- Author: Michelle Leinfelder-Miles
UC Davis and UC Cooperative Extension will host the UC Dry Bean Field Day on Thursday, August 15, 2024 from 9:30am to 11:45am. The field day will begin at the Agronomy Field Headquarters (2400 Hutchison Drive) on the UC Davis campus. From the Agronomy Field Headquarters, follow the UCCE sandwich board signs to the field location. Look for the pop-up tents. The agenda is pasted below, and a downloadable version is attached to the bottom of this post. DPR continuing education (1.0) is pending. CCA continuing education credits have been approved (1.0 Crop Management, 1.0 Pest Management). Light refreshments will be provided. Thanks for your interest, and we hope to see you at the field day!
Agenda:
9:15am Arrival and sign-in
9:30am Welcome and introductions: Christine Diepenbrock and Antonia Palkovic, UC Davis; Michelle Leinfelder-Miles, UC Cooperative Extension
9:35am Developing breeding resources to improve lima bean adaptation and quality: Christine Diepenbrock and Paul Gepts, UC Davis
9:40am Seed and culinary traits in limas and evaluation of the USDA lima collection: Jaclyn Adaskaveg, UC Davis; Sarah Dohle, USDA-ARS
9:55am Improving heat tolerance in grain legumes (with use of sensors and 3-D models): Sassoum Lo, Heesup Yun, and Earl Ranario, UC Davis
10:05am Choosing varieties for pest resistance, high yields, and high quality – regional trial results: Michelle Leinfelder-Miles and Nick Clark, UC Cooperative Extension
10:20am Cowpea breeding for California: Bao-Lam Huynh, UC Riverside
10:35am Travel to Bee Biology Road
10:45am Lima and chickpea breeding for California: Antonia Palkovic and Christine Diepenbrock, UC Davis
11:00am In-field agronomic evaluation of lima lines for culinary testing: Antonia Palkovic and Jaclyn Adaskaveg, UC Davis
11:10am Genotypic and environmental variation in nutritional traits in common bean: Tayah Bolt, UC Davis
11:15am Improving chickpea for aluminum tolerance and more effective nitrogen fixation: Laura Perilla-Hanao, Ali Said, and Douglas Cook, UC Davis
11:25am Defending lima beans from lygus bugs: breeding and emerging technologies: Kimberly Gibson, UC Merced (alumna of UC Davis)
11:40am Discussion and evaluation
2024-8-15 Dry Bean Field Day Agenda FINAL
- 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.
Summary:
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.
- Author: Michelle Leinfelder-Miles
My observations of the field were that there were patches of several nearby plants with symptoms, but across the three contiguous fields, the patches were widespread. I suspected a vascular disease because of what appeared to be a progression of the disease from yellowing to necrosis to eventually plant death. I submitted samples to the plant pathology lab at UC Davis, and they diagnosed Fusarium oxysporum f. sp. ciceris, which is the Fusarium wilt pathogen for garbanzos. Fusarium wilt (also called Fusarium yellows) has the external symptoms previously described, but in addition to these symptoms, splitting the stems may reveal reddish-brown streaking in the vascular system at the center of the stem (i.e. xylem). The roots won't show discoloration with Fusarium wilt like they will with Fusarium root rot. Fusarium wilt should not be confused with yellowing caused from virus, which will exhibit discoloration in the phloem. Fusarium wilt can reduce yield by reducing seed quantity and size.
In general, cultural practices are the only ways to manage this disease. Luckily, the Fusarium wilt pathogens are crop-specific, so this pathogen will only infect garbanzos. The pathogen, however, can survive for a long time in the soil (upwards of 6 years or more) because it can survive under wide temperature and pH ranges. Therefore, crop rotation is an important management practice. Crop rotation will help to slow the proliferation of the disease, but it generally won't eliminate it. Growers should plant certified disease-free seed. They should not save seed for planting because Fusarium wilt (and Ascochyta blight) can live externally on the seed. Growers should also consider planting UC-27, which has disease resistance and is adapted to the Central Valley. Disease management may also include cleaning soil from equipment when moving from an infected field to a non-infected field. In some studies, soil solarizaton has been shown to reduce Fusarium wilt in subsequent garbanzo crops, but to my knowledge, there hasn't been any work on soil solarization in California garbanzos.
Garbanzo beans are an important crop worldwide for human and animal nutrition. In California, they are grown during the winter months, like small grains, and provide growers with another crop choice that can be winter rain-fed. Because they are a legume, they can fix atmospheric nitrogen to fulfil some of their nitrogen needs. Garbanzos also are more tolerant of soil salinity than common beans and limas. In California, we annually grow approximately 10,000 acres of garbanzos. California garbanzos are generally a high-quality product grown for the canning industry. More information on garbanzo production in California can be found in the UC production manual.
- Author: Michelle Leinfelder-Miles
I recently visited a bean field in the southern part of the county with a PCA. From a distance, the beans in certain areas of the field appeared to be drying up and dying. A closer look showed that the leaf margins were drying up first before the whole plants declined. Pulling up plants by the roots, they appeared to show some reddish root lesions. Soil moisture was good – it seemed neither too wet nor too dry, but there was white crusting on the soil surface of the furrows.
As I was thinking about what could be happening with the beans, a couple things were running through my mind. The patchiness of the problem in the field and the reddish roots made me think that Fusarium root rot (Figure 1) may be a problem. The PCA believed that there had been tomatoes in the field the previous year but that there may have been beans in the field just two years ago. I wondered whether the white crusting on the soil was due to salt. The PCA said that he thought the field was irrigated with groundwater.
To put something behind my hunch, I sent plant samples up to the disease diagnostics lab at UC Davis. Tests confirmed that both Fusarium and Rhizoctonia inoculum were present on the plant roots and that the Fusarium inoculum was particularly high. Fusarium spores can survive in the soil for several years, and UC IPM guidelines suggest rotating out of beans for at least three years in Fusarium-affected fields. Unfortunately, Fusarium spores will live in the soil even when bean hosts are not present.
Stress conditions in the field can worsen Fusarium infection, particularly conditions of too much or too little water, compaction, and salinity. We tested the soil salinity at this site and found the electrical conductivity (EC) of the surface soil to be around 5.0 decisiemens per meter (dS/m). Beans are very sensitive to salinity, and yield declines are expected when rootzone soil salinity is as low as 1.0 decisiemens/meter. It would appear that salinity could be stressing the beans and causing them to be more susceptible to the Fusarium inoculum in the soil. Because this grower is irrigating with groundwater, I would recommend that he get his water tested for salinity. If the water salinity is acceptable, then he should consider how he will leach the field this winter, perhaps augmenting rainwater with irrigation water (assuming normal-to-low precipitation this winter). If his groundwater is high in salts, then he should consider using a different water source for irrigating and leaching (if available) and rotate to more salt-tolerant crops, like small grains, for at least three years.