 Hello, I'm Tom Scherer. I'm an Extension Agricultural Engineer at North Coastal University. And we're at the Oaks Irrigation Field Day. And I'm going to ask to talk about irrigation during a drought. We're in the middle of a drought right now. Started late last year. We don't know how long it's going to go. And when it comes to irrigation, different things show up and problems show up with irrigation systems. So I'm going to cover some of those problems and some of the management. I titled my talk Irrigation Considerations in a Drought. And as my contact information there, as you can see on the screen, first off, when you talk about a drought, everybody should be concerned about their water sources. And on the screen here, I've got the map showing where the glacial drift aquifers in light blue are located throughout the state. And if I were to superimpose where the irrigation in the state is, most of it would be located on top of those light blue lines. The dark blue are the surface water systems. And we have a lot of irrigation that comes out of there, almost 50%. And if you don't know it, the State Water Commission has a large, large number of observation wells in all of the major glacial drift aquifers in the state. And they measure them periodically. Some are continuously monitored, some are not. But anyway, I checked them. And after this first year, actually our aquifer levels, probably because of the rains in late 2019, are actually at a pretty good high level. We're doing okay in terms of aquifers. They're not being depleted. But as this drought continues, the amount of pumping that takes place increases. And so there's going to be more of a strain on that. And the surface water systems obviously decrease in flow. And they can pose problems for intakes. So the irrigator has to be very conscious about their water supply and what's happening to it. But as of right now, I think most of our water supplies are in pretty good shape, especially the aquifers. The surface water systems, that's really dependent on the flow and rainfall amount. So some can actually get low. Here's another map showing the same thing. And I put this one in here because if you're a new irrigator looking to establish irrigation because of the drought, the green area is on this map. So where there's still open permits, you can obtain an irrigation water permit, although there might be some limitations. But the brown areas, the state water commission labeled them as poor because they're almost fully allocated for either rural water systems or irrigation or industrial use. So the competition for water in our aquifers has been increasing. So if you're a new irrigator, you really need to visit with the state water commission in your area to find out if they know what the water sources are and how hard it is to get a permit. So anyway, that kind of covers the basic water sources and what you need to be cognizant of during a drought. Now, it's been my experience over the last 40 years that when you get into drought, I got a picture here of a typical irrigation well goes up to the surface. Most of them in this area have a gravel pack around the casing. Casing can be metal or plastic. And then you have a screen where the water enters. And the problem is that even with normal pumping in good years, water entering through that screen and the gravel pack can slowly over time can tend to plug them. And when when the aquifers are fairly high, and irrigation demand is not as high when you got a let's say a normal or relatively wet year, these problems don't show up. But when you get to a dry year and you start pumping a lot more, this partial plugging starts to become a problem because the actual water table will drop because of the increased demand for the water, the aquifer levels. And so these the production during the critical time of the season, the growing season decreases. So what happens a lot of times over time, these screens can get plugged with either minerals or rust accumulation, or you can get iron bacteria on them. And so how do you take care of that? Well, if you've noticed this past year with the heavier pumping, if your well is not producing or you start to suck air and you had to valve it back to get the flow, you're reducing the amount of flow that you can get. It's probably a good time to visit in the off season with a well driller to have your system cleaned, jetted or chlorinated. It may be due to iron bacteria, maybe the mineral accumulation may be due to both. But if you don't take care of this problem and the drought continues into next year, this problem will get even worse. So the suggestion is to have your wells checked in the off season is the best time. And iron bacteria, it's always been a recommendation of mine. If you've got iron, if you see red on your center pivot, you should be chlorinating your well every year. That's about the only way you can really control and manage iron bacteria, otherwise it'll just keep building up and building up. Eventually it can plug up the motors, can plug up the well screen, can plug up the gravel packs surrounding the screen, and therefore it hinders any flow of water into it. And the next thing that I noticed during a drought is that a lot of center pivots, because they're out in the field, they're out of sight, out of mind, a lot of times the sprinkler packages are not taken care of. And during a drought, these streaks in the field as shown in this picture start to show up. And as you'll notice, these are right near the pivot point. And a lot of times, and this pivot is actually supplied by a surface water system, the Cheyenne River. And the Cheyenne has a lot of floating debris, probably during the season it drops. And typically the first nozzles that it'll plug or hinder water coming out is right near the pivot point. So this is a real good graphic. But you can see streaking throughout this field, which may indicate that the sprinkler package is not quite right for the flow rate. There may be several reasons to have this, but anybody that's been around irrigation knows that during a drought, these problems with sprinklers start to show up. So what do you do? Well, if you see this, and sometimes this shows up in your, if you've got a yield monitor on your combine, this starts to show up. So what do you do is in the off season you visualize your irrigation dealer and you look at what it would take to renozzle that pivot to check it out. But the easiest thing you can do is start to pivot up, run water through it and just walk the full length of it. And a lot of times you can identify where there's mechanical problems where sprinklers are not operating properly or they're broken or the pressure regulators are leaking. I walked a lot of them and you can visibly pick out individual sprinklers and or boots on towers that are leaking that can contribute to these types of problems. So during a drought, I would say if you see this type of action on your center pivot, I would visit with your irrigation dealer to see about what it would take to renozzle your pivot. But in order to do that, you need a pretty good accurate reading of the flow rate. So this is one of our pivots up at Carrington, and this is the same sprinkler head. You can see on the left, that was what it looked like in 1999 was put on. And on the right is that same sprinkler head. And when I looked at this one operating, it was turning, wasn't turning very well. There were some leaks out of the pressure regulator. This one should have been replaced. The normal life of a sprinkler