Subscribe
Share
Share
Embed
Welcome to University of Minnesota Extension's Nutrient Management Podcast. Each month we bring you the latest research in nutrient management for crops and how you can incorporate the latest tips and best management practices to your farm.
Hello and welcome back to University of Minnesota Extension's Nutrient Management Podcast. I am Jack Wilcox in communications here with Extension.
Jack Wilcox:Today we're going to talk about irrigation in Minnesota. We'll discuss some current conditions, what's new or on the horizon regarding irrigation and irrigation research. We'll also talk about resources available for farmers interested in adopting irrigation tech or maybe better irrigation tech.
Jack Wilcox:Joining us are three specialists and educators. Could you each please introduce yourselves?
Carl Rosen:My name is Carl Rosen. I'm a Extension Soil Scientist at the University of Minnesota in the Department of Soil, Water, and Climate. My area of expertise is nutrient management, primarily in irrigated systems. So this is a timely topic.
Tim Gieseke:Hello. I'm Tim Gieseke, an extension educator located out of Mankato and Farmington. Position hold is egg water management. I focus on drainage as well as irrigation. Today, we'll be irrigation and cover, you know, the the area the irrigation bell Bentley for irrigation and then Southern Minnesota for drainage.
Vasu Sharma:My name is Vasu Sharma. I am irrigation specialist in the department of soil water and climate at the University of Minnesota, and my research and extension work focuses on topics related to irrigation, precision irrigation, soil moisture sensing.
Jack Wilcox:Vasu, let's start with you. What are current conditions like in Minnesota around irrigation?
Vasu Sharma:Yeah. So if we look at let's start with this season. If we look at this season's weather, we are getting good rains if you think about Minnesota as a whole, but rainfall is very distributed. So I was checking whether yesterday we got good rains in some parts of the but where we have research plots at Becker and at Westport in mostly central region where we are irrigating, we did not get that much. Maybe two tenths to three tenths, which is not enough for, at this time enough for crop growth.
Vasu Sharma:So we are seeing rain rainfall in in some parts where we don't need irrigation, but we also we are also seeing there are parts in the state where we do need irrigation even right now. At the beginning of the season, we, at the research farm, had to irrigate a little bit, like three tenths, four tenths just for germination. So overall, we are seeing that this year, based on the climate projections, what we are seeing is overall more rainfall, but same as last year's, we are going to see those long dry spells where irrigation is needed and will be required for crop production. And when I think about irrigation, I don't it's not it's no more just for drought years. I feel like it's like a risk management tool now because from past years and now in the projections as well, what we are seeing is that overall, we are getting more rain cumulatively, but there are long dry spells during the season when a crop really needs that water and we are not getting that water from mother nature.
Vasu Sharma:So irrigation really helps in in those scenarios.
Carl Rosen:It also depends on the soil that you're on. The the sandy soils that are generally irrigated anyway are the ones that are most vulnerable. And the coarser texture your soil, the more sand in your soil, those are the ones that are going to need the irrigation to mitigate the problems of drought.
Vasu Sharma:We sometimes think, like, okay. We got one inch of rain, and we should be good for another week or so. But when we talk about sands, sands cannot hold that one inch, you know, and give that all that one inch to your crop because the water holding capacity of these sandy soils is very low. Even we get one inch, that water drains very quickly to the groundwater. So frequent irrigation in these sandy soils is very, very important.
Vasu Sharma:The heavy heavy rainfall doesn't always help with with crop water demand. Sometimes the water that we are getting does not match with how much water the crop is using.
Carl Rosen:Yeah. You can get a five inch rainfall, and you would think, oh, I'm good for a long time. But on a sand, it doesn't matter if it's five or one inch. It's about the same because most of it is is moving through the soil profile.
Jack Wilcox:So in that case, the soil profile is not like a bowl. It's more like a sieve where we lose irrigation more quickly than other soil types. Could you talk to us about where the aquifer is and how it gets recharged?
Vasu Sharma:Different kinds of aquifers that we see here in the state, but particularly talking about irrigated region, the the Central Sands Region. We most of the region where we are irrigating, our aquifers are very shallow aquifers. So the main problem, I would say, is not with water the scarcity of water that we are overusing of the water and emptying that aquifer. The main issue that we are seeing in these surficial aquifers is nitrate leaching. So when we are applying more water than our soil can hold, and we talked about it.
