A Buried Drain Erosion and Sediment Loss Control System

The lower ends of most furrow irrigated fields have become convex shaped, meaning the slope progressively increases from a point 20 to 60 feet from the field end to the tailwater ditch. This increasing slope is the result of maintaining tailwater ditches too deep and keeping them cleaned so runoff from these fields is not restricted. The process of forming a convex field end continues yearly at an increasing rate. With each passing year, the slope at the end of the field becomes greater so that runoff water runs faster and has more energy to erode. Over many years, large quantities of soil have been lost from the lower ends of furrow irrigated fields. Field ends 1.5 to 2.0 feet lower than the furrow elevation 20 to 60 feet upslope are common. Much of the soil loss is from the lower ends of fields

A Buried Pipe System for Controlling Erosion and Sediment Loss on Irrigated Land

A new system comprised of a buried pipe, with riser inlets from the surface at intervals, along the lower end of furrow-irrigated fields was designed, installed, and evaluated on 21 fields to determine its effectiveness as an erosion and sediment loss control system for irrigated land. The system utilizes small sediment collection ponds with the riser inlets from the buried pipe serving as overflow outlets for the ponds. This system corrects convex-shaped field ends caused by erosion and solves an energy related erosion problem common on furrow-irrigated land. During the first season, these system removed from 80 to 9S% of the sediment from runoff water and collected from 4.1 to 40.5 Mg ha-¹ from 12 fields on irrigated land where detailed data were collected. All systems performed without problems and all convex end problems except one were corrected the first season. After the convex ends are corrected, the system continues to reduce sediment loss. This new system eliminates the tailwater ditch, puts more land into crop production, reduces weed problems, and prevents the usual problems associated with a wet tailwater ditch. The buried pipe erosion and sediment loss control system is a major advance in the control of erosion and sediment loss on irrigated land

Crop sequences and conservation tillage to control irrigation furrow erosion and increase farmer income

Five years of research show that there are many benefits to conservation tillage on furrow-irrigated land. Benefits are enhanced when cropping sequences are altered to accommodate the fewest number of tillage operations over the entire cropping sequence. Results showed that soil erosion can be reduced 47 to 100 percent, crop yields can be sustained, and farmer net income can be increased an average of more than $125 ha-1 each year over a 5-year cropping sequence

Furrow Erosion and Sediment Losses on Irrigated Cropland

Sediment losses from furrow erosion on irrigated cropland ranged from 0.5 to 142 metric tons per hectare (0.2 to 63.0 tons/acre) on 49 Idaho fields during one irrigation season. Field slope varied from 1.0 to 5.0 percent and furrow stream size from 11.3 to 49.9 liters per minute (3.0 to 13.2 gal/min). Erosion increased sharply on row-cropped fields when slopes exceeded 1.0 percent. Furrow erosion can be reduced by: (a) reducing furrow stream size when water reaches the furrow ends, (b) avoiding irrigation of row crops on slopes that are too steep, (c) keeping the tailwater ditch shallow and the water in it moving slowly, (d) installing tailwater control systems, and (e) alternate-furrow irrigation. Sediment losses from irrigated lands can also be reduced markedly by planting vegetative filter strips and using sediment retention basins. Total phosphorus losses were reduced in proportion to the reduction in sediment losses

Debye screening and Meissner effect in a two-flavor color superconductor

I compute the gluon self-energy in a color superconductor with two flavors of massless quarks, where condensation of Cooper pairs breaks SU(3)_c to SU(2)_c. At zero temperature, there is neither Debye screening nor a Meissner effect for the three gluons of the unbroken SU(2)_c subgroup. The remaining five gluons attain an electric as well as a magnetic mass. For temperatures approaching the critical temperature for the onset of color superconductivity, or for gluon momenta much larger than the color-superconducting gap, the self-energy assumes the form given by the standard hard-dense loop approximation. The gluon self-energy determines the coefficient of the kinetic term in the effective low-energy theory for the condensate fields.Comment: 29 pages, RevTe

Longitudinal gluons and Nambu-Goldstone bosons in a two-flavor color superconductor

In a two-flavor color superconductor, the SU(3)_c gauge symmetry is spontaneously broken by diquark condensation. The Nambu-Goldstone excitations of the diquark condensate mix with the gluons associated with the broken generators of the original gauge group. It is shown how one can decouple these modes with a particular choice of 't Hooft gauge. We then explicitly compute the spectral density for transverse and longitudinal gluons of adjoint color 8. The Nambu-Goldstone excitations give rise to a singularity in the real part of the longitudinal gluon self-energy. This leads to a vanishing gluon spectral density for energies and momenta located on the dispersion branch of the Nambu-Goldstone excitations.Comment: 16 pages, 4 figures, minor revisions to text, one ref. adde

The Effect of Furrow Irrigation Erosion on Crop Productivity

Furrow irrigation erosion redistributes topsoil by eroding upper ends of fields and depositing sediment on downslope portions causing a several fold topsoil depth difference on individual fields. This investigation was conducted to evaluate the effects of this erosion and deposition process on crop yield and to develop crop yield-topsoil depth relationships. Studies were conducted on 14 farmer-operated fields and on field plots with a continuous topsoil depth gradient from 10 to 66 cm. Severe erosion on the upper ends of fields combined with tillage has mixed light-colored subsoil with topsoil and caused these areas to become whitish in color. Crop yields have sharply decreased on these whitish areas compared to areas where the topsoil depth is 38 cm, or the original depth. Yields were increased, but less sharply, where sediment deposition has increased topsoil depth above 38 cm up to a depth of about 66 cm. Yield-topsoil depth relationships followed the equation Y = a+b 1nX with significant correlation coefficients for wheat (Triticum aestivum L.), sweet corn (Zea mays L.), barley (Hordeum vulgare L.), alfalfa (Medicago sativa L.), dry beans (Phaseolus sap.) and sugarbeets (Beta vulgaris L.). Yield decreases per unit loss of topsoil were greatest for wheat and sweet corn and least for sugarbeets. Yields on whitish soil areas could not be improved more than indicated by these relationships by adding additional fertilizer phosphorus or potassium

Furrow Erosion Reduces Crop Yields

Furrow irrigation erosion redistributes topsoil within fields and causes serious topsoil losses from farms. Erosion occurs on the upper portions of fields where the furrow streams are largest and the energy greatest. The furrow stream must be large enough at the head end of the furrow to supply sufficient water for infiltration over the entire furrow length

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