Comparison of three methodologies for efficient seed extraction in studies of soil weed seedbanks

Determination of weed seeds in the soil is tedious and time consuming. To evaluate the different seed extraction methods to improve seedbank estimations, three extraction methods (sieving, cloth bag and flotation) were compared, based on their accuracy and time needed for separation processes and enumeration. Seeds of Datura stramonium,Amaranthus retroflexus,Portulaca oleracea and Plantago major were used to artificially infest soil samples of four textures, namely clay, clay loam, loam and sandy loam containing 19%, 27%, 38% and 65.5% sand respectively. Soil textures had a significant effect on counting time in all extraction methods. In flotation, four submethods involving different solutions and centrifuge rotation speed were examined, but showed no differences, so data were pooled. Counting time in flotation, cloth bag and sieving methods was 9, 16 and 30 min respectively. However, when the time needed for other processes was taken into consideration, flotation and bag methods did not differ significantly. Species‐wise seed recovery was not affected by soil texture in the bag method, suggesting an advantage for this approach as its accuracy is not soil texture‐dependent. Total seed recovery for flotation, sieving and bag methods was 61%, 67% and 75%, respectively, and was not significantly different. Considering the efficiency of methods, the cloth bag technique could be recommended, because it was as time consuming as the flotation method, but required the same minimum equipments and costs as the sieving method.     

冬季彩条布覆盖棚香梨树体气温特征分析

为了揭示冬季香梨园彩条布覆盖棚内外树体温度的变化特征,在2014～2015年库尔勒市上户镇原种场果园进行气温观测试验,对2015年1月7日～3月8日不同天气类型下彩条布覆盖棚内外树体气温进行分析。结果表明：⑴彩条布覆盖棚内平均气温、逐时气温高于棚外,棚内外气温总体变化趋势一致,不同天气类型下棚内外白天气温变化速度总体表现为：晴天＞多云＞阴天,夜间各天气类型气温变化均较平稳。⑵棚内树体阳面与阴面平均气温差逐渐较大,夜间树体阳面与阴面的逐时气温几乎相似,不同天气类型下棚内树体阳面逐时气温较阴面变化幅度大。⑶不同天气类型下棚外树体阳面最低气温均出现在9:00,阴面滞后1 h,晴天树体阳面最高气温出现在16:00,多云、阴天滞后1 h,阴面滞后2 h。     

葡萄清土与防寒布回收机械化技术研究现状与展望

目前葡萄清土与防寒布回收作业仍以人工作业为主,劳动强度大、效率低下、成本高,且该作业环节时效性强,过早过晚都不利于葡萄生长,因此亟需研究切实可行的葡萄清土与防寒布回收机.阐述国内外葡萄清土与防寒布回收机及关键部件的主要类型、工作原理及特点,提出机械化发展的制约因素和现有机具存在的问题,从农艺方面指出种植模式的不规范降低...     

不同颜色防雨布对杨梅生长发育及果实品质的影响

为提高杨梅综合品质及经济效益,研究延迟杨梅成熟期、降低落果率的技术措施,在杨梅硬核期和转色期分别设置覆盖防虫网及防虫网配合覆盖白、蓝、绿、红、黑色防雨布处理,以无覆盖处理为对照(CK1),测定不同处理对杨梅生长发育及果实品质的影响。结果表明,与CK1相比,绿色和蓝色防雨布有利于降低温度和相对湿度,而红色和黑色防雨布有利于温度升高,所有处理均显著抑制光合速率和枝梢的伸长,光合速率抑制率达30.62%~66.75%,其中转色期覆盖防虫网+绿色防雨布处理的抑制率最高。CK1的果实在成熟时100%脱落,硬核期和转色期进行防虫网单独覆盖和防虫网+黑色防雨布共4个处理的落果率在35.23%~70.49%之间,其他处理能显著降低杨梅果实落果率,落果率在16.44%~19.9%之间;防虫网+绿色防雨布处理、防虫网+蓝色防雨布处理延迟杨梅果实成熟时间最长,达5~9 d。综合分析杨梅果实总糖含量、维生素C含量等品质指标,转色期覆盖防虫网+蓝色防雨布处理的果实综合品质最佳,而覆盖防虫网+黑色防雨布处理的最差。本研究结果为有效利用不同颜色防雨布开展杨梅设施栽培、延迟杨梅供应期提供了理论指导。     

地布-地膜覆盖对渭北旱塬区土壤水分的影响

[目的]研究地布—地膜覆盖法的保湿效果及其耐久性,为渭北旱塬地区节水农业技术的进一步发展提供科学依据。[方法]针对地膜易风化,耐用性差,使用寿命短,残膜碎片对环境危害较大,而防草编织地布强度高,耐风化,但保水性差等优缺点,采用地布—地膜相结合(地膜在下,地布在上)的覆盖方式,开展为期1a的浅层土壤水分动态原位监测试验。[结果](1)无论地布—地膜覆盖区还是裸地区,其土壤含水量随深度的增加呈现出高—低—高的变化趋势。(2)地布—地膜覆盖区地面以下15,30,50cm土层的土壤水分比不覆膜处理区日平均提高11.2%,8.0%,5.3%。(3)有限的降雨对裸地土壤含水率的影响主要反映在表层15cm深度范围内,对覆盖条件下土壤含水率的影响则扩展到30cm深度。(4)试验期内,地布性能保存完好,地膜除了边缘外露处部分风化外,地布覆盖部分基本保持试验初期的完好状态。[结论]地布—地膜覆盖方式不但具有良好的保水防草效果,同时有效延长了地膜的使用寿命。     

