Wetting agents play their part in turf husbandry

With high temperatures forecasted, it may well be worth looking at your current wetting agent programme to make sure you are using the correct product for your surfaces. In most cases, if the forecasters are right, holding moisture and dealing with dry patch will be the main priorities, therefore, the products you are using need to be well suited to the needs of your turf.

Water plays a significant role in all chemical, physiological and biological processes of plant growth. The soil/plant water relationships is crucial in relation to the sustainability of any grass plant. Having an understanding of these relations is critical. All grass plants are a continuum of water movement, with over 90% of the plant's water requirements being transported through the plant from the soil profile, via the roots and stem tissues, into the leaves and out into the atmosphere.

In recent years we have seen a rise in demand for wetting agents to help improve the soils ability to take in water. Wetting agents are used to reduce the surface tension of water and improve the ability of soils on golf courses to make best use of available water and help increase water absorption. In the UK, numerous wetting agents are available, with each product performing slightly differently depending on its mode of action, dose rate and suggested programme of use.

Soil wetting agents are available in three forms - Residual, Penetrants and Curatives:

Residuals keep working over a given stated period, depending on the amount of time you require it to work they hold water near the surface.
Penetrants help remove standing water as well as move water through the profile. Many turf managers use penetrants in a tank mix, when using other chemicals to get the product through the profile immediately.

Curatives combat the problem of dry patch by stripping off the waxy organic coating on the soil particle which renders the soil profile water repellent. However this may never totally alleviate the problem as every time you top-dress with sand, you add a further layer of water repellent organic coating to your soil profile. This type of wetting agent is believed by some to also remove beneficial bacteria from the soil and therefore can be controversial. Although, one of the lesser known facts is that when using curatives your water consumption can reduce by up to 30% year on year.

The best results of applying wetting agents are achieved by starting early in the season before symptoms are observed. Blanket applications are recommended as opposed to spot treatments as a more effective approach. The longevity of each product depends on the dose rate, therefore, subsequent applications should occur after the suggested period of effective control has elapsed for each product. Attention should also be paid to the form of each product, as mentioned previously.

For example, a curative does not help water penetration but helps to remove the organic coatings on sand grains and flush them through the rootzone. Therefore, it should be used in a programme with another soil wetting agent that helps water distribution.

To achieve the best from wetting agents, any factors contributing to the dry patch should be addressed before application. This may include alleviation of compaction, removal of thatch and preventing the rootzone from reaching the critical moisture content by ensuring even and timely irrigation.

These factors may affect the results of the wetting agent depending on the circumstances, i.e. if you have a high thatch content, a wetting agent with a high polymer content could be detrimental as it prevents the surface from drying out. In this situation, a penetrant would be more effective by drawing moisture through the thatch layer. Conversely, a substrate that is very free-draining, e.g. a USGA spec green, would benefit from a wetting agent with a high polymer content as water retention within the rootzone is a limiting factor.

Ray Hunt is a Technical and Regional Sales Manager for Amenity Land Solutions. You can contact Ray Hunt on Ray.Hunt@amenity.co.uk or phone 07815 578920.

Please see a range of wetting agents available from amenity.co.uk