首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3篇
  完全免费   2篇
     5篇
  2021年   1篇
  2018年   1篇
  2009年   1篇
  2005年   1篇
  2004年   1篇
排序方式: 共有5条查询结果,搜索用时 63 毫秒
1
1.
蚯蚓粪覆盖对土壤水分蒸发过程的影响   总被引:1,自引:0,他引:1       下载免费PDF全文
李彦霈  邵明安  王 娇 《土壤学报》2018,55(3):633-640
通过模拟试验研究蚯蚓粪覆盖对土壤水分蒸发过程的影响,以蚯蚓粪覆盖厚度和覆盖度为试验变量,试验处理设置如下:覆盖度90%时,4个处理分别为覆盖1 cm、2.5 cm、4 cm和裸土;覆盖厚度2 cm时,4个处理分别为覆盖度30%、60%、90%及裸土,均连续测定15 d的土壤日蒸发量和12 h的日变化量,以及蒸发前后蚯蚓粪和土壤的有机质含量。结果表明:在覆盖度一定的条件下,土壤蒸发量随蚯蚓粪覆盖厚度的增大而减少;当覆盖厚度一定时,覆盖度越大,对土壤蒸发的抑制作用越强,但覆盖度对土壤蒸发过程的影响小于覆盖厚度。因此,蚯蚓粪覆盖对土壤蒸发有一定的抑制作用,土壤蒸发量随着蚯蚓粪覆盖度和厚度的增加而减小。由于蚯蚓粪具有良好的保水性能,且能够有效增加土壤有机质含量,因而对提高土壤持水能力有促进作用。  相似文献
2.
It is established that soil hydrophobicity reduces soil infiltration rates, and enhances runoff flow and soil erosion. Water repellency has been studied with special interest in coniferous and eucalyptus forests, particularly after burning, but the number of studies concerning Mediterranean heathlands is still very low. In this paper, we study the occurrence and persistence of water repellency in soil samples collected under different plant species susceptible to induce soil hydrophobicity (Erica arborea, Erica australis, Calluna vulgaris, Quercus lusitanica and Rhododendron ponticum) in a natural protected area in southern Spain. Great attention has been paid to the relationships between soil water repellency and environmental factors as organic matter content and soil acidity. The largest hydrophobicity was measured in soil samples collected under E. australis, E. arborea and C. vulgaris. For these species, the organic matter content and pH showed positive and negative correlations with the persistence of water repellency, respectively. The hydrophobicity originated by humic substances in the soil seems to be the only explanation for slight soil water repellency under Q. lusitanica or R. ponticum. The patchy patterns of occurrence and persistence of soil water repellency is governed by the spatial distribution of the studied species and modulated by other factors. Soil surface water repellent layers reduce the infiltration rates and limit the water storage capacity. However, the macropore flow can be enhanced on non-repellent layers, cracks or roots such us the wetting's front shown. The vegetation effects on soil hydrology should be considered for afforestation works and flooding control.  相似文献
3.
本文通过ASDFR便携式光谱仪对132个风干土壤样品的光谱反射率进行了实验室测定。根据土样光谱反射率变化,获得了褐潮土土壤剖面的不同诊断层反射光谱特征。结果表明,在400~1200nm范围之间,土壤有机质含量与土壤光谱反射率有较好的相关性。利用导数光谱方法建立了预测土壤有机质含量的方程,提出了预测北京地区褐潮土有机质光谱的最佳波段。在波长447nm处采用反射率和A值(反射率倒数的对数)所建立的预测方程的预测精度较高。采用反射率的一阶微分建立的预测方程的最佳波段在516nm处。而A值一阶微分光谱在615nm处相关性最好。作为一项参考指标用光谱分析法评价土壤中有机质含量,以期对精准农业中土壤养分或肥力的预测具有一定的指导作用。  相似文献
4.
Phosphomonoesterase (PMEase) activity plays a key role in nutrient cycling and is a potential indicator of soil condition and ecosystem stress. We compared para-nitrophenyl phosphate (pNPP) and 4-methylumbelliferyl phosphate (MUP) as substrate analogues for PMEase in 7 natural ecosystem soils and 8 agricultural top soils with contrasting C contents (8.0-414 g kg−1 C) and pH (3.0-7.5). PMEase activities obtained with pNPP (0.05-5 μmol g−1 h−1) were significantly less than activities obtained with MUP (0.9-13 μmol g−1 h−1), especially in soils with a high organic matter content (>130 g kg−1). Only PMEase activities assayed with MUP correlated significantly with total C and total N (r=0.7, P<0.01 all), and pH (r=−0.71, P<0.01). PMEase activities obtained with the two substrate analogues were correlated when expressed on a C-content basis (r=0.8, P<0.001), but not when expressed on an oven-dry soil weight basis. This indicated that interference by organic matter is related to the quantity rather than to the quality of organic matter. Overall, assaying with MUP was more sensitive compared to assaying with pNPP, particularly in the case of high organic and acid soils.  相似文献
5.
土壤颜色是反映土壤发生、分类及肥力特征的一项重要物理指标。黑色土壤一般有较高的有机质含量,但砂姜黑土是低有机质含量的黑色土壤典型代表。以黄淮海平原3种典型砂姜黑土为研究对象,分别采用添加六偏磷酸钠分散剂后振荡并结合多层次超声处理(HP)、添加碳酸钠分散剂后振荡并结合多层次超声处理(SC)和仅超声波处理(US)等3种方法分散土壤,然后依次提取土壤浅色组分(颗粒态有机质(POM)、白(W)、 浅白(LW))和黑色组分(浅黑(LB)、 黑(B)、深黑(DB)),旨在建立土壤黑色物质的有效提取方法。结果表明, HP方法提取黑色物质(LB、B和DB)的量最多,且提取量与土壤黑度间相关性最显著(P<0.01),是提取砂姜黑土黑色物质的最佳方法。不同提取组分中的土壤黑度与有机质含量无明显相关性,砂姜黑土的显色主要取决于由蒙皂石吸附有机质形成的黑色纳米有机-无机复合体,受有机质含量的直接影响相对较小。本研究提出了一种砂姜黑土黑色物质提取方法,并初步明确了黑色物质组成特征,可为揭示砂姜黑土有机质形成与累积机制提供参考。  相似文献
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号