Episode 38: Ag in the Delta
“We all know that the Delta is this hub for water movement throughout the state and also for water wrangling, so there is certainly some conflict or questions about management”
A conversation with Dr. Michelle Leinfelder-Miles (University of California Cooperative Extension Delta Crops Resource Management Advisor) about different types of crops, soils, salinity, and water management in the Sacramento-San Joaquin Delta region. Released April 29, 2022.
guests on the show
Michelle Leinfelder-Miles
Dr. Michelle Leinfelder-Miles is the Delta Crops Resource Management Advisor with UC Cooperative Extension serving San Joaquin, Sacramento, Yolo, Solano, and Contra Costa counties. In her role as Delta farm advisor, she conducts a research and extension program that addresses agronomic crop production and water and soil resource management. Specific interests include variety evaluations in grain corn, small grains, and rice; cover cropping and soil health; and soil salinity management in Delta cropping systems. Her educational background includes a B.S. in Crop Science and Management from U.C. Davis, and a M.S. and Ph.D. in Horticulture from Cornell University. At Cornell, her research focused on soil management in apple orchards. Michelle has also done research in Spain, Chile, and New Zealand studying olives, wine grapes, and kiwifruit, respectively. Learn more about Delta Crops and Resource Management and stay connected with Dr. Leinfelder-Miles here.
Transcript
Mallika Nocco
Welcome to Water Talk. In today's episode we are talking about the Sacramento San Joaquin Delta with Dr. Michelle Leinfelder-Miles. Michelle is the Delta Crops Resource Management Advisor with the University of California Cooperative Extension serving San Joaquin, Sacramento, Yolo, Solano, and Contra Costa counties. Her educational background includes a BS in Crop Science and Management from UC Davis, and an MS and PhD in Horticulture from Cornell University.
At Cornell, her research focuses on soil management and apples. But Michelle has also done extensive research all over the world in Spain, Chile and New Zealand, studying olives, wine, grapes, and kiwi fruit respectively. In her role as the Delta Farm Advisor, she conducts research and has a fantastic extension program that really addresses agronomic crop production, as well as water and soil resource management.
I'm really excited about having Michelle on our podcast today. And one of the reasons I thought it would be wonderful to talk about the Delta and to invite her on, I had heard about the Delta before I moved to California, and I was introduced to it. And I think a lot of folks in the water world might be introduced to it as an area that is contentious around water management issues. And that was my first introduction to it.
What I didn't realize was how beautiful it is. And over the past couple of months I've had the opportunity to actually visit the Delta. And it is just such a unique and special place. And I was really, I was really just blown away by its features like its land landscape, the features, the creatures, the plants, everything about it is just really special and really exciting. So I wanted to think about it more and talk more with an expert about the topic, which would be Michelle. Sam, Faith, what are your thoughts?
Faith Kearns
You know, Michelle is one of my favorite colleagues at UC Cooperative Extension for sure. I've known her for about a decade. And I think in terms of the person that you run into in the hallway or at a conference, she's definitely somebody who I just really enjoy talking to about extension work. She's really a professional Cooperative Extension Advisor, and someone whose advice I seek out. I think the Delta is this just really unique and beautiful place that can become this stand in for conflict and water in California, but there really is so much more to it. And so I really look forward to talking with Michelle about the Delta in particular today.
Sam Sandoval
Likewise, Faith. I'm really looking forward to humanize, to describe the Delta beyond policies, beyond the contentious issues, beyond the discourse of a place that is in the middle of something. I think it has its uniqueness. And I'm really looking forward to see that uniqueness. The one other thing that I'm looking forward is to learn from Michelle, as you're mentioning, we started around the same time 10 years ago. And she's been doing also very important research related with water, soils, and drought. And I am really looking forward to listen and to learn from her.
Mallika Nocco
Wonderful. She unfortunately wasn't able to join us today, but I also want to give a shout out to our Water Talk intern, Victoria Roberts, because Victoria really helped to develop this episode and is one of the folks who is very excited about the Delta and learning more, and I just wanted to give her give her a shout out.
So welcome to Water Talk. Michelle, we're so happy to have you here today.
Michelle Leinfelder-Miles
Thanks for having me, you guys.
Mallika Nocco
So you have been a UC Cooperative Extension Advisor in the Delta for over a decade. And you've also worked all over the world, as we mentioned. So what made you decide to settle in the Delta and work there? And what do you think is unique about this area?
