Final report for OW19-348
Project Information
Enhancing Vegetable Farm Resilience through Dryland Production
Some farmers have no water rights and all farmers run the risk of irrigation failure or lack of irrigation water supply in the future due to climate change. Dryland production of specific varieties of tomatoes and winter squash has been shown to be profitable and to produce high quality and long storing crops. This project will coordinate on-farm participatory research trials and collect and interpret site, soil, and crop data; train farmers in dryland vegetable production techniques, how to assess soil suitability, and how to measure soil moisture availability; engage farmers in production of dryland tomatoes and squash; engage farmers in collaborative learning about dryland production and site suitability evaluation through workshops, field days, social media, and listserves; and disseminate project resources to a broader group of farmers through an OSU Extension Publication, the OSU Small Farms newsletter, social media, and the Farmer to Farmer Exchange listserve. Changes in farmer understanding, intentions, and practices will be assessed though surveys and interviews. The project’s intensive on-farm trialing data, and strong farmer engagement with this data, will further our collective data-based understanding of factors related to dryland site suitability and dryland vegetable production success. This understanding will enhance farm resilience in the face of climate change, and will improve environmental, economic, and social sustainability of vegetable production in Oregon and beyond.
Irrigation in Oregon’s Willamette Valley is dependent on Cascade mountain snowmelt; in the future, snowmelt will be variable and of lower quantity and shorter duration. In addition, many farms in the valley have no water rights and cannot irrigate. Farmers are increasingly interested in dryland production.
While dryland production is profitable on many soils, not all soils are suitable. Soils can be assessed for suitability by taking deep soil cores to accurately identify taxonomy and to characterize chemical and physical properties related to moisture availability; available soil water can be measured at different depths by farmers using soil moisture sensors.
In past work we have identified tomato (Early Girl) and winter squash (Winter Sweet and N. Georgia Candy Roaster) varieties that can be reliably and profitably grown dryland in the valley. In addition, dryland tomato varieties have a long shelf life and intense flavor and dryland winter squash varieties store longer than when grown with irrigation.
This project will build on past OSU efforts by the OSU Dry Farming Collaborative and Stone, Garrett and Gallagher to expand farmer understanding of, and success with, dryland vegetable production. Specifically, it will collect a second year of intensive on-farm trialing data and strongly engage farmers with this data in an effort to further our collective data-based understanding of factors related to dryland vegetable production success. This understanding will enhance farm resilience in the face of climate change.
Objective 1: Coordinate on-farm participatory research trials and collect and interpret site, soil, and crop data.
Objective 2: Engage project farmers in collaborative learning about dryland vegetable production techniques and site/soil suitability.
Objective 3: Engage a broader group of farmers in project findings through publications, social media and newsletters.
Objective 4: Evaluate changes in farmer understanding, intentions, and practices
April 2019: Project begins. Farmers recruited, sites identified, plan and timeline for on farm trial installation and management developed.
May-June 2019: Plots installed (crops, sensors). Site initial data collection (soil column, soil samples, photos) completed.
May – September: Ongoing site visit and harvest data collection (photo, sensor, yield). Social media posts.
August 2019: Two on-farm site field days coordinated. Field day evaluation surveys completed.
September – December 2019: Data aggregation and analysis. Farm and anonymous aggregated data sent to farmer participants.
January-February 2010: Winter workshop/meeting. Clicker evaluation survey. completed. Articles in OSU Small Farm newsletter, distributed through websites and listserves. Social media posts.
February-March: OSU Extension Publication published. Final Qualtrics evaluation survey completed. Final report to SARE.
Cooperators
- - Producer
- - Technical Advisor
- (Educator)
- - Producer
- - Producer
- - Producer
- - Producer
Research
Objective 1: Coordinate on-farm participatory research trials and collect and interpret site, soil, and crop data.
In 2018, this project coordinated and collected data (site, soil, sensor, yield) from 28 on-farm trials. In 2019, 20 sites were identified in collaboration with Dry Farm Collaborative. Farmers prepared sites for the on-farm trials. Project staff took 5 foot soil cores (for identification to soil series by Andy Gallagher, soil scientist) and soil samples at 0-6 and 30-40 inch depths at a location next to the vegetable experimental plots.
Five tomato plants (Early Girl) and 5 winter squash plants (N. Georgia Candy Roaster) were transplanted into 100 square foot plots. After transplanting, watermark sensors were installed in the squash plots at 1,2,3, and 4 foot depths. Squash were covered with row cover to protect plants from cucumber beetles. Staff took sensor data and photos and collected tomato yield data every week, and collected winter squash data at harvest.
Site, soil and yield data were interpreted through ANOVA/mean separation, regression and other statistical analyses as appropriate.
Objective 2: Engage project farmers in collaborative learning about dryland vegetable production techniques and site/soil suitability.
The Dry Farming Collaborative has engaged farmers in dry farming learning and research for more than five years. Farmers provide input into the overall project and participate actively in all aspects of research and outreach. This project is nested within the overall Dry Farming Collaborative process, activities, and structure.
Amy Garrett, the leader of the Dry Farming Collaborative, coordinated four on-farm and research station summer field days (August/September 2019) and a winter meeting (March 2020).
Field days: Attendees (project and other DFC farmers and staff) walked the trials, learned how Gallagher describes soil series from 5 ft soil columns, discussed soil taxonomy and how it impacts site dryland performance. Project data on individual and collective site factors and performance from 2018 and 2019 was discussed.
Winter Meeting:
Participants received their farm’s weather, soil series, soil chemical analyses, sensor, and yield data in advance of the meeting, as well as charts displaying anonymized cross-farm data. Farmers also received information on how to interpret their data.
At winter meeting: Participants (project farmers and other Dry Farming Collaborative members) introduced themselves. Project farmers summarized their 2019 experiences and learning. Gallagher displayed and interpreted specific columns and discussed specific sites/soils as case studies to further explain how to assess site suitability for dry farming. Stone/participants discussed how to interpret soil analyses. Stone presented anonymous individual and collective soil, sensor and yield data from past years and the 2019 season, including case studies of specific sites. Gallagher and Stone walked participants through the project’s understanding of site factors important to dry farm site selection and how to collect that information, followed by discussion.
Objective 3: Engage a broader group of farmers in project findings through publications, social media and newsletters.
See Educational Outreach section.
Objective 4: Evaluate changes in farmer understanding, intentions, and practices
See Evaluation and Producer Adoption section.
Climate and Weather:
Climate and weather are the major drivers of plant water use. This is why most commercial dry farmed tomatoes are grown in cool humid coastal areas in California. The Willamette Valley (WV) is hotter and drier than coastal California, so the WV may be less suitable for dry farming.
Average tomato blossom end rot (BER) incidence in WV sites in 2018 was 37%, while tomatoes grown in coastal sites had almost no BER. In 2018, hot and dry WV sites had a higher incidence of BER than cool and humid WV sites. In 2019, sites that were partially sheltered from the wind and sun had larger fruit.
Soil Properties:
Plant roots absorb water from the soil, where it is held in the soil pores. Gravelly and sandy soils have large pores and little surface area, so they drain quickly and hold the least water. Clay soils have the most surface area and hold the most water, four times as much as sandy soils. However much of the water is unavailable to plants. A soil’s available water holding capacity (AWHC) is the amount of plant available water it can hold, and is estimated by assessing the texture and depth of the soil’s horizons.
A soil’s AWHC is a strong determinant of dry farming success. In 2018, squash yields increased as soil AWHC increased. Additionally, Early Girl tomato fruit size increased and the proportion of fruit with BER decreased as AWHC increased. In 2019, tomato yields increased with increasing soil AWHC. Additionally, soils with impermeable layers may restrict root growth. In our work in 2019, yields of tomatoes and squash were lower in soils with impermeable layers than in soils with unlimited friability to 5 ft.
Management: strategies to improve WV dry farm success
These management practices were associated with higher yields and quality of dry farmed tomato and squash in OSU research trials:
- raise pH to >5.5 by liming (soils of pH <5.5 were less productive)
- Sufficient soil nutrients (as determined by soil test)
- Early planting date
- Variety shown to perform well when dry farmed
Tomato only:
• High planting density (10 to 30 sqft/plant) • Grafting (Early Girl grafted onto Fortamino rootstock)
Blossom end rot
Blossom end rot (BER) is a physiological disorder that can be very prevalent in dry farmed tomatoes. In 2019, the average farm lost 33% of their fruit to BER, though rates were as high as 90% at some farms. The proportion of fruit affected typically increases as the season progresses.
Our work suggests that %BER is higher on sites where luxurious early season growth (from high soil nutrient content) is followed by severe drought stress when soil moisture is depleted. Thus, soil nutrient content may interact with soil AWHC to determine BER incidence.
In addition, tomatoes grown in sheltered sites (partial shade, wind barriers, high humidity due to overhead irrigation nearby) typically had lower % BER than tomatoes grown in exposed sites.
Research Outcomes
Education and Outreach
Participation Summary:
Fact sheets:
- OSU Dry Farm Site Suitability Project: what is site suitability?
- Dry Farming Early Girl Tomatoes
Social Media:
- Facebook: Dry Farming Collaborative (multiple postings)
- Instagram: Dry Farming Collaborative
Field Days and winter meeting:
Oak Creek Center for Urban Horticulture (variety trials): 8/28/19. 45 participants
OSU Vegetable Research Farm field day (variety trials): 8/29/19. 34 participants
Luckiamute Watershed Council (on-farm site suitability trial); https://www.luckiamutelwc.org/dry-farming-field-day.html: 9/11/19. 50 participants
Gathering Together Farm field day (on-farm site suitability trial, grafted tomato trial): 9/2/19. 47 participants.
Winter Meeting of the Dry Farming Collaborative: March 10 2020. Day-long meeting of collaborative members including WSARE project farmer collaborators. Presentations/discussions on WSARE project findings. 74 participants.
Journal article: In preparation. Site Suitability for Dry Farmed Tomatoes and Winter Squash in the Willamette River Basin, Oregon. For submission to HortScience.
Education and Outreach Outcomes
More work (more sites, more years) relating site factors to crop productivity and quality is needed to fully understand the relationships between site factors and crop yield and quality, as site factors are diverse and variable, and weather (important to dry farm productivity) changes from year to year.
As a follow up project to this project, we were successful in obtaining a grant from WSARE to develop a dry farm tomato production system. This project will screen hundreds of tomato varieties for dry farm performance, and evaluate the utility of diverse management strategies to improve dry farm tomato production success, including soil management (dust mulching, mulching, fertilization), pruning/staking, grafting, and shading.