Amelioration strategies for saline soils: a review

Soil salinization is one of the major causes of declining agricultural productivity in many arid and semiarid regions of the world. Excessive salt concentrations in soils, in most cases, cannot be reduced with time by routine irrigation and crop management practices. Such situations demand soil amelioration. Various means used to ameliorate saline soils include: (a) movement of excess soluble salts from upper to lower soil depths via leaching, which may be accomplished by continuous ponding, intermittent ponding, or sprinkling; (b) surface flushing of salts from soils that contain salt crusts at the surface, a shallow watertable, or a highly impermeable profile; (c) biological reduction of salts by harvest of high‐salt accumulating aerial plant parts, in areas with negligible irrigation water or rainfall available for leaching; and (d) amelioration of saline soils under cropping and leaching. Among these methods, cropping in conjunction with leaching has been found as the most successful and sustainable way to ameliorate saline soils. Cropping during leaching or between leachings causes an increase in salt‐leaching efficiency because a decrease in soil water content occurs under unsaturated water flow conditions with a concurrent decrease in large pore bypass and drainage volume. Consequently, anaerobic conditions in soil may occur during leaching that can affect crop growth. Thus, in addition to the existing salt‐tolerant crop genotypes, research is needed to seek out or develop genotypes with increased tolerances to salinity and hypoxia. Since salt leaching is interacted by many factors, evaluation of the traditional concepts such as the leaching requirement (LR), the leaching fraction (LF) and the salt balance index (SBI) demands incorporation of a rapid, efficient and economical way of monitoring changes in soil salinity during amelioration. Besides this, numerous models that have been developed for simulating movement and reactions of salts in soils need evaluation under actual field conditions. Copyright © 2000 John Wiley & Sons, Ltd.     

基于变权云模型的灯泡贯流式水轮机状态评估方法

为了对灯泡贯流式水轮机的运行状态做出客观评价,基于云模型提出了灯泡贯流式水轮机状态评估的多重指标体系,并建立了部件级-设备级的多层灯泡贯流式水轮机综合评估模型.通过引入云理论直接得到各指标对贯流式水轮机各状态等级的隶属度,从而列举出每个设备的隶属度矩阵,并结合变权理论来确定各指标的组合权重,再由加权平均算子转化为对应的评分,即得到了灯泡贯流式机组的运行健康状态.结合实例研究发现,此方法简单易行,可操作性强,在水轮机部件级评估方面较传统方法更加准确,为灯泡贯流式水轮机状态检修工作提供了新的途径.     

农业科技成果转化的“官产学研金”合作研究*——以海南大学与中国热带农业科学院为例

文章分析海南农业科技成果转化发展状况，以海南大学和中国热带农科院为例，对“官产学研金”合作的意向和存在问题等进行调研，努力构建海南农业科技成果转化的模式，并提出建议。     

农业环境损害司法鉴定法律制度检视与完善理路

推动农业环境损害司法鉴定从科学事实认定活动向法律事实认定活动的转化，需要建构完善的法律制度。本文通过法律规范及实践状况检视，总结了农业环境损害司法鉴定法律制度建设取得的成就，剖析了存在的问题，提出了完善建议。目前我国业已围绕农业环境损害司法鉴定行政管理、司法适用以及鉴定规程制定了数量众多的法律制度，推动其有效服务环境资源审判工作。但随着生态文明建设的进一步推进，农业环境损害司法鉴定的制度缺陷、监管难题、司法困境也逐步显现。因此应当通过健全法律制度、强化监管能力、提升司法效能推动农业环境损害司法鉴定的系统完善。     

关于设立农业环境损害学的思考

农业环境损害学源于农业污染事故调查处理与突发事件应急，萌芽于损害鉴定评估。本文系统阐释了学科背景、学科需求、学科定位、学科特色与学科体系等内容。研究认为，农业环境损害学是一门研究人类生态环境行为与农业受体损害发生发展规律，调节人与自然关系，协调社会经济发展、环境健康与农业绿色发展，规范人类生态环境行为的新兴综合交叉学科，是以农业受体损害为对象，研究受体损害的预测预防、诊断识别、基线确定、损害确认、因果关系及原因力、损失评估、损害救治等的科学活动。