绿洲农区土壤资源数据库的建立——以河西走廊临泽样区为例

以河西走廊临泽样区为例 ,应用 Microsoft Access97建立基于 Windows平台的绿洲农区土壤资源 (土系 )数据库 ,为干旱地区 (特别是绿洲 )土壤资源的合理利用与管理、农业合理布局、农用土地土壤质量评价、田间养分管理中的应用问题等方面提供理论依据     

小麦矮化腥黑穗病菌侵染能力的研究

中美专家合作在美国犹他州对小麦矮化腥黑穗病菌的侵染能力进行了研究。试验采用不含抗病基因的小麦品种Cheyanne,播种前用溴甲烷对试验小区进行了熏蒸。接种物为含有多种致病型的冬孢子悬浮液,采用土壤表面喷洒冬孢子悬浮液的方法进行接种,接种密度为每cm20、0.88、8.84、88.45、884.49、8844.89、88449个孢子。结果表明,接种密度为每cm20.88个孢子时即可产生0.21％的穗发病率。对试验数据进行分析后表明,小麦矮化腥黑穗病菌的侵染规律符合侵染概率理论,在本试验条件下,单个孢子的侵染概率为0.0002。     

Vegetation fractional coverage change in a typical oasis region in Tarim River Watershed based on remote sensing

Vegetation fractional coverage(VFC) is an important index to describe and evaluate the ecological system.The vegetation index is widely used to monitor vegetation coverage in the field of remote sensing(RS).In this paper,the author conducted a case study of the delta oasis of Weigan and Kuqa rivers,which is a typical saline area in the Tarim River Watershed.The current study was based on the TM/ETM+ images of 1989,2001,and 2006,and supported by Geographic Information System(GIS) spatial analysis,vegetation index,and dimidiate pixel model.In addition,VBSI(vegetation,bare soil and shadow indices) suitable for TM/ETM+ images,constructed with FCD(forest canopy density) model principle and put forward by ITTO(International Tropical Timber Organization),was used,and it was applied to estimate the VFC.The estimation accuracy was later proven to be up to 83.52%.Further,the study analyzed and appraised the changes in vegetation patterns and revealed a pattern of spatial change in the vegetation coverage of the study area by producing the map of VFC levels in the delta oasis.Forest,grassland,and farmland were the three main land-use types with high and extremely-high coverage,and they played an important role in maintaining the vegetation.The forest area determined the changes of the coverage area,whereas the other two land types affected the directions of change.Therefore,planting trees,protecting grasslands,reclaiming farmlands,and controlling unused lands should be included in a long-term program because of their importance in keeping regional vegetation coverage.Finally,the dynamic variation of VFC in the study area was evaluated according to the quantity and spatial distribution rendered by plant cover digital images to deeply analyze the reason behind the variation.     

农艺措施和保水剂对土壤蒸发和夏玉米 水分利用效率的影响

为进一步研究黄淮海地区免耕夏玉米栽培节水问题,于2011年进行大田试验,研究了农艺措施(播后镇压、秸秆覆盖)和保水剂对土壤蒸发和夏玉米水分利用效率的影响.结果表明,夏玉米整个生育期平均,处理A(播后镇压)、B(播后镇压+秸秆覆盖)、C(播后镇压+保水剂)和处理D(播后镇压结合秸秆平茬覆盖和保水剂)比处理E(播种后覆土)在0～40 cm土层,土壤含水量增加了4.78％、7.96％、5.50％和11.08％,水分蒸发减少了16.33％、103.78％、28.37％和128.77％,产量提高了9.68％、17.60％、11.78％和24.01％,水分利用效率也增加了9.64％、17.55％、11.71％、23.96％,效益增加了1 536.34、2 516.42、801.74、2 553.10元/hm2.这种作用在夏玉米的生长前期更明显,拔节前的土壤水分比较,处理A、B、C、D比E增加了8.74％、15.81％、10.48％和20.28％,水分蒸发减少了17.81％、164.68％、40.35％和209.43％.处理D集成了镇压、秸秆覆盖、保水剂的作用,能够充分提高土壤水分含量和抑制水分蒸发.建议在黄淮海区夏玉米实行播后镇压结合秸秆覆盖等农艺措施,有条件的地方可以再结合增加保水剂的应用.     

Influence of Portland cement amendment on soil pH and residual soil termiticide performance

Soil adjacent to new brick veneer work is likely to have a higher pH owing to the mixture of cement with the soil. In the Gainesville, FL, area, soil samples taken from such locations had a range of pH values from 9.0 to 10.1; similar soils used in bioassays had a pH of 5.6 before the addition of cement. Addition of 15 mg of Portland cement to 33 g of soil increased the pH to 6, and addition of 291 mg of Portland cement increased the pH to 9. The pH of soil amended with cement was stable for the first 5 months. After 10 months, soil pH values decreased from alkaline to near neutral in all cases. Eastern subterranean termite workers, Reticulitermes flavipes (Kollar), were exposed to the treated soil at pH 6-9 for 24 h, and percentage mortality was recorded at 5 days, 5 months and 10 months. Termite mortality significantly decreased at higher soil pHs for bifenthrin, chlorpyrifos, fipronil and imidacloprid treatments at 5 months and similarly for bifenthrin, permethrin, chlorpyrifos, fipronil and imidacloprid treatments at 10 months. There was an inverse linear relationship between soil pH and mortality. Increased soil pH diminished residual activity of termiticide in the following order: imidacloprid > fipronil > chlorpyrifos = bifenthrin > permethrin > cypermethrin.     

