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.     

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.     

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.     

吉林省西部生态现状及治理对策

吉林省西部生态环境恶劣,处于风口地带,且由于地质运动、气候影响与人为破坏等因素,土地盐碱化和沙化严重,本文从实施洗碱种稻工程、发展种桑、养蚕业、发展麻黄草等中草药栽培及制药产业、实施移民工程等方面提出了一些建议,旨在促进生态环境的进一步好转。     

策勒县盐渍化农耕地耐盐冬小麦品种种植试验

重点探讨了策勒县盐渍化农耕地采用耐盐冬小麦新冬26号品种引种种植的适应性前景,以及生物改良技术的生态、社会、经济效益。2005年,经过深入实际调查,确定在策勒县固拉哈玛乡盐碱地采用生物改良措施,开展引种耐盐冬小麦品种种植试验。根据2006～2008年共3年的引种种植试验发现,撂荒地表层土壤播前pH值8．64,碳酸根和重碳酸根离子总量0．025％,C1—0．019％,属于轻、重碱化土壤;该品种从引种、示范各个生长阶段观测结果看,在偏碱性地不但出现了良好的适应性,而且表现出了高产特征。2006年固拉哈玛乡阿克莱克村引种种植的耐盐冬小麦平均单产为4515kg/hm^2,2007年耐盐冬小麦单产6675kg／hm^2,比对照增加2625kg／hm^2,2008年平均单产6854kg/hm^2,比对照增加2577kg/hm^2,而且生态、社会效益非常显著。     

松嫩平原盐碱化形成影响因素研究进展

土壤盐碱化形成影响因素研究是开展土壤水盐运移规律、水盐运移模拟研究、水盐调控、预测预防土壤盐碱化以及进一步改善、改良和治理开发利用该区盐碱地的基础。在回顾松嫩平原盐碱化成因及形成影响因素研究历史的前提下,总结并分析地质构造因素、水文地质因素、气候因素和人为因素等对盐碱化形成的影响,并给出松嫩平原盐碱化形成影响因素体系架构图,确定出影响松嫩平原盐碱化形成过程中的可控与不可控影响因素,为进一步研究工作提供建议。     

中国盐渍土研究：历程、现状与展望

盐渍土研究是以盐渍土和盐渍生境作为主要研究对象，以盐渍土和盐渍化的发生与演变过程、环境要素和人类活动对盐渍化的影响与作用机制、盐渍土的治理、改良和利用的理论与技术为主体的研究领域。我国盐渍土面积巨大、种类繁多，盐渍化问题突出，对农业生产和生态环境造成不同程度的影响。我国科学家提出的盐渍土“水盐调控”“水盐平衡”，“淡化肥沃层”和“障碍消减”等理论与技术方法，为发展农业生产、提高土地产能、保障粮食安全、拓展耕地资源等发挥了积极作用。近期我国在土壤盐渍化演变过程的监测与多源数据融合、土壤水盐运移过程模拟与尺度转换、盐渍农田养分循环与减损增效、盐渍障碍的生态消减、盐渍障碍微生物修复、盐渍农田灌排优化管理与边际水安全利用等方面取得了积极的进展和成果。建议今后深入开展盐渍土精准控盐的高效和安全用水、土壤盐渍障碍的绿色消减与健康保育、盐渍农田养分库容扩增与增碳减排、土壤盐渍化与区域生态的耦合响应和协同适应等方面的理论与技术研究。应面向农业、资源、生态、环境等领域和行业，致力于拓展理论和新技术的研究，为国家农业升级、粮食安全、耕地保护、生态安全、高质量发展发挥重要作用。本文回顾了我国盐渍土研究工作的...