.png)
Thoughts on Rice
This podcast is for growers, PCAs, consultants, and other industry professionals in the California rice industry. We'll primarily be focusing on the Sacramento Valley and Delta Region of California. The UCCE Rice Farm Advisors aim to deliver extension information relating to the California rice industry.
Find out more about UCCE and California rice here!
Thoughts on Rice
Rotating rice and winter cover crops (Pt. 2) with Sara Rosenberg
Feedback Form
Together, the UCCE Farm Advisors seek to provide relevant, topical research-backed information relating to CA rice production.
In this two-part episode, Sarah Marsh sits down with Dr. Sara Rosenberg, who is currently the UCCE Regenerative Agriculture Farm Advisor for Mariposa, Merced, and Stanislaus Counties to talk about her work in rice crop rotation systems. Sara worked with rice growers in her graduate school experience at UC Davis, where one of her focuses was to understand the barriers to adoption, opportunities, and required resources for successful implementation of crop rotation in rice systems.
Upcoming Rice Events
Rice Winter Grower Meetings - February 10-13th, 2025
Rice Crop Rotation Tools
Rice Crop Rotation Calculator
Publications on Rice Crop Rotation
Resources and Links from Sara Rosenberg
Regenerative Agriculture Information and Listening Session
Part 1: Nut Tree Orchards of Central Valley: Future Directions - December 16, 2024
Regenerative Agriculture information
Other Resources
UC ANR is an equal opportunity provider and employer
Just a reminder that this is the second part of our two-part episode covering the rice crop rotation system and cover crops in that system with Sarah Rosenberg. If you're interested in hearing more about crop rotation in rice systems, go back now. Really, really recommend that. And then come back and listen to this episode because there's a lot of great stuff that you're not going to want to miss. Thanks. Hello and welcome to Thoughts on Rice, a podcast hosted by the University of California Cooperative Extension Rice Advisors. I'm one of your hosts, Sarah Marchionish, and I'm a rice farm advisor for Colusa and Yolo counties.
SPEAKER_00:I'm Whitney from DeForest. I'm the Cooperative Extension Rice Advisor for Sutter, Yuba, Glasser, and Sacramento counties.
SPEAKER_01:My name is Luis Espino. I'm the Rice Farming Systems Advisor for Butte and Glen counties. I'm Michelle Leinfelder-Miles. I'm a farm advisor in the Delaware I work on all sorts of field crops, grains and forages, but one of those is rice. And the counties that I cover are San Joaquin, Sacramento, Yolo-Salano, and Contra Costa counties.
SPEAKER_02:Together, the UCCE farm advisors seek to provide relevant, topical, research-backed information relating to California rice production. Today, I had the privilege to sit down with Sarah Rosenberg, who is currently the UCCE Regenerative Agriculture Farm Advisor for Mariposa, Merced, and Stanislaus counties. We're continuing her interview from last week, where she talked about the basis behind the rice crop rotation calculator, as well as some of their results from their interviews with farmer and grower stakeholders. Today, she's continuing on in a similar vein, talking about the use of winter cover crops in rice systems. Thank you. I think we're going to move on to talk a bit about your work in the winter cover crops. And so would you mind giving us a definition of what a winter cover crop looks like in a rice system?
SPEAKER_03:I can certainly try. Well, a cover crop in general is a intentional crop with certain benefits that is not planted for economic purposes. So it's not harvested for food production or forage production. It tends to be seeded in fall and then it will remain as a cover over winter and then terminated in spring. And winter cover crop use across California is pretty diverse. There's a lot of species that are used for different cropping systems. And there's certain cover crops that are used in rice that I know of more so than others. But relatively speaking, rice systems has a pretty low use of cover crops generally.
SPEAKER_02:So it's a pretty diverse grouping of cover crops, but is there some examples of specific cover crop species or mixes that you tend to see more represented?
SPEAKER_03:Yeah, I think, I mean, I think the most common one in rice is vetch, right? Which makes a lot of sense. I mean, we have this, you know, rice is a grass, it's a relatively heavy nitrogen user And then we want to put in something, particularly growers are really concerned about the nitrogen addition factor for their cover crop use. And so putting in a vigorous, highly biomass growth legume like vetch that is known to fix a high amount of nitrogen is kind of the go-to. I do think there's some... There's also some mixes that people use with, you know, using both a legume and a grass. So, vetch plus rye or vetch plus oat or some, there are other legumes that I know are used like bell bean. And I think that, yeah, I think those are kind of the top contenders that I know of. I actually also do know, thinking about it now, I have heard of some growers using mustard as a I
SPEAKER_02:think I've usually heard the mixture of three to maybe five species, but I went to a field day recently and they were talking about using 16 different types of plant species in their cover crop mix. And it was. Wow. It's a lot. It was very impressive. I think kind of expensive, but. Yeah.
