Evaluation of immobilizing agents as soil quality conditioners in addition to their metal(loid) immobilizing effect

In trace metal (TM)-contaminated agricultural soils,management of TM availability is important for safe crop production.In addition,maintenance or improvement of soil quality is vital for sustainable crop cultivation.Decreased TM phytoavailability and increased soil quality can be achieved by the application of various immobilizing agents to soil,which can supply both macronutrients and organic matter.This study investigated the long-term influences of four common immobilizing agents on soil biogeochemical properties and the phytoavailability of TMs in mixed metal-contaminated soil from a cultivated upland near an abandoned mining site.Lime (L),gypsum (G),fly ash (F),and animal manure-based compost (C) were applied to pots containing contaminated soil,either individually or in combination.After incubation for three years under sequential cultivation of two crops and fallow,soil biogeochemical properties were determined,and Brassica rapa plant bioassay was performed.The phytoavailability of all TMs (both cationic metals and anionic metalloids) remained significantly lower in soils treated with immobilizing agents even after three years,when compared with the no-agent control (CK) soil.In addition,the soil quality was significantly improved by treatment with immobilizing agents.For instance,the C and L+C treatments were the most effective in improving soil physical (bulk density,porosity,and water-resistant aggregate stability),chemical (pH,organic matter,total nitrogen,cation exchange capacity,and plant-available phosphorus,magnesium,and potassium),and biological (microbial biomass carbon and dehydrogenase activity) properties.The improvement of soil properties and lowering of TM bioavailability were also consistent with the most significant increase in B.rapa biomass production observed in the C treatment,followed by the L+C,G+F,L,G,F,and L+G treatments,as compared with that in CK.These results indicate that the function of the TM-immobilizing agent as a soil quality conditioner,in addition to its TM immobilizing effect,should be considered when selecting such agents for agricultural or ecological applications.     

基于mtCOI基因序列的我国云南省和缅甸、柬埔寨草地贪夜蛾种群遗传多样性分析

为制定有效的草地贪夜蛾防控措施,分别自缅甸、柬埔寨和我国云南省采集4、2和8个种群共542个草地贪夜蛾样品,基于mtCOI基因序列分析这14个种群的遗传多样性指数、遗传分化系数及基因流。结果表明,缅甸草地贪夜蛾种群的单倍型多样性指数和平均核苷酸差异数分别介于0.273～0.396和4.643～6.727之间,高于我国云南省的草地贪夜蛾种群,分别介于0.047～0.214和0.791～3.636之间;除ZT种群、LS种群和TO种群外,其它11个种群的Fu’s F均为显著正值,表明缅甸、柬埔寨和我国云南省的草地贪夜蛾种群未经历种群扩张事件;在14个种群中,LS种群与其它种群分化较明显,TK种群、MY种群、CP种群、MS种群和KY种群有效迁入个数和有效迁出个数之和较高,分别为699.41、682.50、855.76、684.56和701.31,推测这5个种群在草地贪夜蛾基因交流中起着类似"中转站"的作用。     

2019年缅甸草地贪夜蛾发生情况考察报告

缅甸是我国草地贪夜蛾的重要境外虫源区, 为了掌握草地贪夜蛾在缅甸的发生与防控情况, 2019年5月19-25日, 云南省农业科学院与缅甸农业研究司专家联合对缅甸南部、中部、中北部和东部草地贪夜蛾开展了实地调查。结果表明: 缅甸全境均有草地贪夜蛾发生, 为害严重, 田间多种虫态并存。其中, 南部玉米大部分已经收获, 虫株率62.50%~97.50%; 中部区域种植少量的商品甜玉米, 防治到位, 虫株率6.00%~7.50%; 中北部曼德勒敏建玉米种植面积最大, 达8 000 hm2, 80%的地块已成熟收获, 处于吐丝-乳熟期的田块虫株率达100%, 受害严重; 东部掸邦虫株率59%, 虫口密度2.60头/株。玉米是缅甸第二大种植作物, 全年玉米种植面积达47万~52万hm2, 其中与我国云南接壤的东部掸邦是主要种植区。到5月前因无有效降雨, 全境玉米尚未大面积种植, 仅有零星种植, 随着雨季的来临, 玉米种植面积将全面增加, 草地贪夜蛾种群数量也将随之增加。因此, 加强与缅甸相关部门合作, 密切掌握缅甸玉米种植及草地贪夜蛾的发生与防控情况, 对我国草地贪夜蛾的监测预警及防控有重要的参考价值。