Reciprocal influence of crops and shallow ground water in sandy landscapes of the Inland Pampas

In regions with shallow water tables, ground water may have a positive (water supply) or negative (waterlogging or salinization) impact on crops. Reciprocally, crops can influence ground water, altering water table depth and chemical composition. We quantified these reciprocal influences along natural gradients of groundwater depth in flat sedimentary landscapes of the Inland Pampas occupied by wheat, soybean, and maize during two growing seasons (2006/2007 and 2007/2008). We correlated crop yield and groundwater depth maps at the field level and made direct plant, soil and groundwater observations at the stand level across topographic gradients. Water table level largely accounted for spatial crop yield variation, explaining 20–75% of their variance. An optimum groundwater depth range, where crop yields were highest, was observed for all three crop species analyzed (1.40–2.45 m for maize, 1.20–2.20 m for soybean, and 0.70–1.65 m for wheat). The areas within these optimum bands had yields that were 3.7, 3 and 1.8 times larger than those where the water table was below 4 m for wheat, maize, and soybean, respectively. As groundwater levels become shallower than these depth bands, crop yields declined sharply (∼0.05 kg m⁻² on average for every 10 cm increase in water table level), suggesting negative effects of waterlogging, root anoxia and/or salinity. Groundwater levels below these depth bands were associated with gradually declining yields, likely driven by poorer groundwater supply.     

耐盐碱转基因大豆(SRTS)生存竞争能力评价

为评价转BADH基因耐盐碱大豆(SRTS)在盐碱条件下的生存能力,在安达市盐碱地比较了耐盐碱转基因大豆(SRTS)、受体大豆黑农35和当地栽培品种抗线王的竞争性(出苗率、复叶数、株高)、自生苗、种子落粒性和繁育能力(生育时期和产量)。分期播种4次,适宜季节和非适宜季节各2次。结果表明:在适宜季节SRTS和抗线王竞争性相似,而受体品种竞争性弱于二者,在非适宜季节3个品种的竞争性差异不显著;SRTS产生自生苗的可能性很小;SRTS的落粒性不强;在适宜季节SRTS的繁育能力最强,抗线王居中,受体品种最弱,SRTS更适于盐碱地生长;在非适宜季节3个大豆品种的繁育能力相似。综合分析上述指标,由此表明SRTS并没有因为转入外源基因而具有更强的适应能力和生存竞争能力,自身杂草化风险很小。     

荒漠植物的适应策略

从荒漠植物对荒漠干旱、盐渍化和养分贫瘠的适应策略方面进行了阐述,并概述了荒漠植物种群延续的适应策略;同时,对荒漠植物适应策略问题的研究进行了展望。     

SOIL SALINIZATION AND ITS COUNTERMEASURE IN ARID DISTRICT

<正> 1. Present Situation All the Hetao irrigation district covers an area of 24.8 thousand sq.km, including thecultivited area of 345.4 thousand ha. It is the greatest gravity irrigation district drawing theYellow Rive's water in North China.     

辽宁省保护地土壤盐渍化特征的研究

在进行全面生产调查的基础上,自辽宁省主要蔬菜保护地生产区采集保护地及其相邻露地大田0~20 cm和20~40 cm土层土壤样品,测定全盐含量,探讨了当地保护地土壤盐渍化程度及其成因。结果表明:(1)保护地土壤全盐含量显著高于相邻露地相应土层土壤,0~20 cm和20~40 cm土层土壤全盐含量分别是相邻露地土壤的1.5~17.0倍和1.2~11.3倍,盐分表聚现象明显;(2)保护地土壤盐渍化现象较为严重,0~20 cm土层、20~40 cm土层全盐含量超过2 g kg-1的土样分别占46%和29%,而露地大田0~20 cm和20~40 cm土层土样全盐含量均在2 g kg-1以下。(3)区域间保护地土壤盐渍化程度不同,沈阳法库、大连瓦房店、朝阳喀左和鞍山海城等地土壤盐渍化程度相对较重,沈阳新民和丹东东港土壤盐渍化程度相对较轻,其它地区保护地土壤盐渍化程度居中;(4)土壤盐渍化与改种保护地前土壤盐分含量及改作保护地后种植年限、施肥量、复种指数等因素关系密切。因此,应加强相关研究,采取措施,积极防治保护地土壤盐渍化。     

