Author: Matthew Kleinhenz

Wintertime Programs to Refresh, Reflect, Reconnect, and Prepare

Participating in wintertime educational programs offers opportunities to refresh after and reflect on the recent season, reconnect with friends and peers, and prepare for the upcoming season. Each year, Ohio fruit and vegetable growers have a range of programs available to them within relatively small distances of the farm (and other programs much farther away, too!). The flyer for a program featuring Wayne County is above and a partial list of state and regional programs to be held in upcoming months is below.

Ten State and Regional Winter-time Programs for Commercial Fruit and Vegetable Growers to be held in or near Ohio December 2022 – March 2023 (as of 10/15/22)

* Programs listed below occur annually with some having been held each year for decades. These programs tend to be comprehensive in terms of the number of crops and topics discussed. Watch VegNet and other outlets for announcements of additional programs focusing on specific crops and/or issues. Programs are also offered and announced via OSUE County Offices (https://extension.osu.edu/lao).
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1. Great Lakes Fruit, Vegetable, and Farm Market Expo … December 6-8, 2022; Grand Rapids, MI (https://glexpo.com/)

2. Kentucky Fruit and Vegetable Conference … January 2-4, 2023; Bowling Green, KY (https://kyhortcouncil.org/2023-kentucky-fruit-and-vegetable-conference/)

3. The 77th Annual Muck Crops School … January 5, 2023; Willard, OH (Mike Gastier, OSUE Huron County – https://huron.osu.edu/people/mike-gastier)

4. Mid-Ohio Growers Meeting … January 12-13, 2023; Mt. Hope, OH (http://midohiogrowers.com/2017-brochure/)

5. Ohio Produce Network … January 16-17, 2023; Columbus, OH; (https://www.opgma.org/ohio-produce-network/)

6. Indiana Horticulture Conference and Expo … January 23-24, 2023; (https://www.indianahortconference.org/)

7. OAK Conference … January 26-28, 2023; Frankfort, KY (https://www.oak-ky.org/annual-conference)

8. Mid-Atlantic Fruit and Vegetable Convention … January 31-February 2, 2023; Hershey, PA (https://www.mafvc.org/)

9. OEFFA Annual Conference … February 16-18, 2023; Newark, OH (https://www.oeffa.org/events.php)

10. Purdue Small Farm Conference; March 2-3, 2023 (https://extension.purdue.edu/anr/_teams/dffs/small_farm_conference/index.html)

Greater Success through Improved Management of High Tunnel Environments

Crop yield and quality can be maximized through properly manipulating or managing environmental conditions inside the high tunnel (e.g., light, temperature, relative humidity, and wind in addition to soil moisture, fertility, and other key variables). Temperature, relative humidity, and air movement inside the high tunnel follow conditions outside it and the position (open to closed) of the end-walls, sidewalls, and vents, which are set by the grower. Research underway in Wooster and on the farms of grower-cooperators is designed to minimize the guesswork associated with knowing just what the ventilation status of a high tunnel should be at any one time to achieve the desired cropping outcomes.

One study involves testing the impacts of “kneewalls,” which are sections of plastic installed behind approximately two-thirds of each sidewall for the fall through spring period. Most high tunnel sidewalls roll up to open. When ventilating fall through spring (e.g., to reduce temperature and/or relative humidity and/or increase carbon dioxide levels), opening standard sidewalls can expose crops or seedlings directly to cold air or wind and lower soil temperature, which is also undesirable. We suspect these problems can be mitigated by using kneewalls. We have experimented with them informally on a limited basis for four years and have been excited by our observations. We will soon begin rigorous, comprehensive assessments of the effects of kneewalls on crops and soils.

That effort is part of a much larger examination of relationships among: (a) outside weather conditions (light temperature, wind), (b) high tunnel ventilation status (sidewall and endwall position), (c) air and soil temperatures and relative humidity level inside the high tunnel, and (d) crop yield and quality and soil status.

This effort is starting with our recording data on those variables every five minutes in multiple high tunnels on a continuous basis; our current pace is approximately 130,000 measurements every thirty days in each high tunnel. This approach and pace are essential to achieving our goal of helping growers and others by clarifying relationships among the weather conditions, ventilation status, conditions inside the high tunnel, and crop and soil variables. Findings may reinforce some of what is commonly thought about those relationships and challenge other commonly popular ideas. We are optimistic that, ultimately, what is learned through the work will save growers time, money, and headaches … i.e., will help them be more successful. Stay tuned and contact us if you would like to participate in this research!

