吉林通榆氟中毒区地下水中氟来源及防改对策     

孙述海  孙亚红  迟宝明  熊绍礼 《安徽农业科学》2012,40(9):5428-5430

地下水氟来源是防氟改水的重要基础之一。通过水文地质调查,查明了吉林通榆氟中毒区地下水中氟的来源。大兴安岭来源是地下水中氟来源的主体,地下水含水介质和围岩释放的氟均是富集了大兴安岭来源的再释放。研究区含水介质中可溶性氟含量为3.15～8.00 mg/kg,围岩可溶性氟含量为5.2～10.4 mg/kg。1984～2006年,地下水氟含量有升高现象。根据研究区地下水资源特点,选择5个示范井,进行防氟改水,将上第三系大安组含水层作为目的水层,水中氟浓度符合生活饮用水质标准。  相似文献   

果蔬气调包装保鲜效果的影响因素分析     

吴雅静 《安徽农业科学》2014,(21):7194-7195

气调包装技术是近年来应用于果蔬产品保鲜的新技术,其保鲜效果受多种因素影响。主要就包装材料、气体成分、温湿度和果蔬自身条件等因素对果蔬气调保鲜效果的影响进行了分析,并对果蔬气调包装技术的发展进行了展望。  相似文献   

杉木幼林地水土流失与降雨特性关系研究   总被引：2，自引：0，他引：2  

吴擢溪 《福建林学院学报》1996,16(4):304-309

本文通过连续三年定位研究，全面探讨降雨特性对炼山与不炼山的杉木幼林地水土流失的影响，结果表明：本区年均降雨量和降雨侵蚀力（ＥＩ３０）为１５０８．０ｍｍ和６０２．１［１００Ｊ·ｃｍ／（ｍ２·ｈ）］，侵蚀性降雨占全年降雨次数的３４％～４０％；杉木幼林地水土流失随降雨侵蚀力增大而增加；林地水土流失量主要由大雨和暴雨两种降雨类型所引起，充足的前期降雨会加剧林地水土流失，尤其是在旱季；炼山的杉木林地水土流失随降雨的年分布特点而呈明显的季节性变化；在不同降雨条件下，炼山林地水土流失均明显大于不炼山林地．因此增加地表覆盖和选择合适的营林作业方式和时间是防止炼山林地大量水土流失的有效途径。  相似文献   

控释氮肥对棉花生长发育及产量的影响   总被引：5，自引：1，他引：5  

李学刚  孙学振  宋宪亮  陈二影 《山东农业科学》2009,(6):79-81

以鲁棉研28号为材料,研究了控释氮肥对棉花生长发育及产量的影响,结果表明：与生产对照CK2相比,不同控释氮肥处理的棉花最终果枝数、果节数及单铃重无显著差异。100％控释氮肥处理对棉花前期生长具有一定的不利影响：苗期的单株叶面积、倒四叶叶面积、地上部干重和6月17日的株高均显著降低（P〈0．05）,但苗期叶片数和中后期（7／20—9／15）棉花株高无显著差异;单株结铃数增加0．77个（P〈0．05）,籽棉产量和皮棉产量分别增加6．2％和6．4％（P〈0．05）。50％速效与50％控释氮肥基施处理,苗期倒四叶叶面积和7月2日果节数显著增加,苗期叶片数、单株叶面积、地上部干重和不同时期的株高均无显著变化;衣分显著降低,籽棉和皮棉产量及产量构成均无显著变化。控释棉花专用BB肥对棉花苗期生长有一定的促进作用,促进了棉花早现蕾,从而增加了中后期（7／20-9／15）棉花株高,单株结铃数增加0．84个,籽棉产量增加5．0％,均差异极显著;但衣分无显著差异。  相似文献   

施用尿素和控释氮肥的双季稻田表层水氮素动态及其径流损失规律   总被引：40，自引：1，他引：40  

纪雄辉  郑圣先  鲁艳红  廖育林 《中国农业科学》2006,39(12):2521-2530

【目的】通过比较研究洞庭湖区双季稻田施用尿素（CF）和控释氮肥（CRNF）的表层水pH、电导率（EC）、总氮（TN）、NH4+-N和NO3--N浓度变化动态及TN径流损失规律，寻找有效控制氮素流失的最佳施肥管理措施。【方法】在渗漏池中按河沙泥（ASP）和紫潮泥（PCP）土壤的剖面层次填装土壤，对天然降雨引起的稻田氮素径流损失进行模拟试验。【结果】稻田土壤施用尿素后，表层水TN、NH4+浓度分别在第1、3天达到高峰，然后随着时间的延长而迅速下降；早稻表层水pH在施用尿素后15 d内（晚稻3 d）逐渐升高，EC表现与NH4+的变化同步。与施用尿素相比，施用CRNF能显著降低稻田表层水TN、NH4+浓度峰值，pH、EC峰值也有明显下降。氮素径流损失监测结果显示，洞庭湖区双季稻田施用尿素TN径流损失量为7.47 kg•ha-1，占施氮量的2.49%；施用CRNF、70%CRNF的TN损失量比施用CF的分别减少了24.5%和27.2%。早稻施肥后20 d内发生的2次降雨径流事件，施用尿素、CRNF和70%CRNF处理的2次TN径流损失量分别占全生育期径流损失总量的72%、70%和58%。其中，早稻施肥后第10天发生的第1次径流的2个控释肥处理的TN损失比施用尿素分别降低了42.9%和44.2%。【结论】双季稻田施用尿素后15 d内表层水氮素浓度高，是氮素流失的关键时期；控释氮肥能显著降低这个时期的表层水和所发生的径流液中的氮素浓度，从而显著削减水稻全生育期内的TN径流损失量。  相似文献   

