57 research outputs found
Influence of irrigation water properties on furrow infiltration: Temperature effects
For surface irrigation, the rate and spatial
characteristics of infiltration processes influence crop
productivity, water use efficiency, and erosion potential
of stream flows. A change in infiltration rate alters
furrow stream flow velocity and shear, and hence
irrigation-induced erosion. Furrow irrigation models
may be improved if they can account for the influence of
water properties on these processes. Water temperature
may influence furrow infiltration by altering fluid
viscosity. We conducted laboratory soil column intake
(constant head), and field recirculating furrow
infiltrometer experiments, to determine whether
irrigation water temperature significantly altered
infiltration. The soil was Portneuf silt loam (coarse-silty,
mixed superactive, mesic, Durinodic Xeric Haplocalcids).
Soil column intake increased by 0.8 to 3.0 percent per
degree C. This increase was not significantly different
from that observed for furrows, 2.0 to 2.9% deg.-1. While
more field studies are needed, these data show that
diurnal and seasonal changes in irrigation water
temperature can significantly alter furrow infiltration
and stream flow. These effects may help explain observed
field-infiltration variability. Inclusion of temperature
algorithms in furrow irrigations models may increase
their predictive accuracy
PAM and straw residue effects on irrigation furrow erosion and infiltration
Water soluble anionic polyacrylamide (PAM) is a highly effective erosion deterrent in furrow irrigation, but little
is known about the effect of plant residue on PAM efficacy. We hypothesized that increasing plant residue in
irrigation furrows may decrease PAM's ability to control erosion. Treatments included furrows with 3.2 g and
10 g m-1 straw applications irrigated with PAM or untreated water, and conventionally irrigated furrows (no PAM
and no straw). Five irrigations were monitored on a field with 1.5% slope and silt loam soil (Durinodic Xeric
Haplocalcids). PAM was applied as a granular patch at the furrow inflow end (33 g or 1 kg active ingredient ha-').
Irrigation inflows of 23 L min' were cutback to 15 after runoff began. Adding more straw, or adding PAM to straw-treated
furrows decreased furrow sediment loss and increased net infiltration, but only for the first two irrigations
after treatment. For fresh furrows, straw treatments reduced sediment loss an average of 86% and straw + PAM
reduced sediment loss nearly 100%, compared to conventionally irrigated furrows. High-straw+PAM and lowstraw+PAM treatments produced the same furrow sediment losses and net infiltration amounts, i.e. increasing plant
residues in furrows did not decrease PAM's efficacy on these soils
Sediment pond effectiveness for removing phosphorus from PAM-treated irrigation furrows
Polyacrylamide (PAM) greatly reduces erosion on furrow-irrigated fields and sediment ponds can be constructed
to remove suspended sediment from irrigation runoff. Both practices are approved for reducing phosphorus (P) loading in
the Lower Boise River Pollution Trading Project in southwest Idaho, but information is not available about using both
practices on the same field. The objective of this study was to measure the combined effects of PAM application and sediment
ponds on sediment and P losses from a furrow-irrigated field. Small sediment ponds (5.8 m 2) with a 60-min design retention
time were installed on two fields to receive runoff from PAM-treated or control furrows. Pond inflow and outflow were
monitored during a total of 11 irrigations on the two fields. Three crop years of data showed that applying PAM to furrows
reduced sediment and total P mass transport to the ponds 50% to 80%, which reduced the mass of sediment and total P retained
in the ponds. However, PAM application did not change the percentage of sediment (86%) and total P (66%) retained. The
PAM-sediment pond combination reduced average total P loss by 86% to 98%, based on the difference between untreated
inflow and PAM-treated outflow. PAM and sediment ponds had little or no effect on dissolved reactive P (DRP)
concentrations. The mass of DRP retained in sediment ponds was directly related to the amount of water that infiltrated within
the ponds. Applying PAM to irrigation furrows and installing sediment ponds at the end of the field can be an effective
combination for reducing sediment and total phosphorus losses from furrow-irrigated fields, but these practices only reduced
soluble P losses by decreasing the volume of water that ran off the fields
Polyacrylamide and straw residue effects on irrigation furrow erosion and infiltration
Water-soluble anionic polyacrylamide (PAM) is a highly effective erosion deterrent
in furrow irrigation, but little is known about the effect of plant residues on PAM efficacy. We
hypothesized that increasing plant residue in irrigation furrows may alter PAM's ability to control
