Cultivation Influences on Soil Organic Carbon Associated with Texture in Seasonally Frozen Zones     

Xiao PU  ;Jing XIE  ;Hongguang CHENG  ;Shengtian YANG  ;Shuangbao WANG 《农业科学与技术》2014,(7):1147-1151

[Objective] This study aimed to examine indicative roles of texture representing soil organic carbon presence and variability subsequent to cultivation under cold temperate climates with seasonal freeze-thaw events.[Method] Three chronosequences were selected for paired comparisons.Soil samples were collected at six depths with a 10 cm increment.Analysis of variance with general linear model and regression was performed for statistical analysis.[Result] In seasonally frozen soils where fragmentation of macroaggregates was stimulated,soil organic carbon level was positively associated with clay ＋ silt proportion due to a wider textural range,better than sole clay content.Exponential function better fitted the experimental data to present progressively increased effectiveness of clay ＋ silt content in maintaining carbon.Clay content explained 12％-41％ and 14％-43％ of variation via linear and exponential functions,respectively.Accordingly,clay ＋ silt content explained 47％-65％ and 46％-70％.[Conclusion] Texture reflected soil organic carbon occurrence as consequences of reclamation.For seasonally frozen soils with wider textural ranges,it is robust to adapt clay ＋ silt content as dependent variable and exponential function.The generated algorithms provided an available pathway to estimate soil organic carbon losses following cultivation and to evaluate soil fertility.  相似文献   

基于支持向量机的农机装备水平差异分类研究     

袁玉萍  安增龙 《中国农业大学学报》2015,20(4):167-173

针对黑龙江垦区各农场农机装备水平不平衡差异问题,采用支持向量机多类分类和主成分分析相结合的方法进行研究。将农机装备水平分为3个等级水平,从总量、速度和均量3方面选取10个评价指标;采用主成分分析法确定5个主要合成指标;建立多类分类支持向量机新模型,把新模型转化成一个互补问题,利用Lagrangian隐函数进一步转化成一个强凸的无约束优化问题,采取快速牛顿算法进行求解;利用实证调研数据,从发展差异度的角度对黑龙江垦区98个农场农机装备水平的差异进行多指标分析,在分类的准确度和训练速度方面都有很好的表现。  相似文献   

Visits to the U.S. Bureau of Reclamation from South Asia and the Middle East, 1946–1990: An indicator of changing international programs and politics     

James L. Wescoat Jr.  Roger Smith  David Schaad 《Irrigation and Drainage Systems》1992,6(1):55-67

International study programs have contributed to the diffusion of modern irrigation technologies, approaches, and problems. But the patterns and processes of international travel have received little attention to date. This paper examines foreign visits to the US Bureau of Reclamation (USBR) from South Asia and the Middle East from 1946 to 1990. Using data from the Foreign Activities Branch of the USBR, we compare the participation rates from 16 countries in South Asia and the Middle East. India, Turkey, and Egypt had the highest rates of participation, followed by Pakistan, Iran, and Israel. The frequency of visits is influenced by political, economic, cultural, and institutional factors. But the most important factors appear to be foreign relations and geopolitics. Given the problems faced by national irrigation bureaucracies around the world, there is a need to focus more directly on political factors than in the past.  相似文献   

中国低产田状况及改良策略   总被引：14，自引：0，他引：14  

曾希柏  张佳宝  魏朝富  宇万太  黄道友  徐明岗  徐建明 《土壤学报》2014,51(4):675-682

从新阶段我国农业、特别是土壤学发展的需求出发,总结了国内外有关低产田方面的研究成果。从"低产田"的界定入手,对我国低产田的状况及其负面影响、低产田形成的自然要素和人类活动的影响以及主要障碍因子等进行了系统分析,并初步测算了低产田改良的粮食增产潜力等。我们认为"低产田"可以定义为"在现有的正常耕作栽培管理技术水平条件下,因为耕地本身存在的障碍或者限制因子,导致作物生长发育差,产量较当地高产田低30%以上,且年际间变异大的农田"。我国低产田具有面积大、类型多,而且分布相对集中、障碍因子较明显等特征,低产田主要的障碍因子包括:有机质贫乏、养分匮乏或失衡、土壤酸化、土壤盐渍(碱)化、沙化、土壤板结、潜育化、表土大量流失、严重干旱、多因子组合。在此基础上,最后从我国现代农业发展的迫切需求出发,提出了今后一段时间内低产田改良研究的重点及有关政策和对策建议。  相似文献   

考虑空气影响的干旱区土壤水分运移模式研究     

朱红艳  贾志峰  李佩成  刘秀花 《农业机械学报》2014,45(12):126-138

在前人研究的基础上,根据石河子垦区的实际情况,确定模型特定的边界条件及参数,建立适合该区的包气带-饱和带水、气二相流的质热传输模型,模拟土壤水分、温度的动态变化,并利用实测土壤温度、土壤含水率数据进行模型检验。结果表明:模拟的土壤温度和含水率能够较好地反映实测值的变化规律,各土层模拟精度评价指标表明考虑空气影响的模拟结果更接近实测结果。对于9.7 mm日降水量的入渗深度,耦合模型可影响20 cm深土壤含水率,单相模型可影响到30 cm深左右。降水当日考虑空气模拟的蒸发速率比不考虑空气模拟的蒸发速率大7.7%;降水后1 d,不考虑空气影响导致蒸发速率比考虑空气的小3.19%。计算模拟期2种模型土壤总蒸发量,相差不大。根据2种模型水量平衡分析结果对比蒸发量的计算值与模拟值,发现考虑空气影响的模型模拟结果更可靠。  相似文献   