Vasu Sharma:It's coarse textured soil, which is kind of draining water very quickly. If we are applying fertilizers, you know, all the all the good things that we need, the crop needs, and we are applying more water than our soil can hold, all of these nutrients are going into the groundwater and very quickly because our our aquifers are not very deep. So that's one issue. There are regions in the state where we are also seeing issues with water quantity. We know that these surficial aquifers are interrelated with nearby lakes and streams.
Vasu Sharma:So when in in the year when it's very dry and irrigation systems are continuously working, there are some instances where we have seen decline in surface waters as well, which is in connection with these surficial aquifers.
Jack Wilcox:And when you say they're shallow, do you mean that the quantity of water is less, or do you mean that the water access is closer to the surface?
Vasu Sharma:It's water access to it's closer to the surface.
Jack Wilcox:Carl, what's new in terms of irrigation research at the University of Minnesota?
Carl Rosen:Most of my irrigation research is done in collaboration with the SU, but my expertise is potatoes. And potatoes are very sensitive to dry conditions, particularly early in the season. It's it's kind of interesting. Certain varieties are very sensitive to drought. And what happens is there's two things that can happen.
Carl Rosen:One is some certain soil borne diseases such as scab can be more prevalent under dry conditions. And so, making sure that, you have adequate moisture will help suppress that scab org organism. The other issue is is more related to processing of the potatoes. And if you're under dry conditions during tuber initiation and early tuber formation, you can get what we call sugar ends, which is a a an accumulation of sugars in those growing points. But when you process it, it leads to an off color in the potato.
Carl Rosen:And so trying to reduce sugar ends is is extremely important. One way of doing that is making sure that they're not under stress drought stress conditions early in the season. Certain cultivars are more susceptible to that, and one of the main cultivars that we grow in in Minnesota is Russet Burbank. So our research that we're doing now, related to irrigation has to do with cultivars, nitrogen management, and then different irrigation regimes. It's a very integrated study.
Carl Rosen:A lot of people are involved with it, but it's one that I think is going to help answer some questions. So some of the cultivars that we're looking at in addition to Russet Burbank, which is the one the main cultivar that's still grown here, are some newer cultivars such as Dakota russet and Hamlin russet. And those are cultivars that seem to be more tolerant perhaps to some of these dry conditions, particularly early in the season in terms of causing these problems that I just talked about. So we're testing those cultivars out. We're also trying to find more efficient, nitrogen utilization in these cultivars.
Carl Rosen:So we're looking at, the Hamlin russet and the Dakota russet as being a little more efficient than, russet Burbank. So we're testing different nitrogen rates in addition to the cultivars. And then on top of that, we're looking at the irrigation, which is a a a major part of this study. We have basically six irrigation street treatments where we're looking at, you know, the conventional irrigation based on the checkbook method. And then we have 80% of the checkbook method and then 60% of the checkbook method.
Carl Rosen:Those are fixed irrigation regimes. But then we're also looking at different timing of irrigation. So we have maybe 80% early in the season, 100% in the middle part of the season, and then 80% later in the in the season. So the idea is that if we can reduce a little bit in certain times of the year, we may be more efficient in water without affecting yield. We're still concerned about the quality part, and that's why we're hoping these newer varieties of potato might be able to tolerate that relative to us at Burbank.
Carl Rosen:So without going into too much more detail, I mean, we had different nitrogen rates. We had the these different, irrigation regimes, fixed irrigation regimes, different timings. So we go down to 60%. And even in some of our other studies, we're even going lower than that. But in this particular study, our lowest is is 60%.
Carl Rosen:So we're just trying to see what the limits are for potatoes, kinda stretch those limits, and see what they can tolerate. We're in our second year. That's being conducted at the, the sampling research farm at Becker with that nice linear irrigation system. We hope to be able to conduct at least another year, but we are also measuring nitrate leaching, which is a important component of this study as as well.