erosion. Furrows with 10 g (485 kg ha-1) on treated area and 3o g m-1 (1490 kg ha-1) wheat
straw applications, irrigated with PAM or untreated water, and conventionally irrigated furrows
(no PAM and no straw) were used. Five irrigations were monitored on a field with 1.5% slope and
silt loam soil (Durinodic Xeric Haplocalcids). PAM was applied as a granular patch at the furrow
inflow end (33 g or 1 kg active ingredient ha 1). Compared to controls, individual straw and
PAM+straw treatments reduced sediment loss in all irrigations by 64% to 100%, but increased
infiltration (1.3x to 2.54 only for irrigation one, when furrows were fresh. Adding more straw to
low straw (with or without PAM) treatments increased average sediment loss reduction from
86% to 94% in the first two irrigations, but provided no extra benefit in subsequent irrigations
(relative to controls). Adding PAM to low and high straw treatments increased average sediment
loss reduction from 80% to 100% in the first two irrigations, and from 94% to 99.8% in
subsequent irrigations. Combining plant residue and PAM in furrows produced greater erosion
control and larger infiltration enhancements than with straw alone. An important additional
benefit of PAM is that it greatly reduced detachment, transport, and redistribution of residue in
furrows, which helped prevent furrow blockage and attendant overflow problems, allowing
farmers to use conservation tillage in furrow irrigated fields
Influence of polymer charge type and density on polyacrylamide ameliorated irrigated furrow erosion
Previous experiments have shown that an initial application of 5-10 g m-3 (5-10
ppm) polyacrylamide to furrow irrigation water during flow advance can substantially reduce
sediment loss. This study determined polyacrylamide charge type or charge density
influences on furrow erosion. The study area was located near Kimberly, Idaho; soil was
Portneuf silt loam (coarse-silty, mixed, mesic, Durixerollic Calciorthid); and slope was 1.5%.
Polyacrylamides with contrasting charge type (neutral, anionic, cationic) and charge density
(0, 8-10, 19-20, 30-35%) were employed in the treatments. Polymers were applied at a
concentration of 10 g m-3 (10 ppm) during the initial 30 min of each treated irrigation, and
a 10 min additional application was introduced every 4 hrs (twice) during the remainder of
the irrigation. Inflow rate was 23 L min-1 (6 gpm) during furrow advance, and 15 L min-1
(4 gpm) for the balance of the irrigation. The nature of charge on the polyacrylamide did
influence efficacy of erosion control. On Portneuf soils, the order of effectiveness with
respect to PAM charge type was: anionic > neutral > cationic. Within anionic and cationic
charge types, polyacrylamide efficacy increased with increasing charge density
Furrow irrigation water-quality effects on soil loss and infiltration
Irrigation-induced erosion is a serious problem in the western USA
where irrigation water quality can vary seasonally and geographically.
We hypothesized that source-water electrical conductivity (EC) and
sodium adsorption ratio (SAR = Na/[(Ca + Mg)/2]^0.5, where concentrations
are in millimoles of charge per liter) affect infiltration and
sediment losses from irrigated furrows, and warrant specific consideration
in irrigation-induced erosion models. On a fallow Portneuf silt
loam (coarse-silty, mixed, mesic Durixerollic Calciorthid), tail-water
sediment loss was measured from trafficked and nontrafficked furrows
irrigated with waters of differing quality. Treatments were the four
combinations of low or high EC (0.6 and 2 dS m-1) and low or high
SAR (0.7 and 12 [mmolc L-1]^0.5). Slope is 1%. Twelve irrigations were
monitored. Each furrow received two irrigations. Main effects for
water quality, traffic, and first vs. second irrigations were significant
for total soil loss, mean sediment concentration, total outflow, net
infiltration, and advance time. Average tail-water soil losses were 2.5
Mg ha-1 from low EC/low SAR furrows, 4.5 Mg ha-1 from low EC/
high SAR furrows, 3.0 Mg ha-1 from high EC/high SAR furrows;
and 1.8 Mg ha-1 from high EC/low SAR furrows. Elevating water
EC decreased sediment concentration from 6.2 to 4.6 g L-1, but
increasing SAR increased sediment concentration from 6.2 to 8.7 g
L-1. Net infiltration decreased 14% in high SAR compared with low
SAR treatments. Soil loss increased 68% for second irrigations, and
net infiltration fell 23% in trafficked furrows, but water-quality effects
were the same. Water quality significantly influenced infiltration and
erosion processes in irrigated furrows on Portneuf soils
Influence of irrigation water quality on sediment loss from furrows
Agricultural erosion research has focused on rainfall-induced soil loss, with comparatively little attention to furrow
irrigation-induced erosion. One rationale for this is that rill erosion is mechanistically similar to erosion in irrigated
