I am pleased to announce the following two meetings:
1. UC Cooperative Extension and UC Davis will host a Healthy Soils Program Workshop on compost. The meeting will take place on Tuesday, October 26th from 9:00am to 12:30pm (BBQ lunch provided). The meeting will take place at Rominger Brothers Farm (28800 Co Rd 29, Winters, CA). Presentations topics include how to acquire compost, different types of compost and how it can improve soil health, and nitrogen management in tomato systems receiving compost. At the end of the workshop, there will be a compost spreading demonstration. Attendance is free, but registration is required. Continuing education credits will be offered (0.5 of N management for ILRP program; 0.5 NM and 1.0 SW credits for CCAs). The agenda is available from the registration page.
2. UC Cooperative Extension will host an online workshop on Using N-rich Reference Zones to Guide N Management in Small Grains. The workshop will take place on Thursday, November 4th from 2:00-4:00pm. Presentation topics include how to implement N-rich reference zones, online N management tools, and case studies from local sites. Attendance is free, but registration is required for anyone requesting continuing education. Continuing education credits (2.0 of N management) will be offered for the ILRP program. The agenda is pasted below, and the meeting link is here.
Thanks for your interest in UC Cooperative Extension programming.
Agenda: Using N-rich Reference Zones to Guide N Management in Small Grains
2:00 - 2:15 Overview of concepts and tools related to utilizing N rich reference zones to guide N management in California small grains. (Mark Lundy, UC Davis/UCCE)
2:15 - 2:30 Introduction to The Nitrogen Fertilizer Management Tool for California Wheat and other web tools for optimizing N management in California small grain crops (Taylor Nelsen, UC Davis)
2:30 - 2:35 Questions and Discussion
2:35 - 4:00 Case Studies: Using N-rich reference zones to guide N fertilizer management in diverse California environments. Presentations will discuss specifics of implementing N rich reference zones and using UC decisions support tools to make in-season N fertilizer decisions.
- Yolo County irrigated site N rich case study (Mark Lundy, UC Davis/UCCE)
- Yolo County rainfed site N rich case study (Konrad Mathesius, UCCE)
- Kings County N rich case study (Nick Clark, UCCE)
- Sacramento County Delta N rich case study (Michelle Leinfelder-Miles, UCCE)
- Siskiyou County N rich case study (Giuliano Galdi, UCCE)
- Colusa County N rich case study (Sarah Light, UCCE)
- Wrap-up discussion and survey
In previous years, we trapped for both true armyworms and western yellowstriped armyworms. It appears, however, that the true armyworms are the ones that damage rice, so this year, we focused our trapping on them. I trap on three islands in the Delta, and I did see some leaf feeding damage in June. Moth flights peaked in late June (Fig. 1), but overall, damage was not severe this year. In fact, the moth counts were the lowest that I have seen since I started trapping in 2016. Some growers indicated needing to spray, but others did not. For those who sprayed, populations fell and did not resurge later in the season. I saw very little, if any, panicle injury in August and September.
You can find more information about my Delta rice research and extension program on my website. I wish you a successful harvest season!
Figure 1. Delta true armyworm trap counts. The trap counts represent the number of moths caught per day, averaged across three Delta locations. The 2021 counts were the lowest seen since trapping began in 2016.
UC Cooperative Extension will host the annual Delta field meeting on Thursday, September 30th from 10:00-11:30am, on Tyler Island in Sacramento County. The agenda is pasted below and attached. In addition to providing information on the annual field corn variety trial, this year's agenda includes presentations on nitrogen management in corn and wheat. The attached version of the agenda includes a map and directions to the field site. We have applied for CCA and CDFA INMP continuing education credits. The University is attentive to the ongoing Covid-19 pandemic. Please monitor yourself for Covid-19 symptoms before coming to the event, and do not come if you are experiencing symptoms. While this meeting is outdoors, we will be following University safety precautions for in-person events. Please practice social distancing, or wear a mask if within 6 feet of another person. Thanks for your interest in UC Cooperative Extension programming, and we hope to see you in the field!
10:00am Field corn variety evaluation – preliminary results, Michelle Leinfelder-Miles, UCCE, SJC/Delta
10:15am Variety traits for the Delta, Seed company representatives
10:30am In-season nitrogen management in wheat, Michelle Leinfelder-Miles, UCCE, SJC/Delta
10:45am Development of site-specific nitrogen fertilization recommendations for annual crops, Suzette Turner and Daniel Geisseler, UC Davis
11:00am Viewing of field plots
I am pleased to announce the following meetings and webinars.