Vasu Sharma:I can go into the corn soybean irrigation studies that we are conducting right now. So last year was the first year. This growing season is the second year of that study. And what we are trying to do is looking at some conservation practices like no tillage and cover cropping, right cover cropping, and integrating them into corn soybean rotation and trying to figure out the soil water dynamics, like how these conservation practices will help or not help with maintaining that soil moisture and how it would impact irrigation management. So in this research, we have we also have four irrigation treatments where we are kind of mimicking weather or climate scenarios when we have optimum water, when we have excess water, when we have just lower than optimum water, so deficit.
Vasu Sharma:And then if just the ambient conditions if we don't irrigate at all, so rain fed plots. And under each of these irrigation scenarios, we have plots with no cover crop, then cover crop that is planted in fall. So it's cereal rye that we plant after harvesting of corn and soybean. So it goes dormant. It comes back in spring.
Vasu Sharma:We terminate it, and then we plant our corn or soybean in respective plots. But then other plots will have no cover crop. And then two tillage practices, which is conventional tillage, so deep tillage, and then the other is no tillage. So we are kind of trying to see which combination is best. As I said, nitrate leaching is one of the major issue we have.
Vasu Sharma:So we are also looking at nitrate leaching. We have suction cup lysimeters in each of these plots, and we are looking at how much under each of these practices nitrate is leaching below the root zone. So the collection cups are at four four feet depth. And then two crops, corn and soybean, and we kind of swap it every year. So where last year, it was corn, this year, it's soybean, and vice versa.
Vasu Sharma:And we are doing this in two locations in Central Minnesota. One is at Becker Samprin Research Farm, and other is at Westport Roshold Farm.
Jack Wilcox:Vasu, how many years is your study in total length?
Vasu Sharma:For these kinds of studies, what we are seeing is that longer term is required because these practices takes time to give us some answers. For now, I have funding for three years, but depending on funding, I would like to keep this going for several more years so that we can actually look at what these practices are telling us.
Jack Wilcox:In our last irrigation episode on the podcast, we covered what are some of the benefits and risks of irrigation, and then in what ways can risks be mitigated, maybe through timing. And Vasu, you just talked about cover crop adoption. If a farmer is considering adopting irrigation practices, what should they focus on first?
Vasu Sharma:Yeah. So so starting with the benefits and risks, I would see all benefits. One risk that I I see is if we are not managing irrigation efficiently, if we are over irrigating or under irrigating. Right? So if we are under irrigating, of course, there's a direct impact on yield.
Vasu Sharma:But same for over irrigating. We usually think if we are over irrigating, we are providing enough water to the to the soil, our crop is going to do great. It's just the problem of wastage of water. But it's not just that. Even with water overwatering, we are not we are not giving enough oxygen to our roots, so it's not going to grow.
Vasu Sharma:So there is a direct impact on yield even with overwatering. So it's it's wastage of water, wastage of nutrients, but at the same time, it's going to impact yield too. So that's the only problem I would see if we are not efficiently irrigating. And that's what we are promoting that use the tools like soil moisture sensors, weather data. Try, you know, integrate those in your irrigation management.
Vasu Sharma:So this is not replacing what, like, a human. Right? Technology can never do that. Of course, you have to go out in the field, look at the soil crop. How is it doing?
Vasu Sharma:You cannot 100% rely on these, technology and tools, but integrating them into your decision making is very important because they give you insights into what you cannot see through your eyes. Right? If you have a soil moisture sensor, you can track where the water is going. If you are under irrigating or over irrigating. Right?
Vasu Sharma:If your water is if you're irrigating, your water is not reaching, let's say, to the bottom of your soil profile or the rooting zone, let's say, two feet, that means you have to irrigate more. So soil moisture sensors are not only for telling you irrigate less. They can also give you information if your water is reaching where you want it to reach. Right? So integrating these tools with your decision making, I think, is really, really important.
Vasu Sharma:The other question I'm getting from farmers is how we can trust these tools, right, that are available to us. So my answer would be, as I said, it cannot 100% replace. Like, you sit in your office and you just start and stop your irrigation based on that single number. The soil moisture sensors usually give you data from a single point in the field. Okay?
Vasu Sharma:So that's something that is important, but that also doesn't give you a whole picture. Right? What's happening in the field? It's important that you, you know, scout the field, go out in the field, look at your crop, and make that decision integrating all of data together. So there are other tools like OpenET where you can look at your field from satellite.
