1a.Objectives (from AD-416)
The objective of this funded research will be to determine agrichemical leaching levels from container nurseries in regions of the U.S. with no soil surface freezing. Oregon is a major production region of the U.S. where crops are primarily temperate plants that undergo winter dormancy, but where winter temperatures are mild (USDA Zone 7b) and generally above freezing. It has been previously assumed that leaching of agrichemicals (pesticides and fertilizers) is negligible during winter months. This research will initially document agrichemical loads in leachate during winter months, then develop remediation techniques to reduce those loads if necessary.
1b.Approach (from AD-416)
The experiment will be a 2 (CRFs) x 2 (taxa) factorial in a randomized complete block design with four replications and ten plants per replication. Broadleaf evergreen and deciduous shrub liners will be potted in summer (July-August). Both taxa will have either Osmocote (resin -coated) or Polyon (plastic-coated) CRFs. All plants will be potted in a industry representative substrate and receive additional micro-irrigation when there is not adequate rainfall.
The experiment will be initiated with established plants in September and be completed in March. Plant, CRF, and substrate nitrogen and phosphorus content will be determined at both the beginning and end of the study to determine CRF release and plant uptake through the winter in mild climates. In addition, effluent nitrogen and phosphorus concentration will be monitored weekly. This data will be used to determine environmental impact of CRF’s. Substrate temperature, air temperature, and rainfall will be recorded hourly throughout the course of the experiment.
All variables in the study will be tested for differences using ANOVA Fishers Least Significance Difference means separation where appropriate.
This is a congressionally mandated specific cooperative agreement. Research was conducted to determine extent of nitrogen and phosphorus release from controlled release fertilizers throughout fall and winter months in the Willamette Valley. In addition, we evaluated uptake of nitrogen and phosphorus of deciduous and evergreen plants and assessed environmental impact on experimental nursery sites. This work was published in abstract form at one science meeting and is being prepared for journal publication. It was also presented to nursery producers at four different nursery workshops. Activities were monitored via two research meetings and by written reports every six months.