SPEAKER_03:Yeah. The mix, the mix, there's a lot of kind of back and forth around the benefits of mixtures. And then if there's more benefit with mixture, compared to just a monocrop cover crop. I think one of the really good things about mixtures is it helps growers kind of hedge their bets. If one species fails, there are other species that will still have a turnout. And so we see that a lot, I think. And I think we saw that a bit in our research with cover crops and rice systems where you are kind of at this really risky, in this really risky environment for putting in cover crops because of how the environment Yeah, well,
SPEAKER_02:earlier we were talking a bit about we're getting some rain up here north and I think it's going to hit you soon, but we started planting our rice cover crops. We got them in just before the rain hit, which was kind of fortunate, but we're a little concerned about how much rain, how it's going to take a bit of a beating on them. But can you touch on, I guess, recommended planting timing and then method of planting? methods for planting for successful cover crop establishment?
SPEAKER_03:To be humble and honest, I feel like the best management practices with cover crops and rice is still TDA. We still have a lot of work to do on that. I can go anecdotally and a lot of experience I've had in terms of what I hear other growers doing. And then I can talk about what we tried to do in our research plots.
SPEAKER_02:To hear what other people are doing and what we tried. I think that'd be awesome.
SPEAKER_03:Yeah. So first off, I think that the timing is everything and trying to get the cover crop in before, you know, you have, you definitely want to get the cover crop in earlier rather than later if you're going to have a wet year. Yeah. I know of growers that talked about actually doing this really interesting seeding method where they fly on the vetch before they harvest the rice after it's dried out. Then they harvest and then the germination happens and the vetch kind of helps with the decomposition of the straw and they don't really do much in terms of like coming in and doing the prep for tillage or anything. The same person I suppose that I know of that does this method also grows vetch for seed. And so they've been able to do a really fascinating system where they allow the vetch to reseed itself. And so for some time, they don't have to come back and reseed. They just let that vetch regrow. I think we should be looking into some of these techniques and seeing how well they work in different different kind of rice fields. But I only know of one particular grower that does this. The other ones will harvest after harvest, have maybe one tillage pass and then fly on the seed and will either incorporate the seed with the light till or not, depending on if the weather allows them to get back in the field with the tractor or not. And this was the way that we kind of went with it in our trials and you know there's there was definitely you were mentioning there was a lot of kind of like challenges and unknowns particularly with the weather and for how successful the cover crop was going to do in the rice field. And you either, you know, California, we're known for our extreme weather events. And so you either don't have enough water or you have too much. And this is particularly impactful in those super heavy clay flat soils that are laser level. So if you have a huge rain event, particularly if the cover crop has already started to germinate and then it floods for too long, you're just going to suffocate everything out. So one trick that we see working well and that's really recommended for growers if they're going to do some cover cropping is to make sure you put some drainage in the field. Come in and run a drainage ditch down in the middle of the field to allow for better drainage in the case of a flooding event. And that's been really, that was something that we did the second year of our trial, and it was very, very helpful, particularly in our site in Colusa. So yeah, so a couple different ways that I've seen it done, but to be providing best management options for cover cropping, I think we're not there yet. I think that there definitely is a lot more work to be done in terms of looking into the best management practices for planting.
