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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Dairy Forage Research » Research » Research Project #440890

Research Project: Oregon Alfalfa Nutrient Survey

Location: Dairy Forage Research

Project Number: 5090-21500-002-011-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 15, 2021
End Date: Sep 14, 2026

The overarching objective of this project is to understand alfalfa yield constraints, with initial emphasis focusing on soil fertility. Specific objectives are to: 1. Evaluate the nutritional status of alfalfa in Oregon by conducting a plant tissue and soil sampling survey. 2. Summarize previous Oregon studies of alfalfa response to phosphorus (P) and potassium (K) application and contribute to the Fertilizer Recommendation Support Tool (FRST).

In this project, one of our focus areas will be to supply the Fertilizer Recommendation Support Tool (FRST) team with data from Oregon and potentially neighboring states, focusing on P and K response studies specific to alfalfa. These efforts will be used to develop initial P and K recommendations for alfalfa produced in Oregon and other parts of the Pacific Northwest within the FRST tool, based directly on alfalfa research findings as opposed state-based extension recommendations that may or may not be based on local alfalfa research findings. Moving forward, there is interest in building on these previous research efforts to improve our understanding how current varieties and management practices in alfalfa production are influenced by soil nutrients today. One approach to improve our understanding of nutrient deficiencies and toxicities in alfalfa as they relate to soil nutrient properties throughout Oregon will be to survey soil nutrient properties and plant nutrient uptake on existing cooperator alfalfa production fields. Specifically, 40-60 alfalfa fields in Oregon and possibly neighboring states will be sampled each year for two consecutive years by a master’s level soil science graduate student, working in collaboration with forage and soil extension faculty. Soil and plant tissue will be sampled at similar growth and cutting stage across fields. These samples will be used to determine soil nutrient characterizations, plant nutrient concentrations, plant biomass, and plant nutrient uptake. Regression analyses and other analyses will be conducted to establish relationships between soil nutrient status and plant nutrient uptake by field, by state, and across Oregon. Study findings will be used to establish baseline information regarding nutrient relationships between alfalfa and the soil, especially in terms of nutrient deficiencies, nutrient toxicities, and biomass production response. These findings will also be used to determine the next steps in alfalfa nutrient research efforts in Oregon, focusing heavily on nutrient deficiency and toxicity issues and how they relate to soil nutrients. In addition, this effort would be conducted in a multi-state effort, applying a similar protocol to insure consistency in findings. This would allow data to be compiled into one comprehensive dataset, which could be used to further identify crop response trends on a national level.