Evaluation of cultural practices (surface burning,deep ploughing,organic amendments) for management of rice root-knot nematode in rice - onion cropping system and their effect on onion (Allium cepa L.) yield     

E.B. Gergon  S.A. Miller  R.G. Davide  O.S. Opina  S.R. Obien 《国际虫害防治杂志》2013,59(4):265-272

Rice hull burning (RHB) is a traditional cultural practice of many onion growers in San Jose City, Nueva Ecija, Philippines, mainly for weed control and increased yield. The resulting carbonized rice hull (ash) is incorporated into the soil during land preparation before transplanting of onion. Studies to evaluate the effect of RHB on the population of the rice root-knotnematode, Meloidogyne graminicola, and onion yield were conducted in a farmer's field naturally infested with the pathogen. Burning of 15-cm-deep rice hulls significantly reduced the nematode populations in the soil and increased onion yield. Increasing the thickness of rice hulls burned to 30 cm deep resulted in a yield increase of 44.2% over no RHB and 11.9% over 15-cm-deep rice hulls, while the yield increase with 15-cm-thick hulls was 28.8% over no RHB. Plots that received rice hulls 30 cm deep also produced 37.7% more large bulbs for export than those plots that received 15-cm-deep hulls, and 151.7% more than those plots with no RHB. Deep ploughing did not significantly affect nematode populations compared with standard ploughing. Organic amendment did not contribute to an increase in onion yield and has no effect on the population of rice root-knot nematode.  相似文献   

近52年卫辉浅层地温的变化特征分析     

张惠霞 《安徽农业科学》2013,(14):6380-6382

利用1961～2012年卫辉市0～20 cm各层逐月平均地温,采用气候倾向率、累积距平、信噪比等气候统计方法,研究了近52年卫辉市浅层平均地温的变化趋势、气候突变和异常年份等。结果表明,近52年卫辉市年平均浅层地温除地面外均呈现极显著的升高趋势,升幅为0.07～0.18℃/10a,15 cm升温率最大;四季浅层地温中,冬、春季呈现极显著的升高趋势,尤其是15～20 cm,升幅为0.17～0.34℃/10a,夏、秋季升高趋势不显著。浅层地温冬季、春季和年平均分别在1976、1986年和20世纪90年代前期发生了突变,夏、秋季无突变;年平均地温异常偏高多发生在20世纪90年代,异常偏低多发生在20世纪60年代和21世纪。气温升高及降水减少是影响地温上升的主要原因。  相似文献   

浅基础在大兴安岭林区应用的探讨     

刘云龙  王之林 《东北林业大学学报》1988,(3)

本文对大兴安岭林区冻害原因进行了分析。根据工程实例证明,在大兴安岭林区,根据不同的地质条件,在该地区大量应用浅基础是可能的,这样在该地区的许多工程构造物基础可从3.25m(该地区冻结深度为3.00m)降到1—1.5 m,从而使工程造价降低10％左右。因而可以取得明显的经济效益。最后论述了浅基础的应用条件,对林区应用浅基础有一定借鉴作用。  相似文献   

草型浅水湖泊富营养化评价的浮游植物指标比较     

潘鸿  唐宇宏 《安徽农学通报》2016,(3)

基于藻类的不同指标对草型浅水湖泊富营养化评价的结果存在差异：藻类丰度、Pielou均匀度指数评价的富营养水平偏高,绿藻指数、Margalef指数评价的富营养水平偏低,藻类综合指数评价富营养水平可靠性不高,该文探讨了适于草型浅水湖泊富营养化评价的浮游植物指标,结果表明,Shannon-Weaver指数评价的富营养水平具有较高的准确性,藻类生物量评价标准不适用草型浅水湖泊富营养化评价。  相似文献   

Failure of peat-covered hillslopes at Dooncarton Mountain,Co. Mayo,Ireland: Analysis of topographic and geotechnical factors     