furrows. However, significant differences exist between the two processes. These are related to soil conditions during
initial stream advance, downstream flow rates, and chemical characteristics of the water stream. The salinity and
sodicity of water in rills are low, owing to its atmospheric origin, whereas, irrigation water quality varies geographically
and seasonall
Changes in groundwater quality and agriculture in forty years on the Twin Falls irrigation tract in southern Idaho
Better understanding agriculture’s effect on shallow groundwater quality is needed on the southern Idaho, Twin Falls irrigation tract. In 1999 and 2002-2007 we resampled 10 of the 15 tunnel drains monitored in a late-1960s study to determine the influence of time on NO3-N, dissolved reactive P (DRP), and Cl concentrations, and flow rates of shallow groundwater outflows.Since the late-1960s, an 8-fold increase in the dairy herd has driven shifts toward increased feed cropping, which, along with improved hybrids and production, increased inorganic and manure fertilizer use. The late-1960s to early-2000s period saw a consistent 1.4-fold increase in mean tunnel-drain outflow NO3-N concentrations (from 3.06 to 5.06 mg/L), a 10% decrease in mean Cl (from 49.2 to 44.2 mg/L), and an overall 14% decrease in DRP (14 to 12 µg/L). However, 3 of the 10 tunnels exhibited increased DRP concentrations during the period, and the rate of DRP increase was positively related to increasing encroachment of confined animal feeding operations or residential development. Decreases in tunnel flow between sampling periods were linearly related to corresponding increases in the fraction of sprinkler irrigation employed on lands drained by the tunnels (P = 0.01). Further conversion to sprinkler irrigation is unlikely to reduce tunnel drain NO3-N concentrations since the latter were unrelated to changes in sprinkler coverage. The amount and timing of applied N, and availability for crop uptake or leaching should be more carefully managed in these soils to prevent continued increases in groundwater NO3-N concentrations
Preventing irrigation furrow erosion with small applications of polymers
Soil erosion is a serious problem threatening sustainability of agriculture
globally and contaminating surface waters. The objective of
this study was to determine whether low concentrations of anionic
polymers in irrigation water would appreciably reduce irrigation furrow
erosion on Portneuf silt loam (coarse-silty, mixed, mesic Durixerollic
Calciorthid), a highly erodible soil. Furrow slope was 1.6%,
furrow length was 175 m, and irrigation rates ranged from 15 to 23
L min-1. Inflow during the first 1 to 2 h of the first 8-h irrigation was
treated. Subsequent irrigations were untreated. Polyacrylamide (PAM)
or starch copolymer solutions were injected into irrigation water entering
furrows at concentrations of 0, 5, 10, and 20 g m-3 . Sediment
loss from polymer-treated furrows was significantly less than that of
control furrows in the first (treated) and second (untreated) irrigations,
but not in the fourth (untreated). The PAM provided better
erosion control than the starch copolymer. Efficacy of PAM treatments
varied depending on its concentration, duration of furrow exposure,
and water flow rate. In the initial (treated) irrigation and at
low flow rates, 10 g m-3 PAM reduced mean sediment load by 97%
compared with untreated furrows. Residual erosion abatement in a
subsequent irrigation, without further addition of PAM, was approximately
50%. The PAM increased net infiltration and promoted greater
lateral infiltration. Effective erosion control was achievable for a material
cost below $3 ha-1 irrigation-1
Unique aspects of modeling irrigation-induced soil erosion
The mechanics of soil erosion from irrigated and rainfed lands are similar. Soil particles are detached,
transported and deposited. However, there are some systematic differences between irrigation and rainfall
erosion. Electrolyte concentrations in irrigation water, for example, are almost always greater than in rain
water. Differences between rainfall and irrigation are more prominent for surface irrigation than for
sprinkler irrigation. For instance, rainfall wets the soil before runoff begins, but water initially flows onto
dry soil in irrigation furrows. Furthermore, furrow flow rate decreases with distance and increases with
time, while the opposite tends to occur with rainfall. For sprinkler systems, travel direction and slope
aspect interact, so runoff can flow within the irrigated area or from the irrigated area onto dry or wet soil.
Thus, a sprinkler-irrigation erosion model must consider both the rainfall-runoff situation and the furrow
flow situation. These differences in soil and water interactions must be considered before computer
models can accurately simulate irrigation-induced soil erosion
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