نتایج جستجو برای: except for soils with clay content 35
تعداد نتایج: 13918089 فیلتر نتایج به سال:
Puddling is the most common method of land preparation for lowland rice cultivation. The purpose of this study was to assess the influence of various intensities of puddling on percolation rate, water retention by soil and the amount of water used for different puddling intensities in three dominant soil textures of paddy fields in Guilan province. Undisturbed soil samples were taken from 3 dif...
Knowledge of forms of phosphorus (P) is important in the evaluation of soil P status and also in understanding soil genesis and fertility. Amounts and distribution of P in different organic and inorganic fractions were examined in 39 soil samples of Fars province. Soils were sequentially extracted to determine organic P and inorganic P fractions. Total P with an average of 597 mg/kg soil was ...
The vertical migration of M. incognita juveniles introduced at 20 cm from the roots was studied in five natural soils, 100% silica sand, 95% silica sand with 5% clay, 90% silica sand with 10% clay, and 95% silica sand with 5% clay as a concentrated layer. In natural soils the percentage of juveniles capable of migrating 20 cm and penetrating the roots decreased when the percentage of clay and s...
a r t i c l e i n f o In Soil Taxonomy three diagnostic subsurface horizons reflect clay enrichment: the argillic, kandic, and natric horizons. Clay illuviation is recognized in Soil Taxonomy at some level in 10 of the 12 orders, including the percent of the soil series in the USA contain taxonomically defined clay-enriched horizons. However, many other soils contain Bt horizons that do not qua...
Pyrogenic carbon (PyC) is considered one of the most stable components in soil and can represent more than 30% of total soil organic carbon (SOC). However, few estimates of global PyC stock or distribution exist and thus PyC is not included in any global carbon cycle models, despite its potential major relevance for the soil pool. To obtain a global picture, we reviewed the literature for publi...
In semi-arid regions, soils are weakly aggregated and subjected to water erosion processes especially rill and interrill erosion. There is no information on the rate of these water erosion types in semi-arid soils located in the hillslopes. Therefore, this study was conducted to determine the soils susceptibility to these erosion types in semi-arid region. A laboratory experiment was done in ei...
ited on sandy or on loamy sediments. Therefore, it is important to study not only the extent of surface spatial Analysis and interpretation of spatial variability of soils is a keyvariability, but also the distribution of subsurface and stone in site-specific farming. Soil survey maps may have up to 0.41ha inclusions of dissimilar soils within a mapping unit. The objectives deep soil horizons. ...
Urea is one of the most commonly used nitrogen fertilizers in agricultural lands. The fate of this fertilizer in soils is greatly related to the soil urease enzyme activity, while this enzyme commonly exists in the adsorbed state on the surface of soil colloids, and especially clay minerals. In order to examine the kinetic properties of free and adsorbed Urease on the surface of sepiolite and v...
Speculation about the association of soil characteristics with the expression of ovine Johne's disease (OJD) prompted this cross-sectional study. We enrolled 92 sheep flocks in Australia during 2004-2005 and in each enrolled flock collected pooled faecal samples from an identified cohort (group of same age and sex) of sheep and soil samples from the paddocks grazed by this cohort of sheep. Faec...
The toxicity of chromium (Cr) to biota is related to its chemical forms and consequently to the redox conditions of soils. Hexavalent Cr[Cr(VI)] may undergo natural attenuation through reduction processes. In this study, the reduction kinetics of Cr(VI) in seven soils and its relationships with soil properties were investigated with laboratory incubation experiments. The results indicate that t...
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