Assessing Soil Fertility and Soil Health in Midwest Hop Production

Final report for LNC18-401

Project Type: Research and Education
Funds awarded in 2018: $98,561.00
Projected End Date: 12/31/2021
Grant Recipient: The Ohio State University
Region: North Central
State: Ohio
Project Coordinator:
Dr. Steven Culman
Ohio State University
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Project Information


The hop production industry has benefited greatly from the continued popularity of craft beer. The U.S. is second in the world in total hop acreage and production with new farms entering the market each year. Within the Midwest, harvested hop acres have increased greatly over the past few years with the majority of production coming from Michigan, Indiana, and Ohio. Research in this area has primarily focused on integrated pest management (IPM) and disease control with very little attention provided to soil fertility and soil health. However, soil fertility and health have consistently been identified by North Central hop growers as a critical area where they need better information for effective management. This proposal addressed this knowledge gap with the following objectives: i) document relationships between soil fertility and soil health with hop cone quality and yield, ii) develop more reliable leaf petiole nitrate values for N management of hops, and iii) develop educational materials and continue outreach efforts for optimized nutrient management in North Central hopyards. We partnered with 35 hop growers primarily in Ohio and Michigan and sampled 87 total hop yards over two years. Hopyards were classified by stand age: 0-3 yrs (57%) and 4+ yrs (43%) with 88% of the hopyards having one of the following varieties: Cascade, Chinook, Centennial or Columbus. Farmers sampled and shipped us soil, petioles and hop cones and we quantified soil fertility and health, nutrient levels and hop cone quality. We found that more than a quarter of hopyards were below optimal pH levels, but were typically sufficient in soil test phosphorus and potassium. We documented typical leaf nutrient ranges for 3-4 key hop varieties grown in the Midwest. Finally, we developed education and outreach materials that provide guidance and best practices targeting soil and nutrient management. This work addressed a widely identified research need by the hop growing community in the North Central region and provide tools for growers to optimize soil and nutrient management and subsequent economic profitability.

Project Objectives:


Learning Outcomes

Farmers will learn:

(1) Soil health basics and its importance in crop production;

(2) Interpreting soil tests to inform nutrient management decisions; and

(3) Using petiole sap testing to monitor nutrient uptake in hops.

Action Outcomes

Upon completion of our project, farmers will:

(1) Include monitoring soil health in their hopyard management plans;

(2) Use fertilizers to boost overall soil health as necessary based on first interpreting soil test results; and

(3) Monitor nutrient uptake in petioles in order to make real-time nutrient management decisions in the field.


The hop production industry in the North Central region is growing rapidly, and with this growth there are numerous production issues that have yet to be comprehensively addressed. Of the many challenges in growing hops profitability, soil fertility, nutrient management and soil health have consistently been identified by growers as a major challenge to the success of their operation. For example, in a recent survey of hop growers in Ohio and Michigan (n = 28 responses) conducted by our team, soil fertility was listed closely behind plant diseases and insect pest as their largest management challenge. Nutrient management information that does exist on hops was not developed in the North Central region, but rather in places with different environments, soils and production constraints. Profitable hop farming requires managing hopyards not only for yield, but also for hop cone quality. Many farmers believe there is a strong relationship between the quality of their soils and the quality of the hop cones grown on their soils. However, work to determine these relationships has not been fully explored. Therefore, our long-term goal is to develop a set of robust soil health and nutrient management best management practices in North Central hopyards.



Our objectives are to:

1. Document the relationship between soil fertility and soil health with hop cone quality and yield.

2. Develop sufficiency level values for leaf petiole nitrate in hops specific to the Midwest region.

3. Develop educational materials and continue outreach efforts focused on soil health and nutrient management for Midwest hopyards.