Michelle Leinfelder-Miles
Yeah, you've provided a really nice overview of my educational and research background. And I've been really fortunate to learn and work in many different places, even around the world. But I feel very fortunate to be working now right back where I grew up. I grew up on a farm here in San Joaquin County and my parents are still farming. And in fact, my brothers and I are part of the sixth generation of our family who's been farming on the same ground. Our farm is not in the Delta, it's on the other side of the county.
And a funny story, when I first started as a farm advisor I met with some of the growers in the Delta. I thought I would at least have something familiar to relate with them about since I'm from San Joaquin County, but then when I described that I was from the other side of the county, they told me I was from a completely different world. So it kind of made me laugh and about how I can be home and yet be from somewhere so far away.
Going back to kind of how I got here, I graduated from Cornell and I came back I had a year as a Science and Technology Fellow at the state capitol through the California Council for Science and Technology. And that was a really interesting experience that allowed me to interface with policymakers. But really I think my heart was missing something. I really enjoy working outdoors and working with people who work in agriculture. I was really missing that.
I felt very lucky and fortunate that Cooperative Extension started hiring again after a period of time where there was a hiring freeze. And one of the first positions that was released as part of that hiring was this one as the Delta Crops Resource Management Advisor. So I applied and I was lucky to get the job. And here I am, 10 years later.
Mallika Nocco
That is so interesting to hear the story about having a farming background and then it still being such a different world. And I'm wondering if you could share a little bit about which crops are grown in the Bay Delta?
Michelle Leinfelder-Miles
Yeah, I'll talk about the crops and then I'll talk about some other things about the Delta that make it seem like a totally different world. So I'll come back to that story again. The Delta is actually really diverse in terms of what crops are grown. In fact, the Delta Protection Commission has a report on their website that talks about the Delta Economy and I'm pulling a few numbers from that report. It's a great report that's, like I said, available on their website.
Over 70 crops grow in the Delta on over 400,000 acres of land. And you mentioned the five counties where my programmatic responsibility is: San Joaquin, Sacramento, Yolo, Solano and Contra Costa, so those are the five counties that have at least part of their area in the Delta. Those 70 crops range from field crops, which is where most of my research is being done. So Field Crops include things like grains and forages. But there are vegetable crops that grow in the Delta as well as perennial crops, different tree and vine crops. Alfalfa and corn are two of the predominant crops in terms of acreage, but processing tomatoes and wine grapes are also very common in the Delta.
And the Delta Protection Commission Report that I mentioned indicates that almond is an up and coming crop in terms of the acreage is growing quite rapidly. But in terms of the crops that I work on in my research program, rice is also an up and coming crop. The acreage is not quite as expansive as some of the others that I've mentioned, but I think it's a really interesting crop for the Delta.
Mallika Nocco
So you mentioned a little bit about the crops, one of the questions that I have, and just as a soil scientist, and someone who thinks a lot about soil formation processes, the Delta is really interesting, and it has unique soils. So I'm wondering if you could just tell us a little bit about how unique the soils are, and how that creates and impacts soil management.
Michelle Leinfelder-Miles
This goes back to my little story at the beginning about how the Delta is a totally different world. So Delta soils are very fertile, they're very variable, and they're very unique. So most of the soils in California are what we call mineral soils. So they're derived from, basically, rock that's been broken down over time.
The Delta soils, like I said, they're quite variable. There are mineral soils in the Delta, and particularly in the northern and eastern and southern parts of the Delta. But as you move toward the center of the Delta and westward, the soils are what we would call muck soils. So they're derived from decomposed tules, and other wetland plants. And those plants have broken down over a long period of time. And they've been made into very fertile soil. And so that's the primary difference between Delta soils and other soils in California is that they're derived from plant material, instead of being derived from rock.
These soils are high in organic matter, and that's what helps them be so fertile is that they hold a lot of nutrients. Basically they just provide a really good foundation for a plant to grow. These soils were reclaimed in the mid to late 1800s, when people built levees to contain the water and direct the water through these channels that we now know of. And so what we basically consider the farmable area of the Delta we call, “the islands”, because the soil is surrounded by water on all sides. But these are these channels that were built up because of the levees that have been constructed.
Mallika Nocco
We didn't plan this, but we actually have talked about soil organic matter quite a bit on Water Talk season three. As a follow up, I know you mentioned that it's high, like how high would it be, if you happen to know, like a range of organic matter content in these soils?