Vasu Sharma:Right? You get a satellite image of how much water your crop is using. So integrating all of that weather information, satellite information, soil moisture, make that informed decision of how much and when to irrigate. So trust will be built up over time. It won't be like a one day thing.
Vasu Sharma:Once you start using these tools like sensors, over time, you will know what they are, you know, what information you are getting from those and how to use that information into your decision making.
Tim Gieseke:It's kind of ironically, I I I come across this in my drainage world where soil types would be your your risk that you want to check. So see we talked about sandy soils, but there are variable soils out there in some places. And I've been come across where people install tile line under their irrigation system because surface soils get too much water. So, you know, mitigating that risk upfront, would it be, you know, wiser to look at variable rate systems before you install, or do you put a system in and then try to, you know, compensate for that those tighter soils? So there's some risks there associated with soil types.
Jack Wilcox:Let's talk about some different resources that might be available for farmers. Are there any partnerships or financial resources that we should talk about?
Tim Gieseke:Yeah. Probably the prominent one of late the last few years is the Regional Conservation Partnership Program, so RCPP. It's a federal program with the word regional in it and partnership, so it really seeks out regional approaches with state and local partnerships. In the USDA NRCS state agency and local government, that's the soil and water conservation districts, are really the the the first stop on on understanding this. So there's the soil water conservationists do do a gamut of work.
Tim Gieseke:I would say the, you know, looking at the soils, as I just mentioned, would be a a key to see what what kind of, you know, irrigation potential or risk you have there, as well as any soil quality. You know, as we talk about these sands not holding much water inherently, how do you manage that field to increase maybe organic material? Use cover crops. How do you how do you keep that ET balance more transpiration than evaporation? So that's really the fundamental there of the of the soil water conservation districts.
Tim Gieseke:But then this this RCCP kinda takes that at another level. It provides funding. Last fall, I think, it would be, like, $11,000,000 for irrigators in a dozen or so counties. This spring, I think they offered 5,000,000 of that and had a large demand on that. Those funds can be used for variable rate irrigation, as we talked about, soil moisture sensors, other precision water systems, anything that can help the producer fine tune their system they're putting on there.
Tim Gieseke:And I believe it's also yeah. It's for upgrading, retrofitting existing systems to make them more efficient and bring these technologies in. So contact your soil and water conservation district. The RCPP covers kind of like from Dakota County as you go Northwest through Stearns and up to the Northwest at irrigation sand belt areas is the counties. Not all counties are eligible for it, but there's about, I think, 18 or something like that or 20 counties.
Tim Gieseke:So quite a significant piece there. So the RCPP is a would be the first good stop to go.
Vasu Sharma:I I second that. I think your first stop would be your soil water conservation district. Talk to them. They have various resources, including RCPP, some local resources that are just for the county. So talk to your SWCD partner.
Tim Gieseke:And I should mention the Department of Agriculture is the state agency that manages that fund and receives the applications. But, yeah, the soil and water is the first stop, then that process goes through the Department of Agriculture.
Jack Wilcox:Are there straightforward ways for a farmer to perhaps step into irrigation rather than jump in? Maybe not do everything all at once?
Tim Gieseke:If I could start just from the aquifer perspective, had some background in how that works. So Department of Natural Resources provides the appropriation permit. So you'd wanna know the capacity of the aquifer you're tapping into, and then if it is being tapped extensively, there's generally conditions that the Department of Natural Resources puts on there. I don't believe they can we're in a riparian state, so you have access to water that you're by, but they're they're allowed to put conditions on maybe when it's being used and how and how much. There's anyway so the first step is really understanding your water source and make sure the limitations aren't too restrictive than you wanna use for your crop.
Vasu Sharma:And if you are already irrigating and your question is what kind of technology I should adopt, where to start. I think the best way is to get involved with us with extension. So we also do programming. Like, Minnesota Irrigation program is a good way to start learning about the basics of irrigation, what kinds of tools and technologies available, and where to start if you are a beginner in in in that area. So I would say, we do this every year.
Vasu Sharma:Contact us. We can, guide you through that, on timing and everything and, start with the educational course and see what you want to do next.
