的影响

针对宁南山区春季降雨少、低温不利于马铃薯出苗,而作物生育中后期高温胁迫限制马铃薯块茎形成导致减产等问题,于2016年设置垄覆地膜沟内覆盖塑料地膜(DM)、玉米秸秆(JG)、生物降解膜(SM)、麻纤维地膜(MM)、液态地膜(YM)及沟不覆盖(BM),以传统平作为对照(CK),研究沟垄覆盖模式对土壤温度、土壤水分、旱作马铃薯生长及块茎产量的影响.结果表明:处理DM,SM,MM和YM马铃薯生育期耕层土壤温度表现出增温效应,而处理JG和BM表现为降温效应,其中处理DM增温效果和处理JG降温效果最佳.处理YM,JG对马铃薯生长前期保水效果较好,分别较CK显著提高13.3%,27.0%,而处理JG,DM对生育中后期的保墒效果较佳,分别较CK显著提高22.4%,13.2%.处理JG可显著促进马铃薯生长,其增产效果最为显著,DM次之,分别较CK增产47.8%,44.8%,其他处理较CK差异不具有统计学意义.可见,在宁南山区实施垄覆地膜沟覆秸秆模式可调控土壤水热环境,对旱作马铃薯生长及增产效果最佳.     

Effect of germination time and temperature on the functionality and protein solubility of sorghum flour

Sorghum was germinated for different time (12, 24, 36 and 48 h) at different temperatures (25, 30 and 35 °C) and the changes in their nutritional and functional properties of germinated sorghum flour were assessed and compared with native sorghum flour. Germination inversely affects the crude protein, fat, fibre and ash content. A decrease in water absorption and swelling power and increase in oil absorption capacity was observed due to enzymatic starch modification as the germination duration progressed. Germination of sorghum increased the gel consistency while paste clarity was decreased as compared to native flour. Proteins were modified by action of enzymes during higher germination time and temperature conditions, which results in significantly higher protein solubility of germinated sorghum flour, which also result in enhancing the foaming and emulsifying properties of the flour. Lowest % synersis value and least gelation concentrations were observed in native sorghum has, which increased during germination and were highest in sorghum germinated for 48 h at 35 °C. Germination in overall can be used as low cost natural bio-processing technique for the preparation of modified flour with enhanced function properties without chemical modification or genetic engineering.