强沙尘暴降尘对北京土壤的影响

对2002年3月袭击北京的强沙尘暴降尘的物理、化学性质进行了研究,结果表明:强沙尘暴降尘给北京土壤带来了改善土壤物理性质的大量粉砂粒,也带来了可作为天然有效化学肥料的大量有效养分和交换性离子,丰富了北京土壤的有机质、全N、大量元素养分和微量元素养分,提高了北京土壤的潜在肥力;强沙尘暴还给北京土壤带来了大量可溶性盐分和重金属微量元素污染物,影响了北京土壤环境的质量。     

四季柚贮藏试验初报

通过分析不同采摘时期，不同冷藏时期的四季柚果实理化成分的变化。探讨四季柚树藏，冷藏保鲜效果，为四季柚延长供果模式提供理论根据。     

黑杨派新无性系木材物理力学性质研究

伐取浙江临海无性系试验林 5年生 10个速生黑杨新无性系 30个样株 ,测定木材的物理力学性质。结果表明 ,其木材密度高于同地区速生杉木、柳杉 10年生木材的测定值 ,力学性质与之相近 ;木材物理性质在速生无性系间无显著差异 ,而力学性质差异显著或极显著 ;木材密度与力学性质显著相关 ,而木材性质与胸径生长相独立 ;参试无性系中 36 7、36 6、370、1388、12 1等无性系最适于营建短伐期工业用材林。     

Selected physical and chemical properties of mechanically extracted neem seed oil sourced as a preservative for ligno-cellulose in southwestern Nigeria

Most of the seeds produced by neem (Azadirachta indica A. Juss) trees in Nigeria are currently underutilized. Hence, relevant literature provides only limited information concerning many of the seed oils from this country, especially where it concerns the potential applications of these oils as preservatives for ligno-cellulose against bio-deterioration. Using standard procedures therefore, this study was carried out to evaluate and document selected physical and chemical properties of neem seed oil (NSO), mechanically extracted using a cold press at 31.03 N·mm -2 pressure and a room temperature of 25 ± 2℃. The results show that oil yield was 38.42% with a specific gravity of 0.91 ± 0.01. The amount of acid was 18.24 ± 1.31 mg KOH·g -1 and that of iodine 93.12 ± 2.01 g·100 g -1 , while saponification and peroxide values were 172.88 ± 2.06 and 1.42 ± 0.04 mg·g -1 respectively. The implication of the values obtained, particularly those for the chemical properties, as they concern the potential application of NSO as a preservative for ligno-cellulose, is likely that it may be useful in this regard since the values may support some of the documented anti-microbial properties of the oil, although other physical and chemical properties that may affect this potential are recommended for investigations. Conclusions and other recommendations follow in line with the results of the study.     

Interrelationships between certain physical and chemical properties of dry bean (Phaseolus vulgaris L.)

The interrelationships among certain physical and chemical properties of ten cultivars of dry beans (Phaseolus vulgaris L.) were investigated. The length/breadth ratio was similar (1.51–1.65) except for kidney beans (>2.0) and sanilac (1.37) cultivars. The breadth/thickness ratio ranged from 1.17–1.65. The 100-bean weight indicated a wide variation of 15.03–50.33 g. The density, bulk density, and porosity characteristics were within a narrow range of 1.18–1.36 g/cc, 68–75 g/100 cc, and 40.7–48.5%, respectively. Water uptake rates during the first 6 h of soaking at room temperature (21 °C) were characteristic of the cultivar. At the end of 24-h soaking, however, all cultivars had absorbed similar amounts of water (approximately 1 g/g bean). Leaching losses (g solids leached/100 g beans) had characteristic trends and ranged from 0.54 for cranberry to 3.46 for sanilac cultivars after 24-h soaking. Most correlations between selected chemical constituents and physical characteristics of the dry bean were relatively low.Journal Paper No. 2751 of Utah Agricultural Experiment Station and a contribution of Western Regional Project W-150.     

Management evaluation of Water Users Associations using benchmarking techniques

The development of different tools to evaluate the performance of Water Users Associations (WUAs) is an important practice for improving water and energy management, together with other production costs. One of these tools is the Benchmarking technique, which is based on the comparison between different WUAs to determine the best practices in each of them.In this paper, a Benchmarking process is applied to seven WUAs located in Castilla-La Mancha (Spain) during three irrigation seasons (2006-2008). The performance indicators developed by the International Programme for Technology and Research in Irrigation and Drainage (IPTRID) are used, while new indicators dealing with production and energy are proposed. The goals of this paper are to group WUAs with the same characteristics, using performance and energy indicators, and to reduce the set of indicators using statistical methods. The most important indicators, easy to obtain and yielding result in maximum information are retained for further use.Three proposals reducing the initial number of indicators were proposed, with an aim of being useful for future applications based on characterizing WUAs. Indicators results highlighted that irrigable areas can be grouped based on the application of drip irrigation systems and those with sprinkler irrigation systems. When using groundwater resources, no significant differences were observed for energy consumption between these irrigation systems. This can be explained by the indicator energy load index (ICE, m), which had similar values in all WUAs analyzed. According to annual irrigation water supply per unit irrigated area (V_TSr, m³ ha⁻¹), the highest values (between 5200 m³ ha⁻¹ and 6800 m³ ha⁻¹) were obtained in WUAs with sprinkler irrigation systems, which contained crops characterized by high water requirements, compared to the V_TSr (less than 1800 m³ ha⁻¹) of WUAs with drip irrigation systems, with crops that required less volume of irrigation water. Regarding production efficiency indicators, in drip irrigation systems the high presence of vineyards, almond and olive trees, crops with low water requirements, explained high values of gross margin per unit irrigation delivery (MBVs, € m⁻³)(close to 0.82 € m⁻³) in comparison with sprinkler irrigation systems (close to 0.36 € m⁻³).     

