Irrigation Management Consistent with Environmental Protection and High Quality Production

Dr. Clinton C. Shock

Water use, conservation, and quality are key factors in the economy and quality of life in Malheur County. A decade ago, Malheur County was faced with groundwater contamination by nitrate and residue of the herbicide Dacthal. Growers, growers' associations, and agencies have cooperated to creatively solve problems. Agencies divided the roles of research, education, implementation, and funding to goals to clean up groundwater while respecting economic needs of producers. Consumer demand is moving in the direction of higher quality products requiring precision irrigation.

Malheur County in southeastern Oregon contains millions of acres of sagebrush steppe used principally for extensive grazing and secondarily for recreation, relatively small areas of forest, and 250,000 irrigated acres. Rainfall is far less than crop water needs, averaging only 10 inches per year at lower elevations. Rainfall is distributed mostly in the non-growing season. Irrigation water comes largely from snow melt and runoff from rangelands. Reservoirs capture the seasonal. The region was developed based on gravity flow irrigation prior to 1940. Sixteen irrigation districts manage water delivery. Family farms predominate and use sound crop rotations that include onions, sugar beets, wheat, corn, beans, potatoes, alfalfa, alfalfa grown for seed, spearmint, peppermint, and other crops.

Northeastern Malheur County was designated Oregon's first Groundwater Management Area by The Oregon Department of Environmental Quality (ODEQ) in 1989 due to nitrate and the di-acid breakdown product from Dacthal in the groundwater. Soil loss, groundwater contamination, and surface water quality problems challenge the sustainability of intensive agricultural crop production in Malheur County. Groundwater became contaminated with nitrate because nitrogen chemical fertilizer inputs were considerably greater than crop N removal. Dacthal, a grass herbicide, degrades to a stable di-acid residue that is also soluble and mobile in the soil solution.

Community members realized in 1989 that remediation would be difficult. Immediate reductions in groundwater contamination faced hurdles including; 1) furrow irrigation systems that promote leaching, 2) fertilization and irrigation technology based primarily on the assurance of yields, 3) vadose zone contamination, and 4) aquifer hydrology that moves slowly.

The Northern Malheur County Groundwater Management Committee cooperated with ODEQ to write the Northeastern Malheur County Groundwater Management Plan and implement it starting in the fall of 1991. The citizens' committee embraced environmental goals, the value of producers, and a cooperative voluntary approach.

In implementation, local agency personnel accepted responsibility and coordinated the development of creative research, demonstration of useful practices, and implementation of practices as documented in the annual reports and HUA reports of the SWCD. From 1990 through 1999 new practice options were tested at the Malheur Experiment Station to reduce N fertilizer use, DCPA use, reduce sediment loss, and improve irrigation efficiency and were published in the annual reports of the station. Work proceeded from relatively small plots on the experiment station to large strips through growers' fields, and eventually to large-scale implementation.

Research proposals were reviewed, improved, and funded by growers associations and the public. Education and demonstration occurred largely through the SWCD and OSU extension. Implementation of new practices was facilitated by FSA. From 1993 to 1998 new practices were demonstrated on 6,509 acres per year. Research, demonstration, and implementation projects covered the following:

1) evaluation of the irrigation management of potatoes, onions, and hybrid poplar trees (Populus deltoides x P. niger),

2) comparison of irrigation systems for the production of onions and potatoes,

3) irrigation practices to reduce sedimentation from irrigation induced erosion,

4) re-examination of the N requirements of potatoes, onions, sugar beets, and wheat,

5) use of sugar beets and wheat to remove nitrate following shallow rooted crops,

6) alternatives for Dacthal and Dacthal banding vs. broadcast applications,

7) alternatives for useful recycling of waste streams from agricultural productions and processing.

Examples of innovation and change for irrigation management are highlighted below.

Technological transfer has been promoted through over 100 meetings including field days at research plots, field tours of growers' fields, workshops, and presentations to grower association regular annual meetings. Results have been distributed in extension and SWCD newsletters, newspaper and trade journal articles, radio shows, widely distributed videos, and scientific journals. As growers realize that the implementation of new technology will not only help alleviate environmental problems, but also be cost effective, the technology is spreading into a widening circle of growers. Chemical applicators incorporate refined procedures into their routines. Intensive agricultural systems are changing from a period of very liberal use of nutrients and irrigation water per acre toward more precise applications of nutrient and water resources, which more closely match crop needs.

Malheur County's highly active participatory program has resulted in downward trends in Dacthal residues and an overall downward trend in groundwater nitrate. Progress has come about through wide cooperation. Necessary elements have included interagency cooperation, grower involvement in plans and ideas before research was conducted, creative research, effective extension and education, and volunteer implementation. The program has increased public consciousness of the environmental effects of farm operations.

Those engaged in the use and management of natural resources in the public and private sectors need to respect and value each other and value economic as well as environmental goals. Although economic and environmental problems evade simplistic answers, cooperation over the past decade in Malheur County sets a positive precedent for further progress.

Dr. Clinton C. Shock
Malheur Experiment Station
Oregon State University
Ontario, OR 97914
Tel: (541) 889-2174
Clinton.Shock@orst.edu
www. primenet.com/~mesosu/

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