Water balance and water applied

The water balance tells you, surface by surface, how much water has been lost to the weather since it was last topped up — so you know which greens need watering and roughly how much.

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How does the water balance work?

Every night TurfWise takes your local weather and works out ET0 — the reference evapotranspiration, or how much water a standard grass surface would lose that day. It uses the FAO-56 Penman-Monteith method.

Each surface type loses water at a different rate, so ET0 is multiplied by a crop coefficient (Kc) to give that surface's water loss (ETc):

• Greens and Nursery — 0.85
• Tees and Practice — 0.8
• Fairways and Approaches — 0.75
• Other — 0.7
• Rough — 0.6

Rain and logged irrigation are then added back. What's left is the surface's deficit in mm — the higher it is, the drier the surface.

What do the risk badges mean?

Each surface gets a risk level based on its deficit. Greens are the most sensitive, rough the least, so the bands are different for each type.

• Low — "No action needed"
• Medium — "Monitor closely"
• High — "Irrigate within 24 hours"
• Critical — "Immediate irrigation required"

For a green, Medium starts at a 2 mm deficit, High at 4 mm and Critical at 6 mm. For a fairway those are 4, 8 and 12 mm, and for rough 8, 15 and 25 mm.

If a surface is Critical and no irrigation has been logged for a couple of days, the overview shows an amber note saying the deficit is climbing.

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How do I choose which surfaces are irrigated?

The water balance only runs for surfaces you've switched on. Open Irrigation › Setup › Irrigated surfaces (the first step of the Setup checklist).

You'll see a card for every course area in your course area library. Click a card to turn irrigation tracking on — it turns blue. Click it again to turn tracking off; TurfWise asks you to confirm, because the daily water balance stops for that area.

The surface type (green, tee, fairway and so on) comes from the course area's type, and so does its size. The first water balance appears after the next overnight calculation — until then the surface shows Pending and "Awaiting first ET calculation".

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What's on a surface's own page?

Click View → on a tracked surface, or click its name on Irrigation › Tonight. You'll see:

• The surface type, its area and the Kc being used.
• Today's deficit, and two buttons — Rate Green and Log Irrigation.
• An Irrigation Recommendation card, when the surface needs water.
• Stats for the period — Avg ET0, Total ETc, Rainfall and Net Balance.
• Charts for ET0 History, Water Deficit Trend and Rainfall. Use the buttons above the charts to switch between 7, 14, 30, 60 and 90 days.

How is the recommendation worked out?

The recommendation takes the deficit and allows for the fact that not every drop reaches the rootzone. It assumes 80% application efficiency, so it suggests applying 1.25 times the deficit.

It also gives a run time using the surface's precipitation rate. If no rate is set for the surface, it uses 15 mm/hr and says so.

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How do I log an irrigation run?

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Where can I see every run?

Open Irrigation › Water › Runs applied. It lists every run logged, newest first, and shows each surface's total. The full walkthrough, including Log a run, is in Runs applied.

Depths aren't added up across surfaces, because 5 mm on one green and 5 mm on another don't make 10 mm of anything. Volume and run time are totalled instead.