HydroLOGIC was released in 2003.  Can you just give us a rundown of the program please?

The HydroLOGIC software is an irrigation management software that we have put together through the CRC and CSIRO that couples together the Ozcot Crop Growth Model which is a specific model developed for the Australian conditions and a user friendly interface that help our growers and consultants to schedule irrigations and look at different risk management strategies for their water during the season. 

For the last couple of seasons you have been validating the HydroLOGIC program.  Can you just give us a rundown on the work involved and what you are finding?

We have been doing a range of different trials over the last three or four seasons now.  Probably the most visible to the industry would be the demonstration trials that we have been running with some of the Extension Officers and Irrigation Officers within the CRC.  Where we are simply splitting a field in half and managing half with HydroLOGIC and the other half as the grower would do it.  We have had a range of different results with these trials indicating that HydroLOGIC has been useful in optimizing the scheduling and in some cases has saved a last irrigation which has had no detrimental affect on yield.  In 2003/04 season we had a limited water trial comparing scheduling using HydroLOGIC with a standard management under a full allocation and a limited water situation which demonstrated that when you are in a tight situation like that HydroLOGIC can assist to schedule irrigations and maximize the yield.  So those results were reported in 04 Cotton Conference.  Just this last season we have had some trials with AquaTech Consulting through the Cotton CRC where we are looking at applying and integrating the HydroLOGIC tool with some of the tools that they have got in terms of the Irrimate Evaluation Service and the Watertrak software.  So we are looking at how these tools can be integrated together, how they can value add to a growers water management strategy.

Dirk if growers are interested in having a bit of a play with HydroLOGIC where can they get extra information from?

I guess the first stop would be to jump onto the Cotton CRC website.  There is information there download a information sheet on HydroLOGIC.  You can also pick up a CD from the CRC, you just ring up Dave Larsen.  There is further information in the industries WaterPAK publication and I guess the final point would be there will be a range decision support workshops – probably in September this year after the Cotton Conference where we will be going around and just talking about these different tools and products in which people can ask any questions they want there.  

Dirk where do you see HydroLOGIC going in the future?

I guess some of our future plans for HydroLOGIC involve trying to incorporate some type of seasonal climate forecasting within the predictions for our next irrigation and our yield response and also trying to characterize down the different season whether you have got, what you should be doing in an extremely hot season like last season or a wet season if we should get one of those in the future.   I guess we are also looking at whether we can develop a similar sort of concept for other crops because most cotton growers are more than just cotton growers. We are also, along the lines of the integration project with AquaTech seeing whether we can imbed or value add our tools together with that.

Steve, we came down and had a little bit of a chat about two months ago and you gave some preliminary results in regards to some of your irrigation trials.  Can you just give us a final rundown on what you have seen?

Yes the trials that I was talking about were looking at the response of Bollgard to water stress at different growth stages compared with conventional.  What we found this year was very similar as it turned out to last year, that when we put the Bollgard under stress around cutout, say 4 ½ nodes above white flower, yield dropped right off compared with conventional.  We got the same result the year before.  As distinct from what we first thought when we started these experiments the Bollgard would be more sensitive around flowering time.  Yes the yield falls if you put it under stress at flowering but it doesn’t fall any more than conventional but we think because of the greater boll load or more rapid increase in boll load on the Bollgard it can’t compensate for the stress because once we put it under stress we went down to a deficit of about 120mls or greater we then irrigate it again and the conventional because it still had flowers that were able to become bolls it was able to recover and compensate where as the Bollgard couldn’t.  So the message there is it is a bit sensitive once it starts to get some bolls on it from two years data.

Could you just give an outline on what you think the water use between the two technologies is or you know the megalitres per bale kind of figures are?

Yes, one of the things we are doing with these experiments and Monsanto are involved with this with us is to measure the water use of conventional against Bollgard and Dirk Richards is working with me on this and we are using oddessy probes and flumes doing it quite accurately to get a field water balance and what we have found in the last two years is that the yield levels that we are getting here at ACRI which are around the 10 bales per hectare the Bollgard is slightly ahead in terms of bales per megalitre and we think the reason for that is that the Bollgard is actually setting its fruit in a shorter period of time so therefore its sucking water for less time and it has got a lower leaf area.  Now some preliminary data out of ‘Keytah’ in Moree suggests that probably a higher yield levels that difference may not be the case it could be the other way around, but we have got more data to collect there.

Steve you mentioned that under the Bollgard system that water use was a little bit down on the conventional system.  Could you just give us an idea of what sort of numbers you are talking about there?

For about the same yield level which in 2005 was just under 10 bales a hectare both yielded about the same the conventional in that year needed nearly a meg more irrigation water applied to the field.  The reason for that was as much to do with the quirk at the season in the field here in Narrabri as anything else but basically the conventional grew longer.  It was more early fruit loss, it grew a little bit longer and had a bigger leaf area and therefore it needed more water.  In 2006 there was less difference. The Bollgard was slightly higher yielding and the Bollgard used about ½ meg less water and again we think that difference as we work through the data in the situation here was that the Bollgard didn’t grow a set fruit over a shorter period and therefore used water for a shorter period of time.

Steve as part of your trial down here at ACRI you cancelled out an irrigation or a sequence irrigation.  Can you just give us a rundown of what the affects were of say missing the first irrigation.

Yes the first irrigation in the last two years has been around start of flowering and the obvious thing was yields reduced even though you put the second irrigation on but the Bollgard really wasn’t behind the conventional. We originally thought  because it loads up fruit faster and has a smaller plant that it would be set back more by a stress at that time but it  hasn’t, it has the same yield reduction as conventional.  However, as I said earlier when we get to cutout in the Bollgard and usually the conventional hasn’t cutout at that stage it is still fruiting the Bollgard yield drops further under stress than the conventional.

What about in regards to say missing the last irrigation?

OK well we didn’t have the space to do that last year but this year we included a treatment where we actually skipped the last two irrigations so imagine you have got Bollgard and conventional and they have had all the irrigations the first three it was in this year and then I think was after February we didn’t irrigate, we just let it go through from there.  So they were post cutout and in that instance the Bollgard actually yielded better than the conventional.  There is two reasons I think for that.  One is that we had a fair bit of rain.  It was 100mls in that time which helped and the second was the greater boll load of the Bollgard meant that it only had to finish bolls off where the conventional still had flowers to set and convert to bolls.  So it wasn’t able to compensate as well.

What do you think the key points are in regards to this work?

I guess the first thing is that it is work in progress and we have mainly looked at the affect of stress.  We haven’t tried to say how do you optimize Bollgard and make it better but in terms of its reaction to stress compared to conventional its more sensitive towards cutout and I think you have got to be much more careful with Bollgard stretching irrigations once you start to get a bit of a fruit load on it.  I think its probably at yield levels 10 bales less like we got down here.  It seems to be a slightly more water use efficient plant under full irrigation but in terms of if you convert it to bales per megalitre and probably we need to do some more work at higher yield levels to see what happens there with the Bollgard and the water use.