Plant sap analysis as a diagnostic tool for winter wheat nutrient use efficiency

Project Overview

Project Type: Professional + Producer
Funds awarded in 2023: $74,929.00
Projected End Date: 03/31/2026
Grant Recipient: Palouse Conservation District
Region: Western
State: Washington
Principal Investigator:
Ryan Boylan
Palouse Conservation District


  • Agronomic: wheat


  • Crop Production: nutrient management, tissue analysis
  • Education and Training: on-farm/ranch research

    Proposal abstract:

    In recent years, producers and conservationists alike have focused on increasing nutrient use efficiency to decrease production costs and protect the environment from the detrimental effects of fertilizer overapplication. Plant sap analysis can enable precise, real-time monitoring of nutrient deficiencies and crop health, potentially providing producers with more accurate information than traditional methods. While its use as a diagnostic tool has been explored in other agricultural systems, little information is available for the Inland Pacific Northwest (iPNW) and winter wheat specifically.

    The proposed research will compare traditional nutrient management and monitoring practices with periodic plant sap analyses to guide foliar fertilizer applications on three farms. Cost-benefit analyses of the trials will quantify the economic feasibility of adding this diagnostic tool to crop fertility management.

    Project results will be disseminated through education and outreach activities, including field tours, presentations at industry meetings, newsletter articles, social media posts, webpages, and informational handouts.

    Study results will help producers evaluate the efficacy of adopting plant sap analysis and will have the potential to significantly advance precision agriculture thereby increasing yields while reducing costs and harmful nutrient runoff and leaching from overapplication of fertilizers.

    Depending on the research findings, the project will either aid the widespread adoption of plant sap analysis through education and outreach activities or save producers time and resources by preventing unnecessary or ineffective adoption of technology. Educational resources will be used by agricultural professionals beyond the funding period.

    Project objectives from proposal:

    The goals of this project are to 1) assess plant sap analysis as an effective and economical winter wheat nutrient diagnostic tool for the Inland Pacific Northwest and 2) disseminate research results and recommendations to producers. Plant sap analysis has potential to improve the accuracy of late-season foliar crop nutrient applications. If it does, plant sap analysis could help producers improve yields and crop and soil health while reducing the overall amount of fertilizer applied, thereby reducing costs and environmental impacts in contrast to fertilizer applications based on recommendations from traditional soil and tissue testing.

    Three objectives will guide this project:

    Objective 1: Assess the performance of winter wheat produced using fertilizer applications informed by plant sap analysis compared to the performance of winter wheat fertilized according to traditional soil and tissue testing results.

    Objective 2: Evaluate producer attitudes and the economic cost-benefits of using plant sap analysis for winter wheat nutrient management.

    Objective 3: Disseminate agronomic and economic cost-benefit research results through online resources, publications, and in-person events to inform adoption of sap analysis as a tool for precision nutrient management.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.