高新节水灌溉技术在甘肃防沙治沙中的应用

甘肃沙区地处大陆腹地,气候干燥,降水稀少,水资源短缺,地下水位不断下降,固沙植被大面积衰亡,荒漠化蔓延速度加快,因而将高新节水灌溉技术引入防沙治沙显得十分必要。实践应用证明,应用滴灌、喷灌、渗灌等技术可在极端干旱地区建立有效的防沙治沙体系,能起到防风固沙,保护绿洲的重要作用。但是在应用中还存在一些问题,需要通过政府扩大投入、提高意识、完善制度体系和加强科学研究去解决。     

荒漠、半荒漠地区渠道防沙措施的研究──以内蒙古阿拉善盟孪井滩扬水灌溉工程引水总干渠为例

本文依据非堆积搬运理论和饱和路径学说的原理，以内蒙古阿拉善盟孪井滩扬水灌溉工程引水干渠为例，提出了荒漠、半荒漠地区渠道防沙措施，包括：（１）渠道横断面结构选择“Ｕ”型断面；（２）渠道两侧固沙防护林草体系。     

Soil properties and plant production after short-term fallows in Senegal

Abstract. Field trials of vegetation modification were carried out to test the hypothesis that the management of key plant groups such as trees, perennial grasses and legumes would improve soil chemical properties in short-term fallows. Soil properties and plant production during a 4-year fallow period and millet yields after clearing were recorded at two sites representing dry and subhumid climates in Senegal, West Africa. During the four years of fallow, soil organic matter did not vary significantly at either site. A decrease in amounts of Olsen P, calcium and potassium in soil (0–10 cm depth) by 42–50% occurred at one site due to an effect of perennial grasses. The highest millet yields were measured in plots on which the largest amounts of biomass had been burnt after clear-cutting. These results confirmed that short-term fallows do not replenish soil organic matter and nutrient contents. The introduction of planted species did not arrest the decline in soil quality.     

11个造林树种在京北荒滩应用固体水效果比较研究

以往研究表明,固体水能够提高造林成活率,特别在困难立地造林应用中已取得较好效果。为进一步选择应用固体水效果较好的树种,为今后困难立地造林树种选择提供参考,于2004年4月在北京市延庆县龙庆峡荒滩进行固体水多树种造林应用试验。通过分析树种成活率和相关生长指标,对比研究固体水多树种应用效果。结果表明,在荒滩造林绿化中,固体水能够提高各供试树种成活率和生长指标;银杏、旱柳、国槐、新疆杨、白榆、侧柏、刺槐、毛白杨和樟子松等9个树种应用固体水效果较好。     

宁夏毛乌素沙地不同密度柠条林对土壤结构及植物群落特征的影响

通过对种植不同密度的柠条对退化草原恢复效应的研究，结果表明随着柠条带间距的增加，土壤的物理性质得到极大的改善，容重逐渐减小，土壤的毛管孔隙度、总孔隙度、透气性、排水能力、则呈增加的趋势，其中10m带距的增幅最大。植被恢复后柠条带间土壤水分呈现10m〉7m〉对照〉4m的趋势。建立柠条林后随着植物种类的增加，个体重要值相对下降，各项生态指数不断升高。说明随着带间距的增加，群落结构在逐渐发生变化，使原来的荒漠化群落结构变得相对复杂并逐渐向稳定阶段发展。     

平原高沙土区合理种植及耕作方式对土壤性状的影响

研究了平原高沙土地区合理种植、水旱轮作、合理轮耕和秸秆还田增肥改土技术对土壤理化性状的影响。结果认为"两旱一水,两年五熟"不仅产量高,而且土壤理化性状得以改善;水旱轮作可增加土壤黏粒含量,提高高沙土肥力水平;合理轮耕可充分发挥少免耕的优势,达到增肥、改土、省工的目的;通过稻麦留高茬和玉米秸秆还田,可直接提高土壤肥力,从而提高农作物产量。该试验与推广取得了明显成效,促进了生态农业良性循环。     

Nitrolimigation: A Nutrient-in-Water Resource for Sustainable Crop Production on ‘Acid Sands’ of Southern Nigeria

