Soil samples and soil clods were collected from ten potato fields
in Eastern Oregon. An index of grain size distribution was sought that
would correlate well with compacted soil bulk density. The Hazen
coefficient of uniformity was best related to bulk density. The
limitations of various indices and their relationship...
Capillary pressure-saturation data obtained for unconsolidated porous media with different liquids are examined to investigate the effects of clay-liquid interactions on liquid retention. Liquid retention functions are assumed to reflect the effective pore-size distributions. The hydraulic variables, capillary pressure and saturation, are transformed to account for changes in liquid retention...
Water shortage is one of the biggest problems facing
agricultural development in the United Arab Emirates, because of
the extremely arid climate and the large amount of irrigation
water that is used for crops. Prediction of crop water requirements is essential to solve water management problems in this
country.
Two...
Lack of stability of soil aggregates for water
movement is a major problem in arid soils due to low
organic matter and higher sodium contents. Soil
amendments for improving stability of structure and
increasing infiltration of water are essential to solve
water management problems in these areas.
Different rates of...
Prevention of groundwater contamination by agricultural
chemicals requires an understanding of the complex
processes that control pesticide movement below the soil
surface. Through this understanding it is possible to try
to predict which areas may be most vulnerable to
contamination. The many models that have been developed to
characterize pesticide...
Published literature about six Pacific Northwest stream systems was contrasted
to provide a regional perspective on channel response to disturbance. This
investigation was prompted by a combination of recent environmental legislation,
mounting social pressures to plan projects at a drainage basin scale, and the difficulty
in defining and predicting the...
Geostatistical methods were used to find efficient and accurate means for
salinity assessment using regionalized random variables and limited sampling. The
random variables selected, sodium absorption ratio (SAR), electrical conductivity
(EC), and clay content were measured on samples taken over an area of fifteen
square miles. Ordinary kriging and co-kriging...
Sandy soils are among the least productive soils because of their inability to
store adequate water for plant growth. Their high percolation rate not only allows
water to move quickly beyond the root zone, but also washes nutrients below the reach
of plant roots. High evaporation occurs from the soil...