Becky Maden, the vegetable nutrient management specialist at UVM Extension, is passionate about maximizing plant growth and yield through proper nutrient management of the soil.
Through Maden’s research, she has found that growers can produce nine times the total yield per square foot in high tunnels compared to fields. Growers should take advantage of the vertical space available in the high tunnel, as “the more [plants] you can put in without losing them to disease, the more money you’re gonna make.”
Although growing in high tunnels allows you to influence the growing environment, and even extend the growing period, it’s essential to constantly monitor your soil’s health. Unlike soil in the field, the soil in a high tunnel isn’t being naturally watered through rainfall, and it’s much more difficult to use cover crops or even conduct crop rotations.
When it comes to managing the soil in a high tunnel, there isn’t a one-size-fits-all growing guideline because not all high tunnels are identical. Tunnels come in all different shapes, styles, sizes and varying technical abilities. Additionally, two farmers may have identical high tunnels but manage them completely differently, leading to different yields.
With all of these varying factors, growing recommendations will be different for each high tunnel and growing method.
Grower Micah Schonberg inside his high tunnel of greens. Photo by Bill Lamont
Maden mentioned how many variables – such as size, heat and ventilation from the tunnel, as well as the plant variety and its duration in the soil – “are going to inform your [soil] nutrient management.” Without proper nutrient management, growers can create problems in the high tunnel that are hard to reverse.
High tunnel growers shouldn’t solely rely on a field test to check their soil nutrients. “A field soil test isn’t going to give you [all] the information you would need to make changes” to your soil, Maden said. She recommends high tunnel growers conduct a field soil test, potting soil test and tissue analysis.
The field soil test will measure reserved nutrients in the soil; the potting soil test will measure soluble nutrients; and the tissue analysis will measure the nutrients already in the plant.
Through research, Maden has realized that “potassium is really hard to meet in the tunnels.” There are a lot of factors that play into potassium uptake that make managing the amount very complicated.
Growers need a solid irrigation plan for their high tunnel, since the soil and plants won’t access the rainfall outside. Maden stressed how “water is important not just for plant growth, but this whole nutrient puzzle,” as water helps the plants take up nutrients from the soil.
Before you adjust your nutrient management system, determine your desired yield goal for the high tunnel and how you’re going to track your yield.
As Maden stated, “Understanding what we want to know and what we’re trying to track is the most important step” in reaching your goals.
by Kelsi Devolve
