橡胶园酸性、中性土壤交换性钙、镁测定方法研究     

许木果  丁华平  刘忠妹  陈桂良  陈永川  黎小清 《中国农学通报》2020,36(18):73-79

为了获得简单、易操作、准确度高的橡胶园酸性、中性土壤交换性钙、镁测定方法,本试验通过响应面优化试验,建立称样量、提取液体积、提取方式与交换性钙测定结果之间的数学模型。结果表明：在25℃条件下,以1 mol/L的乙酸铵为土壤浸提液,称样量为2 g、提取液体积175 mL、振荡36 min,为橡胶园酸性、中性土壤的最佳提取条件。将上述条件下得到的结果与标准方法条件下得到的结果相对比,两结果的相对误差在1.25~3.04之间,均属合理范围。利用标准样品对优化方法进行试验验证,结果与推荐值相符。改进后的方法分析成本低、操作简便、测定结果准确、稳定性好,可用于橡胶园酸性、中性土壤交换性钙、镁的测定。  相似文献   

Factors influencing decline in soil pH in Hawaiian Eucalyptus and Albizia plantations     

C. Rhoades  D. Binkley 《Forest Ecology and Management》1996,80(1-3):47-56

Soil pH declined from 5.9 to 5.0 in 8 years beneath plantations of Eucalyptus saligna (Sm.) in Hawaii. In stands of Albizia falcataria, (L.) Fosberg, the soil pH change was more dramatic, declining from 5.9 to 4.6. We measured several components of soil acidity beneath four mixtures of the two tree species to gain insight on the processes responsible for the decline in soil pH. These components were studied using an empirical method of comparing acid quantity, degree of neutralization (depletion of base cations), and acid strength. The decline in soil pH differed between species as a result of differences in the degree of neutralization of the soil exchange complex; the larger decrease in soil pH under Albizia was produced by greater acidification of the exchange complex. Empirical titration curves suggested that differences in acid strength moderated the divergence in soil pH beneath the species. Had the acids accumulating in the soil under Albizia been as strong as those in the Eucalyptus soil, the difference in soil pH would have been greater. Though the two species had contrasting effects on soil pH, the differences in degree of neutralization, responsible for the pH decline, were small compared with differences in the amount of cations stored in tree biomass. Continued supply of nutrient cations (from weathering or fertilization) will ultimately control both the extent of soil pH decline and the level of productivity sustained by the forest.  相似文献   

经济绿肥覆盖对西双版纳胶园土壤性状的综合影响   总被引：1，自引：0，他引：1  

杨春霞  李国华  李春丽 《中国农学通报》2005,21(2):280-280

论述了经济绿肥覆盖对提高土壤肥力、改善土壤物理性状、水土保持、提高抗病性、增加收入等方面的作用和重要意义。阐明了经济绿肥覆盖在西双版纳胶园的应用前景，它将实现经济效益和生态效益并重的胶园可持续发展。同时提出了在胶林行间特别是保护带陡坡地种植绿肥覆盖物的发展思路及相应措施，即完成胶园经济绿肥良种的筛选、经济效益和生态效益评价、及配套栽培技术试验示范。  相似文献   

A logistic analysis of the factors determining the decision of smallholder farmers to intercrop: A case study involving rubber–tea intercropping in Sri Lanka     

S.M.M. Iqbal  C.R. Ireland  V.H.L. Rodrigo 《Agricultural Systems》2006

The factors influencing the decision of smallholder farmers to adopt new farming technologies were studied with reference to rubber–tea intercropping in Sri Lanka. Rubber–tea intercropping has been recommended previously to rubber farmers as a means to improve productivity and income during the early pre-tapping phase of rubber growth. Although crop trials have shown that the two crops are agronomically compatible and potentially produce a combined economic yield superior to the yield of a sole crop grown on the same area of land, there is little evidence of widespread adoption of this practice among smallholder farmers in Sri Lanka. The aim of the study was to determine the major factors that influence the decision to undertake rubber–tea intercropping and to construct a predictive model that describes the likelihood of adoption of intercropping by traditional smallholder rubber growers. A rapid rural appraisal (RRA) was undertaken based on semi-structured interviews of 90 smallholder farmers in the main rubber growing low wet zone of Sri Lanka. Among a number of factors shown to significantly influence the decision to intercrop tea with rubber, three were shown to operate independently, namely level of income, source of income (i.e. solely from own farm or from farm plus additional off-farm enterprises), and availability of land considered suitable for tea cultivation. A statistical model developed through correlation and logistic analysis, which predicts the likelihood of a smallholder adopting intercropping based on these factors, is presented and discussed. The most likely combination of circumstances (82% probability) under which rubber–tea intercropping is practiced is shown to be where the farmer’s income is greater than Rs. 10,000 per month, where the farmer’s income is based solely on own farm enterprises, and where more than 80% of the farmer’s land area was judged to be suitable for tea cultivation. Conversely, 30% of smallholder farmers that chose not to intercrop did possess land suitable for tea cultivation. Qualitative responses to the RRA indicated that limitation of technical knowledge was the main problem subsequently faced by rubber farmers who had adopted rubber–tea intercropping. Results indicate that there is need for both income support through farm subsidies and further agricultural extension services, if rubber–tea intercropping is to be adopted more widely in Sri Lanka. The wider usefulness of the developed logistic model in determining the likelihood of adoption of intercropping by smallholder farmers is discussed.  相似文献   