吉林省大安市盐渍化土壤特征及现状研究

吉林省大安市，现有盐渍土面积约２４７６８０．２８ｈｍ２，占全　市土地总面积的５０．３９％，其中碱土面积占盐渍土面积的７７％．盐渍土中，分布最广、面积最　大的是苏打型盐渍土．碱土主要分布在大安古河道的北段和查干湖西、霍林河下游的散流区．　由于人类活动的胁迫，把松嫩平原水系变成内外流两种水系，破坏了原来水的自然流势，打　乱了水盐的自然动态平衡，这可能是大安市土壤盐渍化日趋恶化的最主要原因．重建湿地，　是改良利用盐渍土的有效途径．     

草地盐碱化对角果碱蓬出苗及生长的影响

探讨草地盐碱化对角果碱蓬出苗及生长的影响。试验结果表明,样地1、样地2和样地3土壤pH值及可溶性盐含量分别为10.10及0.59%、10.55及0.73%、10.58及1.14%,各样地出苗数分别为1143.13株/m2、71.25株/m2和99.59株/m2,样地1角果碱蓬平均株高为34.63cm,样地2和样地3角果碱蓬平均株高只有21.0cm和11.5cm,与样地1角果碱蓬株高差异达极显著水平,株高与土壤可溶性盐之间呈极显著负相关(R2=-0.921)。     

疏勒河灌区土壤剖面盐分分布及组成特征分析

在甘肃省疏勒河灌区黄花一号点上利用"S"型布点法分3 层采集土壤样品,对不同层次土壤总盐、pH 及EC的空间变异性进行研究.通过土壤盐渍剖面的聚类分析,研究并探讨该地区不同盐分剖面类型土壤含盐量在垂直方向的分布特征.结果表明:研究区土壤剖面点盐分除个别点外,大多数剖面盐分分布具有表聚性,土壤含盐量在垂直方向上变异较强,剖面的平均盐分,表层比中间层高56.44%,比底层高93.86%;土壤盐分离子组成中,阳离子含量Na+>Mg2+>Ca2+>K+,阴离子含量SO42->Cl->HCO->CO32-;就各离子与CE的相关性而言,阴阳离子均与EC成显著正相关,其中阳离子以Na+相关性最好,阴离子SO42-相关性最好.     

Prediction of soil salinity in the Yellow River Delta using geographically weighted regression

It is essential to determine the content and spatial distribution of soil salinity in a timely manner because soil salinization can cause land degradation on a regional scale. Geographically weighted regression (GWR) is a local regression method that can achieve the spatial extension of dependent variables based on the relationships between the dependent variables and environment variables and the spatial distances between the sample points and predicted locations. This study aimed to explore the feasibility of GWR in predicting soil salinity because the existing interpolation methods for soil salinity in the Yellow River Delta are still of low precision. Additionally, multiple linear regressions, cokriging and regression kriging were added to compare the accuracy of GWRs. The results showed that GWR predicted soil salinity with high accuracy. Furthermore, the accuracy was improved when compared to other methods. The root mean square error, correlation coefficient, regression coefficient and adjustment coefficients between the observed values and predicted values of the validation points were 0.31, 0.65, 0.57 and 0.42, respectively, which were better than that of other methods, indicating that GWR is an optimal method.     

Quaternary aquifer pollution in the notec valley,Poland

The problem of salinization of ground and surface waters and soils in the Notec valley, Poland is reviewed. the effects of salt mining and the results of a drainage barrier to prevent salt water intrusion in the aquifer and wetlands are considered.