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For questions or comments, contact Claire via email at claire.phillips@usda.gov.
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Episode Transcription:
Drew Lyon: Hello. Welcome to the WSU Wheat Beat podcast. I’m your host, Drew Lyon, and I want to thank you for joining me as we explore the world of small grains production and research at Washington State University. In each episode, I speak with researchers from WSU and the USDA-ARS to provide you with insights into the latest research on wheat and barley production. If you enjoy the WSU Wheat Beat podcast, do us a favor and subscribe on iTunes or your favorite podcast app and leave us a review so others can find the show too.
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Drew Lyon: My guest today is Dr. Claire Phillips. Claire is a research soil scientist with the USDA-ARS North-West Sustainable Agro Ecosystems Research Unit. She holds B.S. and MS degrees in biology from Stanford University and completed her Ph.D. at Oregon State University in 2009. She was a research associate with the USDA-ARS in Corvallis from 2015 to 2020 and a research soil scientist in Ames, Iowa, from 2020 to 2021. She began her current position in Pullman in January of this year. Today she will tell us more about her past research on making and using biochar in wheat cropping systems. Hello, Claire.
Dr. Claire Phillips: Hello, Drew.
Drew Lyon: So could you tell us why you started looking into biochar and wheat systems?
Dr. Claire Phillips: Absolutely. I did my Ph.D. at Oregon State University as you said, and my training there was in soil organic matter dynamics and evaluating how persistent organic matter is and how sensitive decomposition is to management and to climate. And so that soil carbon expertise was why I was recruited to the ARS Unit in Corvallis, which already had an established program on biochar, because one of the benefits of amending soils with biochar is is the carbon sequestration value. The feedstocks get converted to a form that’s really resistant to decay. But as I started working on biochar and working with producers, it was clear that there had to be more incentive beyond carbon sequestration to make it a compelling conservation activity. And so I did a research focused on the water retention benefits of biochar in the liming benefits. Both the liming and water retention benefits of biochar made it a good match to wheat systems in the interior northwest. And we also had a great cooperator in the Gatey family. They farm outside of Spokane and Rockford, Washington. And David Gatey had been a Masters student in Ag Engineering at WSU and had built a gasifier. So he was trying to produce on farm energy and was producing biochar and we had a great cooperative with the Gatey’s in doing some field trials looking at biochar impacts on wheat in at their farm.
Drew Lyon: Okay. Can you tell us what you learned from that work?
Dr. Claire Phillips: Yeah. So we looked at whether biochar could be used as a liming amendment and compared it to regular hydrated lime. And we found when we applied quantities of biochar that matched the liming value of the lime we were applying, the biochar outperformed in the sense that they both increased pH soil similarly, but the crop we had a greater yield with the biochar. And we think that was because there were some moisture benefits of the biochar. We found changes in the microbial soil community, although it’s hard to know exactly how that’s impacting plant growth. And then I also looked at how much material could be sustainably removed in terms of crop residues and also seed cleanings in converted to bio char and how much of a liming amendment that process of on farm biochar production could sustainably return. And the basically the take-home was that the Gatey’s could amend about 10% of their farm area a year with a sustainable level of straw removal and using all their seed cleanings and that would mean bringing up their pH from a pretty acidified level. They were below the 5.5 threshold for so bringing up their age to 5.5 over the time span of about ten to 12 years. So those are on paper calculations. Right. And didn’t account for the fact that actually producing biochar is a whole enterprise unto itself with quite a bit of labor involved. But that would be the return on material that they could see with their on farm gasifier.
Drew Lyon: Okay. You mentioned putting on the amount of biochar to kind of equal a liming application. How much are you putting on? How much biochar goes on per acre about?