SPEAKER_02:I think even just having that information of, hey, we're not actually certain what the best management practice are yet. I think just having that information out there is important too. And then for termination of the cover crop, I mean, as far as I understand it it's it's not really a hard and fast termination other than you want it gone before planting is that correct
SPEAKER_03:well i guess it just also depends on what ends up happening in terms of your your success or not success it's also dependent on where you are so i know that in um Sacramento Valley, rice can be planted a bit later into the season compared to in the Delta, right? And so you actually have this spring period that if you, especially if you're using things like legumes that are really crucial for getting that biomass growth and having things, that's where you get the majority of your growth habit for those, for a lot of the legumes that we use as cover crops. So if you can push your planting out for rice and you allow for that springtime growth habit to occur, you're going to get more benefit from that cover crop. But if you have to come in and plant really early March or even end of February, the termination is, if you're using something that requires that springtime growth, there's probably not going to be very much above ground biomass to begin with. And so the termination might be a bit easier to deal with. I would also caveat that that should also direct you to maybe perhaps making decisions on the types of cover crops that you're using if you're not able to plant later in the spring months. But if you do end up with a lot of biomass growth, then yes, that becomes a challenge for field prep. So I was never involved with the termination on our field trials. So I don't know exactly what the growers were doing, but I imagine similar with other cropping systems you know you're going to incorporate the above ground biomass through a few different tillage passes and then um You also then need to wait a few weeks before you come in and plant or prep for the rice season. So there's going to be a delay for when your incorporation of the cover crop is happening and then when you can get in to do your rice crop. I think one thing to note about management decisions for growers who are interested in cover crops with rice systems is that it's really, really important to think about what your goals are. And this is for any cropping system. But if you're particularly interested in... you're providing a high-end cover crop for high nitrogen provision, then definitely looking at a legume. But perhaps you're also really interested in scavenging some leftover end from the system. And so a grass cover crop would be really important to attain that goal. And perhaps mixing the two together will be really important for kind of a balancing effect of nitrogen provision and nitrogen retention. Also, this is really something I think that coming out of our research with cover crop variety trials, looking at some of these seasonal differences between the Delta sites and the Sacramento sites in terms of when growers are used to planting rice and when they're used to terminating rice or harvesting rice. And for sure in the Delta, people tend to get a much earlier jump on the season than up in the Sacramento Valley. So when you're picking a cover crop, looking at the duration of time it's going to take for that cover crop to reach peak biomass is really important. And for sure, some of the legumes are going to need a bit longer duration of time to reach peak biomass than, for example, perhaps some of the grasses like oat, rye, and even some brassicas like mustard, radish. And I do think that bell bean was an earlier, is a better term choice for a legume that is going to produce biomass earlier in the season. So those are just some things to think about when going into picking your cover crop varieties as a rice grower. Lots of variables to, I guess, reflect on and think about for factors that are influencing the decisions.
SPEAKER_02:Yeah, absolutely. If we can also talk a bit about some of the benefits and drawbacks of cover crops, especially relating I guess, to rice systems.
SPEAKER_03:The benefits of cover crops are numerous and pretty well known for cropping systems. In general, cover crops support soil health by increasing the organic nitrogen pools and also increasing soil organic matter accrual. They have the ability to support in keeping living roots in the ground year round, which has a huge effect on the rhizosphere and the health of microbial communities. So you see an increase in microbial biomass and microbial activity. All of this is really, really important for supporting the soil's ability to cycle nutrients, both providing it through mineralization to a plant available form as well as retaining it in some organic form to reduce nutrient loss. There's also the side of supporting soil health by improving soil structure, and that is really important for water infiltration and holding on to water. But translating all of that over to a rice system is really interesting. For example, soil structure's importance for an aerobic cropping system is really focused on holding on to that water in the soil. soil profile when there's not enough water and then moving it through the soil profile when there's too much. And of course for rice systems, we're really concerned with flooding and holding on to that water above the soil profile. So how cover crops may support soil structure and translate that to supporting a rice system is still kind of an interesting area. There is for sure a number of benefits that we see as far as the nutrient provision side as well as the microbial side, and they're both really linked to each other. So for sure, growers are really concerned with nitrogen provision, reducing the need for external inputs, and cover crops are a great way to increase the organic nitrogen pool. But beyond just specifically nitrogen, we do see that rice fields that have used cover crop Over time, more long term, they tend to have a different microbial profile than a conventional rice system that doesn't use cover crops. And this kind of came out in some of my research recently where we looked at organic fields that were rotated and organic fields that weren't rotated and then conventional fields that were rotated and those that were not. And overall, most of the organic fields that we sampled from used cover crops in their management design. And the organic fields showed much higher fungal to bacteria ratios than the conventional fields. And we know that fungal networks are really, really important for nutrient cycling and that they act like natural recycling. They reabsorb and redistribute nutrients back to plant roots. They're really crucial for breaking down plant litter and they're really important for that mineralization process. And so generally, I can say that cover crops are a key component if you're interested in moving towards more of this ecological nutrient management strategy. I do think that there is also a big role that cover crops are playing in terms of the ability to support soil organic matter accrual. in rice, but I don't think that it's nearly as big of an impact in rice systems as it is in another cropping system because the rice straw that remains at the end of the season, that turnover rate into the soil is really where these fields are seeing their carbon addition. So it is an interesting conversation in terms of thinking about the benefits of cover crops specifically for the rice system. I also do think that there's some question marks that need to be answered as far as the impact of cover crops with greenhouse gas emissions, as far as looking at some of the trade-offs. So we don't have a lot of that data yet, but I imagine that there is a trade-off in terms of improving upon some of these organic nutrient pools in our soil, but also perhaps increasing some of these greenhouse gas emissions. Interesting.