包膜型缓/控释肥技术的研究与进展   总被引：9，自引：1，他引：9  

黄永兰  罗奇祥  刘秀梅  侯红乾 《江西农业学报》2008,20(3):55-60

系统论述了缓/控释肥料的概念、分类及作用机理,并阐述了控释技术体系的3个方面：包膜材料、控释路线和生产工艺,重点介绍包膜缓/控释肥料的国内外研究进展、肥料养分释放机理及评价方法与标准,分析了包膜缓/控释肥的生物学效应,并提出了包膜缓/控释肥料研究的重点问题和应用前景。  相似文献   

低分子量有机酸对钾长石中结构钾释放的影响研究   总被引：1，自引：0，他引：1  

王文华  王东升  姜戈 《辽宁农业科学》2005,(3):9-11

草酸络合能力强，水解能力亦很强，活化钾能力最强，其次为苹果酸。柠檬酸、酒石酸、乙酸、乳酸活化钾的能力基本相同。Elovich方程判定系数R^2为0．953～0．996，双常数方程的判定系数R^2为0．958～0．996，拟合效果较好，达极显著水平；抛物线扩散方程判定系数R^2为0．846～0．941，拟合效果较差。  相似文献   

Effects of tillage and traffic on crop production in dryland farming systems: II. Long-term simulation of crop production using the PERFECT model   总被引：1，自引：0，他引：1  

Y.X. Li  J.N. Tullberg  D.M. Freebairn  N.B. McLaughlin  H.W. Li 《Soil & Tillage Research》2008,100(1-2):25-33

Soil water conservation is critical to long-term crop production in dryland cropping areas in Northeast Australia. Many field studies have shown the benefits of controlled traffic and zero tillage in terms of runoff and soil erosion reduction, soil moisture retention and crop yield improvement. However, there is lack of understanding of the long-term effect of the combination of controlled traffic and zero tillage practices, as compared with other tillage and traffic management practices.In this study, a modeling approach was used to estimate the long-term effect of tillage, traffic, crop rotation and type, and soil management practices in a heavy clay soil. The PERFECT soil–crop simulation model was calibrated with data from a 5-year field experiment in Northeast Australia in terms of runoff, available soil water and crop yield; the procedure and outcomes of this calibration were given in a previous contribution. Three cropping systems with different tillage and traffic treatments were simulated with the model over a 44-year-period using archived weather data.Results showed higher runoff, and lower soil moisture and crop production with conventional tillage and accompanying field traffic than with controlled traffic and zero tillage. The effect of traffic is greater than the effect of tillage over the long-term. The best traffic, tillage and crop management system was controlled traffic zero tillage in a high crop intensity rotation, and the worst was conventional traffic and stubble mulch with continuous wheat. Increased water infiltration and reduced runoff under controlled traffic resulted in more available soil water and higher crop yield under opportunity cropping systems.  相似文献   

桐油包膜尿素养分释放机理的研究   总被引：2，自引：0，他引：2  

施卫省  罗小林  唐辉  王亚明 《中国生态农业学报》2006,14(4):109-111

以桐油为包膜材料,采用土壤盆栽试验和水中静置试验,对控释肥料养分释放动态进行了研究。结果表明,以桐油为包膜材料的包膜尿素,在土壤中养分初期溶出率为12.6%,在水中养分初期溶出率为20.1%,是比较理想的包膜材料。在水中与土壤中养分释放期为1∶1.2;N素的释放可用LOGISTIC动力学方程描述,释放常数k值可用来判断控释尿素的N素释放速率大小。  相似文献   

Effects of controlled drainage on N and P losses and N dynamics in a loamy sand with spring crops   总被引：1，自引：0，他引：1  

Ingrid Wesström  Ingmar Messing 《Agricultural Water Management》2007

The effects of controlled drainage on N and P losses from soil were examined in a 4-year field drainage experiment on a loamy sand in Southern Sweden. Of the three plots (0.2 ha each), one was drained by conventional subsurface drainage (CD), and two by controlled drainage (CWT1 and CWT2). The groundwater level in the CWT plots was naturally drained to at least 70 cm below the soil surface during the vegetation period between early spring and harvest but allowed to rise to 20 cm below the soil surface during the rest of the year. Measurements of precipitation, drain outflow, weir depths and air and soil temperatures were carried out hourly. Groundwater levels were measured and samples of drain outflow for analyses were collected twice a month. Mineral N contents in soil were measured three times a year and grain yields and N uptake in crops after harvest.  相似文献