1. The Rice Experiment Station (RES) Annual Field Day will takes place next Wednesday, August 25, 2021 from 7:30am to 12:00pm, followed by lunch. The RES is located at 955 Butte City Highway (Hwy. 162), approximately two and one half miles west of Highway 99, north of Biggs, California. The field day is an opportunity to learn about the research being done at the RES, including variety development. It is sponsored by the California Cooperative Rice Research Foundation (CCRRF) and University of California (UC). For more information, please visit the RES website.
2. Farmers' Rice Cooperative and Wetlands Preservation Foundation will host a Delta Rice Field Day next Thursday, August 26, 2021 from 8:30am to 1:45pm. The event will start at Canal Ranch (23011 Blossom Road, Thornton, CA 95686), followed by a bus tour of nearby Delta rice production. I will be present to answer questions about my rice research and extension program, including the Delta variety trial, armyworm monitoring, herbicide trials, and weedy rice outreach. Space is limited, so please see this flyer to reserve space.
3. The UC Dry Bean Field Day will take place on Tuesday, August 31, 2021 from 9:00am to 11:30am. The field day will begin at Honey Bee Haven, Bee Biology Road, on the UC Davis campus. Due to Covid-19 safety precautions, preregistration for this event is required. There is no registration fee. I invite you to view the agenda and register here. CCA continuing education credits (2.0) are available (0.5 of NM; 0.5 of PM; 1.0 of CM).
4. The UC Alfalfa and Forage Field Day will take place on Thursday, September 23, 2021 from 8:00am to 12:15pm, followed by lunch. The field day will take place at the Kearney Research and Extension Center, 9240 S. Riverbend Ave., Parlier, CA 93648. Due to Covid-19 safety precautions, preregistration for this event is required. There is no registration fee. I invite you to view the agenda and register here. We have applied for DPR, CCA, and N management (ILRP program) continuing education credits.
5. The Vertebrate Pest Council is hosting vertebrate pest webinars on September 28 (field rodents), September 29 (use of rodenticides), and September 30 (managing commensal rodents). The webinars run from 8:00am to 10:00am each day, and registration is required. Please see this flyer for more information.
Finally, the Covid-19 pandemic is a fluid situation. At this time, I plan to hold an in-person field meeting at the Delta field corn variety trial, as I have done in the past. The date is TBD but will take place in late-September or early-October. I will send a separate blog announcement when the date has been set.
Thank you for your interest in our programs. Stay healthy, and hope to see you soon at one of these events.
- Author: Michelle Leinfelder-Miles
- Author: Mohamed Nouri
- Author: Brent Holtz
In 2020, we established a trial to evaluate soil properties and kidney bean yield following whole orchard recycling of a walnut orchard. Whole Orchard Recycling (WOR) occurs after the productive life of an orchard and is the process of grinding or chipping trees, spreading the wood chips evenly over the soil surface, and then incorporating the biomass into the soil. WOR has become more common in recent years because air quality regulations restrict growers' ability to manage biomass by burning. Additionally, half of California's biomass power generation plants have closed, and those that still operate are no longer paying for wood chips.
While the process of WOR came about due to biomass management restrictions, researchers have been evaluating its potential benefits for soil health and water management. This is because the practice incorporates large quantities of organic carbon (C) into the soil, and soil C influences other soil properties. The California Department of Food and Agriculture (CDFA) Healthy Soils Program (HSP) now recognizes the practice in their incentives program and provides growers with up to $800 per acre for WOR. The San Joaquin Valley Air Pollution Control District also supports growers who recycle orchards with up to $600 per acre.
While there are benefits associated with incorporating large quantities of C into the soil, there are also tradeoffs. The woody biomass of the trees has a high carbon to nitrogen (C:N) ratio. The C:N ratio is the mass of C relative to the mass of N. It is an important characteristic of soil amendments because it influences soil biological activity. When the C:N is high, as it would be with woody biomass, the N is primarily used for microbial energy and maintenance. In other words, the N is ‘tied up' by the microbes and not available for plants.
Our understanding of nutrient cycling and availability is most advanced in almond WOR sites replanted back to almond. Previous research at WOR sites that were replanted back to almond found that doubling the N fertilizer recommendation in the first year could help to avoid reduced growth of the new orchard. We established this trial because more research is needed on WOR in other orchard systems, and when annual crops are subsequently planted rather than orchards. Our objectives were to evaluate soil properties and bean yield following WOR compared to a non-WOR control, and to evaluate two N fertilizer rates. We hypothesized that bean yield might be compromised following WOR due to N immobilization but that a higher rate of N fertilizer might overcome the yield gap.
The trial took place on an approximately 35-acre site near Linden, following the June 2019 walnut orchard recycling that incorporated approximately 70 tons of wood chips per acre (Figure 1). At that time, three approximately 0.5-acre plots were kept without wood chips, as ‘untreated controls'. We then identified three 0.5-acre WOR plots adjacent to each control plot.
Figure 1. Recycled orchard site showing wood chips spread over the field and the depth of wood chips applied.
More information about our procedures can be found in the full report, available from https://ucanr.edu/sites/deltacrops/files/352144.pdf. Soils were sampled three times during the season to inform our fertilizer rates and understand C and N cycling. The UC production manual for dry beans indicates that a bean crop that yields 2000 lb/acre needs approximately 80-120 lb of N to grow the crop. While beans are a legume and can fix atmospheric N and turn it into plant-available N, they do not fix enough to satisfy their own N requirement. They fix about 20-40 percent of their need. Nitrogen inputs for the trial are listed in Table 1. The beans were planted on July 10th and harvested on October 19th.
Table 1. Nitrogen inputs in 2020 trial.
Soil samples were evaluated for organic C, total N, and nitrate-N. With the pre-plant samples collected in June, there were no differences in organic C, total N, or nitrate-N between the WOR treatment and control. Total organic C averaged 1.2 percent across all plots, total N averaged 1052 ppm, and nitrate-N averaged 2.78 ppm. In August, prior to sidedress N application, we observed differences in plant size, with plants in the WOR treatments being smaller than those in the control plots (Figure 2).
Figure 2. Bean plants in August 2020, prior to sidedress N application, where plants in the WOR treatment were observably stunted compare to those in the control plots where no wood chips were previously incorporated. A) Plants to the right of the pink flag in the foreground are in a control plot. B) Bean plants in the foreground near the pink flag are in a control plot.
By October, soil organic C, total N, and nitrate-N differed among treatments. (See full report for graphed data.) Organic C and total N were significantly higher in the WOR treatment compared to the control, and neither had differences between the N fertilizer treatments. Nitrate-N, however, had an opposite result. It was significantly higher in the control compared to the WOR treatment, and there were differences between fertilizer rates, with the lowest nitrate being in the grower N rate plots of the WOR treatment. The soil results suggest that, by October, the wood chips were decomposing and contributing to the soil organic C and N pools. The organic N, however, was not yet mineralizing to nitrate. Nitrate was limited in the WOR treatment, where it was possibly tied up by soil microbes, unless boosted by the doubled sidedress fertilizer rate.
Whole orchard recycling and nitrogen fertilizer rate impacted yield in this trial. Yield was statistically higher in the control plots, averaging 2652 lb/ac across replicates, compared to the WOR plots where the average was 1820 lb/ac (Figure 3A). There were also differences in yield among N fertilizer rates (Figure 3B). In the control, the grower N rate and the doubled N rate performed statistically similar. In other words, there was no benefit to applying the doubled sidedress rate in the control. Additionally, the grower rate in the control performed statistically similar to the doubled rate in the WOR treatment. This indicates that while WOR may tie up N – limiting its availability for plant growth and yield – doubling the recommended N rate overcame the yield penalty imposed by WOR. Thus, when coupled with additional N fertilizer, WOR can augment soil health properties, like organic C and N, without penalty to yield.
Figure 3. Bean yield in October 2020 averaged across three replicated blocks. A) Bean yield between WOR treatment and the control were statistically different. B) Bean yield for N fertilizer rates were also statistically different. Bean moisture averaged 10.5 percent across all treatments.
This project evaluated soil properties and kidney bean yield following walnut WOR. By incorporating a large quantity of organic C into the soil, WOR has the potential to improve soil health properties, but a tradeoff may be that N becomes limited for subsequent crops. We found organic C and N to increase with WOR from the beginning of the bean season to the end, but plant-available nitrate was limited by WOR. Bean yield suffered as a result of WOR, but doubling the fertilizer N recommendation mitigated the yield penalty. Under the circumstances of this trial, a total N rate of just over 200 lb/ac maintained bean yield where WOR had been implemented compared to the control plots with no wood chips. It does appear, however, that the yield in the WOR treatment might have benefitted from an even higher rate of N. To our knowledge, this trial was the first of its kind and more research will be needed to develop N fertility guidelines in dry beans following WOR. Other tree and annual crops should also be studied. We will continue this trial in 2021 to evaluate whether the impacts of WOR continue in the second season after recycling.