head is really seven to eight years in our environment because regulators where that blue and that gray joined together, that they were water will leak out there if the diaphragm inside starts to become degraded. So if you got old sprinkler heads, now is a good time before next year to make sure that they're in good work and order. And what happens if your sprinkler package isn't right? This is, we did a can test. As you can see, I'm standing out in a field where we put out a bunch of cans, ran a pivot over the top, we catch it and we measure the amount. We know from what's dialed in at the pivot about how much should be applied. And then we measure it along there. And you can see that we had some areas that were under irrigated and some areas that were over irrigated. And I could pick those out just walking it when it was operating. You could actually see where that under irrigated area, the sprinklers are too far apart. When they put those drops on, they're actually too far apart. They should be closer together. In the over irrigated area, the nozzles were worn. So it's very important, especially during the drought, that you don't have these areas here because you're losing yield. And the over irrigated area, the yield there is not going to necessarily make up for what's under irrigated. If you really want to see how this can test was done, you can go to the end of issue extension YouTube channel. You can do a search on the internet for YouTube in the issue extension uniformity and it'll take you to this video and you'll be able to, it's only about a six, six and a half minute video, but it'll show you how the can test was done and how we measured it and even pointed out some of the sprinkler problems. And of course, I've mentioned this before, but typically during a drought, if you're on a well, the flow rate will drop because the static water level can drop or the water table, you're lifting the water higher, the pump may be worn because of age. Any number of the screen is partially plugged. And if you don't have a good, accurate working flow meter, you don't know how much you're pumping. Along with that, if you don't have good pressure gauges and they're relatively inexpensive, every pivot should have new pressure gauges every other year because they can wear out. But the only way you really know if the operation is, if the system is performing is you got to have an accurate reading of the pressure at either at the pivot point or at the pump. And you got to have an accurate flow meter. Now, flow meters are fairly expensive. And I've recommended for years that as you see the one on the left, that one is to cut a hole in the pipe and this fits into it. Well, how long would it take to take those nuts off, take the flow meter off, put a unit over, seal the hole with some type of banding, and take that flow meter, take it inside and keep it warm over the winter. Because the freeze thought cycles really wears out the gearing on these propellometers. But just for a drought, people really should be looking at these devices. They provide a lot of useful information, especially when competition for water and pumping really starts in July and August. So the last thing I want to talk about is the agricultural water year. And this has to do with when's the most effective use of your irrigation water. So I always talk about the agricultural water use starts in October. So on October 1st, and whenever you get a killing frost, and it's usually around October 1st, when you kill all the plants, there's nothing using water out of the soil. So any rain or snow that you accumulate between that killing frost and when the frost goes out in April, a lot of that might run off, but a lot of it might infiltrate during the fall and the spring. And that's the water that contributes to your soil. So hopefully most years, even in drought years, we may go in where the root zone actually has is at near field capacity or the maximum can hold for plant use. So when you look at the short season crops, like wheat, barley, oats, canola, they use a lot of water and their peak water use is usually around the first part of July and then starts to taper off. And typically we don't irrigate these crops because there's enough soil moisture that we get with rainfall during the season. It's these long season crops like potatoes, corn, soybeans, alfalfa, that's where the problem comes in. So this blue line I just put on there is represents the average rainfall we get through those months in most of North Dakota on an average year if there is such a thing. But anyway, so if you look at this area, that is the time when irrigation pays off is in that hatched area that I put on there because that's when we're not getting enough rain to supplement the peak water use of the crops. So what that tells you is that these are the time periods between usually July 1st and September 1st is when we need irrigation. That is when we get the most benefit. So this is usually true. We usually design for six gallons a minute per acre on a standard center pivot. So on a quarter section pivot, we look to have around 800 gallons a minute. And if you can get, if your water source will provide that, if you're growing potatoes, they like to have seven gallons a minute per acre. And as you can see on here, this is a seasonal corn water use for one year in 2012, which was a dry year. So that crop water use in July, as you can see, anything above that six gallon a minute line is where the irrigation system cannot supply the daily water demand of the crop. So you can see there's some peaks and valleys there. And those are the times when you get, you can get behind with a pivot. So hopefully you got some cool periods that come in. But some years you don't get those and you can have a long period there where you don't keep up seven gallon a minute. You can see that you got less of those those periods when you can't keep up. If you have five gallons a minute, that's even lower. That's about supplies about 2.2 inches per day. Well, now you can see that if you got less water, what do you do? Well, you probably have to start irrigating earlier if you only got five gallons a minute per acre. And you got to store it in the soil. So you got to watch you got to manage your irrigation water much more closer when you get less water. Some other options is if you know you have a low water use on your pivot, you might plant half the pivot to an early season crop, such as wheat or something like that, and the other half to corn. That way you're when you get to the high water use period, you've got enough water to water that that long season crop adequately. So those are just some suggestions for irrigation in a drought. So kind of a summary, if you suspect well problems, have it checked in the off season. It may need chlorination, it may need cleaning, depending on how old it is. If you notice crop streaks this year, maybe it's time to replace or in nozzle sprinkler package. If you have a low volume well, you might have to start considering starting irrigating earlier to maintain soil moisture or split the field and go with a short season crop as opposed and half to a long season crop. And a number of irrigators have done that. Now just remember that July and August is the highest crop water use period, but most research has shown that the most bank of your buck regarding yield is going to occur if you can keep your crop irrigated usually after the 4th of July up until the end of August. If you can keep it well watered, you're going to maximize your yield.