Using pot tests to check the uniformity of watering
combination of science and experience. The operator needs to have a sound basis for calculating the frequency and duration of watering. A basic soil water balance is a good starting point here, enabling the operator to get a ball park estimate of the scheduling requirement. Using a water balance approach will require routine collection of rainfall and evapotranspiration data, plus a knowledge of the soil water holding properties, irrigation system efficiency and specific crop factor information. Soil moisture measuring devices, such as a theta probe, could then be used to fine tune the water balance process. Routine soil moisture monitoring (even if done by core sampling and visual observation) offers the additional benefit of checking on the uniformity of watering, enabling problems to be picked up before they start to show up in the turf.
Experience comes in to the equation when accounting for seasonal variation and recognising the variation in watering needs of different areas (for example
Measuring pressure at the nozzle using a Pitot gauge
reduced water use in shaded areas; more frequent water requirement in shallow rootzone areas).
Consider what happens below ground
Having a watering system that applies water evenly to the surface, and at the correct rate and frequency, is still not the end of the story. What happens once water hits the soil surface also impacts on water use efficiency and our auditing process must account for this. We need to ensure the soil is capable of accepting, storing and releasing applied water. Points to look for here include:
• Identifying the water repellency (hydrophobicity) potential of the soil
• Recognising the potential for by-pass flow i.e. where water moves directly via large cracks, worm channels or similar to the sub soil or the underlying drainage system
• Rooting depth and distribution, in so far as it impacts on water storage and retrieval capability
TWENTYQuestions
Sam Breeden, Sweepfast - he don’t need another hero, but would like life to be a ‘beach’!
Who are you? Sam Breeden of Sweepfast, artificial pitches maintenance contractors.
Family status? Married with one daughter.
Who’s your hero and why? I can honestly say that I don’t have any ‘heroes’ but there are a number of people I admire.
What is your dream holiday? A secluded beach with Julia Roberts.
What annoys you the most? Speed limits on motorways.
What would you change about yourself? My back, I could do with a new one!
Who wouldn’t you like to be? I guess, like many people, Gordon Brown.
Favourite record, and why? Easy, Albatross by Fleetwood Mac. It’s fantastic and so evocative!
Who would you choose to spend a romantic evening with? Julia Roberts (see above).
If you won the lottery, what is the first thing you would do? Probably drink too much!
If you were to describe yourself as a musical instrument, what would you be and why? A guitar - there’s lots of different ways to tune me!
What's the best advice you have ever been given? Treat people the way you want to be treated.
What’s your favourite smell? Greek cooking and oregano.
What do you do in your spare time? Write, paint and play the guitar.
What's the daftest work related question you have ever been asked? Does an artificial surface need any maintenance? - every week!!!
What's your favourite piece of kit? My sat nav!
What three words would you use to describe yourself? Honest, ingenious, poor.
What talent would you like to have? I’d love to be a better musician.
What makes you angry? Questionnaires!
What law/legislation would you like to see introduced? A separate driving test for competence to drive on motorways.
Using a theta probe to measure soil water content
• Soil water retention characteristics (soil type, organic matter etc)
Without an understanding of the soil and its properties the system operator is flying blind.
Summary
Irrigation is a significant investment, both in terms of capital outlay and the ongoing costs of water and maintenance. Therefore, it would seem logical that due regard be given to ensuring it is properly designed and managed. Auditing allows us to benchmark current performance of the system and, more importantly, identify what could be done to make best use of the water resource. A professionally conducted irrigation system audit will investigate not only the system hardware, but also how it is used and the impact of the soil reservoir on water use efficiency.
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