Coastal Oregon Nitrogen Recovery

Coastal Oregon Nitrogen Recovery

Summary

On the southern Oregon coast, four- and five-generation farms that produce a variety of agricultural products, including grass, hay, cranberries, sheep, beef and meat goats, have followed a trend evident for the past 30 years in American agriculture: increased dependence on added fertilizers for grassland productivity. Building on research results from Wisconsin Pennsylvania that show a direct correlation between added nitrogen and improved economic return, this project wants to maximize the benefits from nitrogen applications and to prevent runoff and excess nutrients from entering streams and rivers. The project will be designed to measure the uptake of applied nitrogen by the southern coast’s highly productive grasses and to see if any nitrogen is “lost” to the watershed. The research will be conducted on three ranches with replications of 0 pounds of nitrogen per acre (for control), 100 pounds, 200 pounds and 400 pounds. A series of grass harvests will be completed during the season to measure yields and N content, and water that runs from fields will be assessed for quality. Information from the research will be disseminated via tours of the experimental sites, producer study groups already being conducted in the area by the technical advisor, several websites and peer-reviewed journal articles.

Objectives/Performance Targets

The objectives of this project are to investigate the effects of various levels of nitrogen fertilizer on the nitrogen use efficiency, forage quality and water quality in well-managed, dense grass pastures on the Oregon coast. The idea is to maximize the benefit received from nitrogen applications and present leaching of excess nutrients into rivers and streams.

Accomplishments/Milestones

In autumn 2004, the project team fenced areas on three cooperating ranches, worked the soil and planted heavily with an improved variety of perennial ryegrass (Lolium perenne, “Kingston” from PGG Seeds). The team established dense stands of grass and excluded broadleaf plants. Based on the results of soil tests and recommendations from Oregon State Extension, they added P and K to improve the soil fertility.

In October, the team laid out 15 test plots and applied the various treatments of nitrogen fertilizer. Between November 2005 and July 2006, seven yields were collected and three split applications of nitrogen added, according the project protocol. For each collection, forage dry matter and nitrogen yields were measured for each plot and the nutritional value of all samples was tested for energy, fiber and minerals. The collections continued until July when rain ended forage growth. With help from Oregon State University, forage data have been analyzed statistically using GLM procedures of Statistical Analysis System (SAS) using a randomized complete block design model with five treatments and three blocks.

From April 2006 through July 2006, the water quality portion of the project was initiated. Ranchers designed efficient water-collection equipment, dug 15 wells between 9 and 15 feet deep, with one well located at the center of the downhill edge of each forage plot, and installed collection equipment. The ranchers worked closely with personnel from the local Soil and Water Conservation District to design the equipment and develop collection and analytical procedures.

Forage data from the 2005-06 growing season are still being analyzed and summarized. However, across the growing season, forage crude protein levels averaged across all plots were: Nov. 8, 2005, 27.7%; Jan. 23, 2006, 29.2%; March 17, 2006, 26.0%; April 13, 2006, 25.7%; May 15, 2006, 19.5%; June 22, 2006, 16.9%; July 25, 2006, 15.9%.

The overall “Apparent Nitrogen Recovery” (ANR, the amount of N retained in forage as a percentage of N added as fertilizer) averaged 22.7% across all treatments, with a decreasing percentage as the amount of N increased. The overall “Nitrogen Use Efficiency” (NUE, the pounds of forage dry matter produced per pound of added N) averaged across all treatments was 6.9 pounds of DM/lb N, also decreasing with increasing levels of N fertilizer.

Work remaining and its anticipated schedule is:

• December 2006 to June 2007, collect and analyze water samples
• July 2007 to September 2007, conduct statistical analysis and summarize data
• September 2007 to November 2007, conduct educational events and develop public documents

Impacts and Contributions/Outcomes

For educational activities, the technical advisor has provided ongoing updates and preliminary data to ranchers in three forage study groups in western Oregon. These meetings have been conduced monthly so the ranchers can be routinely apprised of the progress.

Collaborators: