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Growing Greenhouse Crops With the Latest Plant Nutrient Tools

Aug 01, 2023Aug 01, 2023

In hydroponic installations, Moleaer’s equipment can be installed directly to recirculate basin water for improved root development and plant health and reduced pathogens. Many growers are reporting reduced inputs, from fertilizer and pesticides to water usage. Photo: Moleaer

2022 showed us that conventional practices and solutions could be turned on their head. Rising costs for everything, supply chain issues, and a war in Europe combined to raise operating expenses for nearly everyone. From electricity to diesel fuel and fertilizer, producers faced headwinds.

For controlled-environment agriculture (CEA), whether that means a hoop house, a greenhouse, or an indoor vertical farm, plant nutrition and crop health are at the crux of the issue. Nutrient uptake efficiency, plant root mass and vigor, disease resistance, and yield are all areas where improvements can heftily impact your bottom line. Whether it’s cutting expenses — less fertilizer — or increasing yields, this economy makes it more critical than ever. Here’s a snapshot of where efforts are focusing for 2023.

You may not have heard of nanobubbles before, but they have been around for a long time. They can be found in the ocean and are used today in horticulture, aquaponics, reversal of lake eutrophication, mining, and many other areas.

Nanobubbles are, in essence, tiny, tiny bubbles. As their name suggests, they are measured on the nanoscale, typically 100 nanometers in diameter, or about 2,500 times smaller than a grain of table salt. Remember, a nanometer is one billionth of a meter.

These super small bubbles of gas, in this case, oxygen, remain suspended in solution instead of rising to the surface, like a regular bubble, because they are neutrally buoyant.

The CEA community is adopting nanobubbles for several reasons. Research and results point to increased oxygen availability to plant roots, encouragement of an aerobic environment in the rhizosphere, suppression of pathogens like Pythium and Fusarium, and increased nutrient availability and uptake.

In other words, growers using nanobubbles report lower fertilizer usage, increased plant health, more plant root mass, and higher yields. Unlike ozone or other treatments, nanobubbles can’t be overdosed and harm plants.

This relatively new technology shows other benefits, as well. Because of the oxidizing properties of nanobubbles, the reduction of biofilm in irrigation and fertigation systems is significant.

Nanobubbles and organic nutrient sources work well together with less clogging, less system maintenance, and better nutrient uptake. It works well with hydroponic systems, especially as the temperature rises and traditional systems have challenges keeping dissolved oxygen (DO) high in warmer water.

Incorporating nanobubbles into an existing operation is entirely scalable. Davey Rock is the Moleaer Business Development Manager for the Midwest territory. He first became interested in nanobubbles when he saw their benefits in his own growing operation. Now, he works to bring this capability to others.

“Any grower can benefit from nanobubble technology,” Rock says.

Nanobubbles can be incorporated into any size operation with units to fit irrigation system configurations and water use from a few hundred gallons per day to more than 100,000 gallons per day.

The return on investment can be quick as well. Effects like increased yields, shorter cycle times, less line maintenance, and less fertilizer and fungicide use stack up like compound interest. While the answer for the specific timeline to recoup investments always depends on the individual operation, Rock says many growers see quantifiable benefits almost immediately and return on investment in as little as months.

Many minerals and compounds found naturally in the soil are absent in modern soilless CEA. The nutrient receiving much attention in the current environment is silicon.

While silicon is the second most abundant element in the earth’s crust, plants growing in soilless media in your CEA operation may lack it. Pine bark, coco coir, peat, and other mediums have little silicon. Sand, perlite, rock wool, and vermiculite, while having silicon as part of their makeup, don’t have it in forms available to plants.

Since silicon isn’t strictly necessary for plants to grow, flower, and reproduce, it was ignored as our modern CEA systems developed. Erica Hernandez, a CEA Technical Specialist with Griffin Greenhouse Supplies, advises producers on crop health. Today, she sees growers looking for advantages in pest resistance and heat/drought tolerance. They are interested in silicon and in forms more easily broken down and available to plants than traditional potassium silicate.

When present, silicon is taken up by plant roots as silicic acid. This compound travels throughout the plants’ water-conducting vessels, gets deposited, and then solidifies. Plants gain stronger cell walls, which results in increased resistance to harmful fungal spores and insect attacks. Silicon also aids in damage resistance during shipping and heat tolerance.

Like a lack of minerals found in soilless media, many of our beneficial biologic factors are also missing. The sterility — lack of soil life — was part of the initial appeal of soilless growing mediums to reduce pathogens, but CEA operators may be missing the beneficial soil life as well and losing out on the boost it can provide to plant vigor. Healthier plants are more resistant to biotic and abiotic stresses.

Hernandez says she and others are finding increased grower interest in biostimulants to reduce disease pressure and fertilizer use. These biostimulants come in two basic types: mycorrhizal and bacterial.

Mycorrhizal or fungal biostimulants can be applied at transplant. Mycorrhizae form symbiotic relationships with plants, increasing their functioning root mass to increase nutrient uptake efficiency and water absorption.

Bacterial biostimulants add those beneficial bacteria, like Bacillus spp., back into the soil. These bacteria function to break down nutrients into plant-available forms. B. subtilis is a rhizobacterium with a proven record of solubilizing soil phosphorous, enhancing nitrogen fixation, and suppressing diseases.

Bacterial biostimulants are more commonly used in crops with shorter cycle times as they are faster to establish. Due to their increased establishment time, fungal biostimulants are often applied to longer rotation crops, including ornamentals, hemp, and cannabis, says Hernandez. For organic producers, some products are now available that are OMRI listed.

Growers looking to gain an edge may find combining several methods advantageous and a scalable solution to reducing operating expenses and increasing revenues from existing efforts. Lower fertilizer costs, lower maintenance, and happier plants, whether for food or ornamentals, can be a much-needed win for 2023.

Andy Wilcox is a flower farmer and freelance writer with a passion for soil health, small producers, forestry, and horticulture. He and his partner run Stone’s Throw Flowers, providing cut flower arrangements to retail and wholesale customers. Andy is an active member of the Farmer Veteran Coalition of Wisconsin. See all author stories here.