The Ruminant: Audio Candy for Farmers, Gardeners and Food Lovers - e.05: Irrigation Tips from Troy Peters

Episode Date: September 25, 2015

This episode: Troy Peters, an irrigation expert with the Washington State University Extension Service, talks about best practices in crop irrigation. We discuss a cool new smartphone app that helps farmers decide when and how much to irrigate, I learn techniques for deciding when it's time to water, and Troy explains how to approach irrigation of different soil types.

This is the Ruminant Podcast. I'm Jordan Marr. TheRuminant.ca is a website dedicated to sharing good ideas for farmers and gardeners. At The Ruminant, you can find past episodes of this podcast, essays I've written, a few book reviews, and a whole lot of photo-based blog posts, some of which were made by me and some of which were submitted by you. So I hope you'll check it out, TheRuminant.ca. And if you want to get a hold of me, editor at theruminant.ca or at ruminantblog on Twitter. Okay, let's do this show. Hey folks, I am just about to head out into the mountains for some hiking Hey folks, I am just about to head out into the mountains for some hiking with my wife, Vanessa.

So it's a rerun this week. This week I'm putting up a past conversation with Troy Peters about irrigation because it never made it onto the new feed when I switched over to my new feed about a year ago. So I hope you enjoy it and I hope you'll consider sending me an email or a text message or something to that effect telling me about a good decision you made on your farm this year because I would really like to to share your insights on the podcast here editor at theruminant.ca 250-767-6636 if you want to send me a text or you can call my voicemail hotline [phone] and leave a voicemail there. Thanks, have a great week, and I'm going to try real hard to have some new content for you next week. In this episode, I interview Troy Peters. Troy is trained as an irrigation engineer and works out of the extension service at Washington State University. In this conversation,

Troy and I talk about an app that he and his colleagues have developed to help farmers and gardeners figure out the best way to approach the irrigation of their crops. We also talk about some common mistakes that farmers and gardeners make when irrigating, as well as some techniques for determining when it's time to water your crops. By now you must be teetering on the edge of your seat with bated breath. But I need to tell you that I record this podcast out of my house and while I recorded this interview, there were men here at the house doing stuff to the house. I'm having some renovations done right now and three quarters of the way through the podcast, you'll hear some very annoying power tool sounds. So I apologize for that.

But so it goes. And I'm going to think a little bit more about avoiding power tool sounds in future interviews. So you have that to look forward to if you check out the next episode. Okay. Enjoy this conversation. So Troy Peters, thanks very much for coming on the podcast. I'm glad to be here. So I've asked you on today to talk about a topic about which you claim to be very passionate, irrigation scheduling, but first maybe you could tell us a little bit about your work

that you do at Washington State University and perhaps what you've studied in the past. Sure. So my degree actually is in irrigation engineering, and so this is what I do. I'm an extension irrigation specialist at Washington State University. I work here at the Irrigated Ag Research and Extension Center, and I'm also a registered professional agricultural engineer. Ag Research and Extension Center, and I'm also a registered professional agricultural engineer. So basically, for those of you that don't know what extension is, it's part of the land grant university system, and our purpose is to reach out and extend your research-based information to the masses and to help develop tools and things for growers. And so it's to take the research and then get it out to the people. Excellent. Well, that's what this podcast is all about. I'm really glad that we have you on today.

Do you spend a lot of time, Troy, talking to farmers or how are you spending most of your days at work right now? We do have a research expectation and so I do quite a bit of research. We're doing some research on the deficit irrigation of various types of crops like mint and hops and canola and switchgrass and some of these things. What we're trying to do is determine exactly how much water these plants need under different conditions and what happens when you cut it back a little bit because in the future you know with water shortages they're thinking of you know strategies

to manage those shortages by cutting back a little bit water cut back the water a little bit to these various crops so I want to look at that and see how that works however in terms of my extension responsibilities, most of that I speak at a lot of events, grower organizations or education events. I speak probably 20 to 30 times a year to growers and do education type of things. I also maintain a website to help growers who have questions about irrigation, somewhere where they can go and get answers to those questions. And I do field quite a few phone calls as well, you know, and I'm not, that's fine. Oh, great. Okay.