SPEAKER_02:So that's a lot on the benefits of cover crops in terms of soil health metrics. It seems like there's a lot of good things to say about cover crops. What about any drawbacks?
SPEAKER_03:Sure. Yeah. So, I mean, the challenges with cover cropping and rice fields are many. In general, even though you do have this support with your building your nitrogen reserves in your organic nitrogen pools, the variation is going to be high. It's variable in terms of, you know, you may have some parts of your field that have higher growth than others. And so, trying to get a standardized nutrient management plan is going to be much more difficult. I would say that's one of the biggest challenges. Then the other one, as we kind of alluded to, was you have to really adjust your timing for getting into the field. And that's going to have to probably adjust year after year based on the variability of the weather. I would also say that the question around rice straw is... a big one in terms of we've seen it be a huge hindrance for success rates of cover crops. So straw management is a challenge with growers who want to do cover cropping. I mean, the go-to for flooding the field and using that flood for decomposition, right, is not possible when you're doing cover cropping. So what to do with the straw management is kind of a question mark.
SPEAKER_02:Yeah. And I imagine if you can't flood over the winter, you're also perhaps not able to participate in providing migratory waterfowl habitat or participating in some of those incentive programs.
SPEAKER_03:Yeah. And I do know that there was an incentive program. I don't think it's current anymore, but there was at one point incentives for cover cropping with rice to provide upland breeding habitat for waterfowl. So I think the cover cropping environments don't necessarily, I mean, unless you were to scale it up across the valley, I'm not certain if you're going to disrupt migratory waterfowl, waterbird habitat significantly. You may also be creating different niches of needs for that waterfowl.
SPEAKER_02:I think that's a good point. Just because some people do cover crops in the winter, it's not going to have a massive impact on the overall landscape.
SPEAKER_03:Yeah, exactly. But there is that kind of, you know, bare fact that yes, if you're cover cropping, you're not winter flooding. And so in general, if you are using your, I I do know some growers that have their fields kind of come out into for duck hunting in the winter or something like that. That function is taken away. And that's also taken away when you rotate. You know, if you're rotating out of rice into another crop, you're also not flooding in the winter. So those trade-offs are for both management practices.
SPEAKER_02:So Sarah, we've spent all this time talking about your past work. And once again, let me just say, thank you so much for doing that. Let's talk about what you're working on now So, how long have you been in this new role?
SPEAKER_03:Oh, man. So, I started this position now about seven months ago, a little less. So, it's still very new. And it's not only new for me, it's new for UC ANR. So, this is one of two positions that have recently been filled with the title as a regenerative agriculture advisor. There's one other, she's a regenerative agriculture specialist based at UC Merced. But Her and I are pretty much the only ones. And yeah, the rules are brand new for cooperative extension.
SPEAKER_02:You get to make your own role, it sounds like.
SPEAKER_03:Yes, yes. And that is exciting. It's also challenging. There is no roadmap. The job description is very broad. It is not system specific. So as yourself as a rice advisor, it's pretty obvious what type of cropping system you work with. And as a regenerative advisor, I am not... system specific. So I work with all systems based in my counties.
SPEAKER_02:Since you have such a wide spanning reach, do you have a current focus for now? Or are you pretty, pretty wide spreading at this point?
SPEAKER_03:I'm definitely taking the tactic of throwing out a wide net, so to speak. But, you know, it's also going to be very, very dependent on my region. So context specific, adopting my programs, the context of my regions is very important, I think, for the success. And what I mean by that is what particularly the differentiation between Mariposa County up in the central Sierra foothills and the landscapes here, what agriculture looks like here versus the valley and Merced and Stanislaus and what agriculture looks like there. And so the role that I play really is going to be a bit more delineated between those two agro environments. And up in the foothills, we have, you know, it's dominated by rangelands. And we also have a lot of small diversified farms. And that is an area that's actually starting to expand more, which is really exciting. But so those are the two paradigms in the foothills that I'm working with is rangeland ecosystems and small diversified farm ecosystems or agro ecosystems. And then in the valley, I am really still exploring this area, but I imagine to be working a lot with perennials being that tree. Production is such a huge area in these counties. The valley is so diverse in itself too that I could be taken in many directions.