Michelle Leinfelder-Miles
If you look at soil maps that are available, some of the soils can range anywhere from 20 to 40% organic matter, which is extremely high. In most California soils we're probably looking at 1 - 2% organic matter, or maybe 3% if that land has had some nice improvements made to it, and has been able to accumulate more organic matter. But I would say 1 - 2% is pretty typical. And in the Delta, we could be looking at 20% or more.
Mallika Nocco
Just for folks who are thinking back to some of the other things we've talked about, of how we can build soil health or cover cropping and those types of issues, that's what we're talking about. We're like, maybe we can push this up to 3%. You know, whereas here in the Delta, it's like these are really, really high values for organic matter content. And so that, yeah, that's super fascinating.
I know that you've also done some work on salinity issues and management in the Delta. Can you just tell us a little bit about the connections, for example, between salinity and drought in the Delta, or where the salinity issues arise?
Michelle Leinfelder-Miles
I was really lucky when I started as a farm advisor to have a couple retired scientists as my mentors, retired from Cooperative Extension. So they were very familiar with the Delta and had done a lot of work looking at salinity and soils in the Delta. I got some funding from the California Institute for Water Resources as a young new career farm advisor to look at salinity in the Delta. In particular, how surface water salinity impacts soil salinity.
So in the Delta, the farmers are primarily, if not exclusively, irrigating their crops with surface water, they're not drawing groundwater like in other parts of the state. And that's because the groundwater is very shallow anyway. So hydraulically, it's just water channels in the Delta, the level of water is sometimes higher than the land, the water is basically falling by gravity in a controlled way, but into the islands, and that water is therefore used for irrigation and then the water has to get pumped off of the island to maintain the groundwater at sufficient depth for the plant roots to grow and not be drowned out.
So all that being said, the salinity and the surface water is coming on to the islands and being used for irrigation. And when that water is applied to the soils it accumulates at a higher level than what it had been in the surface water. Well, why is that? Well, that's because evaporation is drying off water and plants are transpiring water, but the salts aren't going with that transpired or evaporated water, the salts are staying behind in the soil. And with the groundwater being shallow in the Delta, there's not a lot of depth for that salt to move down below the root zone. So that salt basically stays at a pretty shallow depth of the soil where the roots of plants are trying to grow. So that's why salinity is a problem for crops in general, but especially in the Delta with these unique environmental conditions.
You can add on to that, that in the Delta, we all know that the Delta is this hub for water movement throughout the state, and also for water wrangling. So there's certainly some conflict or at least question of management around how we move water around the state. And certainly water is coming through the Delta to get that water to other places, whether it's to keep it flowing out to the ocean for environmental purposes, or to move it through to other parts of the state for use by agriculture or urban uses. When that water is moving toward other uses, it also can get recirculated back into the Delta, when it eventually drains into, say, tributaries of the San Joaquin River, and it comes back into the Delta, it might be picking up salts there from previous uses. But also depending on drought, and how much flow we have coming from upper watersheds.
One thing that I feel is sometimes misunderstood is that the flows that are being directed through the Delta are not only to help with, you know, fish populations and their needs, or other environmental needs, but it's also helping to keep ocean water back and keep those salts from the ocean back so that the Delta can stay fresh. And all the ways that we use water that flows through the Delta certainly we need to keep it fresh for all of those reasons, whether it's for in-Delta use or for use in other parts of the state.
Faith Kearns
All right, so shifting gears a little bit, you've definitely touched on so much of the complexity involved in your work. And, you know, you're someone who I think of is such a sort of quintessentially excellent Cooperative Extension professional, because you know your science, you know the place, and I really think you operate with a lot of integrity.
I'm wondering if you can just talk a little bit about your approach to Cooperative Extension work? For example, what you call “small s” science. And maybe how you use a mix of in person and online methods? And yeah, just in general, how you approach your extension work?
Michelle Leinfelder-Miles
Yeah, thanks for that question Faith. I feel it's really important as a Cooperative Extension agent, to work on problems that can have short, medium and long term impact on my community. And so the “small s” science that, that you refer to, I see those projects, the “small s” projects, as being the ones where I can hopefully deliver on something in a short time period.