Well, I should mention, Troy, that my partner and I have a small-scale market garden, organic market garden that we run in the Okanagan Valley of British Columbia. The climate of which would be very similar to the Okanagan Valley as it extends into Washington, very dry, hot climate. And in our future with population growth, I think water conservation is going to be an increasingly important issue. So I think I'll end up wanting to ask you a few questions specific to growing mixed vegetables in my context. But maybe first you could just talk a little bit then about irrigation scheduling, because that's what you told me you wanted to talk about today. And I have to admit, I wasn't even really that familiar with the term. So you can treat me like the ignoramus that I am. No. So it's very typical that people are not very educated about irrigation scheduling. This is kind of what I hope to do with my career because I think this is where I can get the biggest bang for the buck in terms of what I can do with education. And so you did mention water shortages, and that is a reality for more and more people. There's just not enough water to go around for all the needs,

and there's always downstream demands and um and uh for fish and wildlife habitat restoration and things um and in the future it's only going to get worse with climate change and with the the demand to grow additional crops for biofuel production as well as the demand to grow more food for a growing population. But water supplies are limited, and so it's going to get a little tighter in the future. So what we're trying to do is help people get the most out of the water that they do have. And basically, the best way to do that is to have an idea of when to turn the water on and when to turn it off and how much to apply when you do water and are you sure you really need that first irrigation, do

you need that last irrigation, those kind of things. That's what I hope to kind of help people learn how to do. And so what we've done is, you know, there's several different ways to do this. There's soil moisture sensors. There's, you know, some basic irrigation scheduling techniques. But in order to make it kind of simple for folks, what we've done is we've put together an irrigation scheduling app, or it kind of acts like an app basically it's a website that is made

for a very small screen so it'll work across a whole variety of different mobile platforms such as iphone or android or blackberry or even some windows 7 or or uh or whatever the Windows one is. But you set up your field. You tell it, okay, here's my nearest weather station. Here's the crop that I'm growing. Here's an estimate of my soil. And with that, we can estimate how much water the plant is using based on the weather data, you know, how much water is plant is using based on the weather data,

how much water is in the soil, how much water the soil can hold in your crop root zone based on your crop's growing characteristics and the soil characteristics. And it just kind of does a water balance. It's kind of the checkbook method. You keep track of how much water is going into the water bank account in the soil and how much water is being used by the plant. And with that, we can get a rough idea of when to irrigate. So that's an online tool. Right now, it's integrated with the Washington Agricultural Weather Network. It's called AgWeatherNet. You can go on and get access to it there.

But we're working to expand it to additional weather networks as well. Okay, so right now I'm out of luck for using it because it sounds fascinating. But for now it's just Washington State growers that have access because you're connected to the Washington State weather forecasting? Well, everybody has access to it, but it's only right now it's only hooked into the agricultural weather network. And so you've got to pick a weather station that's in Washington right now. In other words, we measure weather conditions at these weather stations all throughout the state of Washington, and we use that weather data to estimate crop water use. Oh, wow. Okay. I know you're doing work, you're monitoring your own test crops and stuff.

How accurate is it at this point? Is it pretty reliable as a tool for helping farmers decide how much water to use? So the short answer is yes. I mean, it gets you close. The long answer has to do with, you know, there's, there's so much variability in soil type and soil structure and how much organic matter is in your soil and, and, uh, you know, how you've treated the soil in the past and, and your particular location, whether you're downstream of trees, you know, if you're south facing slope,

