Malheur County Sustainable Best Management Practices
Dr. Clinton C. Shock
Malheur Experiment Station, Oregon State University
In cooperation with the Malheur Soil and Water Conservation District, the Malheur Watershed Council, and the Owyhee Watershed Council!
Conversion of Furrow Irrigation to Sprinkler Irrigation
The conversion of furrow irrigation to sprinkler irrigation can reduce labor costs related to irrigation, reduce the water required to grow a crop, make irrigation more uniform, and reduce irrigation-induced erosion.
Conversion to Drip Irrigation
The conversion to drip irrigation can greatly improve yields of onions in fields were furrow irrigation is not uniform. Drip irrigation helps with irrigation management and reduces irrigation-induced erosion to almost nothing. For more information on getting started with drip irrigation, see our publications:
Irrigation scheduling can be just as important as other factors of water management for optimizing sustainability. For more information, see our publications on successful irrigation scheduling for production crops:
Sediment Basin and Tail Water Recovery System
Some of the first sedimentation basins promoted by the SCS in the country were more demonstration-education systems. They demonstrated to growers the dimensions of their irrigation-induced erosion problem. Many functional sedimentation basins with pump back features were built in the late 1980's and 1991 and 1992 with active participation of the SCS, ASCS, and SWCD. For more information, please see our publication:
Polyacrylamide is a synthetic water-soluble polymer that when added to irrigation water can greatly reduce soil erosion and increase water infiltration. For more information, please see our publications:
- Make Polyacrylamide Work For You!
- Benefits and Cost of Applying Polyacrylamide (PAM) in Irrigated Furrows
Mechanical Straw Mulching
Straw Mulching is a practice that can greatly improve yields and help control soil erosion, water runoff, and water infiltration of the soil. It is a practice that is and will be very important with the upcoming water standards to be placed in effect soon. For more information, please see our publication:
Water conservation has become a major issue in Malheur County over the last several years. Total Maximum Daily Load (TMDL) regulations and ongoing drought years make preservation of one of our most important resources a paramount priority. For more information on Water Preservation and TMDL's, see our publications:
- TMDLs and Water Quality in the Malheur Basin: A Guide for Agriculture
- Dealing With Drought: Resources for Growers
A filter strip is an area of grass or other permanent vegetation used to reduce sediment, organic particulates, nutrient, pesticides, and other contaminants from runoff and to maintain or improve water quality. It also has other benefits such as providing a habitat for wildlife and beneficial insects, watershed protection, aesthetics, and it protects riparian forest buffers from erosion and sediment. For more information on Filter Strips, see our report:
Gated pipe was introduced to allow more uniform furrow irrigation on many surface irrigation sites. The water set in each furrow can be less than with siphon tubes, and allows surface irrigation with conservation of water, reduced irrigation induced erosion, and less leaching potential. Gated pipe also facilitates the eventual adoption of surge irrigation.
Gated pipe was first used in a substantial way in Malheur County in 1977, a year of severe drought. The 80 miles of fiberglass pipe arrived too late to do much good that year. The project was promoted by the SCS and the costs were shared by the ASCS. The fiberglass pipe proved to have poor durability outdoors in the sunlight.
More durable plastic gated pipe was introduced and supported by cost share programs.
With the upcoming standards regarding water quality, these of best management practices in fields to reduce soil loss, nutrient loss, and water usage, is becoming very important. Studies done at the Malheur Experiment Station on surge irrigation have shown that surge irrigation is an effective tool to improve irrigation efficiency, reduce water runoff, and reduce sediment loss.
Surge irrigation uses a surge controller butterfly valve placed in the center of the top field, with gated pipe leading out of the valve going both directions along the top of the field. In the fields with some side slope, the surge valve can be place in the corner field, and extra pipe used to distribute the water. The valve works by oscillating water from one side of the valve to the other at decided intervals. (In conventional irrigating systems the water flows continuously for the irrigation set.) The alternating flow of water on each side of the valve causes an intermittent wetting and soaking cycle in the irrigated furrow. For more information, see our publications:
Prior to the 1980's, fields had been leveled by conventional means. Fields were surveyed, staked, and soil was moved within a field by farm tractor powered equipment. Fields with slopes of 0.6 to 0.7 or more feet per hundred feet required too much water to irrigate due to excessive runoff and resulted in too much soil erosion. Fields with slightly irregular slopes had parts which required long irrigation durations, and also had flat spots with excessive water infiltration which resulted in excessive deep leaching.
Dressing fields with laser leveling to a slope of 0.3 to 0.4 feet per hundred feet. provided immediate benefits for surface irrigation. Herb Futter was able to show less soil loss from the field and the field irrigated much more uniformly. The uniformity of irrigation allowed for the conservation of water, less leaching in the wetter parts of the field, and improved crop performance. During the early 1980's ASCS would not fund laser leveling, but started in the later half of the 1980's they did participate in cost share based on Herb Futter's results.
Turbulent Fountain Weed Screens
With trash in the water, gates in gated pipe have to be set wider open and larger siphon tubes have to be used to assure that the trash passes through the gate or tube. Under the circumstances of trashy water, more water has to be set on field than is really necessary, hence more water is present in many furrows than required to irrigate the row. The extra water promotes irrigation induced erosion in many furrows than required to irrigate the row. The extra water promotes irrigation induced erosion and excessive leaching of nitrate to groundwater. The cleaner the water, the greater accuracy that gates and siphon tubes can be set, with assurance that the furrow irrigation will continue to run as set.
Herb Futter of the SCS visited the ARS field day in Kimberly, ID and was impressed by the turbulent fountain weed screen (bubbler weed screens) demonstrated by J.A. Bondurant. Mr. Bondurant donated a portable weed screen to Herb and he installed it at the Malheur Experiment Station through cooperation of Dwayne Buxton. The second screen at the station was on the main water supply at the station, and it was excellent for demonstration purposes, but it was insufficient in allowing adequate water to irrigate the station. During the winter of 84-85 the water delivery system was rebuilt with a much larger weed screen on the station. In 1986 three small mobile screens were built and installed at the station on gated pipe delivery lines. These smaller screens helped show the advantages of this type of irrigation water filter. Adoption of weed screens after Herb Futter used the screens at the Malheur Experiment Station in a 1985 Field Day to promote the use of bubbler weed screens to remove weed weed and trash from irrigation water. Growers started building and installing weed screens on their own, with fabrication by local irrigation dealers. Especially noteworthy were the efforts of Dale Cruson, who gave a big boost to screen adoption by manufacturing many of the screens.
The use of underground outlets or other obstructions along the tail end of a field retains most of the soil that has moved with water to the bottom of the filed, avoiding soil loss off site.
Growers have adopted many measures such as soil sampling and tissue sampling to make fertilizer applications more efficient. These nutrient management practices reduce nutrient loading above plant needs and ultimately reduce the amount of nutrients lost in runoff from fields and leaching to groundwater.
Strip tillage is a conservation tillage system where only the planting row is tilled and the area between rows is not tilled. Water runoff, and soil and nutrient losses are reduced. For more information, see our publication:
Elimination of Runoff Water
Water quality of rivers and streams can be protected through the elimination of runoff water from irrigation induced erosion. For more information, see our publication: