Progress report for LNE19-391R
Project objectives from proposal:
(1) Develop best practices for deploying soil moisture sensors on diversified farms in the NE and using sensor data to inform irrigation decisions.
(2) Develop a better understanding about what NE farmers need from soil moisture monitoring systems to enable them to use it effectively.
Our project has two hypotheses and two research questions:
H1: Use of soil moisture monitoring systems (a) improves vegetable yield/product quality, (b) decreases nutrient leaching, and (c) reduces water applied per unit harvested.
H2: Following exposure and education, farmers will demonstrate changes in knowledge, attitudes, and awareness related to soil moisture technology.
RQ1: What are the current barriers that keep NE farmers from investing in soil moisture sensing technology?
RQ2: What changes to current tools/data systems should be made to increase their usefulness for NE vegetable growers?
Note: This section references the experiment as conducted in 2019 in Burlington VT. All research activities were put on hold in 2020 due to COVID-19 restrictions to the UVM Horticultural Research and Education Center, where our plots were located. We requested (and were granted) an extension on this grant due to the pandemic. We should also note that we will be expanding the study (adding a study site) at the University of Maine Rogers Farm using funding from the University of Maine Agricultural and Forestry Experiment Station (MAFES). We believe that replicating the study on a different soil type in a different part of New England will enhance the quality of our data and the generalizability of our findings.
Plot preparation and fertility: An Experimental plot was installed at the University of Vermont Horticulture Education and Research Center, measuring 600 square feet. Prior to plot installation, Modified Morgans soil tests were conducted to determine nutrient needs. At the time of installation, fertilizers were added based on soil test results (20# of 8-2-2 dehydrated poultry manure and 4# sulfate of potash). Rows were then marked, irrigation installed, and the beds were covered with black plastic mulch. Each plot included four of the following: tomatoes (Early Girl), cucumbers (Marketmore), and bell peppers (Olympus F1).
Daily irrigation protocol: Plots were monitored daily for irrigation needs. Specifically, plots irrigated by feel of soil cue were tested each morning and, if determined to be dry, were watered for 2 hrs. Soil moisture sensor readings were observed each morning, and when readings for any plot in a single tensiometer treatment were above 20 cB based on sensor readings at 12”, all plots in that treatment were watered for 2 hours. Plots in the water meter treatment group were irrigated daily for 2 hours regardless of soil or weather conditions. Plots in the control treatment group were never given supplemental water, though they were exposed to precipitation.
Soil collection and testing: Soil samples were taken at 12” depths on a weekly basis starting 6/03/2019. 6 random cores were taken per plot, mixed and collected in cotton bags. The soil bags were kept in a dark container until they were brought to the lab. The samples were dried at 55 degrees overnight to preserve nitrates present in the soil mixtures until PSNT analysis.
Lab Protocol for Soils: The soil samples were placed in souffle cups, ground and put through a 10mm sieve to remove rocks and larger soil debris. 4 grams of sample were weighed out into 100mL erlenmeyer flasks fixed on wooden structures 12 at a time, including a quality control nitrate sample soil and a sample duplicate. 20mL of 1M KCl solution was added to each flask before the samples are shaken for 15 minutes. The samples were poured through filters rinsed with DI water into test tubes. Once filtered, the solution is poured into Lachat tubes and covered with parafilm until lab analysis.
Leachate collection and testing: Leachate samples were collected weekly in addition to soils. A vacuum pump and battery were used to draw the samples into a collection bottle with attaching tubes. Once pumped, the lysimeter volumes were measured and recorded using graduated cylinders and 1000mL pitchers, depending on volume. 50 mL samples from lysimeter draws were stored in plastic test tubes, preserved with two drops of 0.01M sulfuric acid, and kept in a refrigerator until analysis.
Lab Protocols for Leachate Samples: Each sample was pipetted into Lachat tubes for nitrate analysis to approximately ¾ full. The first 40 samples ran above the maximum detection set by the Lachat (10mg/ L), and were diluted 10x with DI water. Two months later, the second round did not require dilution, since they were within the detection limits of 10mg/ L and 0.2mg/ L on their own.
Yield and quality of vegetable crops: Starting July 15th, 2019, vegetables were harvested on a twice-weekly schedule. Vegetables were harvested by plot, weighted and counted. Harvesting was stopped on October 7th, 2019. Quality was evaluated using United States Department of Agriculture (USDA) Agriculture Marketing Service (AMS) guidelines, specifically color uniformity, gloss, size and shape uniformity, defects, and firmness. Quality and yield were averaged across plots in each treatment to determine daily metrics.
Other data collected: On a weekly basis, the team recorded water application rates (U.S. gallons) using Netafim flow meters installed on each treatment. Evapotranspiration readers were also recorded on a weekly basis from an on-site gauge.
We are currently analyzing the data. One graduate student has been brought onto the project (Haley Jean) is conducting the analysis from 2019 this winter (2020-2021), and developing R code that will make analysis of next year’s data easier.
Education & Outreach Activities and Participation Summary
- Presentation at one farmer twilight meeting at in Intervale Community Farm in Burlington Vermont (July 2019). We presented on soil moisture sensors, and discussed our field trials. 23 growers were in attendance.
- Participated in the UVM Horticulture Research Education Farm research field day (August 2019), where we discussed our project with 14 researchers and students.
Because we have not started the outreach portion of this work in earnest, we have yet to collect success stories.
2020: Due to COVID-19, we were unable to implement field trials at either the UVM or UMaine sites. We applied for (and received) extensions both on our SARE project and the UMaine funding that supports the extension at the UMaine Rogers Farm site. However, we were able to install lysimeters at the UMaine site, which means we will be ready to go at both sites in the 2021 growing season. Additionally, a graduate student (Haley Jean) at UMaine was brought on to help with the project. Ms. Jean has been developing R code and analysis procedures using 2019 data from Vermont. Once complete, this “data pipeline” will allow for a relatively easy analysis of the full, multi-year, multi-site data set. Ms. Jean will work with our team in 2021 to collect data in Maine, and will use data from both sites for her M.S. thesis.
Prior to the onset of COVID-19, we were able to collect data at two additional farmer focus groups. The first of these was held at the Pennsylvania Association of Sustainable Agriculture (PASA) in February (5 farmers attended), and at the Vermont Vegetable and Berry Growers Association annual meeting in January (4 farmers attended). Data from all four focus groups still needs to be summarized. I would not recommend holding focus groups at farmer conferences in the future: attendance was lower than we had hoped, and it was difficult to convince people to attend, even with a financial incentive and lunch provided.
2019: This was a very productive season in terms of data collection. We successfully installed the irrigation field trials at the UVM Horticulture Research Education Center (HREC), including a soil moisture monitoring network, and lysimeter pans and ports. We established a successful crop of tomatoes, cucumbers, and green peppers, as well as a harvesting and crop evaluation protocol. Our research team included a lab technician, a field-based research assistant, a nutrient management specialist, in addition to the two project leaders (Schattman and Faulkner).
In addition, we held 2 focus groups: the first was held at the Farmer-to-Farmer Conference hosted by the Maine Organic Farming and Gardening Association (MOFGA) in November (9 farmers attended). The second was held at the New England Vegetable and Fruit Growers Conference in Manchester NH in December (3 farmers attended, and 5 service providers). Two more focus groups are planned for 2020: In January we will hold on at the Vermont Vegetable and Berry Growers Association annual meeting in VT, and in February we will host our final focus group at the Pennsylvania Sustainable Agriculture (PASA) conference in Lancaster PA (where 15 people are already registered).