UISGE BEATHA-The Water of Life
By Adrian Mortram- STRI Irrigation Consultancy Services
For many of us a wee dram is a pleasure, to be taken with a little water, no doubt. However, for grass, water is an essential ingredient in maintaining the quality of the playing surfaces required for sport. With the summer of 2003 being one of the hottest on record and legislation in the form of the Water Bill almost on the statute books, it seems sensible indeed to look at water accountability and consider such topics as:-
- Water conservation measures
- Accurate recording of water usage
- The use of modern technology, and
- Water resourcing
A recent report1 investigated the effects of climate change on water usage. It concluded that both domestic and industrial water use would rise by 2-3% by the year 2020; whereas agricultural use was predicted to rise by 2-3% per annum due primarily to a longer growing season. This predicted additional water usage showed region-specific, with the South East and Thames Valley the most affected.
A second report2 of a worldwide nature and not specific to agriculture/horticulture was alarmist predicting that:-
- In many countries throughout the world there is currently a severe water shortage yet leaders refuse to acknowledge the problem
- There will be a reduction of up to one third in the water supply during the next 50 years
- The water crisis will affect between 2-7 billion people worldwide
The fact that this report is alarmist will probably provoke Western governments into action and the action will be extended to the easiest targets, you the end user. In response to previous reports, the British Government has introduced the 'Water Bill', much of which revolves around 'sustainability' and 'taking water responsibly'.
The principal areas within the new Water Bill which concern users of spray irrigation for sports turf are summarised below.
- Removal of abstraction licensing exemptions currently given on grounds of use,
- Establishing an extraction threshold of 20 m3 per day, above which an abstractor needs a licence,
- Time limiting all new and existing abstraction licences for a duration in the order of 15 years, whereas in the past licences were granted in perpetuity,
- Streamlining the licence application, modification and transfer system, allow trading of water rights between parties,
- Placing water companies under an enforceable duty to conserve water,
- Giving the Environmental Agency powers to revoke an existing abstraction licence without compensation if it has not been used for four years,
and most importantly:-
- Giving the Environmental Agency powers to require abstractors to enter into water management arrangements and to use water in an efficient and effective manner.
So, how will this affect the end user? Well, there is a pressing need for us all to become more 'accountable' and to demonstrate that we are using available water resources efficiently. This initially involves having a good working knowledge of soil water availability and the link between simple soil and plant science, as well as an understanding of the relationship between gravitational water and field capacity. Furthermore, it involves an awareness of infiltration and percolation rates. Such considerations will ensure good conservation practices and prevent water wastage by reducing over application, surface run-off, and inadvertent losses through drainage water. It is also essential to know how much water is being applied, not in 'so many minutes' but in millimetres per hour, as this can then be compared favourably or otherwise with the infiltration rate.
A working knowledge of the above will assist in the ability to better manage available sources of water and, more precisely. to 'calculate' rather than 'guess' the potential irrigation demands of the turf. A water balance sheet3 may help further. This involves not only monitoring the condition of the turf on a daily basis through such cultural skills as the observation of foot printing and the relative dryness of the cores through sampling, but also balancing the water input to water loss from the turf. Water input is by natural precipitation (which is free) and by irrigation (which has a cost). Water loss from the turf is by transpiration through the leaves and evaporation from the soil combining to give evapo-transpiration (E/T). Figures, all be it average figures are available for E/T via the Met Office (MORECS data), and rainfall can easily be measured by a rain gauge. All that remains to produce a simple 'profit and loss' account (water balance sheet), indicating not only the need for irrigation but the amounts required, is the ability to maintain daily records and be aware of the precipitation rates from the irrigation sprinklers. Working with the concept of a little water depletion, that is to say not returning the soil to field capacity, a buffer can exist to allow for dew or unexpected rainfall and noting that the turf/playing surface may perform better in a controlled depletion condition. By constantly returning the rootzone to field capacity, or above, wastage of water can occur, the soil structure can be impaired, surface rooting may be encouraged and nutrients could be lost via gravitational water through drainage.
Modern technology can also play its part in improving water use efficiency. Good irrigation design, computerised irrigation control, variable frequency drive pumping systems and on-site weather stations can all help to build up a picture of irrigation water usage and a maintain a credible 'water audit'.
Irrigation system considerations
The objectives of an efficient irrigation system are to apply water:-
- To the areas requiring irrigation evenly
- At the optimum precipitation rate to allow infiltration into the rootzone
- In quantities necessary to maintain soil moisture at the required level
- At the optimum time during the day or night
Computerised irrigation control brings many advantages which when combined with accurate evapo-transpiration and rainfall data obtained from a weather station provides the user with the ability to 'calculate' rather than 'guess' irrigation requirements, all of which will be essential in the future. Computerised controllers also use sophisticated 'hydraulic management' to minimise hydraulic stress within the system, reducing bursts and saving water. This will be particularly noticeable if your pump station uses variable frequency control whereby the pump flow matches the demands of the system.
An on-site weather station to record meteorological data such as temperature, humidity, wind speed, solar radiation and of most importance to irrigation, rainfall and evapo-transpiration can help with our water use efficiency. Applying only that water which the soil-plant environment requires can save between 10-15% of water within a cycle, which for those who rely on mains potable water can result in a significant saving.
It may also be prudent at the current time to look at water resourcing. One thing is for certain, water will become more expensive in the future. Check abstraction licences and monitor current daily and monthly usage. If your water is mains-only then research potential alternatives. If your predominant water is ground water check your licence agreements. In either case it may be necessary to consider the construction of some form of water storage facility. There has recently been a number of articles on the use of 'grey water' or 'waste water'4. This has to be a potential water source for the future especially where a user such as a golf club has a leisure facility attached. 'Waste water' has both advantages and disadvantages but could be used to supplement other forms of irrigation water.
So where does the Water Bill leave us? I believe as our industry uses only 0.1% of all available water in the UK that if we show accountability by demonstrating a working knowledge of soil water matters, have a written water policy, maintain accurate usage records and effectively demonstrate conservation techniques with the aid of modern technology, we should be in a strong position to meet the demands of the future.
1 DOWNING, T.E., et al. (2003). CCDeW Climate Change and Demand for Water, Research Report, Stockholm Environmental Institute Oxford Office, Oxford.
2 UNESCO (2003). World Water Crisis Worsening, AgraNet.
3 MORTRAM, A. & HUME, R. (1999). How much to apply and when. STRI Turfgrass Bulletin, 199, 5-7.
4 MORTRAM, A. (2003). The effects of irrigating turfgrass with wastewater. STRI Turfgrass Bulletin, 219, 30-32.