A.P. Dykes  J. Warburton 《CATENA》2008

Shallow landslides involving loss of blanket peat are relatively uncommon but can nevertheless be environmentally and geomorphologically significant. This paper describes a cluster of 40 shallow landslides, including significant peat failures, which occurred within 2.5 km² on Dooncarton Mountain (Republic of Ireland) in the evening of 19 September 2003 during an exceptional rainfall event. It examines two hypotheses: (i) that the combination of topography and local soil catena characteristics were the primary site factors that led to the occurrence of most of the failures, and (ii) that anthropogenic disturbance to the slopes in the form of boundary ditches or peat-cutting activities may have contributed to three of the largest peat failures. All of the landslides were mapped and sampled within 4 months of the event. Physical, hydrological and geotechnical properties of the slope materials were determined from samples obtained from nine representative failures. Possible controls on the stability of the slopes were investigated by modelling seven of the landslides and a series of hypothetical slopes using standard limit equilibrium methods. The humified blanket peat was underlain by a dominantly sandy mineral material, including a buried soil horizon, derived from weathering of the mainly schist bedrock. Direct shear tests established the respective shear strengths to be ?′ = 50°, c′ = 0 (buried soil) and ?′ = 21–25°, c′ = 8–11 kPa (basal peat), although back-analyses suggested that the average peat cohesion was lower than this on the failed slopes. Analyses of separate slope segments of the landslides showed that the main slope convexity, where the peat cover gives way to thin peaty soil, defined the zone of minimum stability. Failure of the slope segment immediately above the convexity was controlled by the depth of peat and the hydrostatic or possibly artesian water pressures within the slopes. Thus catena characteristics coupled with local topography (gradient and peat depth) were important determinants of slope instability. Two of the failed slopes were crossed by boundary ditches but, contrary to accounts from elsewhere, stability analyses suggested that these ditches did not contribute significantly to the landslides. Stability analysis of a slope affected by peat extraction also suggested no direct causal association, but the hydrological conditions developed in the vertical tine cuts did probably contribute to a large peat slide. At other locations, therefore, similar anthropogenic factors should be incorporated in landslide hazard assessments.  相似文献   

黄土高原粗质地土壤剖面水分运动与浅层地下水补给可能性模拟   总被引：1，自引：0，他引：1  

盖佳敏  樊军  王胜 《中国生态农业学报》2018,26(2):253-262

黄土高原水土流失严重,生态环境脆弱,水资源短缺,地下水对保障区域社会经济发展和维持生态系统平衡具有重要意义,而该区的地下水转化和补给机制尚不明确。为探究黄土高原水蚀风蚀交错区土壤剖面深层水分运动及降水对浅层地下水补给的可能性,利用六道沟小流域分布的粗质地风沙土样地2013—2016年土壤剖面0~600 cm含水量数据,运用HYDRUS-1D模型对各土层水力参数进行反演和验证,并用于模拟样地土壤深剖面0~1 500 cm水分运移过程。结果显示,在平水年2014年(439 mm)和干旱年2015年(371 mm),0~600 cm土壤含水量生长季末与生长季初持平或略有亏缺;降水充沛年2013年(669 mm)和2016年(704 mm)土壤含水量生长季末远高于生长季初,降水入渗深度超过观测深度(600 cm)。深剖面水分运动模拟显示,2014年和2015年剖面含水量变化不明显,水分向深层运移微弱缓慢;但是,2013年和2016年降水可分别入渗运移至1 100 cm和1 200 cm深度,远超过样地上生长的旱柳根系区域,可能补给浅层地下水。在4年模拟期间,平均土壤蒸发为14.87 cm·a-1,平均植物蒸腾为33.70 cm·a-1,土壤水分主要以植物蒸腾形式损耗。在2个丰水年,得益于较充足的降水和粗质地风沙土壤的高入渗率,降水大量转化为土壤水快速向下入渗运移,模拟显示当年生长季末降水最深运移至1 200 cm,至年末已超过模拟深度(1 500 cm),水分继续运移可能补给浅层地下水。相关研究结果为黄土高原水蚀风蚀交错区地下水来源和补给机制提供理论依据。  相似文献   

急陡黄土坡面薄层水流水力学参数变化特征   总被引：6，自引：1，他引：5  

白玉洁  张风宝  杨明义  李占斌  张加琼 《土壤学报》2018,55(3):641-649

为探明降雨条件下黄土急陡坡坡面薄层水流水力学特性,采用室内模拟降雨的方法,研究了6个坡度(25°、30°、35°、40°、45°和50°)和3个雨强(1.0 mm min~(-1)、1.5 mm min~(-1)和2.0 mm min~(-1))组合条件下坡面薄层水流水力学参数的变化规律。结果表明:(1)坡度相同时,流速随雨强的增加而增大;雨强相同时,坡度对薄层水流流速的影响存在临界效应(40°~45°),小于临界坡度,流速随坡度的增加而增大,大于临界坡度,流速随坡度增加而减小。(2)各坡度条件下,坡面薄层水流的平均径流水深随降雨强度增加呈平稳增长趋势;相同雨强时,径流深随坡度的增大有减小趋势。(3)黄土急陡坡坡面雷诺数(Re)整体较小(远小于580),试验条件下坡面薄层径流属于层流且水流处于层流中的失稳区;弗劳德数(Fr)大于0.8,薄层水流属于急流。(4)阻力系数(f)随着降雨强度增加而增大,随着坡度的增加而减小。(5)方差分析结果显示,雨强、坡度及二者交互作用对急陡坡坡面薄层水流水力学参数均有显著影响(p0.01),但流速、弗劳德数和阻力系数的变化主要受坡度控制,而径流深和雷诺数的变化主要受雨强控制。  相似文献   