of trees, if you're south facing slope, and all kinds of how rocky is your soil, and particular variety of plants and things that all kind of go into that to introduce quite a bit of uncertainty into all crop water use estimation methods and irrigation scheduling techniques, even with soil moisture sensors, such that you're going to find some variability in everything. But it gets us in the ballpark, and it's a lot better than what most people are doing, which is kicking the dirt and looking to see if it's drying the first half a centimeter or so of soil, which isn't very representative of a one-meter deep root zone that's typical of most agricultural crops. Or they just do the guesstimate. Or they look at the crop and wait to irrigate until the crop sees water stress,

and by that time they've already taken a yield hit, and so they're getting less, you know, less yield than they would see otherwise. And just let me mention really quickly that when people, you know, there's been a lot of studies when people do irrigation scheduling and they see, they actually get some sort of data to know when to water and when to stop watering. They use about 20, you know, 10 to 30 percent, you know, depending on what you were doing before, less water than they were before. So they save significant amounts of water and that saves quite a bit of money on pumping

costs. It also saves a lot of fertilizer costs, believe it or not, because before if you water too much, which people tend to err that way, which they water too much, what they do is they rinse those fertilizers out of the soil and it moves it down past the bottom of the root zone and into the ground water. Not only that, so they use less water but they tend to see better yields, like 10 to 25% better yields just by knowing when to irrigate and when not to irrigate. Well, I can say, Troy, that my own approach to irrigation is really, I mean, it's rudimentary and just kind of ignorant. I still have lots to learn. So I'm going to ask

you a few questions about my own garden in a few minutes. But just going back to that application, because I think that's really interesting. Could you give me an example? So if I'm in Washington and I have, you know, say I'm close to a weather station, which I would expect makes the app even more effective. If I sign up to use the app, what information do I have to input about my soil and farm, et cetera, before I can use the application? Yeah, good question. So there's been lots of these types of tools that have been developed by researchers in the past. The problem with most people like myself is that we tend to think that everybody knows what we know and develop tools that are complicated and require lots of inputs. We've kind of gone away from that and specifically tried to – I hate to use the word, but dumb it down a little bit and make it simpler.

And to make some assumptions that most researchers don't like to do because they're not perfectly accurate, but just to make it simpler to use and set up. And so right now the input is there's just five things. You tell it, you give it a name, you name the field, and the way it's set up you can put in an unlimited number of fields. So if you've got 150 fields or you're a consultant and you've got a bunch of them, you can set all those up in there. So you just name the field and then you choose the growing year,

and you can go back and do historical years. So like right now it's at the end of the season. And you can go back and do historical years. So like right now, it's at the end of the season. I could go back and run the data for this year and kind of see when I put water on. And I should be able to see water stress in this model. And that should line up with what I actually saw on the field. So anyway, you could go back historically and get a whole bunch of, even for previous years if you want to look at those.

So you name the field, you choose the year, and then you choose the crop. You choose your soil texture, and then you choose the weather station. So just those five things. Right, okay. And then the soil texture is just going to give the application a better idea of what your watering patterns will be, I guess, then based on how much that texture tends to retain water. Exactly.

So, for example, if I got a sandy soil, people tend to think, oh, sandy soils, you need to really pour the water to it because, you know, sandy soils, but that's a misnomer. Sandy soils just can't hold very much water. And so you need to water less, but much more frequently with sandy soils. And versus, you know, if you've got a deep silt loam soil or, you know, a clay soil, those soils can hold a lot of water. And so in those, you can water deep or put a lot of water on and just do it much less frequently. And so the water holding capacity of that soil is really important.

And so by choosing a soil texture, it kind of makes guesstimates of what your water holding capacity is and your field capacity, which is the maximum amount of water that that soil can hold before it's just going to drain on down through. Right.

