Wetting agents; crucial components of integrated maintenance programmes
With escalating pressure on golf course maintenance budgets and a changeable climate, the selection and use of wetting agents as part of turf management programmes are becoming increasingly scrutinised. With the perception of fewer hot, dry summers and with increasing summer rain across Northern Europe, wetting agents might be considered as non-essential in these regions. However, the reality is they should still play a very important role in quality sports surface preparation and management.
The sand-dominated, free-draining constructions which are so important for year-round play are susceptible to hydrophobic (water-repellent) soil conditions. Additionally, large quantities of sand used to top dress existing surfaces in an attempt to manage organic matter accumulation present the same challenge. Add to this, water shortages in some areas and a new trend to restrict irrigation inputs and the potential benefits of wetting agents cannot be ignored.
Wetting agents are surfactants, a class of chemical compound designed to cause a physical change at the surface of liquids. In simple terms they will lower the surface tension of water. Several different classes of surfactant chemistries are utilised in the manufacture of wetting agents producing different modes of action. Broadly speaking these modes of action can be grouped into ‘summer’ wetting agents , primarily used for water conservation and to prevent hydrophobic dry patch developing and ‘winter’ wetting agents, used to improve water movement, particularly infiltration and downward penetration. More specialist products are also available to aid dew dispersal, flush through salts and to treat dry patch curatively. Understanding the mode of action of a wetting agent is therefore integral to selecting the correct product for the task in hand.
So when should a wetting agent be applied? Well, that all depends on your desired outcome. For fine turf management; where turf uniformity and high levels of playing quality and surface refinement are essential then a full season-long wetting agent programme is recommended. This gives optimum wetting agent performance, allowing effective water management and control of localised dry spot with its associated inconsistent turf quality. The programme should commence early in the season with the initial application being made as early as March. The majority of products are designed to be used preventatively on a monthly basis. In general, their effect is cumulative. This means that the level of wetting agent in the soil increases with each application. The aim is to maximise levels to coincide with the hottest and driest portion of the year (July/August) to maintain a better balance of air and moisture within the soil for optimal plant health and surface performance. As a result, the sward should be stronger and heathier with a deeper root system and as such will provide the best playing surface and will be less vulnerable to disease infections.
Using a quality wetting agent in a programmed approach through the season will provide additional benefits for rootzone constructions dominated by sand. These products will retain a healthy level of moisture deep in the upper profile, keeping any organic matter layer drier at the top but reducing leaching. This can be particularly important where ground cover is restricted, especially in newly sown areas where vulnerable seedlings are particularly susceptible to hot and dry conditions. As well as ensuring the turf has access to enough moisture for healthy growth the potential cost savings are significant, especially where mains water has to be relied upon.
Furthermore, where fairy rings are consistently problematic, regular applications of wetting agent can help to prevent their development and reduce the severity of their impact on the turf when used in conjunction with preventative fungicide applications where organic matter is managed effectively. Type 1 fairy rings cause the most severe damage to turf and if allowed to develop will result in turf death, usually as a consequence of hydrophobic compounds released by the causal fungi (basidiomycetes).
Wetting agents can also bring about significant improvements in playing quality to give the competitive edge required by many sporting venues in these economically competitive times. This is particularly true in fine turf situations such as golf and bowling greens, where the ball to surface interaction is so important. If moisture levels are inconsistent, surfaces will be bumpy and unpredictable with significant variations in pace – not an enjoyable surface to play. A more uniform level of moisture brought about by regular wetting agent inputs will serve to improve consistency of grass growth thereby maintaining a smoother, truer, more predictable surface to be enjoyed by members.
Increasingly, many turf managers are also looking at penetrant wetting agents for use during the winter or periods of higher rainfall. Their use focuses attention on year-round water management which assists in fine turf surface improvement. During wetter periods, turf surfaces can become and remain saturated. This is problematic for a whole host of reasons: reduced sward density; reduced rooting; poor water/air ratio leading to anaerobic conditions in the soil and a reduction in microbial activity; reduction in organic matter breakdown; surface deformation caused by pedestrian and machinery traffic; increased susceptibility to disease infections and moss invasion.
Penetrants work by reducing surface water tension to assist the downward flow of water and can be used all year round to move excess water from the soil surface into the soil profile if that is required. Maximum benefit will be gained when used in conjunction with surface aeration and in the presence of underlying drainage. Regular use will keep surfaces drier and help to maintain a heathier balance of water/air in the profile. The benefits will be a stronger, healthier turf with a good root system that is less prone to disease infections. Additional benefits should also include more effective organic matter breakdown, a more consistent surface with good turf density with less moss, weeds and algae.
Wetting agents are not a silver bullet that will solve problems and improve playing qualities on their own. For maximum benefit they should be used as part of an integrated management plan which utilises effective irrigation inputs to replace water lost to evapotranspiration and linked to frequent aeration operations to variable depths to keep a healthy rootzone environment. A good quality moisture meter is a great agronomic management tool for any turf manager, allowing soil moisture levels to be monitored. Such instruments bring an objective focus to a previously difficult science and allow a much more targeted approach to irrigation and moisture management where surfaces can be allowed to dry out more than could previously be risked and with a greater emphasis on hand-watering.
In summary, moisture management utilising the latest wetting agent technologies is a crucial part of the integrated approach to quality turf management. There are a range of wetting agent products available on the market so know the product you are buying and ensure that it is designed to give you the results you desire. Be prepared and make the initial application early enough to optimise the benefits in quality to be gained; follow the programme recommended by the product label. If possible utilise a moisture meter to assist in decision making and be flexible; don’t be afraid to make changes to your moisture management programme to provide the results required for your surfaces.