Mechanization-Automation in Vegetable Production: It’s Personal and Important

The big picture is that (vegetable) farming has been mechanizing and automating aggressively for more than a century, although the pace seems to be accelerating and the range of tasks targeted for improvement seems to be increasing. There are many reasons for these trends, but all may come down to the fact that technology that addresses peoples’ needs is personal and, therefore, important. Indeed, read nearly any issue of The American Vegetable Grower Magazine (or its online counterpart https://www.growingproduce.com/), The Vegetable Growers News (https://vegetablegrowersnews.com/magazine/), or other farmer-focused magazine, blog, or newsletter, watch videos or listen to podcasts, or attend industry programs and you will be exposed to personal stories of how specific machines or pieces of equipment are assisting growers in some new way at some point from seeding through post-harvest handling. Stories come from input suppliers, growers, people in extension and research, equipment manufacturers and retailers, and others. Collectively, these stories have given me many lessons but three will be highlighted here.

First, overall, mechanization and semi- to full automation of core farm activities will continue. Trends begun long ago are fully established with incentives to mechanize/automate increasing and obstacles to the process decreasing. Second, growers have various options now and will have others going forward. “There’s an app for that” was popularized about thirteen years ago (and trademarked soon after). However, it now also seems to apply to equipment or machines designed to help farmers since some see nearly every major vegetable seedling or crop production activity historically requiring people as eligible for some form of mechanization or automation. GPS and/or laser-guided automatic weeders/cultivators demonstrated at a recent industry program in Ontario, Canada (https://onvegetables.com/2022/02/28/tomato-day-coming-on-march-10-2022/) and available for rent were especially impressive to me, although many other examples of grower-friendly options are available or in the pipeline (e.g., “scouts,” sensors/actuators, samplers, seeders, transplanters, sprayers, harvesters, etc). Examples are often on display at conferences, tradeshows, and expos in and around Ohio and farther away (e.g., https://www.worldagexpo.com/ – see list of exhibitors at 2022 program). It is also important to note that some machines or pieces of equipment are being designed with more than completing the task in mind (e.g., environmental sustainability). The third lesson available from paying attention to mechanization-automation in the vegetable and specialty crop sector is that off-the-shelf technology that reduces down-time, increases efficiency and/or productivity, or provides other benefits is increasingly practical to an increasingly diverse range of vegetable growers, regardless of the size, location, or other characteristics of their operation. Formerly most relevant to very large, heavily capitalized operations, current generations of machines and pieces of equipment are available to a much larger group of vegetable farms. Some developers, manufacturers, and retailers are more willing to discuss or offer: a) machinery and equipment applicable across more production conditions (including farm size) and b) lease or lease-to-own access. So, access to viable options for mechanizing-automating is increasing, and the time may be right to experiment on your farm.

There is much to consider and a lot at stake when mechanizing-automating and various approaches are used. The farmers responsible for https://www.growingproduce.com/vegetables/why-one-small-vegetable-farm-adopted-mechanization/ emphasize relying on input from other farmers, including via YouTube. Going forward, we will feature grower experiences with tools improving vegetable production we are helping pilot, including systems increasing the efficiency and effectiveness of high tunnel ventilation (temperature, humidity) management.

Why Aren’t My High Tunnel Tomato Plants Growing Faster?

Beginning about now and lasting through mid-April, I am often asked by high tunnel tomato growers why their crop is not developing as rapidly as they expect. Troubleshooting covers a wide range of possible explanations. As various ones are considered and ruled out, the possibility they have overlooked the role of soil temperature becomes more important. The high tunnel may be heated, and the crop may have been irrigated and fertilized aggressively, but there is usually no record of the soil temperature, which greenhouse growers know is very important and work to optimize. After all, root growth significantly influences shoot growth and root growth is influenced by soil or root zone temperature.

In my view, we know far too little about soil temperatures in high tunnels — what the optimal ones are at any time and how to achieve them. Still, discussing this with people in Ohio and other states and having done some research on the topic, I was asked to summarize findings at the recent Mid-Atlantic Fruit and Vegetable Convention in Hershey PA (https://www.pvga.org/wp-content/uploads/2022/01/Mid-Atlantic-Convention-Program-22-website.pdf). The subject of the presentation was “root zone heating and root zone temperatures for high tunnel growers” and what follows are a few messages from that presentation.