半湿润易旱区夏玉米翻松聚肥与宽行密植的农田生态效应研究     

李学敏 《中国生态农业学报》1999,7(3):66-69

采用田间试验,研究半湿润易旱区夏玉米翻松聚肥与宽行密植的农田生态效应的结果表明,沿玉米种植带进行播前底翻松和生长期侧翻松,可使土壤犁底层疏松,土壤渗透性提高,深层蓄水效果明显。翻松结合聚肥,可快速形成深厚的条带沃土,促进根系发育。对应栽培所形成的宽行密植结构,改善光照和小气候具有明显的增产效果及年增产的稳定性。  相似文献   

耕翻对稗草、马唐、苋菜三种杂草的防治机理研究     

李善林  倪汉文  张丽 《中国农业大学学报》1998,(Z4)

从1994年～1996年的三年时间内,在北京中国农业大学科学园研究了耕翻对稗草、马唐、苋菜三处杂草在耕地中的防治机理。用标记种子确证了稗草、马唐、苋菜三种杂种子在耕层受耕翻作用后移动特点,测定了这三种杂草种子在耕地地表的平面移动距离和耕层30cm 处停留2年后的活力。结果表明耕翻使杂草种了上下双向移动,向下移动的远大于向上移动的量。在耕层底部的杂草易失活力。耕翻对稗草、马唐、苋菜三种杂草籽在耕地中的防治机理是:耕翻使这三种杂草种子在耕地土壤中移动,部分移动至地表,半年后移动3m 或离开地块;部分移动至耕层底部,不能出苗,逐渐丧失活力。后者作用大于前者。  相似文献   

Long-term experiments with different depths of mouldboard ploughing in Sweden     

Inge H  kansson  Maria Stenberg  Tomas Rydberg 《Soil & Tillage Research》1998,46(3-4):209-223

With the main objective to produce a basis for advice to farmers concerning optimal ploughing depth under various conditions, a series of field experiments were initiated throughout Sweden. At 19 sites on various soils (clay content 72–521 g kg⁻¹, organic matter content 21–89 g kg⁻¹) mouldboard ploughing to about 15, 22 and 28 cm depth was repeated annually for up to 17 years. The total number of location-years was 241. Traditional farming had previously been practised at the sites, including annual mouldboard ploughing to 20–25 cm depth. Spring-sown barley (Hordeum vulgare L.) and oats (Avena sativa L.) were the most frequent crops but many other crops were grown less frequently. Crop residues were generally returned to the soil; straw was chopped at harvest. Post-emergence herbicides were regularly used, generally resulting in an adequate control of annual weeds. However, the control of perennial weeds, particularly couch grass (Elymus repens L. Gould) was often inadequate. At ploughing depths of 22 and 28 cm, the mean crop yields were 2% and 3%, respectively, higher than at 15 cm. However, the results varied considerably between sites. In soils with a high silt content, the shallowest ploughing resulted in up to 10% higher yield than deeper ploughing, provided the control of perennial weeds was adequate. The main reason seemed to be improved structural stability in the surface soil because the concentration of organic matter in this layer became higher the shallower the ploughing. In clay soils with relatively stable structure, as well as in sandy soils, the deepest ploughing resulted in the highest yields, probably because of the deeper loosening. At sites where perennial weeds imposed problems, the weed control was better the deeper the ploughing, sometimes increasing the relative yield after deeper ploughing by several percent as compared with shallow ploughing. Most of this effect was obtained already at the intermediate ploughing depth. The results led to the following conclusions for Swedish agriculture. It may be profitable to plough sandy soils annually as deep as 30 cm, coarse sandy soils perhaps even deeper. In clay and clay loam soils, ploughing deeper than 20–25 cm generally cannot be recommended. In silty soils with an unstable structure, mouldboard ploughing, if any, should be shallow (≤15 cm), and perennial weeds should be controlled by other methods.  相似文献