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.
Research on conventional soilless substrate components continue to result in growers assessing their need and use during the economic downturn, thus resulting in elimination of components (such as peat or pumice) that provide no proven benefit for a given crop or production system. Screening alternative soilless substrates has resulted in narrowing suitable Pacific Northwest alternatives to Douglas fir slash, culled Christmas trees and chipped poplar. All alternatives can be utilized to supplement up to one-third of the Douglas fir bark currently utilized while growing a comparable crop. On-going research is investigating the impact of these alternatives on water, substrate pH, and nitrogen fertility. We believe that with continued research we will be able to make grower recommendations that can result in suitable soilless substrates dominantly comprised of alternative components. We continue to investigate bamboo, which could be produced by the grower or allied supplier to be utilized entirely as an alternative substrate. Research efforts continue to result in scientific, industry and extension publications. Furthermore, information is disseminated via the World Wide Web and stakeholder presentations.
This work applies directly to the ARS project plan under Subobjective 2A “Evaluate the use of regional agricultural/forest byproducts and synthetic materials for use as a substrate in nursery containers.”
The authorized department officer's designated representative maintained contact with the primary investigator via phone and email. A face to face meeting was held in January at the Gulf States Horticulture Expo.