Jack Wilcox:And we'll put links to those programs in the show notes as well.
Tim Gieseke:My experience with irrigation isn't a great many years, but what I've really appreciated is the extent of expertise that really goes into being a high efficient irrigator and the technologies available today. So I could imagine fifteen years ago, it was it was a lot of let's say shoot from the hip. Right? Because there wasn't a lot of technologies to know what's going on in your soil sensors. Now there's a lot of that available, but, again, that's a burden of really understanding all those technologies.
Tim Gieseke:But it's it's highly sophisticated systems that people are are operating.
Carl Rosen:And the sensors are getting better every day, so the technology, as you mentioned, Tim, is really phenomenal.
Tim Gieseke:Maybe mention one of those is on the I believe it was a potato irrigator with cameras attached to AI assessments where they can identify tiny bugs, insects, predators, whatever they may be. Again, it takes a human person to occupy their time to read all these things even though they getting noticed by the AI and the cameras. Steep it's learning curve, and like you say, it's constantly changing, so it's really hard to stay ahead of that game.
Jack Wilcox:What have farmers said who maybe you've met with early on, and they've tried some of the adoption processes, and then they've come back a couple of years later, three, four, five years later, and fill you in about what they've accomplished? Tell us about conversations like that. How do they go?
Vasu Sharma:I work with many growers in irrigated counties very closely. And what I've seen that when we start working with them at the beginning, there are some doubts and, you know, like, what we are doing. But now I feel like I have a grower. I'm working with him from last four, five years on a variable rate irrigation project. And we we have some soil moisture sensing equipment in their field.
Vasu Sharma:We are doing their prescription maps, doing VRI. And I see, like, overall, when I talk to this person that they are more confident now doing this VRI on their own. And when we talk about these topics, there is more confidence. That's what I can say.
Tim Gieseke:Talking to the local conservation districts, they have a lot of these stories. I think part of it, it takes a while to absorb over years what they needed done, and maybe they kind of forget what they did know, but there's a lot of stories of people just gradually becoming experts in this over time by the grants available, but also just the technical assistance and then the research.
Jack Wilcox:Vasu, what's irrigation like throughout the rest of the country, and how do we differ here in Minnesota?
Vasu Sharma:Yeah. Irrigation isn't isn't same as we see in Western states. They cannot grow crop without irrigating. We are very lucky that we are here in Minnesota where we get lot of water through rain, and our groundwater resources are way better than other Western states. We are irrigating, I think, total of three to 4% of our total cropland, but there are other states like Nebraska and California and other Western states where they are irrigating majority of their crop cropping acres.
Vasu Sharma:So if you divide US into two, Western and Eastern, there's most of the irrigation happens in the Western United States. And Eastern United States, we don't have much, but that being said, there is now a trend of moving irrigation from Western United States because of the water scarcity problems. There are less resources there now, so irrigation is moving from Western states to Eastern states because we have to produce that food for our population. Right?
Tim Gieseke:As I think Vasu mentioned earlier about it, it's, you know, it's a risk management even in in the places that do get rain fed because we all you know, this the climatic regime is, you know, gives us longer droughts and longer wet periods, it seems like. Even irrigation with drainage systems is starting to emerge. So in Iowa, they're taking drainage systems where you're getting a lot of the spring rains, and then they're holding them in in ponds and basins and then irrigating them back onto the field. So it's it's kinda managing both water sources. But yeah.
Tim Gieseke:So people are getting very creative, and I think there's also beside of the standard pivot system, there's multiple ways now people apply water even with some, I wouldn't say dragline, but similar to that, as well as sub irrigation. There's a variety of irrigation technologies that are coming in place that fit different fields, different topographies, and different timings.
Jack Wilcox:That was Tim Gieske, Vasu Sharma, and Carl Rosen. Thank you all for being here.
Tim Gieseke:Thank you.
Carl Rosen:Thanks, Jack.
Jack Wilcox:Do you have a question about something on your farm? Just send us an email here at nutmgmt@umn.edu. Thanks a lot for listening and we look forward to seeing you next time.
Jack Wilcox:We 'd like to thank the Agricultural Fertilizer Research and Education Council, or AFREC, for supporting the podcast.