UC Cooperative Extension will host the annual corn field meeting on Tuesday, October 15th, 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 corn variety trial, this year's agenda includes presentations on nitrogen management for the upcoming small grains season. The attached version of the agenda includes a map and directions to the field site. We have applied for CCA continuing education credits, and light refreshments will be provided. RSVP is not required. Hope to see you in the field! 

 

 

 

Agenda:

10:00am         Field corn variety evaluation – preliminary results: Michelle Leinfelder-Miles, UCCE

10:15am         Variety traits for the Delta: Seed company representatives

10:30am         In-Season Nitrogen Management in Wheat: Michelle Leinfelder-Miles and Sarah Light, UCCE

10:45am         In-Season Nitrogen Management in Malting Barley: Taylor Nelson, UC Davis

11:00am         Viewing of field corn plot

On September 4^th, we hosted the Soil Health and Cover Cropping Field Meeting on Staten Island in San Joaquin County. We would like to thank those who attended the meeting. The meeting handouts are now available from the Delta Crops website.

We began the meeting with “lightning talks” from organizations working on cover cropping and climate-smart agriculture, including UC Cooperative Extension, Contra Costa Resource Conversation District, Community Alliance with Family Farmers, and USDA-NRCS. We then showcased the cover cropping trial that we established in cooperation with Conservation Farms and Ranches. A CDFA Healthy Soils Program grant supports the Delta trial, which is part of a larger effort that includes our farm advisor colleagues in the Sacramento and San Joaquin Valleys – Sarah Light, Amber Vinchesi, and Scott Stoddard – along with Jeff Mitchell and Will Horwath at UC Davis.

This is the second of a three-year on-farm trial to evaluate warm-season, annual legume cover cropping between winter small grain crops compared with a standard dry fallow. Cover cropping is a management practice identified in the Healthy Soils Program as having the potential to improve soil health, sequester carbon, and reduce greenhouse gas emissions. Cover cropping is not a typical practice in the annual crop rotations of the Delta region, however, and summer cover cropping is particularly rare. The Delta is a unique agricultural region with unique environmental challenges. Some soils in the region are subsided due to oxidation of organic matter, and some soils suffer from salinity, having limited ability to leach salts due to low permeability soils and shallow groundwater. Because surface waterways provide water for irrigation, summer cover cropping with a legume has the potential to improve soil tilth at a time of year when the soil would otherwise be fallow and dry with no soil cover.

The soil type across the experimental site is a Valdez silt loam. The trial is approximately 4.5 acres and compares three replicates of two treatments: an irrigated cover crop and a dry, fallow soil in between small grain crops. A cover crop of cowpea (Vigna unguiculata cv. ‘Red Ripper') has been planted in July of 2018 and 2019 after small grain harvest and tillage operations. Irrigation is provided to the cover crop plots only. The cover crop is terminated in the fall ahead of tillage and planting of small grains. Soil properties tested to date include bulk density, salinity (EC), pH, total nitrogen (N), and total carbon (C). We have also evaluated cover crop characteristics and 2019 triticale yield.  

Among the soil properties, we have observed essentially no change in bulk density, total C, and total N from the July 2018 baseline condition. We are monitoring salinity and pH semi-annually because we have observed these properties to improve in the cover-cropped plots. After one cover cropping season, salinity increased in both treatments, but it increased more in the dry fallowed plots, averaging 1.22 dS/m from 0 to 12 inches, compared to 0.64 dS/m in the cover crop (CC) treatment. Rainfall during the 2018-19 winter season leached salts in both treatments, but the CC treatment started the 2019 cover cropping season with a lower average rootzone salinity (0-36 in) of 0.78 dS/m, compared to 1.13 dS/m in the dry fallow (No CC) treatment. Soil at this site is acidic, which is typical for the region, but pH was observably higher in the CC treatments.

We made changes to our planting and irrigation scheme in 2019 – changing from flood to sprinkler irrigation – and this has improved cowpea stand in 2019, compared to 2018. There has been a lot of competition from volunteer wheat (2018)/triticale (2019) and weeds, but we decided in both years not to manage these with tillage or herbicides. Both add biomass to the soil, which is an objective of the Healthy Soils Program. Competition, however, likely impedes cowpea growth and nitrogen fixation, and future study should investigate how these soil properties are affected by single-species and mixed cover crop stands. At the end of the first cover cropping season, biomass largely favored the volunteer wheat. Of the total C added to the soil from biomass, the wheat contributed 42-71%, compared to 15-24% from the cowpea, across the three replicate plots. Of the total N added from biomass, the wheat contributed 68-87%, and the cowpea contributed 9-15%. The triticale forage crop (winter 2018-19) yielded 5.4 tons per acre for the CC plots and 6.3 tons per acre for the No CC plots, but there was high variability among subsamples. The overall field averaged approximately 5.5 tons per acre. More detailed methods and results are available in our preliminary report.

In summary, cover cropping, particularly in the warm-season, is not a typical management practice in the annual crop rotations of the Delta region. After the first year of a three-year study, cover cropping had no observed effect on bulk density, Total N, and Total C. We observed better salinity and pH conditions in the cover-cropped plots. Cowpea stand establishment and volunteer grain and weed competition have been the biggest challenges to growing a summer cover crop at this site, and the cover crop was not observed to improve cash crop yield in the following season. We will continue to monitor soil and cover crop properties in 2019 and 2020, and additionally, we will reach conclusions about greenhouse gas (CH₄, N₂O) emissions, which are being evaluated by our UC Davis colleagues.

This project is financially supported by the California Climate Investments program. We thank Dawit Zeleke and Morgan Johnson of Conservation Farms and Ranches for hosting the trial. We thank Tom Johnson of Kamprath Seed and Margaret Smither-Kopperl and Valerie Bullard of the NRCS PMC for information and advice on cover cropping.

UC Cooperative Extension will host a Soil Health and Cover Cropping Field Meeting on Wednesday, September 4, 2019 from 10:00am to noon, on Staten Island in the San Joaquin County Delta. The agenda is pasted below and attached. The meeting will begin with a few presentations at the Staten Island grain silos, on the north end of the island, before showcasing the warm-season legume cover crop that is grown between winter small grains.  We have applied for CCA continuing education credits, and light refreshments will be provided. RSVP is not required. