THE APPLICATION OF ROOT ZONE OXYGENATION IN GREENHOUSE PRODUCTION (OVERVIEW)

Dr. Youbin Zheng, Linping Wang, Johanna Valentine, Sally Taylor and Dr. Mike Dixon

Department of Environmental Biology

Controlled Environment Systems Research Facility

University of Guelph

Alberta, Canada

Study Synopsis

This is a two year study on the response of root zones in plants to increased dissolved oxygen. Four levels of dissolved oxygen where used 8, 20, 30, and 40 (ppm) parts per million. This study shows a direct relationship between increased dissolved oxygen to the root zones and faster, bigger, healthier plants.

Positive Findings from the Study

• “Plants harvested after two weeks of oxygenation treatment revealed that root systems in the 30 ppm treatment were bigger and heavier (both fresh and dry weights), and the main stems were thicker than those of plants in the other treatments.” Note: This study was in a greenhouse controlled environment. 30ppm is the optimal level of dissolved oxygen. On a golf course most untreated irrigation water has 2-4 ppm of oxygen.

• “It is well known that DO at most greenhouse crop root zones under most conditions is lower than 8 ppm and oxygen deficiency can not only cause reduced growth, but can also encourage the infection of root disease.” Note: This is a clear statement that points out the importance of increased dissolved oxygen.

Negative Findings from the Study

• “The reduced growth of roots and stems under higher DO (e.g. 40 ppm) may be due to the fact that high root zone oxygen levels significantly increased root respiration rates.” Note: This statement is a little misleading; after the root zone grew to its limit in 40 ppm solution, it began to reduce in size in-relation to how massive it had become from the treatment. The root zone treated with 40ppm was still substantially bigger than the one with 8ppm.

• “The results imply that tomato root zone DO could be as high as 30 ppm for up to four weeks without causing any negative effects on plant growth.” Note: Again, this is misleading per the above explanation.  It is also worth noting that it is virtually impossible to deliver 40ppm of DO in a golf course environment, 30ppm is about the max.

Thoughts and Comments

It is no secret how important oxygen is to water, turf, and soil, and this study is a perfect basis for this thought. Most golf courses spend tens of thousands of dollars each year on aeration. The main five main reasons for aeration are to loosen compacted soil, reduce thatch layer, improve water infiltration, improve nutrient infiltration, and increase oxygen supply to roots. The combined use of ozone and oxygen gas diffusion has been proven in numerous studies to accomplish all of these benefits nightly through irrigation water gas diffusion. Additionally, this is a non-invasive method which does not cause viable turf disruption or stoppage of play.