A field study was conducted to determine the applicability of multivariate
geostatistical methods to the problem of estimating and simulating pesticide
concentrations in groundwater from measured concentrations of nitrate and pesticide,
when pesticide is undersampled. Prior to this study, no published attempt had been made
to apply multivariate geostatistics to...
A method was developed for assessing the vulnerability
of groundwater to contamination from contaminant sources
at the soil surface, using a numerical groundwater flow
model linked to a digital map database. The method was
applied using the pcARC/INFO Geographic Information System
(GIS) to input, store, and manipulate base maps, resulting...
Summer brooding often requires some form of air modification in
addition to maximizing ventilation rate to prevent animal heat stress
and possible death due to hyperthermia. A rockbed thermal storage
module was designed and constructed to provide sensibly cooled air
for a broiler space under summer brooding conditions. A mathematical...
Moisture loss from fresh fruits results in lost revenue to producers, storage/packing companies, distributors, and increased prices for the consumer. Improved methods of storage and handling are necessary to help prevent moisture loss and retard spoilage. A literature review was conducted to improve knowledge on past and current studies involving...
Increased consumer demand for fresh fruit throughout
the year has created a need for long term storage. Long
term storage of fruit uses more energy than fresh market
products, thus increasing production cost. Pacific
Northwest energy costs and more competition for markets
has made energy conservation an important factor to...
A survey of Oregon sheep producers conducted as part of this research, indicated that lambing losses by sheepgrowers in winter rainfall areas of Oregon currently average 16 percent. The majority of the lambs born in these areas are born in pastures without the benefit of shelter. The utilization of portable...
Conversion of solar energy to mechanical power through the use of
thermostatic bimetals and linear Fresnel lenses was found to be both
theoretically and experimentally feasible. Using linear Fresnel lenses
to concentrate sunlight on bimetallic coils caused a simple sun powered
motor to produce rotational shaft power. However, continuous rotational...
Recycling of water in aquaculture facilities is used to minimize the amount of energy or tempered water required to control water temperatures. The rate of heat exchange between the water and the environment can be an important variable in the design, management, and economic analysis of a recycle system. A...
A helically flighted rotating tube for concentrating dairy and
swine manure solids was developed and evaluated. The solids removal
and concentration factor values were measured with beet pulp,
dairy manure arid swine manure slurries at different influent flow
rates and suspended solids concentrations. A method of estimating
the performance of...
The development of the energy crisis has caused the
use of depletable energy resources to be monitored quite
closely in the United States. Within the agricultural
sector, irrigation is a large user of energy, with the
potential of using many times more energy than all other
agricultural field operations. A...
The occurrence of relatively less permeable soil underlying a
relatively more permeable and shallow soil profile is widespread in
the Willamette Valley Region of Oregon. Recognizing that an understanding
of the water transport process in such a situation would
provide reliable criteria for designing a drainage system has led to...
A water-to-water heat pump was specifically designed and operated
to temper process water for cleansing and sanitizing milking parlor
equipment using recovered energy from the milk refrigeration system as
its heat source. Operation of the water-to-water heat pump in series
with the energy recovery system was found to be both...
Deliberately underirrigating a crop may yield economic
benefits. The optimal use of water by an irrigator
should be achieved under a deficit irrigation regime. It
is important to know how water deficits affect yields and
the interaction of the deficits with the scheduling of
irrigations.
A field experiment was conducted...
Soil moisture in a crop's root zone must be regularly
monitored to accurately predict crop water requirements.
Most irrigation scheduling services currently
use the neutron probe to monitor soil moisture. Unfortunately,
there is a degree of variability associated
with use of the neutron probe creating uncertainty in
measurements of soil...
A large rainfall simulator was used to study infiltration on six
soil plots. Water content and capillary pressure were measured during
steady rainfall at rates less than required to produce runoff. The
equipment and procedures used to make these measurements are discussed.
Water content and capillary pressure data obtained as...
Water tables in many soils of the Willamette Valley of Western
Oregon are often near the surface. This is because they are underlain
by a relatively impermeable layer at a shallow depth, and the rainfall
during the winter months greatly exceeds the evapotranspiration. The
high water tables combined with fine-textured...
The intermittent or cyclic application of water to
furrows or borders, a method known as "surge flow irrigation",
can significantly improve the advance characteristics
of surface irrigation. Numerous field studies have
shown that the advance of furrows is considerably more
rapid when irrigated by surge flow than by the conventional,...
Evaluation and sensitivity analysis of a soil-water---
atmosphere-plant simulation model, SWATRE, developed by
Feddes et al (1978) in The Netherlands was conducted.
The evaluation was performed with the observed data
obtained by Cuenca (1978) for three different irrigation
levels in UC82 variety tomato fields in Davis,
California. SWATHE requires about...
Often low intake rate soils need special consideration when
applying water during an irrigation. Surface flooding for extended
periods may cause adverse crop growth conditions. Properly
designed sprinkler systems often eliminate irrigation problems,
because the application rate and quantity of water applied can be
readily controlled.
Research workers who have...
The purpose of this study was to evaluate the impact sediment has on the survival of
bacteria in a typical rangeland stream. This information is an important component in
determining a time integrated prediction of bacterial numbers in the stream sediment and
overlying water. Bacterial survival in stream is a...
The rainfall regime of the Cape Verde Islands is influenced
by the Intertropical Convergence Zone (ITCZ) resulting in strong
seasonal trends and frequent thunderstorm events. These
events are frequently responsible for the destruction of riverine
structures and valuable crop land.
A menu driven database program (RIS) was developed for
the...
Grazing cattle usually have access to streams as a
source of drinking water. A model was developed for the
personal computer to predict the bacterial quality of
these streams. The model estimates the number of
organisms that enter the stream by the direct deposit of
feces and by runoff from...
Centrifugal irrigation pumps discharge fluids at high velocities that must be slowed
to minimize energy losses due to friction. Pipe expansions make the transition to larger
pipes associated with slower velocities. Expansions convert the upstream velocity head
to static head in the downstream pipe. The transition to a larger pipe...
Four years of daily weather observations from Central Tunisia were available for testing the application of the Penman Equation to estimate reference evapotranspiration in the arid climate of Central Tunisia. The data included minimum and maximum temperature, minimum and maximum relative humidity, 24-hour wind run, and lysimeter measurements of reference...