Materials and methods:

We conducted this research during the 2019 and 2021 growing seasons. Originally a 2-year project, the COVID-19 pandemic shut down our activities in 2020 and necessitated a 1-year project extension. In 2019, we had 33 farmers who enrolled 87 hop yards across Ohio, Michigan, Indiana and Illinois. In 2021, we had a difficult time attracting interest, and only had 11 farmers from 16 hopyards participate. Most growers in 2019 re-enrolled again in 2021. In both years, we mailed a total of 4 packages over the course of the growing season:

  1. Soil sampling: Sent labeled soil bags, prepaid and addressed return boxes and probes
  2. Petiole nitrate meter: Sent petiole nitrate meter at no charge to all participating farmers
  3. Sent materials and shipping for a hop leaf tissue analysis
  4. Sent materials and shipping for hop cone analysis 

Farmers sent in soils, hop petiole nitrate data, hop leaf tissue and harvested hop cones for analysis. Soils and plant tissue were analyzed and data were compiled both at an individual farm level as well as in aggregate across all farms.

Research results and discussion:

Summary of the preliminary results from the first year of research was mailed to all farmers (attached), along with individual raw data from their individual hop yards. Year 1 Hop Research Summary Report for Cooperators


Petiole Nitrate Sampling

We collected a total of 194 petiole nitrate observations over 28 hopyards, which include 124 observations in 2019 and 70 observations in 2021. These observations were collected at mid-June (36), end-June (56), mid-July (60) and end-July (40). The observations were evenly split between the two hopyard age categories, 0-3 yrs (96) and 4+yrs (98). Finally, we collected petiole nitrate from 6 hop varieties: Columbus (26), Cascade (69), Centennial (30), Chinook (62), Mt. Hood (3) and Nugget (4). Petiole nitrate values varied dramatically between hopyards and cooperators, reflecting diverse nutrient management strategies. Our data underscores the need for more consistent and uniform N management among growers. Our data also demonstrated that hopyard stand age greatly impacts petiole nitrate values. Finally, we received feedback from numerous growers, indicating the difficulty of extracting petiole sap from hops leaves. The fibrous nature of the hop petioles makes sap extraction much more challenging that in many vegetable crops. 

Leaf nutrient values

We also sampled hop leaves at the end of the vegetative periods/beginning of the reproductive period and have established ranges of what values would be typically encountered. Growers can use these values as reference and have them help guide nutrient management decisions. 

Hop Leaf Nutrient Concentrations


We also found the petiole nitrate values where largely related to leaf N values, so petiole nitrate should be a accurate indicator of N status. 

Petiole Nitrate vs. Leaf N

Hop Cone Quality

Finally, we evaluated hop cone quality and the ability of a Eurofins infrared (IR) machine to accurately predict hop cone quality. We found Eurofins was able to predict alfalfa and beta acids with a high degree of accuracy. The lab values from Alliance Labs and the values from the Eurofin machine were highly aligned for acids, but not for moisture. Since moisture can be measured easily with a microwave method, we think this technology could be particularly helpful to improve harvest time and overall hop cone quality in the North Central region. 

Hop Cone - IR vs Lab

Research conclusions:
  • Baseline understanding of nutrient management and soil fertility and soil health in North Central hopyards
  • We developed factsheets on hop fertility management and soil health relationships
  • We trained growers and developed information on utilizing and incorporating nitrate meters for hops


Participation Summary
33 Farmers participating in research


Educational approach:

Eduction of hop growers was accomplished through a field day and through several hop-focused conferences throughout the NC region. Details of these activities are provided in the 'Project Activities' page. 

Project Activities

Hop Fertility Project Overview
Great Lakes Hop and Barley Conference
Hop Farmer Advisory Committee Meeting
Great Lakes Hop Working Group (GLHWG) Meeting
Petiole Nitrate Demonstration
Summary of On-Farm Hop Fertility Research - Year 1
Making Your Soil Work for You - An Update on the Ohio Hops Soil Study
Petiole Sap Nitrate Testing of Hops

Educational & Outreach Activities

5 Consultations
1 Curricula, factsheets or educational tools
1 On-farm demonstrations
6 Webinars / talks / presentations
4 Workshop field days

Participation Summary:

180 Farmers participated
12 Ag professionals participated
Education/outreach description:

This educational activities are all outlined in the 'Project Activities' page.

Learning Outcomes

33 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
12 Agricultural service providers reported changes in knowledge, skills, and/or attitudes as a result of their participation
Key areas taught:
  • Hop fertility and soil health indicators and outcomes

Project Outcomes

6 Farmers changed or adopted a practice
Key practices changed:
  • Knowledge

  • Awareness

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.