CHRIS HENRY: My name is Chris Henry, I'm an associate professor and water
management engineer with the University of Arkansas System,
Division of Agriculture, located here at
the Rice Research and Extension Center.
What I'm going to talk about today is irrigation
water management for rice farmers.
And also then what we've been doing to help improve
the furrow irrigated rice production system.
First, I want us to talk about the irrigation contest,
most crop per drop.
This is an extension program where farmers take a 30-acre field
and manage irrigation the best they can to get the highest yield.
So we call it the most crop per drop because
we measure the total amount of water,
both irrigation and rain, versus their yield.
We take a 3 acre or small check plot in every field.
We measure and seal the meters so that we
know how much water goes on the field.
And then we award a first, second, third place to the winners.
This year we have 40 people in the irrigation contest,
14 people are new.
Last year, the person that won it was Cody Fincher.
He used a cascade flooded rice field, which is not what
I would recommend someone entering the irrigation contest,
but did a very good job and won with management,
really manage the water in the field.
And that's really the idea behind the irrigation contest.
It gives us an opportunity to really look
at how we manage water on the field
and get a lot of information about how we're
doing with irrigation on that field.
Every person who enters gets a report card,
so they get to see how they compare to everybody.
So you get to see what your water use efficiency is,
what your yield was relative to everyone else.
And now that we have a lot of repeat people in the contest,
they're getting to see historically how they're doing
if they're improving with the irrigation water management.
Next, I'd like to mention our mobile apps that are available to farmers.
We have the rice irrigation app,
to help design multiple inlet rice irrigation,
and we're going to release a new version of that in 2022.
And also our Arkansas Watermark Calculator tool,
where you can use that to help interpret water mark sensors.
We've been adding some information into that app
about how to manage furrow irrigated rice.
So you put in your soil moisture readings,
your soil type, plant growth stage,
effective rooting depth, and it tells you then
how far away you are from irrigating.
Then lastly, here behind me, we have my main research
program where we look at furrow irrigated rice,
how we can improve that, this has been about a seven-year project.
So it's all no till, it's been no till for five years,
we try to keep the beds intact, continuous rice, usually hybrid.
This particular hybrid here is 7321 RiceTec FullPage rice.
And then what we try to do is interlace things that we can do to
try to improve the furrow irrigated rice production system.
We've developed this novel tailwater recovery
system or pitless recovery system.
So there's no tailwater pit, we basically use this
pump that's behind me to collect the tailwater
that comes off the field and immediately return
it back to the top end of the field.
So we essentially recirculate water around the field, around and around.
And it's allowed us to really reduce our water consumption.
We're over 90% efficient generally.
And last year we grew 200 plus bushel rice
on 12 inches of water using this system.
One of the problems with furrow irrigated rice
is that we irrigate much more frequently.
And as a result we have a lot more issues
with the beds eroding near the poly pipe.
And so we have tried some different things,
ideas to try to mitigate this crossing over
or short circuiting of the furrows.
Last year we tried landscape fabric, that actually worked pretty well,
or it's actually plastic mulch is what it's really called.
And it just wasn't long enough and sometimes the water would
push past it and then start to erode and cut underneath it.
This year we tried a different product.
It's a Tyvek product we made and developed
with a drip fitting to try to push water
down in the furrow and kind of get past
this area where it will often erode.
So we've been working on a variety of different things to try to
make the whole production system work better and more effective.
One of the important questions we're trying
to answer is really how often do
you need to irrigate furrow irrigated rice and how can we improve that?
So we've set up an experiment or we've looked at zero,
three, seven to 10 days,
and this year we've expanded it to zero, three,
five, seven, 10 and 14 days.
And within that, what we try to do is we measure the soil moisture,
we time the irrigations, and then we measure the yield.
And that allows us to build a picture of at what point in the soil water
balance do we need to decide to irrigate with that yield penalty.
So that's what we've done out here.
And then we have the zero day, so we get this comparison between all
of the spectrum of when we might irrigate furrow irrigated rice.
And that provides this information we can
use for our mobile app development,
which is how to schedule irrigation with watermarks.
We're at the top of the field now.
And on my left or your right is the zero
day irrigation where this is the plot
where water has been going down the furrows continuously,
the last two months.
The rice is very tall, filled out well,
and then here on the right is the 14-day irrigation cycle.
The the soil has got a lot drier over here,
the rice isn't as tall, hasn't flushed out quite as much.