毛乌素沙漠地膜\|地布覆盖下土壤温度变化特征

为了研究地膜+地布相结合的覆盖方式对毛乌素沙漠地区土壤温度的影响,在毛乌素沙漠东缘风沙滩区选取试验点,设置地膜+防草地布覆盖(MB)、防草地布覆盖(DB)以及裸地(CK)3个处理方式,开展为期1 a的浅层土壤温度原位监测试验,对比不同覆盖对温度变化规律的影响。结果表明:MB覆盖区地表下5、15、30 cm土层土壤的年均温度比DB覆盖区分别高出0.5℃、0.6℃和0.4℃,比CK分别高出1.0℃、0.8℃和1.0℃;冻融期在同一土层深度处均表现为CK最长、DB次之、MB最短;同一土层深度处3个处理的土壤温度之间存在显著性差异(P0.05),以MB覆盖条件下土壤保温效果最好,CK最差;MB覆盖区在5、15、30 cm土层土壤深度处≥5℃地积温比DB覆盖区分别高4.0%、4.0%和3.0%,比CK分别高8.0%、7.0%和9.0%;降雨前、中、后,同一土层深度处土壤温度日较差以MB覆盖区最大,DB覆盖区次之,CK最小;近地表大气温度与土壤温度呈正相关,同一土层深度处,覆盖条件下其相关性较大,裸地较小。试验表明地膜+地布覆盖处理保温效果明显,适合植物生长。     

浅谈芳纶纤维布在结构加固工程中的应用

介绍了一种新型材料技术--芳纶纤雏布在结构加固工程中的应用.     

“丝绸之路”东段旅游气候舒适性分析

根据＂丝绸之路＂东段12个气象站1971～2005年月平均气温、月平均相对湿度、月平均风速及日照时数等气象资料,采用温湿指数、风寒指数及着衣指数指标,对该地区的旅游气候舒适程度进行了分析。结果表明,＂丝绸之路＂东段最适宜旅游的月份为5月和9月;自东向西,该路段的气候舒适度逐渐降低;最适宜旅游的季节为夏季,其次为秋季和春季,最不适宜旅游的季节为冬季。     

扬州沿运灌区暗管排水土工布外包滤料的水力性能试验研究

农田暗管排水系统建设是提高农业机械化作业效率的有效措施之一.土工布作为排水暗管外包滤料时,需要具有良好的透水性能和抗淤堵能力.文中以扬州段沿运灌区为例,针对当地土壤中粉粒含量较高,土工布外包滤料筛选困难等实际问题,参考相关技术准则,选用2种开孔率和厚度不同的土工布进行了水力渗透试验,并与传统的河砂反滤材料进行了对比,筛选出适合当地土壤的土工布外包材料.研究结果显示,所选用的2种土工布透水性能存在较大差异,其中厚度较大(0.41 mm)、孔径较小(180 μm)的土工布A的透水性能较好,渗透系数为初始值的54.1%,高于河砂滤层的46.1%,而厚度为0.35 mm、孔径为227 μm的土工布B渗透系数仅为初始值的30.2%.相比于土工布B,土工布A具有更好的抗淤堵能力,长期使用后淤堵率比土工布B低16%.通过对土工布表面形成的、透水性较低的滤饼分析发现,土工布B不但自身发生了较大程度淤堵,其表面形成的滤饼较为密实,是影响其渗透性能的直接原因.     

REVEGETATION OF DECOMPOSED GRANITE ROADCUTS IN KOREA: DEVELOPING DIGGER,EVALUATING COST EFFECTIVENESS,AND DETERMINING DIMENSIONS OF DRILLING HOLES,REVEGETATION SPECIES,AND MULCHING TREATMENT

Decomposed granite roadcuts are difficult to revegetate after losing the topsoil and vegetation cover. We developed a new drilling machine, Digger, to efficiently drill six holes simultaneously on decomposed granite roadcuts to facilitate revegetation. The Digger consists of a base machine (0.7 m³‐level excavator) and a mounting body with six hydraulic motors instead of a bucket. We tested its performance on two roadcuts in southwest Korea using time‐motion studies, which showed that the Digger can drill 240 m² of decomposed granite roadcuts daily. The unit cost of the Digger was less than a half of other roadcut stabilization and revegetation techniques in Korea, making the Digger a cost‐effective revegetation technology. Field germination and growth tests were also conducted to identify appropriate diameter and depth of drilling holes, suitable revegetation species, and mulching treatment. We drilled holes with three different diameters and depths, filled the holes with a mixture of plant seeds and cultivated soil, applied mulching treatments (coir geotextile, shade net, and no mulching), and measured the germination and growth results at two field plots after 1 month and 1 year. The results showed that drilling diameter 10 cm and depth 10 cm were large enough to result in better plant germination and growth. Erosion control species, Poa pratensis L. and Eragrostis curvula (Schrad.) Nees, survived and grew better than native woody species. Coir geotextile improved the plant germination and growth. The time‐motion and revegetation results show that the Digger can be a promising technology to restore decomposed granite roadcuts. Copyright © 2013 John Wiley & Sons, Ltd.