Okay. And I'd like to ask you a little bit now, Troy, about just some common mistakes that growers and farmers make. But if I ask you about it in the context of mixed vegetables, are you comfortable with that? Do you have enough experience with mixed vegetables? Oh, yeah, sure. Yeah, yeah. Great. So could you talk, are there a couple, two or three you could point to,

common mistakes that growers are making, especially if they're easy to fix? What I think is probably the most common mistake, there's misconceptions. One is sandy soils, you have to water a lot. And actually, when you water sandy soils a lot, then you're actually making the problem worse because everybody sees stress in sandy soils and you see water stress first in sandy soils because they can't hold the water and so they've got a very small water holding capacity and they just run out of water first well if i water those spots more what i'm doing is i'm continuing to rinse those nutrients out of the soil it still can't hold on to that water if i put a ton of water on there it's just going to go right into the soil and move out of the bottom of the root zone, head down into the groundwater

or the aquifer. And so I think people over-watering sandy soils or putting more on sandy soil, that's a common misconception. And again, for those soils, you've got to water more frequently, but less each time. So if you can do that with like a drip irrigation system where you're watering every day or something, that's ideal. I see. So that's kind of the main approach for sandy soils is frequent watering, but your sense is that a lot of growers are watering way too much per time. way too much per time. Yeah, and in general people think of irrigation as kind of cheap insurance, quote unquote, which means that they water a little bit more just in case when they don't really realize that there's negative consequences to overwatering.

There's reduced yields, you're encouraging diseases like wilts and molds and rots, and you're washing those nutrients out of your soil and moving them down into the groundwater where people don't appreciate pumping that up and drinking it. Okay, well, Troy, I have a question about that. You know, I'm a certified organic veggie grower and I think I may have a misconception about the nutrients in my soil given that anything I'm applying to the soil tends to be in a more stable form so and and you know assuming that I keep my organic matter very high which we try hard to do and and I just had two different sections of our gardens tested and they were both at around four to five percent organic matter um my understanding has been that that that a good a soil high in organic matter that is is not you're not in which you're not applying soluble fertilizers is going to be much less

likely to leach do i have a misconception there i mean if because i can also tell you that i i am one of those farmers who probably not not probably, definitely, you know, approaches watering like, well, I'm rather over water just to be sure it's gone deep enough. Am I still significantly at risk of leaching out a bunch of soil nutrients? So you don't have a misconception that these organic, and I'm kind of delving into an area that's really not my field where it's held on the organic matter. They've only got straws, and so they can only suck up these nutrients that are in solution. to kind of, it's like a slow release fertilizer, which just kind of releases it small amounts over time, which is good for a plant. But still, if you overwater, you are going to leach nutrients to smaller amounts. And it's not as big of a, you know, not as negative of an impact, I guess.

But still an issue, and I think probably I haven't been kind of totally cognizant of that, so I'm glad that I heard you talk about that. Perhaps now, if you don't mind, I'll just quickly describe my approach to irrigation on my farm and then just have you maybe share your thoughts about it. Um, does that sound okay? Sure. Great. Okay. So I honestly, I have to believe that I, if I was given a grade for my irrigation, it would be NI, needs improvement. I I'm, I'm sure of it. And I'm sure that you'll agree when I, when I tell you our approach. So I'm, my partner and I are only in the, we're leasing land on our current farm and we just finished the second season of our business. And like a lot

of new and young farmers, we had very little budget each year so far to invest in infrastructure and equipment. And that is included for irrigation. So this year, our big improvement was, whereas last year, we used all impact sprinklers last year. And then coming into this year, it was basically the same, although we were able to create a grid of impact sprinklers on risers. So except for one 100-foot line of risers with spray nozzles to some lettuce beds, we were using impact. And like I say, I live in a very arid and very hot climate in the summer. And I would say just as a general rule, we were watering for sure every three days, a good dose, and usually every two days. Half of our land that we water is fairly sandy and the other half

is more of like a silty loam. And generally, you know, I wouldn't just water just because it was time. We generally just used a finger test. So if we found that we'd scratched through the soil and we would scratch it and if it was dry up to like our second knuckle, we would water. So is anything I'm saying so far, like do you have any comments on our approach that I've described so far? So what you're doing, I mean, your approach is very typical. And, you know, so suggestions for improvement possibly are, Suggestions for improvement possibly are, so you've got sandy soils and silt soils underneath the same sprinkler set. Is that correct?

