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United States Department of Agriculture

Agricultural Research Service

Research Project: Agrichemical Leaching from Nursery Containers During Winter Months

Location: Application Technology Research Unit

2012 Annual Report


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 an 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.


3.Progress Report:

Multiple studies were conducted in 2011 and 2012 at the Oregon State University North Willamette Research and Extension Center that investigated the influence of substrate related cultural practices on ornamental herbaceous and woody containerized crops. Research was carried out to aid ornamental crop producers in successful implementation of alternative soilless substrates in the Pacific Northwest. Two alternative substrates were processed via hammer-mill to a conventional particle size distribution to produces Douglas fir bark mixes amended with Douglas fir slash and culled Christmas trees, respectively, at 0, 33, 66, or 100% (by vol). Studies were conducted to (1) determine optimal lime rate to maintain a substrate pH of 5.5 to 6.5, (2) quantify the increased nitrogen needs to overcome nitrogen drawdown from substrates containing bark alternatives, (3) comparison of nitrogen drawdown in alternative substrates when using a controlled release versus liquid fertilizer and (4) the effect of substrate physical properties and subsequent crop growth when incorporating conventional amendments (peat and pumice) at 0, 15 and 30% (by vol.) into soilless substrate containing alternative materials. In addition, research was conducted in collaboration with a plant pathologist from Oregon State University to determine if Verticillium spp. was transferable to susceptible plant species when using culled shade trees as an alternative substrate. This project addresses Objective 1 of the parent project. This objective identifies application factors affecting distribution and quality of deposits of pest management materials applied to floricultural crops, shade nursery species, and vegetable crops and to integrate findings into Integrated Pest Management programs.


Last Modified: 8/30/2014
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