160 research outputs found
Road Ditch Spraying can Contaminate Shallow Ground Water
Herbicides are the most often detected pesticides in shallow aquifers in eastern South Dakota. Since most of the people in this part of the state obtain drinking water from these shallow aquifers, there is increasing concern for aquifer water purity. In the Oakwood Lakes-Poinsett project area, Lasso was the herbicide most often detected in the aquifer, followed by 2,4-D. Tordon 22k (picloram) was second to Lasso in 1991 data from Turner County and Bowdle aquifer studies. The road ditch over the aquifer is one of the most sensitive environments to ground water pollution. This is particularly true for naturally shallow soils with only 1 to 3 feet of soil over the gravel aquifer material. In the process of building up the road, an average of 1 foot of soil is taken from the road ditch. This leaves the ditch with O to 2 feet of soil over the gravel. Thus, these road ditches are extremely sensitive to the leaching of herbicides into ground water
Drop Size Distributions from Medium-Sized Agricultural Sprinklers
THE drop size distribution of sprinkler
spray is of practical importance
for two reasons. First, the small droplets
are subject to wind drift, distorting the
application pattern. Second, large droplets
possess greater kinetic energy which
is transferred to the soil surface causing
particle dislodgement and puddling that
may result in surface crusting and runoff.
The drop size distributions from
medium-size agricultural sprinklers were
measured to study the effects of pressure
and nozzle size on the distributions.
These are two parameters that
farmers can change on existing systems
to cope with field problems caused by
low intake rates and runoff
Chapter 21: Metric Conversion
Weights and measures were among the earliest tools invented by
man
Sprinkler-Induced Soil Temperature Changes Under Plant Cover
An experiment was conducted to determine the amount
of soil temperature reduction to be expected from irrigating
potatoes (Solanum tuberosum) at various intervals.
Soil temperatures were measured at the 10-cm depth
under potato ridges with various amounts of plant cover.
The mean daily soil temperature at the 10-cm depth in a
silt loam soil after 7 days following irrigation increased
as much as 2 C above the daily irrigated plot with full
cover and 4 C above the daily irrigated plot without cover.
Similar soil temperature increases occurred in a loamy
fine sand soil irrigated after 5 days which is the normal
irrigation intervals for these soils
Air Temperature and Vapor Pressure Changes Caused by Sprinkler Irrigation
The downwind effect of evaporation from sprinkler
spray was studied in the field to determine if air temperature
and vapor pressure were changed enough to
influence plant growth and water use. Wet-bulb and
dry-bulb temperature profiles were measured upwind
and at three distances downwind from a sprinkler lateral
before and during sprinkling. Wind-speed and direction
were also measured. Air temperature generally was reduced
less than 1 C, and vapor pressure in the air was
increased less than 0.8 mb. This amount of change in
the air temperature and humidity is not likely to be sufficient
to cause any significant change in plant growth or
evaporative loss of water
Sugarbeet Yields Unaffected by Afternoon Wilting
Sugarbeet irrigation has been studied extensively in the western
United States. The present "state of the art" has been reviewed
by Loomis and Haddock (2) 8. Most field experiments
have been run at three or more levels of soil moisture—wet,
medium and dry. Differences in root and sugar yields under
these moisture regimes have not been strikingly different so long
as the "dry" treatment did not cause prolonged wilting, and so
long as the "wet" treatment did not cause leaching of nutrients
Soil Water Uptake by Alfalfa
Water uptake patterns of alfalfa (Medicago sativa L.)
assist us in understanding proposed models governing
plant water uptake. The data in this paper are presented
to elucidate some details of passive water uptake from
profiles with nonuniform soil water distributions. Soil
water content under an alfalfa seed crop was monitored
with a neutron moisture probe. Alfalfa roots withdraw
soil water in the lower portion of the root zone (where
soil matric potentials were between —7 and —10 bars),
while the upper portion of the profile was above —2
bars. This indicates that for passive water uptake to
occur, large water potential differences must exist between
the root xylem and the soil in the upper, moist
portion of the profile. Plant water potential measurements
support passive uptake
A Model for the Stray Light Contamination of the UVCS Instrument on SOHO
We present a detailed model of stray-light suppression in the spectrometer
channels of the Ultraviolet Coronagraph Spectrometer (UVCS) on the SOHO
spacecraft. The control of diffracted and scattered stray light from the bright
solar disk is one of the most important tasks of a coronagraph. We compute the
fractions of light that diffract past the UVCS external occulter and
non-specularly pass into the spectrometer slit. The diffracted component of the
stray light depends on the finite aperture of the primary mirror and on its
figure. The amount of non-specular scattering depends mainly on the
micro-roughness of the mirror. For reasonable choices of these quantities, the
modeled stray-light fraction agrees well with measurements of stray light made
both in the laboratory and during the UVCS mission. The models were constructed
for the bright H I Lyman alpha emission line, but they are applicable to other
spectral lines as well.Comment: 19 pages, 5 figures, Solar Physics, in pres
Irrigation of Crops: Drainage Water Quality
Recent research has provided new knowledge on
managing irrigation water to decrease the degrading
effects of irrigation on the mineral quality of
drainage water and to increase crop yield and quality
by effective use of sprinkler irrigation.
In sprinkler irrigation, water is exposed to the
atmosphere, which enhances evaporation. The
evaporation process cools the droplets, increases
the heat absorbed by the droplets from the air
through which they pass, and adds water vapor to
the atmosphere. It has also been determined that
the plant as well as its environment can he cooled
with water applied by sprinklers
Tow Line Sprinkler Systems
A tow line sprinkler system consists of one or more
sprinkler laterals made from 30 or 40 foot lengths of
sprinkler tubing rigidly connected together. The laterals
are towed from one set to the next with a tractor.
Excluding the cost of the tractor, which is used for
other farm functions, the tow line system is the most
economical mechanical move system available and is
convenient for pasture, hay and grain crops
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