نتایج جستجو برای: soil formation
تعداد نتایج: 703087 فیلتر نتایج به سال:
Soil aggregate stability is an important indicator for controlling soil losses and can improve soil quality, particularly in an area such as the Loess Plateau. The objective of this study was to estimate the differences in soil aggregates across six different land-use systems (grassland, apple orchard, abandoned apple orchard, cropland maize, cropland wheat, and shrub-grassland). For this purpo...
Atrazine is a widely used herbicide and is often a contaminant in terrestrial and freshwater ecosystems. It is uncertain, however, how the activity of soil macrofauna affects atrazine fate and transport. Therefore, we investigated whether earthworms enhance atrazine biodegradation by stimulating herbicide degrading soil microflora, or if they increase atrazine persistence by facilitating herbic...
The kinetics of mixed Ni-Al layered double hydroxide (LDH) precipitate formation on a soil clay fraction was monitored using X-ray absorption fine structure (XAFS) spectroscopy. The kinetic behavior was monitored at pH 6.0, 6.8, and 7.5 in order to determine the effect of reaction pH on precipitate formation. XAFS analyses were performed on a Ni-reacted whole soil at pH 7.5 to determine the eff...
حوضه آبخیز سدمخزنی شهید پارسا در جنوب شرقی شهرستان فردوس استان خراسان واق گردیده است . بااحداث این سد علاوه برآبیاری اراضی موجود، 700 هکتار از اراضی جدید پایین دست به زیر کشت می روند. عمده ترین معضل موجود در رابطه با حوضه آبخیز، وجود بار رسوب فراوان و تجمع آن در پشت مخزن سد می باشد. لذابه علت عدم وجود اطلاعات کافی از وضعیت فرسایش خاک در حوضه آبخیز، دراین رساله بررسی و مطالعه فرسایش پذیری خاک ان...
Having specific properties, clay minerals including palygorskite have considerable influence on soil physico-chemical characteristics as well as the stage of soil development. The objectives of current study were to determine the distribution, origin and formation conditions of palygorskite in the Tertiary sediments and associated soils in Darab, Fars Province. Based on the field observations a...
dans le monde où l’homme est l’élément le plus important de la vie, la formation de nouvelles générations a une importance particulière. en rédigeant emile, jean jacques rousseau, exerce une influence extraordinaire sur la vie humaine et mène à réfléchir sur la question de l’éducation en tant qu’un art. ce penseur du xviiie siècle, grâce à son élève imaginaire, emile, présente son idéal pédagog...
I N T R O D U C T I O N T h e s t u d y o f c lay f o r m a t i o n i n soils m a y b e d i v i d e d i n t o t h r e e p a r t s : (1) a q u a n t i t a t i v e e v a l u a t i o n o f t h e a m o u n t o f c lay f o r m e d f r o m a g i v e n a m o u n t o f p a r e n t m a t e r i a l , (2) a q u a l i t a t i v e e v a l u a t i o n of t h e k i n d o f m i n e r a l s a n d o t h e r s u ...
In 2002, the Biscuit Wildfire burned a portion of the previously established, replicated conifer unthinned and thinned experimental units of the Siskiyou Long-Term Ecosystem Productivity (LTEP) experiment, southwest Oregon. Charcoal C in pre and post-fire O horizon and mineral soil was quantified by physical separation and a peroxide-acid digestion method. The abrupt, short-term fire event caus...
We investigated the effect of leaf litter on below ground carbon export and soil carbon formation in order to understand how litter diversity affects carbon cycling in forest ecosystems. 13C labeled and unlabeled leaf litter of beech (Fagus sylvatica) and ash (Fraxinus excelsior), characterized by low and high decomposability, were used in a litter exchange experiment in the Hainich National Pa...
Soil organic C content, a major source of system stability in agroecosystems, is controlled by many factors that have complex interactions. The purpose of this study was to evaluate the major controls over soil organic carbon content, and to predict regional patterns of carbon in range and cultivated soils. We obtained pedon and climate data for 500 rangeland and 300 cultivated soils in the U.S...
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