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United States Department of Agriculture

Agricultural Research Service

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Location: Application Technology Research

2013 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 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.

3. Progress Report:
This is the final report for this project. The effect of soilless substrate components on the physiochemical properties of the container system is poorly understood. Little research or information has historically been available for growers to make informed decisions when engineering soilless substrates with desired physical properties such as air space and water holding capacity or chemical properties such as pH, cation exchange capacity, anion exchange capacity, and electrical conductivity. Furthermore, we continue to investigate the interaction of culture practices, specifically fertility and irrigation, with multi-component soilless substrates. Numerous workshops and presentations to increase stakeholders’ fundamental understanding of the hydrology and chemistry associated with soilless substrates have been conducted. In addition, research on hydrology, solute transport and physiochemical properties and their effect on pine bark based soilless substrates, to determine nutrient contribution, effect on pH, water availability, and their overall effect on crop growth and water use efficiency have been completed or underway. We continue to conduct research and education programs focused on the interconnected topics of soilless substrates (conventional and alternative), crop fertility, and water management. These efforts continue to result in leveraging additional dollars via non-governmental grants and private contracts as well as continued in-kind support from nursery grower and allied suppliers. Research on conventional soilless substrate components continue to result in growers assessing their need, thus resulting in elimination of components (such as peat or pumice) that provide no proven benefit for a given crop or production system. More basic research on solute transport and hydrology of soilless substrates may be able to lead to improved water and nutrient management. Furthermore, information is disseminated via the World Wide Web and stakeholder presentations. The project helps to address Sub-objective 2A of the parent project: “Evaluate the use of regional agricultural/forest byproducts and synthetic materials for use as a substrate in nursery containers.”

4. Accomplishments

Last Modified: 06/24/2017
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