I communicate with the agriculture community, both growers and consultants, and resource managers, I work with them to try to understand what their needs are. And then in working with them I develop projects to try to address those needs. And when there is a need that I think can be addressed within a short period of time, then that's something I would say is “small s” science. It might not be the big data, it might not be related to, you know, the giant elephant in the room, like climate change, but it's something that is important to the community and I think helps me to understand where the challenges are and how I can make incremental steps from those smaller challenges to maybe those bigger challenges, like subsidence in the Delta, like salinity, or like climate change impacts.
Mallika Nocco
Yeah, I like the frame of “small s” science. But as you were talking and describing it, I was thinking of it as like, maybe the “s” is small, but there's a capital “A” for applied there. Right? Well, really, really useful. And sometimes those questions I feel are the toughest ones. Somebody wants to know something actionable. And I think it can be really hard to just come up with a solution for someone who's struggling with a challenge. So I think it's wonderful that you're taking that approach to it.
Similarly, you mentioned working with a lot of different folks in your community. And anyone who's taken a look at the Delta may have noticed that there are several different organizations working in that area. So there's like the Delta Stewardship Council, the Conservancy, the Authority, there are grower organizations, there's community organizations related to conservation. How do you interact with all of these different groups and what kind of synergies are happening?
Michelle Leinfelder-Miles
Well right now, with our minds on drought, after a couple of years of very little rainfall, there are actually a lot of synergies that are happening. I'm working with many different partners on Delta Drought Response Program. This was a project that was devised by the Delta Conservancy, the State Water Resources Control Board Office of the Delta Watermaster. In-Delta water agencies, North, Central and South, those are organized by grower groups, the users of water in the Delta. And I'm gonna forget some of the agencies, the CDFA is involved, the California Department of Food and Agriculture, the Department of Water Resources. Anyway, there are many different partners on this Drought Response Program.
I was lucky to be asked to be involved in that part of that program is identifying farms and financially supporting farmers who are giving up irrigating their crops this year. And so we have gone through applications from farmers to identify farms where we could potentially save water by not diverting that water from the streams, and instead keeping that water flowing through the Delta, again, to keep the ocean salts back, like I described earlier. So by not diverting water, hopefully keeping more flows, and therefore keeping salinity back and the Delta fresh.
Sam Sandoval
Michelle, associated with that, I know that in 2020, you wrote a paper that analyzed the drought, the previous drought, the 2012, 2016, the drought and the Sacramento, San Joaquin Delta, some reviews and lessons. Well, you mentioned many interesting things. Do you want to share what at that point, kind of, you thought about the drought and how that one, or some, of those lessons learned now can be applied today?
Michelle Leinfelder-Miles
Sure. I was brought into that project for my expertise in agriculture and Delta agriculture. And we talked in that paper about the importance of, or the influence of, surface water salinity on soil salinity. We also talked about how our response to drought, kind of as a society is pretty reactive, instead of proactive, and then that that trickles down to how we collect data and how we do science. And I did some work on salinity and soil salinity in the years of the drought (the 2012 to 2015 time period), but it was more coincidental that they fell during those drought years than as a planned thing because of the drought.
I bring that up because many of our drought responses, whether it's in research or in water management, they're often quite reactive and we don't have sustained funding to keep analyzing data or collecting data in the first place so that we understand, you know, how water and soils and our resources are used, or how those resources change over time, when times are good and when times are not so good. For example, drought or not drought. So that that's one of the things that, you know, we wrote up in that for that paper is just trying to think of drought as something that's not going to go away but something we have to live with and something we have to really be proactive about if we're going to find ways to overcome the impacts of drought, and especially in light of climate change impacts.
Mallika Nocco
So you did mention subsidence, and I wanted to ask a little bit about what is unique about delta soils and delta systems that leads to subsidence being a particular challenge in that area, and what are some of your thoughts for the future to try to manage this subsidence in the Delta?
Michelle Leinfelder-Miles
So subsidence is actually happening all over the state. We've observed that because of using groundwater for irrigating crops and pumping groundwater for all of our uses in the Central Valley. But in the Delta subsidence happens, because the soils are so fertile, because they are this unique soil that's derived from organic material, and we lose carbon very easily from the soil. So when we work the ground, we oxidize the carbon, and that really results in soil loss. And again, this is particularly unique in the Delta because the soils are so high and organic matter.
