A piezometric head method is proposed to estimate the impermeable layer depth used in drain spacing formulae. The method was tested and compared with soil texture changes and the US Bureau of Reclamation (USBR, 1978) criterion of impermeable layer being one with hydraulic conductivity one tenth to one fifth that of the weighted hydraulic conductivity of the upper layers. The proposed method, wh...

The combined effect of soil moisture in unsaturated soil layers and pore-water pressure in saturated soil layers is critical to predict landslides. An improved infinite slope stability model, that directly includes unsaturated zone soil moisture and groundwater, is derived and used to analyze the factor of safety’s sensitivity to unsaturated zone soil moisture. This sensitivity, the change in t...

Phosphorus (P) is one of the most vital elements for all living organisms which acts as aconstituent of essential biomolecules such as nucleic acids, phospholipids, and phosphosugars,and as a major contributor to almost all metabolic reactions including photosynthesis,respiration, and energy delivery. It is one of the most needed nutrients for plant growth anddevelopment. Despite high levels of...

Wetlands are sources of denitrification-derived nitrous oxide (N2O). Thus, the denitrifier community of an N2O-emitting fen (pH 4.7 to 5.2) was investigated. N2O was produced and consumed to subatmospheric concentrations in unsupplemented anoxic soil microcosms. Total cell counts and most probable numbers of denitrifiers approximated 10(11) cells x g(DW)(-1) (where DW is dry weight) and 10(8) c...

Existing studies on surface deformation prediction consider single soil layers and straight-line excavation when investigating caused by metro shield construction. In this study, we provide a new method for studying the curved tunnel construction in upper soft lower hard soil. The equations are derived using Mindlin solution random medium theory verified engineering examples numerical simulatio...

Laboratory studies were conducted to evaluate effect of microwave irradiation of sandy loam soil on thermal energy absorption and control of plant-parasitic nematodes when air dry soil layers were placed on top of less moist, moist, and wet soil layers. The soil was packed in 12 cm high and 10 cm dia columns to a bulk density of 1.4 g/cm3. Moisture contents of air dry, less moist, moist, and we...

Mulching and nitrogen are critical drivers of crop production for smallholders of the Loess Plateau in China. The purpose of this study was to investigate the effect of mulching and nitrogen fertilizer on the soil water content, soil nitrate-N content and vertical distribution in maize root-zone. The experiment was conducted over two consecutive years and used randomly assigned field plots with...

the superficial strata of ground have been perennially exposed to the action of natural agents such as heat, cold and water. however, grazing agent was not different from them when soils were investigated from temperate rangelands of kashmir and caused the soil compaction, soil structure degradation and loss of soil organic c and c/n ratio. soils from three grazing intensities were investigated...