Author: Craig Bratby
Company: NSW Government

Guide to mid season draining of rice
YouTube video transcript 20 March 2013.
I’m John Fowler, Deniliquin District Agronomist. I’m in a rice crop here in the Murray Valley of NSW. This crop was sown about 8 weeks ago and it’s been permanently inundated up until about 2 days ago when the water was taken off. And the water will stay off this crop now until it actually dries down a fair bit. This is a practice that we call mid-season draining and it’s of increasing prominence in the Murray Valley. What we’re trying to do is protect the crop from any damage from physiological straight head, that’s a condition we don’t know much about and it’s a condition we can’t screen for, but what we can do is take water off the crop at this stage and that will minimise the impact of the condition on the rice.
This rice crop is a crop of Opus and Opus is a variety that’s particularly prone to physiological straight head, but we know it’s a condition that will affect other rice varieties as well.
Now the aim of this video is to show you basically the growth stage that we commence the drying process, to show you how dry we’re going to make the crop before we reintroduce the permanent water and also then show you quickly this crop will recover once permanent water is reintroduced.
Now if we have a look here at this rice, we can see it’s well and truly into mid tillering and our aim will be to dry it down probably for about 2 weeks, put the water back on and we’d like the water to be back on definitely 7 days, preferably 10 days before this crop reaches panicle initiation.
Here we are in a bay that’s been dry for about a week now and it’s had a bit over 60mm of evaporation occurring in that time. The soil has started to crack and that’s what we’re really wanting to see, so that the oxygen can get back down into the soil. And we’re starting to see some stress signs developing on areas that have had extra nitrogen or might have been a little bit high and were the first bits to dry out. We’ll keep this water off this bay for at least another 3-4 days, perhaps longer, we’d like to see another 30-40mm of evaporation and then we’ll assess it. Mainly we’ll assess it visually to see the levels of stress and we’d like to see most of it stressed to at least that degree, before we reintroduce water.
Well here we are back in the bay. It’s about 5 days since I was here, probably had about 50mm of further evaporation, so this bay’s probably had about 110mm of evaporation since we dried it off. As you can see it’s looking very dry and this is now ready for the water to come back in. Water in fact will be reintroduced here tomorrow.
Here we are, it’s been about 3 weeks since the water has been back on this area here and the crop has basically recovered. As you see here, we’re in a patch of high nitrogen and you really can’t see any sign of the old leaf. It’s not that the leaf that was withered off has regrown, there’s still withered leaves down there, but it’s the fresh leaves come through and cover it up. If we go over to an area of low nitrogen, you’ll still be able to see the signs of the stress because the fresh growth is a bit slower coming through and doesn’t cover the stress so readily. The signs of stress are still there where there’s low nitrogen but where the nitrogen’s adequate the fresh growth as covered it up.
Acknowledgements: Don Griffin, Technical Assistant and Karen Roberts, District Agronomist Parkes (NSW Department of Primary Industries)