Understanding surfactants and their uses for water repellent soils, drought stress & water conservation practices.

Introduction – the consequences of climate change

The consequences of climate change are impacting the green keeping industry. Prolonged drought periods are likely to increase in severity and frequency due to rising temperatures causing increased evaporation rates. In addition, it has been noted that there is a decline in precipitation throughout the summer months and therefore the level of irrigation required is determined by the amount of precipitation to ensure adequate water for the plant. This is putting ever increasing pressures on the green keeping industry regarding water availability.

In this article there are two main aspects to discuss which effect the visual aesthetics and performance of the playing surface. Firstly, dry patch and water repellent soils, this is an area which is difficult to rewet even when a high volume of water is applied. Secondly this article will discuss drought stress, this is simply the turf not receiving sufficient irrigation water.

Finally, we will discuss the importance of soil surfactants and their use to combat dry patch and drought stress related issues and look at the key points when choosing a surfactant product.

Dry Patch- Water Repellent Soils

Dry patch is defined as an area of turf that dries out and becomes difficult to rewet even when a high volume of water is applied. It is usually characterized by the presence of a water repellent soil, I.e. The soil repels water. This is visually characterized by irregularly shaped areas of dead or wilted turfgrass. These are a cause of concern to greenkeepers across the world due to reduced visual quality and surface performance.

The source of this water repellent soil has been linked to fairy ring activity and the breakdown of organic materials in the root zone as part of natural plant decomposition processes. This process leaves a waxy deposit on the soil and sand particles which is water repellent.

Drought Stress

Drought stress is categorically different; there does not need to be water repellent soil present and the dryness is a consequence of another turf problem. In principle, a golf green may have both dry patch and drought stress.

The main reason is that poor irrigation coverage may lead to drought stressed patches. Simply the area is not receiving sufficient irrigation water.

Another issue which is often overlooked is poor rooting from a variety of causes, meaning the plant cannot take up the water which is available.

Lastly, frequent mowing at low cut heights has been found to reduce the resistance of amenity turf against drought.

What Are Surfactants

Surfactants (Surface active agent) by their presence change the properties of those surfaces.  They reduce the interfacial tension between solid/liquid and liquid/liquid phases. The cohesive forces between water molecules are very strong making the surface tension of water high.

As surfactants absorb, they break these interactions. The intermolecular forces between surfactant and water molecule are much lower than between two water molecules and thus surface tension will decrease.

This reduction in surface tension not only allows water to penetrate the soil, it also allows it to distribute and spread more evenly in the profile. These two aspects are ideal for drought stress turf to facilitate the water to target the roots of the plant.

Finally, for water to rewet and attach to a water repellent soil it first needs to attach to a material which has the right polarities, i.e. a surfactant. It does this due to the polarity of the water, the water repellent soil, and the surfactant.

  • Water is Di-polar – its molecules have both a positive and negative charge (H2+, O-)
  • Water can attach to other polar (+) substances but cannot attach to non-polar (-) substances
  • Water repellent soils are non-polar (-) Due to polarity, water is repelled from water repellent soils.
  • A surfactant chain forms a bridge between or acts as a link between these polarities and the water repellent soil and the water allowing the water repellent soil to re-wet.

Why We Use Surfactants

Surfactants have historically been used to greatest effect in the amenity turfgrass industry for the maintenance of golf courses and sports pitches for drought stress and water repellency issues.

There are three main reasons why we use surfactants in the spring and summer months, firstly surfactants can help overcome drought stressed turf by improving the distribution of water into the rootzone. It achieves this by ensuring the applied water penetrates the soil and does not run off the surface. This ensures the water is available to the plant through the root system.

Secondly, surfactants can temporarily overcome the hydrophobic property of the soil by binding to both the organic coatings and water molecules, effectively joining them together and allowing the soil particles to become ‘wet’.

If used correctly, they have potential to allow for a reduced irrigation frequency and therefore increased water use efficiency. This is achieved as the water penetrates down through the soil profile quickly. This reduces water loss through surface evaporation or surface run off.

For further information on the complete surfactant range contact HITAS using the form below or visit  our product offerings https://hitas.co.uk/product-selection/

Understanding surfactants and their uses for water repellent soils, drought stress & water conservation practices.

Introduction – the consequences of climate change

The consequences of climate change are impacting the green keeping industry. Prolonged drought periods are likely to increase in severity and frequency due to rising temperatures causing increased evaporation rates. In addition, it has been noted that there is a decline in precipitation throughout the summer months and therefore the level of irrigation required is determined by the amount of precipitation to ensure adequate water for the plant. This is putting ever increasing pressures on the green keeping industry regarding water availability.

In this article there are two main aspects to discuss which effect the visual aesthetics and performance of the playing surface. Firstly, dry patch and water repellent soils, this is an area which is difficult to rewet even when a high volume of water is applied. Secondly this article will discuss drought stress, this is simply the turf not receiving sufficient irrigation water.

Finally, we will discuss the importance of soil surfactants and their use to combat dry patch and drought stress related issues and look at the key points when choosing a surfactant product.

Dry Patch- Water Repellent Soils

Dry patch is defined as an area of turf that dries out and becomes difficult to rewet even when a high volume of water is applied. It is usually characterized by the presence of a water repellent soil, I.e. The soil repels water. This is visually characterized by irregularly shaped areas of dead or wilted turfgrass. These are a cause of concern to greenkeepers across the world due to reduced visual quality and surface performance.

The source of this water repellent soil has been linked to fairy ring activity and the breakdown of organic materials in the root zone as part of natural plant decomposition processes. This process leaves a waxy deposit on the soil and sand particles which is water repellent.

Drought Stress

Drought stress is categorically different; there does not need to be water repellent soil present and the dryness is a consequence of another turf problem. In principle, a golf green may have both dry patch and drought stress.

The main reason is that poor irrigation coverage may lead to drought stressed patches. Simply the area is not receiving sufficient irrigation water.

Another issue which is often overlooked is poor rooting from a variety of causes, meaning the plant cannot take up the water which is available.

Lastly, frequent mowing at low cut heights has been found to reduce the resistance of amenity turf against drought.

What Are Surfactants

Surfactants (Surface active agent) by their presence change the properties of those surfaces.  They reduce the interfacial tension between solid/liquid and liquid/liquid phases. The cohesive forces between water molecules are very strong making the surface tension of water high.

As surfactants absorb, they break these interactions. The intermolecular forces between surfactant and water molecule are much lower than between two water molecules and thus surface tension will decrease.

This reduction in surface tension not only allows water to penetrate the soil, it also allows it to distribute and spread more evenly in the profile. These two aspects are ideal for drought stress turf to facilitate the water to target the roots of the plant.

Finally, for water to rewet and attach to a water repellent soil it first needs to attach to a material which has the right polarities, i.e. a surfactant. It does this due to the polarity of the water, the water repellent soil, and the surfactant.

  • Water is Di-polar – its molecules have both a positive and negative charge (H2+, O-)
  • Water can attach to other polar (+) substances but cannot attach to non-polar (-) substances
  • Water repellent soils are non-polar (-) Due to polarity, water is repelled from water repellent soils.
  • A surfactant chain forms a bridge between or acts as a link between these polarities and the water repellent soil and the water allowing the water repellent soil to re-wet.

Why We Use Surfactants

Surfactants have historically been used to greatest effect in the amenity turfgrass industry for the maintenance of golf courses and sports pitches for drought stress and water repellency issues.

There are three main reasons why we use surfactants in the spring and summer months, firstly surfactants can help overcome drought stressed turf by improving the distribution of water into the rootzone. It achieves this by ensuring the applied water penetrates the soil and does not run off the surface. This ensures the water is available to the plant through the root system.

Secondly, surfactants can temporarily overcome the hydrophobic property of the soil by binding to both the organic coatings and water molecules, effectively joining them together and allowing the soil particles to become ‘wet’.

If used correctly, they have potential to allow for a reduced irrigation frequency and therefore increased water use efficiency. This is achieved as the water penetrates down through the soil profile quickly. This reduces water loss through surface evaporation or surface run off.

For further information on the complete surfactant range contact HITAS using the form below or visit  our product offerings https://hitas.co.uk/product-selection/

See also