Roots Need Oxygen — Constantly

Plant roots respire just like animal tissues. They consume oxygen to:

• Generate energy (ATP)

• Absorb nutrients (especially nitrogen, calcium, and magnesium)

• Maintain root cell integrity and growth

Plants rely on oxygen dissolved in soil water and air-filled pores in the soil structure. If you are not sure what dissolved oxygen is, read our article here.

When oxygen availability drops, roots shift to inefficient anaerobic metabolism, leading to reduced growth and vulnerability to disease.

Low-DO Water Creates an Oxygen Gradient

Water with low dissolved oxygen behaves very differently than oxygen-rich water once it enters the soil or substrate.

What actually happens:

• Soil pores normally contain air with ~21% oxygen

• Root zones maintain a delicate balance between water and air

• When oxygen-poor water enters this environment, a concentration gradient forms

Oxygen naturally diffuses from high concentration (soil air and roots) into low concentration (the irrigation water). This means the water literally pulls oxygen out of the soil and root tissues until equilibrium is reached.

Oxygen Is Stripped from the Root Zone

Instead of supplying oxygen, low-DO water acts as an oxygen sink:

• Soil air oxygen dissolves into the water

• Root surface oxygen diffuses outward

• Microbial respiration accelerates oxygen consumption

• Soil pores become waterlogged and air-depleted

The result is a rapid decline in oxygen availability precisely where plants need it most.

Compounding Effect: Reduced Soil Re-Oxygenation

Oxygen-depleted soils recover slowly because:

• Gas diffusion in water is 10,000× slower than in air

• Frequent irrigation keeps pores filled with low-DO water

• Compacted or fine-textured soils trap water longer

This creates chronic hypoxic conditions even when irrigation volumes are modest.

Biological Consequences in the Root Zone

When oxygen drops, several damaging processes begin:

1. Root stress and reduced uptake

• Lower nutrient absorption

• Reduced root branching and hair formation

2. Shift to harmful microbes

• Anaerobic bacteria dominate

• Increased production of toxic byproducts (ethanol, sulfides)

3. Higher disease pressure

• Favorable conditions for Pythium, Phytophthora, and other root pathogens

  Read our article about Pythium here and why it's dangerous

4. Slower growth and yield loss

• Energy deficit limits biomass accumulation

• Plants appear stunted, pale, or uneven

Why This Is Especially Critical in Controlled Environments

In greenhouses, vertical farms, and hydroponics:

• Root zones are highly saturated

• Oxygen replenishment relies almost entirely on irrigation water

• There is little natural soil aeration

Here, low-DO water can rapidly induce root hypoxia — even when nutrients, temperature, and light are optimal.

Oxygen-Rich Water Works the Opposite Way

Water with high dissolved oxygen reverses the gradient:

• Oxygen diffuses from water into roots and soil

• Soil pores re-oxygenate faster

• Root respiration remains aerobic

• Beneficial microbes thrive

This is why oxygen-enriched irrigation consistently improves root health, nutrient efficiency, and crop resilience.

Key Takeaway

Water low in dissolved oxygen doesn’t just fail to deliver oxygen — it actively removes it from the root zone.
Over time, this depletes soil oxygen, stresses roots, and undermines plant performance.

Managing dissolved oxygen in irrigation water is therefore not optional — it is a foundational requirement for healthy root systems and productive crops.