The abundance (yield) and makeup (quality) of a crop are shaped by its genetics and all aspects of its growing environment which extends from root tip to leaf tip. Farmers aim to select crops and varieties that are well-adapted to environmental conditions common to their farm. And, they take steps to alter that environment to favor the crop – to allow it to perform to its full genetic potential.

Most steps are designed to limit a crop’s exposure to one or more conditions that stifle productivity (e.g., extreme temperature, drought or flood, nutrient excess or deficiency, low light, high wind, pests, and diseases). However, they may also significantly impact the total amount and type of resources needed to produce an abundant, high-quality crop. And, micro-environment management can influence when crops are grown.

For example, open field vegetable farming is typically a spring‑to‑fall affair in Ohio and the Great Lakes Region. Without high tunnels, most fresh-market vegetable farmers can sell only 4-5 months of each year. With high tunnels, though, this marketing period can be lengthened dramatically. Production and marketing can start earlier in the spring and continue later into the fall or proceed through the winter. Either way, farmers can take advantage of micro-environments they create with a high tunnel. Low tunnels, mulches, and heating-cooling and lighting systems can have similar dramatic effects on crops and farms.

Our goals in the VPSL are to continue to learn how crop genetics and growing environments influence yield and quality and to assist farmers in using the best micro-environment management approaches.

High Tunnel Environments

We focus on the feedback loop connecting: a) weather, b) grower management as it shapes conditions near crops, c) the genetic makeup and physiology of crops determining their particular responses to nearby conditions, and d) outcomes of crop production. We and our collaborators always ask how outcomes can be improved for growers and from other perspectives. We also ask how desired outcomes can be achieved more reliably and consistently, and with the least amount of time, money, effort, and other essential resources.

This feedback loop is especially active in semi-controlled high tunnel production systems. Covering and fully or partially enclosing crops creates many opportunities to force a range of outcomes, desirable and undesirable. Using a high tunnel(s) requires growers to consider how the weather, status of the tunnel, and crop(s) inside it will react to conditions at that time and in the future. Fluctuations in light, wind, temperature, and other conditions can call high tunnel growers to change the positions of the endwall doors, sidewall curtains, and vents to ensure that conditions inside the tunnel remain perfectly matched with their production goals.

In the OSU Vegetable Production Systems Laboratory, we rely on ten high tunnels located at the OSU-Wooster Campus (OARDC) and partnerships with high tunnel growers in our work. All ten of the high tunnels in Wooster are at Horticulture Unit 1 of The OSU’s Research Farm facility in Wooster. Seven of the high tunnels located in one field are oriented north-south while the remaining three high tunnels in a nearby field are oriented east-west. Nine of the high tunnels contain a single layer of plastic while the other is double layered (and moveable). Additional information about and from inside and immediately outside the high tunnels is below.

The ventilation status of a high tunnel is one of its most key features hour-to-hour since it affects the crop(s) in it. Ventilation status is comprised of the relative “open-ness” of the high tunnel’s endwall doors, sidewall curtains, and vents (if any). As summarized in a previous VegNet News Article, each high tunnel can be in any one of hundreds of ventilation statuses at each moment, as determined by the manager or an automated system. For example, consider that individual endwalls and sidewall curtains can be 0%, 25%, 50%, 75%, or 100% open and it becomes clear that 625 statuses (combinations) are possible (5x5x5x5). We appreciate that testing all 625 combinations across all weather conditions and tunnel sites is impossible. Still, we are confident that an improved understanding of relationships between weather, ventilation status, and cropping outcomes would benefit many, especially if some of that understanding could be gained without the pain of learning the “hard way.” So, in Spring 2022, we began to manipulate ventilation statuses across different high tunnels and weather conditions and record the temperature and other conditions inside the same tunnels. Manipulating and recording ventilation statuses and environmental conditions will help us and high tunnel growers learn what to expect from various statuses across weather conditions and vice versa – i.e., conditions inside a high tunnel given a particular combination of weather conditions and ventilation status. Please contact us if you would like to learn more about the process and/or how to partner in it. Also, please stay tuned for updates on what we are learning.