Root systems are rarely seen but their size, form, and function influence every aspect of the crop, including the size of the canopy and crop marketable yield and profit potential.

Root systems are hard-wired to follow general patterns as they develop. However, conditions surrounding root systems influence their development significantly. Further, those conditions include temperature and are partially set by the grower. So, growers are partially responsible for root system development and function. While a “strong” canopy is good evidence of an equally strong root system, without another canopy to compare it to, it is difficult to be sure it is as strong and productive as it could be. This indicates that a little on-farm experimentation can go a long way in helping optimize total crop management. It also reminds us that since we usually cannot see roots while experimenting or farming, we often need to rely on tracking factors we can measure and that are known to influence root system development and function.

Research findings suggest that tomato growth and production tend to be greatest at root zone temperatures of 65-70 degrees F. This begs two questions.

First, are root zone temperatures in your high tunnel in the optimal range as often as possible? Do you measure soil and irrigation water temperatures? We have recorded soil temperatures every fifteen minutes for various entire seasons in high tunnels and open fields at OSU-Wooster/OARDC and some of the data are shown below (click to enlarge, if needed). Notice the description of the situation in which the readings were taken and when soil temperature readings were in the optimal range. These readings may or may not represent your farm or crops. However, the data may give clues as to the potential temperatures in your fields and high tunnels and encourage you to record those temperatures directly. Reliable, easy to use, inexpensive instruments are available for doing that.

About irrigation water – much of it draws from wells and surface sources and can be very cold (from the crop’s perspective) fall through spring. Although it has not been tested to my knowledge, passing well, surface, or municipal water through drip lines in a high tunnel, heated or not, may be unable to bring its temperature to 65-70 deg F. So, irrigation in the earliest part of the season may amount to bathing roots in water well below the optimal temperature for tomato and other crops and heating the air may overcome that issue only partially.

This brings us to Question 2. Are you convinced that your returns on investments in high tunnel heating, especially of the air for early season tomato production, are as high as possible? If the air temperature is high but soil temperature is low, are you getting as much from the relatively short photoperiods as you could? In early spring, crops may be more limited by a lack of sunlight than below-optimal air temperatures (and excessive heating during extended low-light periods may be counterproductive). We cannot change daylength or cloud cover, but we have some control over air and soil temperatures and may benefit from bringing investments in them into alignment with daylength. For example, should heating increase with daylength? What is the return on investment in aggressive air heating when daylength is very short soon after transplanting?

Addressing those questions opens doors to exploring the relative value of investments in air, soil, or combined heating. That is a subject for other discussions and articles, but it is worth asking if investments in air heating are returning as much as we expect based on the air temperature alone. The 11/6/21 issue of VegNet included an article on root and air heating in fall-time high tunnel leafy vegetable production (https://u.osu.edu/vegnetnews/2021/11/06/soil-heating-effects-on-days-to-harvest-quality-and-regrowth-of-three-high-tunnel-and-fall-grown-vegetable-crops/) and our previous research included spring season experiments, too. Individual crops respond differently to air and soil temperature due to biology and other reasons. For example, the growing tip of lettuce plants is closer to the soil surface than the growing tip of tomato plants and, therefore, may be more strongly impacted by root zone temperature and heating over brief periods.

The point here is that investments in high tunnel heating may be most effective when taking the whole cropping cycle and rotation into account. High tunnel management systems, including temperature, can be designed around one or a set of crops – i.e., around optimizing income from one crop or across the year. Of course, this would occur on a farm by farm, market by market basis. This spring and season, as you are able, consider taking a moment to examine your high tunnel temperature management practices and ask if they maximize your entire annual profit potential.

Solar Energy and Your Farm

Whereas photosynthetic organisms convert light to chemical energy, solar panels begin the process of converting light to electrical energy. No one is isolated from the effects and importance of photosynthesis, and it seems that a growing number of people are increasingly reliant on and affected by solar energy in one way or another, too. Farmers and other landowners in Ohio and throughout the U.S. are currently intersecting directly with solar energy in at least four ways. They are using solar energy from the grid, weighing options for leasing land to solar energy projects adding to the grid, exploring options for integrating farming and solar energy production (the process of “agrivoltaics”), and/or they are experimenting with using electricity they generate using solar capture completed as a ‘private’ activity.