Organic amendments affecting sorption, leaching and dissipation of fungicides in soils

Metalaxyl and tricyclazole are two fungicides widely used in Spain in vineyard and rice crops respectively. In this study an investigation has been made of the effect of three organic amendments [two commercial amendments, solid fertiormont (SF) and liquid fertiormont (LF), and a residue from the olive oil production industry, alperujo (OW)] on fungicide fate in soils. Changes in soil porosity on amendment were studied by mercury intrusion porosimetry, sorption-desorption studies were performed by the batch equilibration method, dissipation of metalaxyl and tricyclazole in the soil was studied at - 33 kPa moisture content and 20 degrees C and leaching was studied in hand-packed soil columns. Amendments with SF and LF reduced soil porosity, while OW increased porosity through an increase in pore volume in the highest range studied. Tricyclazole sorbed to soils to a much higher extent than metalaxyl. With some exceptions, sorption of both fungicides increased on amendment, especially in the case of SF-amended soils, which rendered the highest K(oc) values. In soils amended with the liquid amendment LF, sorption either remained unaffected or decreased, and this decrease was much higher in the case of metalaxyl and a soil with 70% clay. In this clay soil, amendment with OW, of very high soluble organic matter content, also decreased metalaxyl sorption. Tricyclazole is more persistent in soil than metalaxyl, and both fungicides were found to be more persistent in amended soils than in unamended soils. Leaching of metalaxyl and tricyclazole in soil columns was inversely related to sorption capacity. The low recoveries of tricyclazole in leachates and in soil columns when compared with metalaxyl, a less persistent fungicide, were attributed to diffusion into micropores and to increase in sorption with residence time in the soil, both processes favoured by the low mobility of tricyclazole.     

吉林省大安市苏打碱土盐化与碱化的关系

选择了76份苏打碱化土壤样品,对其各盐化与碱化指标进行了测定,分析了苏打碱化土壤盐化和碱化的关系.结果表明,土壤的碱化层和高含盐层出现在土壤中同一层次,因此该土壤盐化与碱化过程有密切联系.土壤含盐量与各碱化参数(ESP、SAR、总碱度、RSC和pH)均为正相关.土壤碱化度随含盐量的升高而增大,高盐分浓度对土壤碱化度的抑制作用,至少要在其浓度达到8.0 g/kg以上时才会出现.土壤中Na 、CO32-和HCO3-离子同各碱化参数之间均是极显著相关,同时Cl-离子与除pH外的各碱化参数极显著相关,这是该类型土壤兼有盐化和碱化特征的反映.统计分析表明,各盐分离子中Na 和CO32-离子对ESP的影响作用更大.     

耕作方式对豫西旱地麦-豆轮作田土壤理化特性和酶活性的影响

为探明耕作方式对豫西旱地麦-豆轮作田不同土层土壤理化特性和土壤酶活性的影响,设置免耕(NT)、旋耕(RT)和翻耕(PT)3种耕作方式,分析了定位试验9 a(2009—2019年)后小麦收获期的土壤容重、孔隙度和有机质、全氮、有效磷和速效钾含量,以及土壤脲酶、蛋白酶、转化酶和碱性磷酸酶活性,并运用相关分析和通径分析研究了土壤理化性质与土壤酶活性的关系。结果表明：不同耕作方式对土壤理化特性和酶活性具有显著的调控作用,其调控效应与其作业深度相关。RT较PT有利于降低0～15 cm土层但增加15～35 cm土层容重,NT较RT和PT显著降低了0～5、15～35、35～60 cm土层的土壤容重,土壤孔隙度变化规律与容重相反。各处理间土壤有机质、全氮、有效磷含量以及土壤脲酶、蛋白酶、转化酶和碱性磷酸酶活性在0～5 cm土层和15～35 cm土层规律一致,0～5 cm土层均以NT最优,分别较最低值处理(PT)显著提高16.7%、53.2%、15.9%、23.6%、18.0%、34.7%和29.0%;15～35 cm土层均以PT最优,分别较最低值处理(NT)显著提高18.3%、23.4%、53.4%、...     

土壤水分研究进展及简要评述

回顾了土壤水分研究的进程及取得的一些成就：从最初的形态学观点到现在的能量观点；从简单研究逐步发展为一门学科，再到多学科交叉；研究方法日趋理论化同时注重应用，理论与实践相结合；研究手段的多样化；研究领域的扩展等等。同时指出了当前土壤水研究存在的一些问题，并对未来土壤水研究进行了展望。