The effects of a low-external-input soil fertility enhancement solution – hereafter termed ‘nitrolimigation’ were examined, as a preferred technique of applying nitrogen and calcium in the “Acid Sands” soils of southern Nigeria. Two types of nitrogenous fertilizer sources [urea and liquid pig manure (LPM)] and two types of lime {limestone (CaCO₃) and hydrated lime [Ca(OH)₂]} were used both in greenhouse and in field experiments at varying levels: Urea [CO (NH₂)₂] 0, 40, 50, 80, 100, 120, and 150 kg ha^?1; lime 0, 0.1, 0.3, 0.5, 1.0, 5.0, and 10.0 metric tonnes per hectare (t ha^?1) and LPM 0, 30, 60, 90, and 120 t ha^?1. The rates were arranged factorially and laid out in randomized complete block design (RCBD). The results indicated that combining lime at 9 t ha^?1 and LPM at 90 t ha^?1 in irrigation water had significant (P < 0.01) positive effects on the fertility status of the “Acid Sands” soils and growth of okra- Abelmoschus esculentus, the test crop. When urea was combined with hydrated lime, it reduced acidity and provided nutrient balance in the Acid Sands of Calabar. Total nitrogen was significantly (P < 0.01) boosted from 0.05 to 0.11%, base saturation (BS) from 46 to 62%, and exchange acidity was reduced from 2.93 to 1.35 cmol kg^?1. Combining urea (46-0-0) at 80 kg ha^?1 with lime (CaCO₃) at 5 t ha^?1 raised the soil pH from 4.4 to 7.1. Exchange acidity was reduced from 0.8 cmol kg^?1 to a negligible value, but electrical conductivity was improved from 170.7 to 291.9 μS cm^?1. When LPM and lime were combined, organic carbon was increased from 2.75 to 2.93%, BS was increased from 46.72 to 75.19%, and pH was raised from 6.0 to 6.73. Plant height was increased from 9.5 to 16.9 cm while mean number of leaves was also increased from 5.6 to 6.3 only with lower level of lime (3 t ha^?1) and LPM at 90 t ha^?1. Of the nitrogen and calcium sources, LPM and limestone were better at 120 t ha^?1 and 9 t ha^?1, respectively, to offset soil acidity, boost nutrient availability, and provide balanced nutrition to arable crops grown on the “Acid Sands” of southern Nigeria.     

Effects of Fines Content on Evolutionary Characteristics of Dynamic Pore Water Pressure of Saturated Sands

With the GDS dynamic triaxial system, undrained dynamic triaxial tests on the saturated sand with different fines content are performed, and the effects of fines content on evolutionary characteristics of dynamic pore water pressure of saturated sands in the process of liquefaction are analyzed based on Seed pore water pressure stress model. It is found that fines content has great effect on the dynamic pore water pressure of saturated sands by the parameter θ for Seed model. The relationship between parameter θ and fines content isnt linear. Parameter θ decreases with the increase of fines content at first, and then reaches its smallest value when the critical value of fines content is 30%. After that, parameter θ increases gradually with the rise of fines content. According to the experimental study on effects of fines content on evolutionary characteristics of dynamic pore water pressure of saturated sands, the existence of critical fines content with 30% is further proved in the sandy soil used in the test.     

榆靖沙漠高速公路格状沙障加植被综合防护效益调查分析

格状沙障,是近地风沙流边界层防止风沙危害的一种经济实用、功能独特、效果显著而应用最为广泛的固沙措施.它增大了下垫面的粗糙度,明显降低了底层风速,进而减弱了输沙强度,使流沙表面得以稳定.调查结果表明,1.0m×1.0m,1.0m×1.5m草方格防沙效果都是显著的,1.0m×2.0m和2.0m×3.0m草鞋方格防风固沙效果差一些.     

结缕草成坪综合因素研究 Ⅱ.赤霉素浸种和表土掺砂对结缕草种子出苗及坪苗质量影响

通过赤霉素浸种和表土掺砂对结缕草成坪的影响试验表明,５ｍｇ／Ｌ 赤霉素浸种２ｄ 和３ｃｍ 表土内每平方米掺砂１０ｋｇ 能显著提高出苗数,但对坪苗质量影响不显著。