Yeah, I'd say that this is our main garden and the upper half of the garden is sandy and the lower half is actually quite, for such a small area, because we're talking like a half acre, it changes abruptly into a kind of a silty loam i would i would describe it as and you probably get better yields in the silty soils that's that's been my experience although this this silty loam was just turned up for us from pasture uh this year so we only had the sandy section last year now we've, this was the first year, but I was really happy with the output in this new section. And it's all on, you know, the same set, you know, you got one valve to control the whole spot or you've got, you can control. Yeah, but in this, in this section, it's, what is it? I think it's 12 sprinklers in total. So essentially I can control the amount of water I'm throwing on the silt versus the sand because there's that, you know, each section has its own array of impacts. Yeah, so, you know, like I said, the one thing that I would do is think about, consider watering, you know, shorter sets but more frequently on the sandy soils than you do on the silt soils. The other thing that is kind of an easy test, you know, the second knuckle, that's, what, two inches.

So I would, you know, another, vegetables are shallow-rooted crops, you know, but they're not 2 inches. It's more like 12 inches deep is where the roots are. So I would, in the future, try to get soil from a little bit deeper than that because it may be dry on the top, but they might have plenty of water deeper. And you might be able to save some irrigation water that way. The other thing is after you irrigate, take like a quarter inch still rod or something and kind of shove it into the ground. You should be able to tell where it's dry and where it's wet. So if you've got dry soil, where it's dry and where it's wet. If you've got dry soil, it'll be hard to get the rod through the soil there. Where it's wet, it'll sink in fairly readily.

You can use that to estimate how deep the water that you applied went. Wow, that's really smart. I was just going to ask you if it's worth investing in one of those cheap probes to stick in the soil. Yeah, and then the other thing is pull some soil up and just kind of do the look and feel test with a ball. If it basically holds its shape, then it has more water in it than if it kind of falls apart. But sandy soils always fall apart, so you kind of have to calibrate yourself to that system.

And how I would do that is watch your soils, I mean, leave the water off just one time and wait until you see water stress. You know, not a significant amount of water stress, but just where you can barely say, well, okay, yeah, it is kind of hurting a little bit for water. And then what I would do is go into the soil and do a look and feel test, bring some dirt up and squeeze it, et cetera, in your hand and say, okay, this is what the soil looks like when it's too dry. And then use that as a way to kind of calibrate yourself to that particular soil

because every soil behaves differently and every person is a little bit different in how they do that. But calibrate yourself to that soil and I think that would be a way to do that. but calibrate yourself to that soil and I think that would be the way to do that. And I guess that advice applies to whether your soil is sandy or silt or clay, right? Exactly, yeah. Just learning how to recognize. Look, I have a decent idea of recognizing water stress in plants, but is there any general thing you'd say in terms of when, you know,

the first indication, that early indication of water stress? Well, every plant behaves differently when it's water stressed like with grass the earliest indication that i can tell is it changes color it goes from like a light green to more of a, they wilt and etc. But maybe color change, I'm not sure. I mean, with lettuce and stuff, everything behaves a little bit different. Right. Yeah, I guess it's a hard question to answer when, in my case, you're talking about whatever,

30 vegetables or something. Right. Well, that was all about whatever, 30 vegetables or something. Right. Well, that was all really interesting, Troy. One other thing that I'd like to bring up that I see common is people water on the same schedule all season long. And so they kind of get into this, and this is very typical of homeowners. they set their automatic irrigation controllers and then just leave it. Oh, I water on Monday, Wednesday, and Friday for 20 minutes each, and then, okay, and I forget it for the rest of the season. What that doesn't take into account is the drastically changing water use needs of plants over a season. Early in

the spring, they just don't need very much water because the temperatures are cool and it's more humid and the plants are small. They just use a small amount of water. But then typically when plants are in their reproductive growth stage, where they're like, and for gardeners, this is the time when the broccoli is putting the heads on. This is when the corn is tasseled and it's actually growing ears. And this tends to happen during the hot part of the summer. And at that time, plants need a lot of water. And then when they're done in the end of the season, it changes again because the weather changes and the plant growth needs to change.