不同开垦时间对喀斯特石漠化地区土壤养分的影响     

周传艳  陈训  唐金刚  吴克华  杨泊 《安徽农业科学》2008,36(36)

[目的]为喀斯特生态系统的恢复重建、农业生产以及相关政策制定提供参考。[方法]采集贵州普定典型喀斯特山区3个不同开垦时间(1959、1968、1980年)的0~10、10~20、20~40 cm土层的土壤样品,进行室内理化分析。[结果]结果显示,普定县喀斯特山区随着农业用地开垦时间的增加,土壤养分变化总体表现为有机质、全氮、CEC下降;土壤pH值下降;全磷、全钾含量没有明显变化;碱解氮、有效磷、有效钾等有不同的变化规律。[结论]普定县喀斯特山区土壤养分随开垦时间的变化主要是受到施肥和微地形的影响。  相似文献   

脱硫石膏对次生碱化盐土的改良效果   总被引：10，自引：1，他引：10  

张峰举  肖国举  罗成科  秦萍  李彦 《河南农业科学》2010,(2)

由于土壤碱化引起物理性质恶化限制了土壤盐分淋洗,降低土壤交换性钠含量,提高土壤入渗率是决定碱化盐土能否改良成功的关键。通过油葵田间试验,探讨了脱硫石膏不同施用量(0、11.25、22.5、33.75、45 t/hm2)对次生碱化盐土的改良效果。结果表明:施用脱硫石膏可有效降低次生碱化盐土pH值、碱化度和总碱度,提高土壤入渗率,促进盐分离子淋洗。当脱硫石膏的施用量为11.25 t/hm2时,土壤pH值、碱化度和总碱度降低至8.20、7.66%和0.12 cmol/kg,并低于土壤发生碱化的临界指标,油葵成熟期株高、根长、单株干质量和产量分别达到74 cm、18.6 cm、57.6 g和1 077.0 kg/hm2。脱硫石膏改良效果和其用量不呈正相关,脱硫石膏过量可增加土壤可溶性全盐含量,抑制油葵生长发育。脱硫石膏中的Hg、Pb、Cr、Cd等重金属元素含量低于我国相关标准要求及试验田土壤背景值,施用脱硫石膏不会引起土壤重金属元素总量变化。  相似文献   

山西煤矿区土地复垦和生态重建工程技术研究     

蔡慧敏  吴荣涛  李晓伟 《安徽农业科学》2008,36(12):5158-5161

山西是产煤大省,矿产资源开发已成为山西省国民经济增长的重要手段,但矿山开采会引发一系列诸如矿区土地破坏、生态退化与环境污染等问题,这严重制约了矿区社会经济的可持续发展。通过分析山西煤矿区土地的破坏,提出相应的预防、土地复垦、生态恢复等措施,并针对山西煤矿区破坏土地进行复垦工程设计。  相似文献   

排矸区沙棘复垦及沙棘果深加工的研究     

孙增光 《林业勘查设计》2008,(4):69-71

从4个方面分别对鹤岗矿区矸石排放区栽植沙棘的技术、利用价值、深加工技术流程及其生态效益和社会效益做了介绍.  相似文献   

The Nutritive Value and Yield of Alfalfa Cultivated on Sulphur Postmining Lands     

T. R. Pucek  J. B. Py&#; 《Journal of Agronomy and Crop Science》1999,182(3):185-192

The study was carried out on the reclaimed lands of a bore-hole sulphur mine. The cropping of two succeeding cuts of alfalfa (Medicago sativa L.) was determined and its chemical composition was analyzed. Alfalfa was cultivated on waste lime (flotation tailings), enriched with a humus layer. The levels of basic nutrients, total S, total F, Ca, P, Mg, K, Na, Fe and Mn were determined in alfalfa. The biomass of an average crop was 6830 kg  ha^–1 in the first cut and 14300 kg  ha^–1 in the second one. The yields of dry matter as well as of crude and true proteins were positively correlated with the phosphorus level in the dry matter of alfalfa (P < 0.01). The level of total sulphur was positively linearly correlated with the phosphorus content (P < 0.01). No harmful accumulation of sulphur or fluoride was observed. A deficiency of phosphorus in alfalfa and an abnormal Ca:P weight ratio was found. The S total level was positively correlated with N total concentration. (P < 0.01). The percentage of true protein in crude protein was negatively correlated with total sulphur (P < 0.01). The level of nonprotein nitrogen compounds was positively correlated with S total level (P < 0.01).  相似文献