Hydraulic conductivity and porosity under conventional and no-tillage and the effect of three species of cover crop in northern France

We studied soil hydraulic conductivity (K) and porosity in five combinations of soil tillage and cover crop management systems. Treatments were winter wheat (Triticum aestivum L.) grown on a conventionally tilled soil (CT), on a no‐till soil (NT), and on an NT with three different cover crops: red fescue (Festuca rubra L.; Fr), bird's‐foot‐trefoil (Lotus corniculatus L.; Lc) and alfalfa (Medicago sativa L.; Ms). Measurements were made on a loamy soil in Grignon, France, in November 2004, May 2005 and October 2005. K and mean size of hydraulically active pores were measured in situ at three water potentials (?0.6, ?0.2 and ?0.05 kPa) at the soil surface and at 10 cm depth. In November 2004 and May 2005, pore space was described using 2D image analysis of pores on undisturbed soil samples in the 0–10 cm layer and in the 10–20 cm layer. The major differences were caused by soil tillage that created two heterogeneous soil layers and increased K in the 0–10 cm layer relative to NT. The effects of cover crop on K and porosity were not affected by the root type: there were no major differences between the grass cover crop (fibrous‐root type) and the leguminous ones (tap‐root type). However, we recorded larger functional pores and more tubules in the no‐till treatments with a cover crop, compared with the no‐till treatment without cover crop; this was probably the result of root activity. Although these changes generally did not result in larger values of K, they participated in the maintenance of soil structure and K over time.     

地膜覆盖下豆禾混播草地根系的动态研究

使用差额法连续分层次地对燕麦＋豌豆人工草地的根系在地膜覆盖条件下的生长发育动态进行了研究，结果表明：燕麦根系的58％分布浅，豌豆的77％根系分布在10～20cm深，两者混播后，其根系可有效地互补，且在地膜覆盖条件下互补性增强。同时地膜覆盖后，使根系的分布更浅，根量减少。     

大口径埋地塑料排水管的应用前景

结合塑料排水管材的自身特点及目前这一管材在市政排水领域的应用现状，通过多年的工程实践，从国家相关的法律法规及经济技术比较等角度出发，笔者认为大口径埋地塑料排水管替代传统的钢筋混凝土排水管将成为市政工程管网建设中的新趋势。     

大棚畦床栽培蘑菇高产的实践与体会

根据一定规模的实践，研究总结出一套成功的大棚畦床栽培蘑茹高产高效技术，具体介绍了大棚构建、畦床制作、堆料配制、适宜播期、优良品种、营养液、相对湿度、棚温和料温管理等的操作关键。文中还就适宜播期、种植方式、保湿越冬和适时补充营养液等关键技术进行了讨论。     

An expression for wind erosion rate from dry and dense soil surface

Wind erosion is a physical process predominated by airborne grains rather than the wind itself. The soil deformation is either elastic–plastic or fully plastic during its collisions with solid grains, corresponding to dense and loose soils, respectively. Only the fully plastic deformation was previously taken into account in the physically-based wind erosion models. The impact erosion of dry and dense soil surface can be well quantified by the contact mechanics and strength theories. In this study, with the help of Owen's uniform saltation model, a simple expression for wind erosion rate is derived based upon the eroded volume per impact when soil deforms in the elastic–plastic manner. The new expression, a simple analytical function of several conventional variables and parameters of wind and soil, describes the effects of saltation flux and soil susceptibility. Its validity is verified by some field and laboratory experiments.     

晋西旱塬地渗水地膜覆盖玉米试验

在位于晋西南黄土残塬沟壑区的隰县旱地进行了渗水地膜覆盖玉米种植试验。结果表明,与常规地膜覆盖比较,渗水地膜覆盖玉米增产３８．３％,增产效果显著;玉米生育期０－１００ｃｍ土层内土壤含水量平均提高２个百分点,天然降水的水分粮食生产效率达到２３．２５ｋｇ．ｍｍ＾－１．ｈｍ＾－２;当气温在３５℃以下时,渗水地膜与常规微膜具有相同的增温效果,当气温在３５℃以上时,渗水地膜下的增温速度明显减慢,玉米生育期株高     

旱塬地玉米耗水特点及提高水分利用率途径

研究结果表明,农田耗水主要在１m以上土层,玉米对０－５０cm土层的水分利用 率达６０％;玉米农田棵间土壤水分蒸发占农田蒸散的４７．６％－７７．５％,整个生育期棵间蒸发与叶面积指数呈负相关,玉米产量与蒸腾呈正相关;秸秆覆盖可有减少棵间土壤水分蒸发;合理施肥能促进玉米对土壤水分的利用。     

烤烟小苗膜下移栽膜内外温度关系研究

为探索烤烟小苗膜下移栽适宜的破口温度及大小,为指导大田生产提供理论依据。笔者通过大田试验,比较了白、黑膜膜内外空气温度、塘底土壤温度及不同破口大小的温度变化。结果表明：随着田间空气温度的增加,膜内空气温度随之大幅度增加,白膜膜内温度均大于黑膜膜内温度。当田间空气温度低于20℃时,通过小苗膜下移栽改变烟苗生长环境可达到保温的作用;田间空气温度高于27℃时,膜内空气温度达到45℃时,应及时进行破大孔处理,以防高温灼伤烟苗。在环境温度可以保障烟苗生长需求的前提下,较早破口相对利于烟苗生长。     

生物降解膜覆盖马铃薯增产机理研究

[目的]为了探明广东省冬种马铃薯使用生物降解膜的增产机理,设置了生物降解膜、生物降解除草膜、普通塑料膜、不盖膜四个处理。[方法]通过大田试验研究了不同覆盖方式对土壤温度、养分以及马铃薯产量和品质的影响。[结果]结果表明,三种地膜覆盖处理下,各耕层土壤温度差异不显著,较不盖膜处理差异显著,其中膜下10 cm上午9点生物降解除草膜、生物降解膜、普通塑料膜较不盖膜处理土壤温度分别提高2.17 ℃、2.57 ℃、2.29 ℃;各处理中以生物降解除草膜和生物降解膜的土样养分含量最低,不盖膜最高;生物降解除草膜和生物降解膜较普通塑料膜商品薯增产2335.5 kg/hm2和2056.5 kg/hm2,但是差异不显著,较不盖膜处理分别增产5947.5 kg/hm2和5668.5 kg/hm2,差异显著。[结论]生物降解膜不仅可以有效解决白色污染问题,而且有利于提高马铃薯的商品薯产量,对推动广东省马铃薯产业升级具有重要的现实意义。     

水稻育苗壮秧剂应用效果初报

为探索适宜旱育秧的壮秧剂剂量,进行了塑盘旱育秧应用壮秧剂对比试验.结果表明：只要用量适宜,壮秧剂对水稻出苗安全;应用壮秧剂,株高变矮,基茎变粗,干重增加,分蘖和发根增多,壮秧效果显著;在育壮秧、促早发基础上,水稻增穗增粒,增产5.1％～7.5％;壮秧剂适宜用量为15～20g/盘.