And so anyway, I think it's important to take that into account and realize that it's kind of a hill. It goes up and it peaks out in July and August. And then, you know, it's really, they're done in the fall. Right. Okay. I think that's another done in the fall. Right. Okay. I think that's another mistake I'm making. Then, I just really wanted to mention, in case you have anything to say, our plan is we started with impact just because it was the cheapest way to go.

What I think we'll do is over time, we'll block by block through our garden, start implementing drip irrigation. That's kind of the idea. garden start implementing drip irrigation. So that's kind of the idea. Do you know vegetables well enough to know whether there's a smart approach in terms of crop families to focus on first? So commercial growers almost do drip irrigation exclusively. And the reason has to do with quality more than, you know, growth. In fact, sprinklerslers there's nothing wrong with

the way that they used to get water to the soil but it gets the tops wet and that encourages diseases and a lot of different kinds of pests and stuff where and also it cools the crop so you get evaporative cooling with drip irrigation, I mean with sprinkler irrigation that you don't get with drip. And so with drip, the soil warms up a little bit sooner and you're going to, or the plants warm up and so you're going to see a little bit earlier production, a little bit later production.

You get really great water use efficiency. Sprinkle irrigation, about 30% of the water is lost to evaporation. Between the time it goes from the nozzle to get stored in the soil, with drip it's only like 2% to 5%. So it's much more efficient, and you have much more control over things with drip irrigation. Right. But there's nothing wrong with sprinkler irrigation especially for like pastures and

things like that. I think it's a great way to go. Yeah, right. Okay. Well, look, that was really fascinating, Troy, and I sure appreciated learning what I did today. I just want to thank you for coming on and to tell you, and I want to tell you that if things don't work out for you as an extension agent, you should put this, you

should put your phrase on a t-shirt, plants don't have knives and forks, and then sell the hell out of that t-shirt because I think it'll sell really well. Anyway, thank you very much for coming on the show. I'm excited to get this up so other growers and farmers can listen to what you have to say. Sure, and I just want to invite anybody who has questions. I've got a website at irrigation.wsu.edu or they're welcome to call me. I'm more than happy to answer your questions.

Sure. Well, I'll put your website name up on the website when the podcast goes up. And can you just say that app website one more time? So this is on AgWeatherNet's website. And so you can just do Google for AgWeatherNet. It's all one word with no spaces. Or it's at weather.wsu.edu. And on there, there's a link. do have to to register you know to get in because mainly um we're trying to show the politicians that we mount that what we're doing is useful and so we count people uh that way but other than that uh i mean they they're not gonna overly spam you or anything so right well that's really cool i'm going to check that out despite

being a little far away to to take to take advantage but um uh one more thing i just want to i want to say you know i'm excited you know for all you washingtonians that that uh you know if you choose you can fairly soon maybe choose to have a little bit of um marijuana for own use after the other day's election so yes we got crop for marijuana and crop for our use. Yeah, you're going to have a lot more calls. That's right. You're going to have a lot more calls from marijuana growers. Anyway, Troy, thanks so much.

Have a good day. And yeah, I'm really grateful that you exist, that Washington's putting funding into this sort of stuff, and that you're doing what you're doing. Thanks again. Yeah, great. Thanks. Thanks for the opportunity. So that's my talk with Troy Peters. Thanks again to Troy. And just for anyone who was interested in the websites he was talking about,

Troy's personal website is irrigation.wsu.edu. And if you're interested in checking out that irrigation app for smartphones that Troy was talking about, you can Google AgWeatherNet on the interweb, or you can check out the website weather.wsu.edu. Hope you enjoyed that episode, and we'll be back with another one in about a week. Thanks. little old you I've met a whole army of weasels a legion of leeches trying to give me the screw but if we bury ourselves in the woods in the country we're no closer we never have laundry

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