Subgrade moisture content varies with environmental and soil conditions and has significant influence on pavement performance. Therefore, it is important to establish realistic estimates of expected subgrade moisture contents to account for the effects of this variable on predicted pavement performance during the design stage properly. The initial boundary soil suction profile for a given pavem...

Installation of subsurface tile lines in poorly drained soils is a beneficial management practice that enhances crop productivity. In some instances, however, they can contribute to offsite losses of agricultural chemicals and sediment in drain flow. Movement of these materials through soil macropores (earthworm burrows and cracks) has been shown to contribute to this phenomenon. In order to de...

Survival of total and fecal coliform bacteria was measured in the 0 to 5, 5 to 15, and 15 to 30 cm soil depths at 1, 3, 7, 14, and 90 to 120 d after swine (Sus scrofa) wastewater application to riparian filterstrips in southern Georgia during each season of the year. Vegetative treatments evaluated were: (i) 20 m grass-10 m forest, (ii) 10 m grass-20 m forest, and (iii) 10 m grass-20 m maidenca...

This study was conducted to assess the influences of soil surface conditions and initial soil water content on water movement in unsaturated sodic soils of reclaimed coastal areas. Data was collected from column experiments in which two soils from a Chinese coastal area reclaimed in 2007 (Soil A, saline) and 1960 (Soil B, nonsaline) were used, with bulk densities of 1.4 or 1.5 g/cm(3). A 1D-inf...

Pre-emergence herbicide residues were detected in domestic wells sampled near Tracy, CA. This study sought to determine the source of contamination by comparing soil distribution of diuron [N'-(3,4-dichlorophenyl)-N,N-dimethylurea] and hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] in an agricultural field where the soil was a cracking clay to infiltration ...

The output from a pesticiie screening model indicated that chemicals with low Henry’s Law constants (A,,) will tend to accumulate at the soil surface when water is evaporating, resulting in an increased volrtilixation with time. Volatilixation losses and surface distributions of two pesticides with widely differing KH were measured to test the predictions of the screening model, particularly wi...

Evapotranspiration (ET) is the movement and transfer (i.e., flux) of water as a liquid at the Earth’s surface to the atmosphere as a gas. ET is a combination of open water evaporation and plant transpiration ( , which is the Sublimation transition of solid water (i.e., ice, snow) to vapor due to low atmospheric pressure (i.e., high altitude), dry air and high sunlight, is generally considered s...

The soil supports plants, is the physical determinant of root growth and extent, and is the main reservoir for plant-available water and nutrients. Therefore, the soil controls the availability of most essential plant nutrients. It regulates availability by means of biophysiochemical processes, which are functions of soil and plant properties. This chapter introduces the concept of soil nutrien...

This paper describes the scientific principles of Darcy’s law and hydraulic resistance as they relate to the in-ground dispersal of onsite wastewater effluent. A clear understanding of how water moves into the ground via dispersal trenches is needed to facilitate proper system design and effect some standardization of dispersal trench sizing and design. Hydraulic conductivity of the media, hydr...