نتایج جستجو برای: loess soils
تعداد نتایج: 52082 فیلتر نتایج به سال:
Soil microbial communities are very sensitive to changes in land use and are often used as indicators of soil fertility. We evaluated the microbial communities in the soils of four types of vegetation (cropland (CP), natural grassland (NG), broadleaf forest (BF) and coniferous forest (CF)) at depths of 0–10 and 10–20 cm on the Loess Plateau in China using phospholipid fatty acid (PLFA) profilin...
INTRODUCTION Lvni-north of the great southward bend o[ the Platte River in central Nebraska but southeast of the sandhills, there are several thousand square miles of rugged uplands known as loess bluffs. They are quite unlike the sandhills with their typical cover, largely of postelimax tall grasses. They also differ widely from the Nebraska plain eastward and south-eastward where mid-grass or...
Introduction The vegetation of great areas of Mixed Prairie has been destroyed by plowing. But even larger ones, still intact , have degenerated far from a climax condition. The almost universal cause for such deterioration, aside from drought, is grazing. The objective of this study has been to ascertain the changes in vegetation that have resulted from 60-70 years of different intensities of ...
Abstract Water erosion could cause wide and serious soil organic carbon (SOC) loss, but differences in SOC loss enrichment sediments among red soil, black loess China have received less attention. This study investigates the transport of generation regulation runoffs during process by collecting data from indoor or outdoor artificial simulated rainfall experiments selecting typical regional int...
In order to study the application of lime-fly ash loess in permafrost subgrade engineering, uniaxial compressive test, fast direct shearing test and permeability tests were carried out on lime-fly ash loess under different curing ages and freeze-thaw cycles. Uniaxial compressive strength of lime-fly ash loess increases slowly with the curing ages, and can reach 3.5 Mpa after the curing ages of ...
Loess shoulder-lines are significant structural lines which divide the complicated loess landform into loess interfluves and gully-slope lands. Existing extraction algorithms for shoulder-lines mainly are based on local maximum of terrain features. These algorithms are sensitive to noise for complicated loess surface and the extraction parameters are difficult to be determined, making the extra...
Knowledge on the lithologically inherited variation in present day Pb isotope ratios in soils is remarkably limited. Such information is essential to determine the anthropogenic Pb fraction and anthropogenic Pb sources in Pb polluted soils. This study presents results of a survey of subsoil samples of approximately 350 rural locations covering the entire Netherlands, for which the bulk geochemi...
The effects of 34 years cultivation on organic carbon content of the loess derived soils were studied in Golestan province, northern Iran. Soil organic carbon (SOC) showed significant decrease in most of cases. The minimum and maximum SOC decreases were 4 and 51.14 Mg C ha-1/30 cm for 34 years. In a few cases there was an increase in SOC up to 16.93 Mg C ha-1/30 cm over the period of 34 years i...
The application of fractal geometry to describe soil structure is an increasingly useful tool for better understanding the performance of soil systems. Only a few studies, however, have focused on the structure of rhizospheric zones, where energy flow and nutrient recycling most frequently occur. We used fractal dimensions to investigate the characteristics of particle-size distribution (PSD) i...
We examined the survival rate of Cochlodinium polykrikoides after yellow loess addition and conducted culture experiments to investigate the possibility that red tides maybe caused by C. polykrikoides individuals that are precipitated when loess is added. At least 15% of the C. polykrikoides cells that precipitated to the bottom layer either by the addition of loess or no addition survived for ...
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