What to look for as you considering leasing land for solar energy development is the subject of three free webinars organized by Penn State University Extension. The webinar held on February 23, 2022 featured Scott R. Kurkoski of Levene Gouldin and Thompson, LLP (https://www.lgtlegal.com/) as the technical presenter. His comments were very practical and informative, especially for landowners in the early stages of evaluating a potential relationship with a solar project. Watch the webinar at https://psu.mediaspace.kaltura.com/media/Leasing+Your+Land+for+Solar+Energy+DevelopmentA+Webinar+on+2-23-22/1_xt3id0rt and consider registering for the webinars to be held on March 16 (Evaluating the Contract Terms When Leasing Your Land for Solar Energy Development; www.bit.ly/solarMarch16) and March 23 (Solar Leasing Questions, Answers, and Wrap-up; www.bit.ly/solarMarch23). Or contact Tom Murphy of Penn State Extension for more information (tbm1@psu.edu) on the webinars.

In an article posted to VegNet on December 19, 2021 (https://u.osu.edu/vegnetnews/2021/12/19/a-simple-inexpensive-diy-system-for-controlling-the-height-of-high-tunnel-sidewall-rollbars-remotely/), I outlined a small but important project involving electricity generated by one solar panel attached to a high tunnel at OSU in Wooster. That panel and the battery it charges has powered an inflation fan, sensors collecting temperature data, four motors driving end wall vents and sidewall motors, and the panel controlling them all nonstop for more than six years. The battery has been replaced once. This is one small example of how on-site solar power generation can benefit a grower.

What happens to and/or can be done with land beneath a large array of solar panels setup to supply the grid (or local operation) is a major question for landowners and solar project officials alike. Officials with no interest in using the land for an additional purpose still tend to require it to be maintained to a basic extent so the project is not compromised. However, in other cases, landowners (farmers) and solar officials explore the “agrivoltaics” (AV) option. Two broad versions of agrivoltaics are taking root but progressing at slightly different rates. In one, land near the solar panels is grazed (e.g., by small ruminants) mainly to control vegetation but also to help generate revenue. In the second version, revenue-generating crops (vegetables? forages? fruit? flowers?) are grown on land beside or below the solar panels. Water released through plant leaves cools the panels by evaporation and reduces the heat-island effect common in solar panel-only facilities. Therefore, the panels operate more efficiently in converting sunlight to electricity. Other potential benefits of AV include more efficient water and land use, less heat stress on plants and panels, and more energy capture – meaningful financial and environmental gains. Clearly, the ‘trick’ is in designing the system to serve and optimize as many functions as possible.

Not surprisingly, agrivoltaics is regarded as a potentially significant partial solution to complex and widespread challenges. AV combines solar power generation and farming. Normally, these processes occur independently and separately. AV theory integrates them in exciting ways by requiring the processes to occur simultaneously on the same land. Early-stage test results in parts of the U.S., Europe, and Australia have created optimism. However, significant challenges exist in integrating photovoltaic power generation and agriculture on working farms. In May, I will be fortunate to begin collaborating with experts at Central Queensland University in Rockhampton, Queensland, Australia and industry partners in identifying the best next steps in utilizing agrivoltaics more effectively, including in Ohio and the region. This Fulbright-supported project will help ensure a rapid and effective transfer of understanding and capacity between OH/the U.S. and Queensland/Australia. Look for updates in these pages and other outlets or contact me anytime for more information on the project.

A Simple, Inexpensive, DIY System for Controlling the Height of High Tunnel Sidewall Rollbars Remotely

The Problem

High tunnel growers come to know through trial and error and some hardship that their success depends on managing the temperature and other conditions inside the high tunnel with care. That is, that maximum yield and quality are possible only when conditions inside the tunnel and near the crop are optimal as often as possible. High tunnel growers also come to learn that achieving optimal conditions round-the-clock and day after day is difficult and costly in various ways. For example, it is difficult because crop needs and conditions outside the tunnel can change dramatically and quickly, especially during key points in the crop cycle in spring and fall. Reacting to changes in crop need and other must-dos on the farm can be challenging. Managing temperature and other conditions inside the tunnel usually also requires undesirable investments in time, effort, and money. Of course, conditions inside the tunnel are usually set by controlling the extent to which sidewalls, vents, and/or doors are open, with the height of sidewall rollbars being particularly significant. The trouble is that the position of most sidewall rollbars is set by hand. This requires the grower or another person to stop what they are doing, travel/go to the high tunnel, and reposition the rollbars manually. This commitment and expense are unfortunate enough. However, the fact that it may need to be done multiple times per day for many days in a row for conditions near the crop to remain optimal becomes problematic for many high tunnel growers. They are required to choose between: (a) continually repositioning sidewall rollbar heights (“babysitting” the tunnel) at some direct cost and at the expense of engaging in other activities or (b) setting sidewall rollbar position at a “compromise” height and accepting the consequences of conditions (e.g., temperature, wind) being above- or below-optimal for potentially lengthy periods. In our view, high tunnel growers should not be required to have to make that choice.