So I mentioned how surface water is the primary irrigation source in the Delta. I talked about how the water basically can flow onto the island in a channeled sort of way. But that's again, because the water level is higher than the soil level. And that has become a that's come about because of the subsidence of the soil, the loss of carbon from the soils. When I was getting started as a farm advisor, there was a group of UC and other scientists who were looking at ways to mitigate soil carbon loss in the Delta by planting wetlands and by planting rice.
One of the things that they learned from that study is that rice is a crop where we can at least mitigate the impacts of subsidence. Rice is a crop that's grown in a flooded state. So it's one of the only crops where we would have standing water on it the whole season long until right before harvest, that is. That flooding, that keeping of the Delta soil wet, is what keeps the carbon in place. It's what prevents the subsidence from happening. And so rice, I think will be a very interesting crop in the Delta moving forward as a way to sustain the agricultural economy and that history of the Delta, but also recognize some of the environmental challenges that the Delta faces and hopefully mitigate some of those challenges.
Faith Kearns
Awesome. Thanks, Michelle. You've already touched a little bit on climate change impact, but I'm just wondering if you can talk a little bit more specifically about how climate change in the Delta is particularly impacting agriculture? And maybe some of the work that people are doing to adapt to climate change in the Delta?
Michelle Leinfelder-Miles
I would say that some of the climate change impacts are very similar to what will be experienced, are being experienced, around the whole state. So certainly in perennial cropping system, the trees and the vines, there are going to be impacts from reduced chill hours over the winter. So if our temperatures don't get as cold, then those trees are impacted, they don't fruit as well in the coming growing season. And there are tree crops in the Delta, as I mentioned earlier, cherries and almonds and, and pears are historical fruit crop that's been growing in the Delta for probably 100 years.
So again, those are kind of temperature impacts of climate change, but then there's the water impacts of climate change. And with the Delta being this water hub in the state, it's not really a question of the quantity of water and reduced quantity, it's more about the quality of water. So it's the salinity impacts that we've been talking about and keeping the Delta water fresh for all of its uses, and for all of its export needs to other parts of the state. So really, when it comes to water in the Delta, it's more about the quality rather than the quantity. Certainly quantity can be reduced as reservoir flows are reduced, but in one way or another, we're going to see water in the Delta, it's either going to be coming from the upper watershed or it's going to be intruding in from the ocean. And so that's where the quality really becomes the focus.
Sam Sandoval
Then I think, correct me Michelle, but on top of that, the sea level rise and the tides I mean in most of the agricultural fields, I mean is what you're mentioning, but then in theory in addition of sea level rise and all that it can damage, or all the work that has to be done to maintain levees and so on.
Michelle Leinfelder-Miles
You know, I don't really have the expertise to talk about sea level rise, but the Delta Stewardship Council has been making a very large effort on a project called Delta Adapts. And so it's looking at climate change impacts on the Delta, including agriculture. I'm serving on a focus group with other members of the agriculture community to try to understand the impacts of climate change, including sea level rise, and try to think of ways of how we're going to manage for those changes, how we're going to adapt to those changes moving forward.
Sam Sandoval
Could you describe the agricultural community? Is it family oriented? How do you see the community of farmers?
Michelle Leinfelder-Miles
I would say that there are a lot of family farms in the Delta–many-generation family farms. But there are also, you know, larger corporate groups that are buying land and farming in the Delta. It's a mix. But I think one of the really unique things is just the history of agriculture in the Delta, and working with many multigenerational farmers through my work has been really rewarding.
Sam Sandoval
Yeah, thank you. Thank you Michelle. Thank you for all the work, we always say I'd like to finish this by asking you how can we help you? How can our audience help the work that you're doing?
Michelle Leinfelder-Miles
I appreciate that. Folks want to know more about delta agriculture. I've really enjoyed working in the Delta, even if it is a different world from where I grew up. I felt really supported by the agriculture community and the work that I do. The growers and consultants and managers that I work with are really receptive to having research done on their farms. And not that they see the value in that they see the value for their own practice, what they can learn and then employ to hopefully, you know, make their farming operation better.
I see a community that wants the research also for the benefit of the broader community. And they know that they can help be a part of that. I'm just appreciative. I'm appreciative of them. And I'm appreciative of the people who want to know more about Delta agriculture. I think it's a really unique part of the state and certainly, with unique challenges, and I'm really fortunate to be doing the kind of science that I'm doing and hoping that it can have some impact on the community.