Dr. Claire Phillips: Yeah, that’s a really great question. So bioterrorists have a liming value if they’re, if they have ash, right. So it’s the ash component rather than the charcoal component that gives the liming value. And so it depends on the biochar. It depends on what the feedstock is. And it also depends on the charring conditions. So we know that materials like municipal compost and some of the wetter, more nutrient rich biochar actually produce more ash, whereas materials produce from wood or straw residues tend not to produce as much ash unless they’re charred with more oxygen during the production conditions. And I mention all this because there is a trade off if you want to maximize the amount of carbon that’s turned into charcoal, that will produce a biochar with a greater carbon sequestration value. But if you want to produce a biochar with a greater liming value, then you create it under conditions with oxygen and you’d get less carbon in the final material. And of course, folks have been using oiler ash and different ash materials for a long time. So this is nothing new, but they’re with biochar systems the idea to is to try and maximize all the value out of the production system. And so we’re looking at with biochar production we’re looking at using low value materials. And in our research, we looked at paring ecological restoration activities with on farm use. So paring forest thinning, for example, or, you know, low value wood biomass removal with biochar production and then putting that biochar into use where it can be, where it can see the greatest benefit.
Drew Lyon: Okay, so not all bio chars are made the same, it sounds. So you have to be know where your bio char comes from to know what optimum uses might be.
Dr. Claire Phillips: Absolutely. Yeah. I like to say is that we shouldn’t call them, we shouldn’t call them material biochar. We should call the materials biochars because they’re all quite different.
Drew Lyon: Interesting. So you also did research to evaluate whether bio char improves soil moisture. What did you find from that work?
Dr. Claire Phillips: Yeah, so I did a study where I incorporated biochar into field stations that were across Oregon and Washington and incorporated a wheat straw biochar and a conifer with biochar at multiple rates at these sites. And so on the Palouse it included Wilkie Farm and it also included Pendleton. They were all wheat producing sites on the east side and the west side. But the idea was to capture a range of growing conditions and soil textures. And what I found from that was much more complex than I expected. So the biochars got incorporated in the fall. And the following spring I came back and took soil cores and analyzed them in the lab for water retention curves. And those laboratory measurements told me that biochar was allowing water to be more extracted at the dry end of the water retention curve. So it meant that there was more plant available water when biochar was incorporated. However, what I saw in the field was looked like biochar actually made at least one of our locations drier. And so what happened was and this was a site in Madras in Central Oregon which had a loam soil. What happened was the biochar increased the hydraulic conductivity, and that allowed water to be lost through evapotranspiration and possibly also drainage much more quickly at higher rates of biochar application. And so that soil actually was drier the more biochar was added in a really clear linear relationship. On the other hand, more of the water that was being extracted would be considered plant available. But it was a little bit perplexing because directly looking at the moisture content in the soil, it was drier when there was biochar. But looking at the laboratory measurements of available water content. Yeah, looks like biochar was was increasing plant available water. But overall across all the sites, I would say that the biochar, the more that biochar was incorporated, there was a slight increase in available water content. So maybe a slight advantage, but overall the effect was pretty small.
Drew Lyon: Okay. Any way of estimating when it when biochar might negatively impact soil water versus when it might be neutral or positive?
Dr. Claire Phillips: That’s a good question and I don’t have an answer for that. I think when we look at biochars, but also when we look at just soil health practices more generally that increase soil organic matter content I think this is something that’s still really debated in the research world, whether increasing organic matter content actually increases plant available water. And there’s folks on the Palouse doing fantastic research with soil water management and so I think it’s hard to just simplify it down to how much of the material is in the soil, whether it’s organic matter, biochar it’s really about tillage and really how the whole system is managed to make water available when it’s needed by the crop. So we really need to look at it with a whole systems approach.
Drew Lyon: Okay, so we’ve talked about organic matter and biochar is effect on soil water. What about soil fertility? Did you find any improvements in soil fertility from biochar applications?
