The Infinitely Deep Soils Myth of the Palouse with Rachel Breslauer


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Contact Rachel via email at or contact Dr. Haiying Tao via email at

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Episode Transcription:

[ Music ]

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 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 podcasting app and leave us a review while you’re there so others can find the show too.

[ Music ]

Drew Lyon: My guest today is Rachel Breslauer. Rachel recently received her master’s degree in soil science from WSU. She was advised by Dr. Haiying Tao, Extension Soil Fertility and Residue Management Specialist. Rachel is originally from New York state. She received her bachelor’s degree in Agriculture and Soil Science at Cornell University. Rachel’s fascination with low rainfall, dryland cropping systems motivated her to come out west. During her Master’s degree, she studied the effects of compact subsoil on winter wheat root systems and productivity in the Palouse region. Hello, Rachel.

Rachel Breslauer: Hi, Drew.

Drew Lyon: So the Palouse is known for deep fertile soils, what could possibly be limiting root systems in this environment?

Rachel Breslauer: Unfortunately, the idea that the Palouse region has infinitely deep soils is a myth. While in many areas, we have deep fertile soils all the way down, we also have many compact paleosols, which are old soils, in the Palouse region and these can be at various steps throughout a Palouse field. These compact subsoils formed over 18,000 years ago and are highly-weathered, which has caused many of them to have high concentrations of clay and to be very compact. On top of these compact subsoils, we have various steps of less and that’s the good stuff, the stuff that it’s easy for roots to develop through. Unfortunately, high-clay subsoils are not a good medium for roots to grow through. They have very small pores that are hard for roots to push through and may limit their ability to grow deeper into the soil. And that was the main aim of the project that we conducted was to see if compact subsoils were limiting rooting depth in the Palouse region for winter wheat.

Drew Lyon: Okay, so in your work, in your sampling, how common was it to find a restricted root zone? Was it something you could find in almost every field or was it fairly rare?

Rachel Breslauer: It was interesting because while we found roots developed deep down in the subsoil, we measured all the way down to 4 feet in 40 profiles across the eastern Palouse, one field in Whitman County and one field in Latah County, and we found that about 38% of the profiles that we measured had roots that had rooting depths of less than or equal to 3 and a half feet. This is pretty surprising to us considering that we account for winter wheat root systems going down to either going down to 6 feet or drawing from resources down to 6 feet in the profile. So it’s a lot, we saw that many many profiles were fairly shallow compared to what we expected. Only about 30% of profiles had roots develop down to depths of 4 feet in the profile.

Drew Lyon: Wow. That is quite a bit different than I would have expected, too. So what impacted shell root system depth have on the crop?

Rachel Breslauer: So we found in general that we had more subsoil water below areas where we had shallow roots systems. This could be because of two main reasons: one is that the root systems could be isolated from subsoil water, and thereby not able to take it up, But it’s also possible that areas where we had roots restricted we also had water flowing sideways in the profile. We know that areas that tend to restrict roots may also restrict the flow of water. So we’re not really sure at this time if areas where we had more roots we also had poor subsoil water or we had wetting late in the season.

Drew Lyon: Okay, and I would assume that a crop that you know a lot of people think their crop is accessing water down to 4, 5, 6 feet in the case of wheat and if it’s not, it’s probably not going to perform up to the expectations they have and maybe even the management of the crop might be different than you’d have if you knew you only had 3 feet of soil there.

Rachel Breslauer: That’s correct, yeah. And another interesting thing, another interesting effect that we had was areas that we had more subsoil water we also generally had lower crop yields, so that suggests that maybe there is some sort of agronomic impact, too, of poor rooting depth and maybe poor subsoil water use.

Drew Lyon: So how can farmers manage their root restriction or how can farmers manage root restrictions in their cropping systems?

Rachel Breslauer: We found that areas where we had fewer roots in the profile, we also had more compact soils. So this suggests that a way to improve root system depth in the Palouse might be to break up these compact subsoils. We haven’t done any studies looking at how effective potential solutions might be but one potential solution would be incorporating a tap-rooted crop, like canola, into the crop rotation. Tap-rooted crops can sometimes open up more pores deep down in the subsoil. They tend to have stronger root systems than winter wheat which has a fibrous root system, so it might not be able to penetrate these really strong subsoils. So it’s hard for us to say exactly what the best way is forward but there are potential solutions such as growing canola and introducing that into rotations.

Drew Lyon: So what’re the next steps in the research that you’re doing or that somebody else might be doing following up on what you’ve discovered in this study?

Rachel Breslauer: There are no direct plans for doing long-term rotational studies with canola and looking at subsoil water use in and soil physical compaction. But I think we’ve had some really good interactions with farmers who are growing canola and hearing back from them about what sort of changes they’re seeing in their systems. So currently we don’t have any plans for future studies following up on this research but we definitely are listening to farmers who are growing canola in this area and seeing what effects they’re seeing.

Drew Lyon: Okay, well congratulations on receiving your MS degree. What’s in your future plans?

Rachel Breslauer: In the immediate future I am currently still working for the Soil Fertility Lab. I did my Master’s in writing extension publications and getting this information out to the public. But I’m looking at beginning a Ph.D. program in the fall and currently applying to programs mostly in agronomy right now. In the summer I’m going to take some time off and go hiking for a while. So I’m really enjoying being able to take advantage of the western U.S. and exploring that.

Drew Lyon: Well, thank you for coming in and spending some time with us and talking about this very interesting project you have on soil restrictive layers in the Palouse.

Rachel Breslauer: Thank you, Drew.

[ Music ]

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 podcasting app. If you have questions or topics, you’d like to hear on future episodes please email me at drew.lyon That’s ( You can find us online at 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.