Understanding the impact of the peaola microbiome on soil fertility, crop yield, and plant nitrogen content

Project Overview

Project Type: Graduate Student
Funds awarded in 2021: $29,982.00
Projected End Date: 08/31/2024
Host Institution Award ID: G234-22-W8615
Grant Recipient: Washington State University
Region: Western
State: Washington
Graduate Student:
Principal Investigator:
Maren Friesen
Washington State University


  • Agronomic: peas (field, cowpeas), rapeseed


  • Crop Production: intercropping
  • Production Systems: dryland farming
  • Soil Management: soil microbiology

    Proposal abstract:

    Nitrogen is a critical nutrient for fertilizing our crops that can be acquired non-synthetically via symbiotic nitrogen fixing bacteria associating with legumes. Legumes are widely used in crop rotations, and there is growing interest in using them in intercropping systems. Effective nitrogen fixation and nitrogen cycling depends on the microbial community, so it is important to understand how our agricultural practices impact these microbial communities. This project will determine how a mixed cropping system of pea and canola impacts microbial communities in the soil, rhizosphere, and roots in this system. Analysis of the diversity of the microbial communities will be done to determine the abundance of nitrogen fixing bacteria, how well they are performing, and how they are contributing to the growth and nitrogen content of pea and canola crops. Results from this study will be available to farmers and stakeholders via talks and posters at producer-focused workshops, conferences, field days, and more. The expected outcomes from this project are (1) to have a clearer understanding on how the way we grow our crops is impacting microbial communities, (2) to have suggestions for the farming community in Eastern Washington to improve the performance and abundance of nitrogen fixing bacteria in order for them to produce their crops more sustainably and efficiently, and (3) to help guide further research on nitrogen fixing bacteria as a means for nitrogen fertilization and to obtain a more sustainable and productive method of farming, while improving and maintaining soil health.

    Project objectives from proposal:

    Our research objective are:

    1. To determine if the peaola intercropping system that we are studying is producing similar results for yield and land equivalent ratio (LER) as other studies have found.
    2. To determine the biodiversity and abundance of the nitrogen fixing bacteria of the microbial populations present in soil, rhizosphere, and root samples collected from pea and canola in monoculture and intercropped, and with varying levels of nitrogen fertilizer application.
    3. To determine if there is a difference in the community structure and importance of nitrogen fixing bacteria in the microbial communities present in the different cropping systems, including the symbiotic ability of the pea-associated nitrogen-fixing bacteria.
    4. To determine the nitrogen content of the crops grown in monoculture and in the peaola intercropping system to determine whether symbiotic nitrogen fixation by pea can meet the nitrogen needs of intercropped canola.

    Our primary education/outreach objective is:

    To improve sustainability and productivity of the agricultural system across the inland Pacific Northwest by quantifying crop yield, changes to the soil and plant microbiome, and economic benefit when peola is adopted as a rotational crop in a dryland wheat-based system.

    Our education/outreach sub objectives are:

    1. To guide agricultural practices in the inland Pacific Northwest through sharing the results of this study with producers and agricultural stakeholders.
    2. To increase the awareness of the general public in the inland Pacific Northwest about the benefits of intercropping and peaola.
    3. To guide future research on intercropping and peaola in the inland Pacific Northwest.
    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.