But this is what it looks like, a 14 day rice,
only irrigated twice all summer and irrigated every day.
So what we've learned so far is that we can probably go to about a 40%
allowable depletion with about a 14 to 24 inch rooting depth.
We recommend putting watermarks at four,
four, six, eight, 12 and 24 inch depth.
And that gives us a pretty good assessment of the soil-water balance.
And everything we've found in the fields over the years,
has the support of that recommendation that we're just now releasing.
So if you use the mobile app, you can use that information
then to help decide how often to irrigate.
One thing that I've learned is that row rice is
incredibly resilient to different practices.
So we haven't seen a huge difference in the zero to 10 day,
it's a very small numerical difference,
but it's not significant, that's what we saw last year.
So the next thing we've looked at also is nitrogen management.
How can we fertilize and what's the interaction
between irrigation and nitrogen?
So this year we've added a nitrogen study
on top of our irrigation study.
To try to answer the question of if we wait to irrigate later,
will we need some more nitrogen to make up because
we might lose it through denitrification.
So that's another study we have out in this field that we're looking at.
We've also looked at ESN, Environmentally Safe Nitrogen,
which is really interesting with row rice.
Because it would allow us to put all our fertilizer
on when we put our potash and phosphate.
So we essentially are done with one pass fertilizer application.
And can that fertilizer sustain us through
the entire growing season with row rice?
And so we've looked at that as well,
and then how that relates to how often we irrigate.
Then lastly, we really wanted to step out
and see if we could fertigate row rice.
It's not a practice, we do it in some other
crops and other production systems.
But it's a novel way of supplementing
and adding nitrogen with irrigation water.
So what we do is when it's time to irrigate,
usually after pre-flood time period,
we start to inject nitrogen into the water stream as we're irrigating.
Last year we did it with UAN or 32% fertilizer.
We inject it basically at three different events,
about 50 pounds of nitrogen per acre per irrigation,
we do that three times.
And what you end up doing is you end up doing
it after sometime around green ring
as you do those three irrigation events,
and that worked really well last year.
This year, what we tried to do was use liquefied urea,
which is a little more challenging, but it's a little less expensive.
So what you do there, you take urea,
you put it in water, it's an endothermic reaction,
it actually chills the water,
so you need really hot water to do this, liquefy it.
And we got to about 40% nitrogen in that solution,
and we did the same thing.
Only this year, we tried to put it on a little sooner,
try to get it all on before green ring.
And that didn't work quite as well as I thought.
I didn't think it worked quite as well
as waiting 'til a little bit later.
One challenge that we had this year was
that we had a really heavy rainstorm
right after we laid the pipe and it really washed our beds out.
And so one of the lessons we've learned this
year is you've got to have really good beds.
Our beds had kind of gotten washed out or packed
down from last year, being five years old.
We just used a furrow runner to clear them out,
and some of them had really started to close up.
And so early in the season, we had a hard
time getting water across the field.
But as the rice grows and gets bigger, it actually self corrects some,
especially with the no till soil.
And so now if we'd had fertilizer, it did just fine,
if we couldn't get fertilizer to certain parts of the field,
the rice isn't as well developed.
So that's one thing that we've learned and encourage people to be
mindful of as you try to use this kind of production system.
So one of the other things that we tried to do was, why we fertigated.
We would take tissue samples, mainly nitrogen,
but also looking at our micronutrients.
And we did that along the top, middle, bottom.
And then what we would do as we irrigated every time we would look
at the tissue samples to see if we're deficient in nutrients.
And then we added that in the fertilizer solution
and injected it as we irrigated.
And we found we were short of several micronutrients.
And so we added that in last year, this year we didn't do that,
and I kind of regret not doing that, but we just ran out of time.
Another thing that we tried to do this
year was to irrigate a conventional
to see how we could improve the conventional row rice system.
We've been mostly using hybrids, so last year we started
using ARoma 17 as a surrogate for conventional.
To see if we could grow it in a furrow irrigated system.
ARoma 17 is an aromatic rice, it's never been grown, to our knowledge,
in the furrow irrigated rice production system.
So we did that last year, so we milled it up and packaged it,
feel free to come by the station and pick up a bag.
I'd like to thank the Arkansas Rice Research and Promotion
Board and the University of Arkansas System
Division of Agriculture and all the rice farmers,
all the companies that support our work.
As well as my crew, especially Russ Parker,
who runs and manages the irrigation contest.
And Travis Clark for taking care of the plots out here on the station.
And thanks for joining us today.