Cotton Seed Distributors article

A video version is available at www.csd.net.au/  

A Lysimeter is a device to measure the drainage of water from under the root zone, so it is measuring the downward flux of water that is lost to the plant and if it is irrigated water of course that is wasted water.

The project has been awhile in the adoption and the building of it.  Can you explain actually when the project was actually started and how long it has taken?

The project was started 2 ½ years ago.  It’s turned out to be quite a technically challenging task to design and construct this Lysimeter.  It involves quite an accurate measurement and so to ensure that we have a long term facility that will last us about ten years we needed to make sure that it was properly designed and it has to meet all the safety requirements and so on.

And it has been funded by several different organisations, obviously it would have cost a lot of money?

Yes it has been funded mainly by the Cotton Research & Development Corporation who have funded a three year grant and we have just been given another three years to collect data.

We are here in a cotton field that will be grown with and irrigation field, will it have cotton next year to actually measure water deep drainage in the cotton field?

Yes, this plot that the Lysimeter is in will have irrigated cotton sown in October.

The use of the Lysimeter, what are the main objectives of the project? 

The first and foremost objective is to get a quantitive handle how much drainage there actually is with some precision.  But because we are only doing this in one place with a very expensive piece of equipment of course that doesn’t give us a wider area so the second objective is to use it as a benchmark to test simpler cheaper methods that can be used much more widely.  All of those methods are only measuring over fairly short spaces of time so the third objective is to collect data to enable the water balance to be modelled over long periods of time so we can model of periods of say 40 or 50 years to see if you have a particular soil type, a particular management system, what would be the drainage that would occur over that period of time?

So really at the moment we know very little about deep drainage.  Where water goes to and where it ends up and things like pollutants going into the water table etc?

We understand the principles of drainage.  The problem has always been that most of the methods used to measure make certain simplifying assumptions and it makes very difficult then to check whether we are understanding the system correctly because of the lack of precision and accuracy.

This information relating back to irrigation farmers.  How will they sort of be able to use the data and how can they apply the findings to their own situation?

The data will help us better understand how drainage is happening, when its happening the role of things like cracks which will then enable us to develop methods that reduce the drainage during irrigation.  So directly this data will help us to understand the system and by understanding the system we can then design management systems that are less leaky.

I guess there is lots of variations in soil types across Australia and certainly across our irrigation areas where cotton is grown.  Would you comment on how much water you think actually goes in deep drainage, how much is lost or what would be the average and what would be the range?

In dryland systems because it is much lower, dryland systems you may be looking under anything from near zero up to maybe under native vegetation up to maybe 50 – 100mm.  Under irrigated systems it is a lot greater than that so you may be looking at over 100’s mm per year.

The Lysimeter has been commissioned today.  When do you think we will start to see some data coming out and new models developed?

Well we are hoping that the first year we should get a huge increase in knowledge just from because that will be our first years worth of data.  So next April we should start seeing some results.

OK thanks very much Anthony.