Pea and wheat starch possess different processing characteristics and affect physical quality and viscosity of extruded feed for Atlantic salmon

The aim of the study was to investigate the effect of starch source, retention time in the preconditioner and screw speed (RPM) on physical quality of extruded fish feeds. The experiment was arranged in a three by two by two factorial design using three carbohydrate sources [wheat starch (WS), pea starch (PS) or a combination (WS_PS)], two retention times in the preconditioner [long (120 s) or short (62 s)] and two RPM in the extruder [high (300) or low (220)]. Physical quality was assessed by hardness, diameter, expansion ratio, Holmen durability (HDI), DORIS value (DV), oil absorption capacity, oil leakage and pasting viscosity. The results showed that retention time in the preconditioner only affected HDI and oil leakage. Long retention time improved HDI but caused a greater leakage. Changing screw speed from 220 to 300 RPM gave a greater expansion ratio, improved HDI and oil absorption. PS resulted in higher pasting viscosity, HDI and DV, but a generally lower hardness than WS. To conclude, PS and WS have different processing characteristics, and the conditions need to be adjusted according to the starch source used when producing extruded fish feed.     

台风“苏迪罗”(1513)强降水特征及成因分析

为提高台风强降水预报准确率,减少台风暴雨造成的农业损失,为防灾减灾工作提供决策依据。本研究利用NCEP 1°×1°再分析资料、区域自动站实况观测资料,并结合浙江省地形特征,主要从台风路径、与降水相关的物理量场、近地层辐合和地形作用等方面分析"苏迪罗"在浙江形成强降水的成因。通过分析发现,台风路径与形势场的相互作用密不可分,"苏迪罗"登陆前长时间维持西北向移动主要是由于副高稳定维持;此外正涡度场轴线也在一定程度上指示台风未来走向。通过分析强降水与各物理量场关系可得出以下结论:(1)台风暴雨多处于东南急流与山地迎风坡相交汇的地区。(2)强降水区与水汽通量辐合区、比湿大值区、正涡度大值区和假相当位温的"双峰结构"有一定的对应关系,此外近地层辐合系统的长时间维持、台州东低西高山脉地形和局地喇叭口状地形是局地产生超强降水的重要条件。     

基于平衡计分卡的农田水利设施管护绩效指标的设定与评价——以农民用水户协会为分析对象

管护机制逐渐成为影响农田水利设施持续应用的重要内容,不断提升设施管护绩效对推进农业现代化具有重要意义。凭借便捷性和时效性的特点,农民用水户协会在水利设施管护中的作用不断凸显,但其会员服务能力、管护组织能力还有待提高。以平衡计分卡为架构标准,从管护效能、会员服务、内部管理、学习与发展4个方面对农民用水户协会参与农田水利设施管护的绩效进行评价,有利于提升用水户协会的设施管护能力,促进协会自身的战略发展,以期对农村基础设施建设有所裨益。     

野生赖草和垂穗披碱草抗旱能力比较

干旱是制约西藏牧草生长发育的一个重要因素,为此,本研究以西藏野生赖草(Leymus secalinus)和披碱草(Elymus nutans)作为试验材料,探究两种野生牧草抗旱能力的强弱,以期为西藏干旱半干旱区域生态恢复和栽培草地建植时草种的选择提供参考依据。结果表明,两种野生牧草的株高增长速率、植株含水量和叶绿素含量均随干旱时间的增加而降低(P0.05);丙二醛和游离脯氨酸含量随着干旱胁迫时间的增加而增加(P0.05)。赖草可溶性糖含量呈先减后增的变化趋势,而垂穗披碱草可溶性糖含量则呈减-增-减的变化趋势;可溶性蛋白含量均表现出先减后增的变化趋势。利用隶属函数{正相关函数模型F_1=(X_i-X_(min))/(X_(max)-X_(min))和负相关函数模型F_2=[1-(X_i-X_(min)]/(X_(max)-X_(min))}法对两种野生牧草的两个生物学特性指标(植株含水量和株高)和5个生理特性指标(叶绿素、游离脯氨酸、丙二醛、可溶性糖和可溶性蛋白)进行综合评价,得出赖草的抗旱能力大于垂穗披碱草。