Dr. Claire Phillips: Yeah, that’s a great question, Drew. And I’m going to back up just for a moment and say that you know, the reason that biochar’s have so much interest in the farming community is the discovery of these manmade soils in tropical regions in the Amazon, but also in Africa, these Black Earth soils where biochar was incorporated. And it’s made really fertile soils over time that have often maintained a high level of fertility, even hundreds of years after they stopped being actively managed. And so one of the core ideas with biochar is that we might be able to create these black growth soils here in North America in temperate regions. And I don’t know if that’s the case or not. I think that’s still being evaluated. But I can tell you that with the biochars that I worked with and I focus on feedstocks that were pretty common in the Northwest, which are wheat straw, grass straws and woody materials, those are all materials that have pretty low fertility values. And when you convert those feedstocks to biochar, they still have pretty low fertility values. So they aren’t themselves fertilizers. The question is whether they improve microbial cycling and whether they increase soil cation exchange capacity to better retain nutrients and in those cases, we see sometimes they have improvements and sometimes they don’t. In short term studies, I did not find improvements in soil fertility. If one applies a biochar that’s made from a material like poultry litter, it will have a higher nutrient value than a biochar made from woody material. And so again, a producer can pick their biochar specifically to try and in part, the qualities that they’re looking to manage for. So if somebody wants the biochar to have some to have a high fertility value, they should move towards like a poultry litter biochar. But otherwise biochars, their main value are that carbon sequestration value and also kind of immediately providing some increase in soil tilth and possibly over time improving aggregation, improving cationic exchange capacity and overall improving soil health. But I would say in my research across the multiple sites where I collected soils and with the multiple biochars that I used, really the most immediate benefit that I saw was in soils that had a low pH. And where we are applying a bio char that had a high ash content. And so we were really seeing a liming effect that was the most clear, immediate effect. But I also worked with folks that were kind of early adopters of biochar. I want to stress that when we were working with early adopters, they were using biochar within a larger soil health framework. And so biochar is one material that they’re adding to soil. But we also saw producers adding compost to provide nutrients and more readily available carbon that can support the soil microbial community.
Drew Lyon: Okay. So again, it goes back to the message of know what your source of biochar is and what it might be helpful on your farm for. Where can our listeners go to learn more about using biochar in the Pacific Northwest?
Dr. Claire Phillips: A great place to find more information about biochar is a website that I helped create. It’s called the Pacific Northwest Biochar Atlas, and it’s that www.pnwbiochar.org. And it provides general information about biochar. It also has a number of case studies from farmers and also gardeners across the Pacific Northwest. And it has within a couple decisions to support tools that can help folks evaluate how much biochar they might need to add to achieve different outcomes and allows users to select from different kinds of biochars, different feedstock materials or if they if folks have a bio char that they’ve tested, they can enter in the information about that, their biochar and it has some calculators to help advise with amendment rates. And that tool is actually getting further developed with support from the NRCS. And eventually will hopefully help NRCS field offices implement biochar recommendations.
Drew Lyon: Sounds like a great site. We’ll make sure we get that website into our shownotes. Claire, thanks for sharing your work with biochar in the Pacific Northwest, and welcome to the Pullman area and the USDA-ARS Northwest Sustainable Agro Ecosystems Research Unit.
Dr. Claire Phillips: Thank you so much, Drew.
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Drew Lyon: Thanks for joining us and listening to the WSU Wheat Beat podcast. If you like what you hear don’t forget to subscribe and leave a review on iTunes or your favorite podcast app. If you have questions or topics, you’d like to hear on future episodes please email me at drew.lyon — that’s lyon@wsu.edu — (drew.lyon@wsu.edu). You can find us online at smallgrains.wsu.edu and on Facebook and Twitter @WSUSmallGrains. The WSU Wheat Beat podcast is a production of CAHNRS Communications and the College of Agricultural, Human and Natural Resource Sciences at Washington State University. I’m Drew Lyon, we’ll see you next time.
The views, thoughts, and opinions expressed by guests of this podcast are their own and does not imply Washington State University’s endorsement.