Existing and New Solutions

Various companies (e.g., https://www.advancingalternatives.com) agree and offer automated ventilation control systems involving sensors, a control panel, and sidewall motors. We have had a version of the Advancing Alternatives system on a moveable Rimol high tunnel since 2015 and have been very pleased with both (control system, high tunnel). The high tunnel’s sidewall motors, endwall vents, inflation fan, and control panel are all powered by a standard 12-volt battery charged by one medium-size solar panel. It’s an impressive system. However, we are also aware that fully automated approaches to ventilation can cost more than some growers are willing or able to pay and place control of the high tunnel conditions largely in the hands of the control panel, not the grower.

Therefore, we have been working to develop a low cost, DIY way to control sidewall motors remotely that keeps the grower directly in control of sidewall position (e.g., to account for conditions that a fully automated system may not monitor, at least without additional cost).

Alex Herridge will soon complete his undergraduate degree in Computer Science and Engineering at The OSU and his contributions to the effort have turned the idea for this alternative, grower-friendly system into reality. Full plans for the system will be available in a separate publication soon but its key features include:

1. Standard sidewall motors powered by a battery-solar panel combination, as described above;
2. A standard voltage-regulating unit converting 12 volts from the battery to 24 volts needed by the motors (approx. $80.00);
2. A motor controller (available at electronics stores or online for approx. $15.00);
3. An off-the-shelf, WiFi-enabled microcontroller to act as the brains of the system (approx. $5);
4. WiFi already present on the farm property or wireless access with a hotspot or similar ($0 to monthly charge typical of a mobile phone plan); and
5. Code for the motor controller (no charge).

To proceed, motors are attached to sidewall bars and powered and a basic network connection linking the grower’s phone (or other device) and the microcontroller is established. The entire process can be completed in approximately four hours once all materials and WiFi are on site. Thereafter, the sidewall motors can be controlled with one’s mobile phone or other linked device using a simple interface setup for the purpose. Pictures of the preliminary, bare-bones version of the interface we used to raise and lower a sidewall bar on a high tunnel at OARDC on December 13 are given here. The bottom-line of this approach and system is that it will allow growers to raise and lower sidewalls from wherever they have internet access using low cost, off-the-shelf hardware. Watch for additional posts regarding this system at VegNet and other locations and contact me (Matt Kleinhenz; kleinhenz.1@osu.edu; 330.263.3810) if you are interested in learning more about or testing the system on your farm.

(OSU Computer Science and Engineering student with the motor and micro controllers and standard battery charged by a solar panel.)

(Exterior of the Rimol moveable high tunnel and the solar panel used to charge the battery powering rollbar motors, endwall vents, inflation fan, and control panel.)

(Simple, password-protected interface for controlling sidewall rollbar position. Usable from anywhere the owner has internet access and allowing them to control sidewall rollbar height remotely.)

 

 

 

 

 

Soil Heating Effects on Days to Harvest, Quality, and Regrowth of Three High Tunnel- and Fall-grown Vegetable Crops

Grower interest in fall-to-spring marketing of crops freshly harvested from high tunnels is increasing, along with the number and types of questions they have about the production side of the process. Excellent resources and information are available on major aspects (e.g., crop selection, planting schedules) but growers continue to seek and test cost-effective steps to enhance yield and/or quality. Managing temperatures near the crop so they maximize yield and quality has become a major focus for some. We say “temperatures” because root-zone and above-ground temperatures are often different and influence crop development and composition differently. So, we have been studying the effects of common production materials and strategies used to alter temperatures near the crop for many years. Experiments have included various combinations of row covers (film, fabric) to increase air temperatures (primarily) and soil heating. The most recent experiment was started in September and is described in the five panels below. Please contact us (Matt Kleinhenz; kleinhenz.1@osu.edu; 330.263.3810) if you would like more information, have questions about your production methods, and/or would like to discuss collaborative research that could be completed on your farm.

