ROOT RESPIRATION: How to Oxygenate Irrigation Water for Healthier, More Productive Crops
Too much irrigation water, especially in soils with poor drainage can lead to crop loss. This is explained by a team of scientists in a new 2023 paper in the journal ‘Agricultural Water Management.’
As they note, “When crop roots are in a low-oxygen environment for a long time, it will lead to a series of problems.” This includes anaerobic root disease or root rot, general poor plant/tree health, or even soil salinity build-up, all of which negatively impact yields.
But why is low oxygen a problem for roots?
How much oxygen is in the root zone directly affects the rate at which root cells can carry out their primary functions: absorbing water and nutrients from the soil.
And to absorb water and nutrients, root cells must first carry out cellular respiration.
During plant respiration in root cells, glucose that’s traveled down from the leaves is converted to a cell-level energy form known as ATP (Adenosine triphosphate). Oxygen is required to complete this biochemical process.
The more oxygen root cells have access to, the higher the rate of cellular respiration and the more ATP is produced. With more oxygen, more ATP is available to drive water and nutrient uptake. This leads to larger root masses, better plant health, better growth – and higher yields.
In fact, this team of researchers points out that in studies such as In Vivo Metabolic Regulation of Plant Respiration Under Salt and Nutrient Stress (Del-Saz et al., 2017), Plasticity of root growth and respiratory activity: Root responses to above-ground senescence, fruit removal or partial root pruning in soybean(Fanello et al., 2020), Growth, root respiration and photosynthesis of a root-sprouting short-lived herb after severe biomass removal(Martinkova et al., 2021), “root respiration is one of the indicators for evaluating root and crop growth.”
They explain irrigating with oxygenated water is so important. Doing so “can effectively bring dissolved oxygen (DO) into the soil” where the root cells lay waiting.
HOW TO OXYGENATE IRRIGATION WATER FOR ROOT RESPIRATION
Various methods are used to oxygenate irrigation water to maximize root cellular respiration.
These scientists did an irrigation oxygenation study in the largest cotton production area of China, Xinjiang, in which mulched drip irrigation is the method of choice.
The scientists note that “when groundwater is used for irrigation directly in Xinjiang, the DO concentration of irrigation water is often too low.”
Two issues exacerbate the problem in this region.
“Long-distance pipeline water conveyance makes the water isolated from the air for a long time, which will also reduce the DO in the water.” In addition, “most drip irrigation systems in Xinjiang are made of black polyethylene, which absorbs a lot of heat, increasing the temperature of water within the drip irrigation system.” Recall that as water temperature increases, its DO holding capacity decreases.
The scientists examined venturi oxygenation, mechanical oxygenation (air pump and bubble stone) and chemical oxygenation (adding sodium percarbonate). They noted limitations with all of them, especially soil salinity issues from long-term chemical oxygenation.
However, they point out that “nanobubbles can better combine with water to obtain higher dissolved oxygen concentration and prolong the duration of DO in water (Application effect of different oxygenation methods with mulched drip irrigation system in Xinjiang). This kind of device has been proven to be beneficial in agricultural irrigation by more and more studies (Application effect of different oxygenation methods with mulched drip irrigation system in Xinjiang, Oxidation of flooded paddy soil through irrigation with water containing bulk oxygen nanobubbles, Novel nanobubble technology in food science: Application and mechanism).”
In another 2023 study, ‘Fundamentals and Applications of Nanobubbles: A Review,’ a team from Greece point out other benefits. “Nanobubble technology has shown remarkable results in the agricultural sector, attributed to the enhancement of the microbial community, encapsulating nutrients, retaining soil humidity, etc.”
ROOT ZONE OXYGENATION THROUGH NANOBUBBLES FOR HIGHER PLANT RESPIRATION
A growing number of agri-food operations, especially those producing high-value crops, have researched and purchased Moleaer’s nanobubble technology as a sustainable, cost-effective way to achieve highly stable and optimal DO levels for their crops.
Moleaer’s patented technology supersaturates irrigation water with dissolved oxygen and injects hundreds of millions of electrochemically charged nanobubbles, which alter the properties of water to deliver multiple benefits.
In addition to more stable DO levels, high concentrations of negatively charged nanobubbles reduce the surface tension of water and improve the infiltration of water through soils and substrates as well as improve the capillary action of water and dissolved nutrients. Nanobubbles are also a chemical-free solution to reduce soil compaction and aid in salt leaching. Producing a natural, mild oxidant, nanobubbles reduce water-borne pathogens and algae. Their hard, stable shell allows them to abrade biofilm and scale from irrigation systems and coat piping walls to limit new accumulation – improving system hygiene and reducing treatment costs.
Over 1000 orchards and horticulture businesses around the world have implemented Moleaer nanobubble technology.
For example, after the installation of Moleaer generators, a Chile-based company, Kapicua, saw DO in their irrigation water increase by almost 200% and better water quality that led to improved avocado tree growth and fruit productivity, with an increase of 40% in the targeted fruit size category.
The higher and more stable DO led to higher rates of plant respiration, maximizing water and nutrient uptake by root cells. This, along with the additional benefits of nanobubbles, drove large root mass creation, robust plant growth and higher yields.
NANOBUBBLES OVERVIEW
Nanobubbles are nano-sized bubbles, 200 nanometers or less in diameter. Each bubble is about 2500 times smaller than a grain of salt or the size of a virus.
Due to their size and other characteristics, nanobubbles move randomly around in water using what’s called Brownian motion. As they move, they constantly participate in many physical, biological and chemical reactions.
For example, through their production of reactive oxygen species on bursting and their physical abrading action, nanobubbles disinfect water and remove biofilm from irrigation system tubing. This prevents both water-borne root diseases and biofilm accumulation.
Nanobubble oxygenation improves water quality naturally, boosting root cell respiration, plant vigor and yield. It also greatly reduces the reliance on chemicals to disinfect water, saving costs and reducing the environmental impact.
With Moleaer technology, Maricopa Orchards in California has seen many benefits. By increasing infiltration and nanobubbles’ negative charge attracting salts, they were able to leach salts below the root zone. They also saw an increased DO in that irrigation water of 30 mg/L.
Optimal DO level can be achieved immediately after installation. Growers set the generator to a target DO for their particular crops, once they’ve found the level at which maximum plant respiration is achieved.
ROI ANALYSIS
Moleaer’s nanobubble generators offer a natural, sustainable, cost-effective and highly efficient way to reach ideal plant respiration and corresponding high yields every year, while disinfecting water and irrigation system piping.