多层组合减振结构参数优化的研究   总被引：6，自引：0，他引：6  

孙大刚  诸文农 《农业机械学报》1997,28(3):9-13

对一种新型的，用于大型履带式车辆的多层管状减振结构的参数特性进行了研究。在分析了参数之间耦连关系后，提出了暂定刚度参数Ｙ和阻尼材料损耗因子β，先求剪切参数Ｘ的解耦观点。把减振结构的几何尺寸作为变量，结构的损耗因子η最大为目标，对结构进行了优化。经对按本文观点优化的橡胶减振器制品的动态实验，表明实验值与理论值有较好的吻合性。  相似文献   

悬架橡胶件对汽车平顺性影响的多体动力学分析     

张立军  李刚 《农业机械学报》2007,38(12):16-19

应用有限元分析了汽车减振器橡胶支撑件的弹性特性,在此基础上,应用SIM PACK软件建立了整车多体动力学模型,分析了橡胶支撑件的刚度、阻尼对汽车行驶平顺性的影响。分析结果表明：在车身共振区,橡胶件对地板加速度功率谱影响较小,但在4-13Hz中频区,即人体比较敏感的范围内,橡胶件可以使地板加速度功率谱峰值减小6.5%-25.4%,因此悬架橡胶件对汽车行驶平顺性有明显的改善。此外,还得出对于刚度较大的橡胶件应选取较小阻尼,对于较软的橡胶件,可以忽略阻尼影响的结论。  相似文献   

对橡胶悬架装置动特性的改进探讨   总被引：1，自引：0，他引：1  

黄鼎友  孔祥华 《拖拉机与农用运输车》2006,33(2):73-75

以橡胶悬架装置为研究对象,考虑其动态特性与高速车辆动力总成低频与高频要求不同之间的矛盾,试图通过改进橡胶悬架装置的结构提高其动特性。建立了改进结构的橡胶悬架装置的力学模型,并对其进行了理论分析和仿真计算,结果表明改进后的橡胶悬架装置的动特性有了显著提高,对我国橡胶悬架装置的结构改进具有借鉴和指导意义。  相似文献   

不同水性高分子异氰酸酯胶对人工林木材胶合性能的影响   总被引：2，自引：0，他引：2  

张玉萍  傅峰 《林产工业》2006,33(3):30-33

采用同一类型的高分子化合物、填料和乳胶按不同配比组成2种主剂,然后与贮存期不等的交联剂组成不同的水性高分子异氰酸酯胶黏剂(API),用来黏接杉木、杨木、巨桉、尾巨桉、柠檬桉和窿缘桉等6种人工林木材试样以研究 API主剂特征和交联剂贮存时间对人工林木材胶合性能的影响。试验结果表明:1)API主剂特征显著影响6种人工林木材的胶合性能。2)随着交联剂贮存期的增长,人工林试材的胶合性能有降低趋势,但胶合杉木、杨树、巨桉和尾巨桉4 种人工林木材时仍能达到标准要求。  相似文献   

基于HJ-1CCD遥感影像的西双版纳橡胶种植区提取   总被引：3，自引：0，他引：3  

余凌翔  朱勇  鲁韦坤  黎小清  赵泽  李春丽 《中国农业气象》2013,34(4)

利用橡胶林第一蓬叶变色-稳定期环境遥感影像作为遥感信息源,根据橡胶林这一时期特有的影像特征,通过监督分类方法实现对西双版纳橡胶种植分布区信息的提取,解决了监督分类时树龄、品种和耕作制度造成的光谱差异问题;监督分类前利用NDVI阈值对非提取目标进行剔除,有效减少了分类数和工作量.分析表明,本次提取精度达到97.6％,较好地反映了西双版纳橡胶种植分布情况,同时对国产卫星的推广应用具有良好的示范作用.  相似文献   

套筒式橡胶减振器的疲劳工况试验研究     

李毅念  赵满全  窦卫国  童淑敏  王竹瑛  赵士杰 《农业机械学报》2004,35(1):125-128

为了准确掌握金穗4SW系列马铃薯挖掘机摆动分离筛新型套筒式橡胶减振器的疲劳工况，进行了田间试验和实验室试验。试验表明，该橡胶减振器能够满足生产实际要求和对橡胶减振器的设计寿命要求。给出了符合橡胶减振器疲劳损失衡量标准的静刚度损失值，经生产实践证明，此值具有指导生产的实际意义。  相似文献