 

Optimizing Film, Fabric, and Root Zone Heating Combinations in Fall-to-Spring High Tunnel Vegetable Production

An increasing number of growers look to harvest and market vegetables grown in high tunnels fall to spring. Selling freshly harvested material (e.g., leafy, root, and other crops) from roughly October through April appeals to some farmers but it also raises many production-related questions in practice. Many of these questions relate to the use of plastic films, fabric row covers, and supplemental heating (including of the root zone). Questions such as which ones to use, when, for how long, under what conditions, and in what combination are common. The Vegetable Production Systems Lab has completed research in this area for more than fifteen years, cooperating with farmers often and using high tunnels at OARDC in Wooster which range in size, approach (conventional, organic; flat ground, raised beds), and other characteristics. Findings from these experiments have been summarized in publications (including VegNet) and during programs around the Eastern U.S. Our newest experiment was initiated on Sept 23 and includes the 20 wood-framed raised beds shown here, each seeded to either Scarlet Nantes carrot, Outredgeous lettuce, or Ovation greens (Brassica) mix from Johnnys Selected Seeds. This experiment will examine the influence of daily (8 am – 5 pm) root zone heating (accomplished with electric cables placed approx. 7 inches below the soil surface) in combination with vented plastic film row cover on crop development, yield, and quality. Vented plastic film covers all twenty plots (beds) while daily root zone heating occurs in ten of the twenty plots. Root zone heating will be discontinued at six weeks after seeding but the film will remain in place through final harvest in December. These treatments were chosen partly because two findings have been common in previous research. First, crops (e.g., lettuce, Brassica greens, carrot) and varieties have responded very differently to the use of film, fabric, and root zone heating — whether used alone or in various combinations. The same trend appears to be underway given the relative sizes of the crops shown in the pictures below (taken 10/9/21; carrot at top, Ovation Brassica mix in middle, lettuce at bottom). Second, in this experiment, we are very interested in root zone heating as a supplement to the above-ground heating that occurs with film in place and is typically pronounced September to early November and late January through March. Finally, temperature and relative humidity are recorded in each plot every five minutes, allowing us to describe treatment effects on these conditions very reliably. The sensor unit shown in the bottom-most picture below also relays the temperature and relative humidity readings to the “cloud,” allowing us to see the numbers in near real-time. This battery- and solar-powered Hobolink monitoring and reporting system from Onset Computer Corporation has been in place for more than two years and has greatly enhanced the efficiency and effectiveness of our high tunnel ventilation management across the ten tunnels in our program.

 

Grafted Watermelon Plants: Under What Conditions and Practices Does Using Them Offer the Best Return on Investment?

A lot of research is focused on answering that two-part question for watermelon and other crops (e.g., cucumber, cantaloupe, tomato, pepper). Full answers will emerge as growers and researchers share and integrate their experiences then evolve as circumstances change. Currently, most agree that using grafted plants is most beneficial when a resistant rootstock is selected to help offset the effects of a significant soilborne disease (e.g., Fusarium, Verticillium), regardless of crop. However, rootstocks with additional traits are being tested under other troublesome conditions (e.g., salinity, heat, cold, drought, flood). Growers are encouraged to listen as peers and research-extension and industry personnel share new information on the performance of grafted plants under various conditions. Information will be specific to crop, setting (field, high tunnel), system (conventional, organic), market, farm size, and other key variables.

Soil and other production conditions are not the only factors that influence the value of grafted plants to growers. Practices used to grow the plants are also important. Plant and row spacings (plant populations), irrigation and fertility programs, and planting and harvesting dates may also affect growers’ experiences with grafted plants.

Industry-research/extension partnerships can help fast-track arriving at answers to where and how grafted plants should be grown for growers to benefit most. We work with plots at OSU and on farms to understand the impacts of in-row spacing, fertility programs, and more on watermelon fruit yield and quality. Grafted and standard (ungrafted) plants are included in each experiment. Results from a multi-year study in Wooster through 2020 are summarized in a short video at https://go.osu.edu/vegeprosystemslab. Overall, fruit number and total weight have been significantly greater in grafted plots and at an in-row spacing of five versus four feet (between-row spacing of six feet in all cases). The results suggest growers can reduce plant populations but increase yield meaningfully – i.e., reduce plant costs while increasing income potential. Importantly, evidence of Fusarium in this experiment has been absent or minimal in all previous years. As explained and shown in the panels below, Fusarium is affecting the experiment significantly in 2021. Standard (ungrafted) Fascination and Sweet Dawn plants are very weak or dead while grafted versions of both (Carnivor, Pelops as rootstocks) remain healthy and vigorous. Harvest will begin soon and fruit yield data will be available by season’s end. Please contact me if you would like more information on this experiment or grafting.