SPEAKER_02:Never a dull day at work, huh? Any upcoming events or workshops that you'd like to promote or talk about?
SPEAKER_03:Yeah. So I am currently, you know, thinking that, I mean, maybe this is kind of fun because we're kind of going back. We're taking it into a full circle here. I am currently working on my needs assessment and I'm doing interviews with a lot of growers and also a lot of partnering farm advisors and cooperative and UCNR and other stakeholders. And a part of this needs assessment is holding these information and listening sessions. And so we have our first one coming up in December, December 16th, and it's being held at the Burroughs Family Farm in Merced. This is one of, I think, four sessions that we're going to be organizing across the regions that I work in. And the main point of these sessions are kind of dual purpose to do a sort of a meet and greet with growers and other stakeholders in my regions and introduce myself and my role being that this role is so new. And then also to do some preliminary sharing of some of the interviews that I've been conducting. The second half of this is the listening session. And so this is where I encourage people to come who want to talk about their experiences in this regenerative space and also challenges and interests and hoping that we can use these discussions to help guide the extension and research programs that are being developed here. So yeah, those are exciting. I will say that the specific one coming up in December is... a little bit more focused on nut tree production. So almonds, walnuts, pistachios. And then from there, we will be having a larger or broader invite at UC Merced. We will also hopefully be organizing one in Stanislaus, as well as one for up in Cathy's Valley for more of the central Sierra Foothill region.
SPEAKER_02:Great. We'll have a link to that in the show notes for people in that area who are interested in attending those. That'd be wonderful. Yeah, absolutely. Excellent. And so just finally, where can people get more information about your research, your role, this new role, and basically how do people contact you?
SPEAKER_03:Sure. I mean, I'm always open for emails. My email is a great way to start. I also do have a Facebook social media presence that I'm trying to expand on. And that is just simply UCCE regenerative agriculture. And then we have some, I mean, I think those are the two easiest ones for people to reach out with or to explore if they're interested a bit more in the work that I'm doing For my email, it's srosenberg at ucanr.edu. And yeah, those are some good starting points. I can also give people a phone number.
SPEAKER_02:Some people give phone numbers. Some people give emails. We told Bruce to stop giving out his phone number because his voicemail box is so full.
SPEAKER_03:Okay, well, so the phone number here is 209-966-2417. And there's an extension 1417 to reach me.
SPEAKER_02:Brilliant. Well, Sarah, thank you so much for coming on.
SPEAKER_03:Yeah, thank you so much for having me.
SPEAKER_02:We have announced the dates for the 2025 Winter Rice Grower Meetings. And so we're going to continue the same format we've had in previous years, having a series of repeating meetings across the rice growing region. So it's okay. In fact, it's suggested, don't go to all of them. You'll be pretty bored, but try to make at least one of them. The same information will be presented at all of them. And so I'm going to read off this list of dates, but please keep in mind, these dates are on our blogs, on our websites, in our newsletters. So anywhere you need to get more information, go ahead and look for that. Without further ado, here are the... dates, and area locations for the 2025 Rice Winter Grower Meetings. The specific locations are currently TBD, but here's just the general town they'll be in so you can kind of plan your early spring. February 10th in the morning will be the Woodland Meeting. February 12th in the morning will be the Richvale Meeting. February 12th in the afternoon will be the Willows Meeting. February 13th in the morning will be the Colusa meeting, and finally, February 13th in the afternoon will be the Yuba City meeting. Again, those specific locations are TBD. They will be in those towns, but we will have more information later on, and we will be sure to get that out to all of you as soon as we have that accessible. To learn more about the UCCE Rice program, please feel free to look at our resources, which include the UC Rice blog, the the UC Agronomy Rice website, and our newsletters, which are Rice Briefs, which covers Colusa and Yolo, Rice Notes, which covers Yuba Sutter, Rice Leaf, which covers Butte and Glen, and Field Notes, which covers rice in the Delta region. Thanks for listening to Thoughts on Rice, a University of California Cooperative Extension podcast from the University of California Agriculture and Natural Resources. You can find out more about this podcast on our website, Hopefully everybody gets to breathe a little bit now that harvest is done. And remember, like the growers like to say, have a rice life. Mention of an agrochemical does not constitute a recommendation, merely the sharing of research findings. Always follow the label. The label is the law. Find out more at ipm.ucanr.edu The views, thoughts, and opinions expressed are the speaker's own and do not represent the views, thoughts, and opinions of the University of California. The material and information The information presented here is for general purposes only. The University of California name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product or service.
