Watering and Drought Management

General

Water is involved with all phases of care and management of turf grass. It is particularly important for germination, cellular development, tissue growth, photosynthesis, temperature control and as a carrier of nutrients in the soil.
Turf grass actively growing is generally 75 – 85 % water.

Transpiration

As turf grasses transpire, water moves up through the plant via the roots. As transpiration increases there is a greater suction imposed on the soil solution drawing water towards the plant. Water is continually lost through the plant by means of transpiration. Transpiration is influenced by temperature, wind and humidity. As the temperature increases there is a tendency for the plant to lose water for cooling the leaf surface under windy conditions. Evaporation from the leaf is high and transpiration is high. Under conditions of high humidity, the transpiration decreases.

Deciding when to Water

The main methods are usually as follows:

  • Hit or miss
  • Careful observation
  • Using instruments
  • Using evaporation figures
Bad Practice

Method of Applying Water

It is preferable to have infrequent deep watering rather than frequent light irrigations. Irrigation should attempt to water to the depth of the root zone. This method encourages good root development.

The irrigation system should have the following characteristics:

  • Apply the required volume of water to root level.
  • The irrigation rate should not exceed the infiltration rate of the soil.
  • Even application of water as poor water distribution especially on uneven surfaces leads to over watering of lower areas.
  • The distribution pattern should not be significantly affected by wind.

Time of Watering

The best time to water is early in the day. This allows the grass to dry off quickly and reduce the likelihood of fungal attack. This is particularly important in the hotter months when dollar spot and brown patch are prevalent. Watering in the evening or late afternoon means the grass is moist for 12 – 14 hours creating good conditions for fungal attack. Watering in the heat of the day is undesirable because the turf is likely to be damaged.

Drought Management

Drought management does not start when water restrictions are imposed. Although the greenkeeper normally knows well ahead that limited water restrictions followed by complete prohibition may be imposed within a certain space of time, he should at all times be aware of the possibility that a drought situation could be in the offing.

Where a Club relies on underground water for its needs the possibility that the supply might suddenly dry up must always be borne in mind.

During the months of November to March most of our grasses are in their prime growth. It is at this time where the use of our irrigation should yield the best results.
In RSA we are continually confronted with potential water shortages, therefore it is important to look at which role water plays in producing good greens.

Planning for Drought Management

Mowing

Proper mowing techniques can make a big difference in whether your green is healthy and able to survive the stress of infrequent rains and water restrictions the objective would be to reduce those operations which increase stress in the grass plant while exposed to drought conditions.

With the onset of watering restrictions the greenkeeper should immediately warn members that he will be obliged to increase the mowing height by, at least, one millimeter. The increased leaf area would produce more carbohydrates (CHO) and at the same time reduce the stress on the grass plant and the defense mechanism.

Irrigation

Having sufficient moisture in the root zone is the cornerstone to the health, growth and survival of the grass plant. With a deep, strong and healthy root system the plant will be healthy, vigorous and more resilient.

Having sufficient water in the root zone is essential, but one must not over irrigate as this will disrupt the balance of air and water in the soil. If the solid soil particles in the root zone constitute 50% then the remaining volume must be made up of 25% water and 25% air. It is when this balance is disrupted, that the plant goes into stress mode.

To encourage a deep root system, one should irrigate depending on the soil texture once or twice weekly. For loam soils water once weekly and for sandy soils twice weekly.

Use a rain gauge to measure how much water you are putting down and then determine how long you want your system to run.

Soil dries from the surface downwards, and under these conditions the roots will grow downwards into the soil towards the moisture. One must not encourage shallow root zone by under irrigating.

The first signs of heat stress are wilted leaves, purple /grey or blue leaf colour and loss of resiliency, for example if your foot print remains on the green when walking on the grass. Drier spots may need more watering, particularly the areas around the two metre mark where players tend to stand during most of the game.

Nutrition

Avoid fertilises high in nitrogen (N) and Phosphates (P).
Fertilise with Potassium (K) as this will make the plant more resilient.
Use Kelp P Max or molasses to promote root development and so to optimise water uptake.

Other considerations

When fertilizing using chemical fertilizers such as 1 : 0 : 1, it is important to water the greens after application so as to avoid damaging the grass. Over application or poor watering can lead to discoloration.

If water is scarce, then an option is to apply an organic fertilizer cocktail which does not require watering in. Such a cocktail can also be applied when the greens are very wet, and the addition of more water could exacerbate the situation.

A cocktail of 1 litre of Ocean Fert and 1 litre of Molasses can be used. This should be thoroughly mixed with 50 litres of water and applied used a knapsack spray.