Optimizing Vegetable Fertilizer Programs

Recent farm visits, questions from growers, and observations of research plots have me thinking about nitrogen and other fertilizer programs for vegetable crops grown in open fields and high tunnels for fresh and processing markets. What are optimal ranges for each production situation, which factors influence optimal rates most significantly, and what steps can growers and others take to identify optimal rates for each farm and planting?

Ranges currently recognized as optimal are published in numerous guides, handbooks, and other resources. The Midwest Vegetable Production Guide for Commercial Growers, Southeast Vegetable Production Handbook, Mid-Atlantic Commercial Vegetable Production Recommendations, New England Vegetable Management Guide, and references available from Cornell (e.g., https://cropandpestguides.cce.cornell.edu/) and other universities are helpful in Ohio and the region. The publications provide operating fertilizer application targets and tips on how to reach them. Targets in the publications are the best available benchmarks. However, it is best to think of them as not fixed in stone and as needing to be validated for individual cropping situations. On-farm validation (adjustment by trial and error) using published, research-based and other reliable benchmarks as starting points saves time, money, and headache.

Indeed, since production conditions change continuously and research-based recommendations require years to develop, evaluating fertilizer programs (material, rate, timing, placement) often is good practice. Like effective crop protection programs, fertilizer ones are not static, they need to be updated as weather patterns, varieties, rotations, fertilizer materials and their costs, and other factors change. Observe crops now and through the remainder of the season and ask if you are convinced their fertilizer programs are optimal. If you aren’t convinced, consider experimenting carefully.

Experiments are most effective when they account for factors that tend to influence their outcomes most significantly and consistently. To refresh my memory on these factors, especially nitrogen application rate effects on watermelon and other Cucurbit crops, I looked at extension resources referenced above and reports from research completed in the U.S. and other countries. I was also very pleased to hear from Ohio growers on the same topic.

That input pointed to the following seven factors as most likely to shape optimal fertilizer, especially nitrogen, application rates for individual farms, soils, crops, and plantings.
1. Soil type and condition. Sandy, loam, or clayey? Organic matter level? Have a prominent plow layer or other condition affecting drainage, etc? Fertilizer programs must be calibrated to soil type and condition since they influence many facets of nutrient availability at any one time.
2. Fertilizer application approach. For example, will fertigation be used? Fertilizer application approaches influence which materials are used, when and where they are applied, and their likely efficiency.
3. Precipitation and irrigation. Soil moisture management is a very large percentage of nutrient management. Are the irrigation and fertilizer programs in sync? Is rainfall cooperating? Can the program be adjusted for weather?
4. Variety(ies). Shifting market expectations (e.g., large to personal-size melon) may have implications for the fertilizer program. Similarly, the program may also need to be adjusted to maximize gains from using grafted planting stock because rootstocks may differ in, for example, their abilities to obtain nutrients and water.
5. Cultural practices. Production on plastic-covered raised beds versus the flat. Standard versus strip- or reduced tillage approach. Row and plant spacings (plant populations). These and other factors are consistently mentioned as factors shaping the four R’s (material, rate, timing, placement) of all fertilizer programs. The fertilizer program may need to be tweaked if any of these factors are changed.
6. Crop growth stage. Especially important for fruiting vegetables, including Cucurbit and Solanaceous crops. Nitrogen and other macro- and micronutrient levels influence many aspects of crop biology directly impacting (fruit) yield and quality from seeding/transplanting to harvest. Metering nutrient availability by crop stage is a proven, essential tactic in soilless greenhouse production. The same level of control is impossible in soil-based field or high tunnel production; however, a realistic application of the principle can be beneficial in both systems.
7. Nutrient credits. There is often little need to apply what is already there. Basing planned applications on current, reliable soil test data is a cornerstone of successful, efficient, cost-effective fertilizer programs.

Finally, setting optimistic but realistic yields goals, especially for non-vegetable rotation crops, if any, is also beneficial. Realistic yield goals help avoid significantly under- or over-applying fertilizer, regardless of crop. Avoiding such deficiencies and excesses enhances the overall return on investments in the current and subsequent crops.