Polyacrylamide decreases furrow erosion

Erosion from furrow irrigated land is a serious problem in southern Idaho and several other areas. Polyacrylamide, a very long chain polymer, increases aggregate stability and flocculates suspended sediments. It thus can potentially reduce furrow sediment detachment and transport. Recirculating infiltrometer studies showed that 0.5 kg/ha/irrigation of polyacrylamide applied with the irrigation water can dramatically reduce furrow erosion

Polyacrylamide Effect on Furrow Erosion and Infiltration

Erosion from furrow irrigated land is a serious problem in southern Idaho and elsewhere in the western United States. High molecular weight anionic Polyacrylamide (a water soluble polymer), increases soil aggregate stability and flocculates suspended sediments, thereby reducing sediment detachment and transport in irrigation furrows. Application of 0.7 kg/ha/irrigation of polyacrylamide in irrigation water has reduced furrow erosion by 85 to 99%. In the present work, sediment movement and infiltration were measured in a recirculating furrow infiltrometer with two polyacrylamide treatments. Mean erosion reduction was 70%. Polyacrylamide increased mean infiltration by 30%, probably the result of reduced sediment movement and furrow surface seal formation. Infiltration was inversely related to maximum sediment concentration in the flowing water for both treated and untreated furrows. Farmers who use polyacrylamide must adapt their irrigation management to the higher infiltration to maintain desired irrigation efficiencies

Net and Tension infiltration effects of PAM in furrow irrigation

The history and fundamental aspects of polyacrylamide (PAM)-use in furrow irrigation water has been covered in depth in several publications (Barvenik, 1994; Lentz et al., 1992; Lentz and Sojka, 1994a; Lentz, 1995; Lentz and Sojka, 1996; Sojka and Lentz, 1996; Sojka and Lentz, 1997). In agriculture, the two greatest benefits associated with this practice are the near elimination of furrow erosion and substantial increases in infiltration compared to untreated water. The large erosion reduction has both on-site and downstream economic and environmental benefits (Agassi et al., 1995 ; Bahr et al., 1996; Bahr and Steiber, 1996; Lentz et al., 1992; Lentz, 1995; Lentz and Sojka, 1996; McCutchan eta!., 1993; Singh et al., 1996; Sojka and Lentz, 1993; Sojka and Lentz, 19946; Sojka et al., 1995; Sojka and Lentz, 1997). Infiltration effects are a substantial aspect of these benefits, but have been less thoroughly considered in data reported to date

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

Polyacrylamide effects on infiltration in irrigated agriculture

Using polyacrylamide (PAM) following the NRCS conservation practice standard increases infiltration in furrow irrigation. PAM at 10 g in-' (10 ppm) during water advance nearly precludes detachment and transport of soil in furrows. If any sediment is entrained in the flow, it is readily flocculated in the presence of PAM and settles to the furrow-bottom in loose pervious structures. It was hypothesized that depositional surface seals that block pores are reduced or made more permeable with PAM. On Portneuf silt beams (coarse-silty, mixed, superactive, Durinodic Xeric Haplocalcid) furrow irrigation net infiltration increased 15%. Net increases on finer textured soils were generally higher. Furrow streams containing more than 5 g L (5,000 ppm) sediment reduced infiltration and infiltration rate more than fivefold compared to streams of clean water. Tension infiltrometry confirmed that PAM's maintenance of open pores to the furrow surface provides the infiltration increase mechanism. Infiltration rates at 40 and 100 min (1.6 and 3.9 inches) tension in PAM-treated furrows were double the rates of control furrows. Recirculating infiltrometer data showed a 30% infiltration increase with PAM use and infiltration was inversely related to maximum sediment concentration in the flow. Furrow inflow of 45 L min-1 (12 gal min-1 ) with PAM treatment decreased stream advance time 13% while reducing sediment loss 76% compared to untreated 23 L min-1 (6 gal min-1) inflows. Use of PAM in sprinkler irrigation streams reduced runoff 70% and sediment loss 75%, but tension infiltration measurements were inconsistent, suggesting changes in surface-sealing effects with sprinkler application of PAM are transient

An Alternative Method to Deduce Bubble Dynamics in Single Bubble Sonoluminescence Experiments

In this paper we present an experimental approach that allows to deduce the important dynamical parameters of single sonoluminescing bubbles (pressure amplitude, ambient radius, radius-time curve) The technique is based on a few previously confirmed theoretical assumptions and requires the knowledge of quantities such as the amplitude of the electric excitation and the phase of the flashes in the acoustic period. These quantities are easily measurable by a digital oscilloscope, avoiding the cost of expensive lasers, or ultrafast cameras of previous methods. We show the technique on a particular example and compare the results with conventional Mie scattering. We find that within the experimental uncertainties these two techniques provide similar results.Comment: 8 pages, 5 figures, submitted to Phys. Rev.

