ET rates for Bermuda grass

To whom it may concern- I am looking for the yearly water usage rate for Bermuda grass (in/yr) for the completion of design on land application of WWTP effluent. If anyone has this information or know where I can find it, I would appreciate your help.

Jason Dearing

You need to know the local area potential evapotranspiration (ETo) by the month. This is the ET of a tall, well watered, cool-season grass that grows year round. Take that ET and multiply by about 0.65 for your warm months. If the bermuda goes dormant in your area in winter then the use is of course zero. S. California area this may mean from 20 to 36" depending on elevation and how close to the ocean.

Blake Sanden

Watering bermuda grass is a complex pastime. We use the TurfSCAN (sister of the EnviroSCAN) in golf courses and water use can vary from enormous to very little depending on rooting depth, watering regime, soil type etc. For example, most golf courses water every night with anything up to 10mms or even more - most of this will either run off to low spots (depending on application rate, thatch, slopes etc) and probably stay on the surface to evaporate quickly in the sun and wind. If you are measuring 'badly' you may say that water use is 10mms per day. However, the grass itself may only be using 1 or 2mms per day. I have done some work on a golf course in Portugal (very hot) with sub-surface drip at 30cms. The roots are fantastic and the water use is no more than .3 times ET. Theory and practice can be a long way apart and unless you are measuring (agronomically correctly) you may = be going in the wrong direction.

Peter White

Water use can be a semantical issue as Peter points out. Assuming one is trying to determine the plant water consumption, or ET, I would have a hard time believing that bermuda would only use 1 or 2 mm/day unless the (low) environmental demand dictated that. If the root zone is extensive, it does not mean it is using less water, only that it can go longer between irrigations as there is more available water due to rooting density and depth. Bermuda is drought tolerant and will adjust to less water, so my take is that bermuda will use what it can get up to the "fully watered" environmental demand which would be some percentage of reference or potential (semantics again) ET. I'm not an expert in bermuda grass crop coefficients so don't know exactly what that would be. Blake Sanden offered some advice on this.

Garry Grabow

I am currently doing my PhD into responses of turf grasses to: Droughting Irrigation Irrigation with effluent Turf grass types include Bermuda, Swazy, Indian couch, Sea Couch, Carpet, St Augustine, Zoysia, Durban and Tif lines. Only preliminary stages of research but will have a clearer understanding for all growing turf in next few years.