Irrigating with polyacrylamide (PAM) - Nine years and a million acres of experience

Polyacrylamide (PAM) has been available commercially since 1995 for reducing irrigation-induced erosion and enhancing infiltration. The first series of practical field tests was conducted in 1991. PAM used for erosion control is a large water soluble (non-crosslinked) anionic molecule (12-15 megagrams per mole) containing < 0.05% acrylamide monomer. In controlled field studies PAM eliminated, on average, 94% (80-99% range) of sediment loss in field runoff from furrow irrigation, with a typical 15-50% relative infiltration increase on medium to fine textured soils compared to untreated controls. Similar but less dramatic results have been seen with sprinkler irrigation. Under some conditions infiltration is unchanged or can even be slightly reduced, e.g. in sandy soils or where PAM application rates are very high. Results are achieved with per irrigation field application rates of about 1 kg per hectare, for furrow irrigation, and 2 to 4 kg per hectare for sprinkler irrigation. Cost of PAM is $7 to$13 per kg. Seasonal application totals vary from 3 to 7 kg per hectare. Farmer field sediment control has been around 80% of test plot results. Substantial runoff reductions have been documented for nutrients, pesticides, microorganisms, BOD, and weed seed. No adverse effects have been seen for soil microbial populations. Crop yields have not been widely documented, though evidence exists for yield increases related to infiltration improvement. High effectiveness, low cost, and ease of application, compared to traditional conservation measures, has resulted in rapid technology acceptance in the US and internationally. PAM-use for runoff water quality protection is one of the most potent new irrigation environmental technologies in the market place. New uses in construction and dryland erosion control are being developed rapidly. This paper discusses new insights and understanding of PAM-use and potential for future development

Classification of Supernovae

The current classification scheme for supernovae is presented. The main observational features of the supernova types are described and the physical implications briefly addressed. Differences between the homogeneous thermonuclear type Ia and similarities among the heterogeneous core collapse type Ib, Ic and II are highlighted. Transforming type IIb, narrow line type IIn, supernovae associated with GRBs and few peculiar objects are also discussed.Comment: 16 Pages, 4 figures, to be published in "Supernovae and Gamma-Ray Bursters," ed. Kurt W. Weile

Polyacrylamide decreases furrow erosion

Erosion from furrow irrigated land is a serious problem in southern Idaho and several other areas. Polyacrylamide, a very long chain polymer, increases aggregate stability and flocculates suspended sediments. It thus can potentially reduce furrow sediment detachment and transport. Recirculating infiltrometer studies showed that 0.5 kg/ha/irrigation of polyacrylamide applied with the irrigation water can dramatically reduce furrow erosion

Polyacrylamide Effect on Furrow Erosion and Infiltration

Erosion from furrow irrigated land is a serious problem in southern Idaho and elsewhere in the western United States. High molecular weight anionic Polyacrylamide (a water soluble polymer), increases soil aggregate stability and flocculates suspended sediments, thereby reducing sediment detachment and transport in irrigation furrows. Application of 0.7 kg/ha/irrigation of polyacrylamide in irrigation water has reduced furrow erosion by 85 to 99%. In the present work, sediment movement and infiltration were measured in a recirculating furrow infiltrometer with two polyacrylamide treatments. Mean erosion reduction was 70%. Polyacrylamide increased mean infiltration by 30%, probably the result of reduced sediment movement and furrow surface seal formation. Infiltration was inversely related to maximum sediment concentration in the flowing water for both treated and untreated furrows. Farmers who use polyacrylamide must adapt their irrigation management to the higher infiltration to maintain desired irrigation efficiencies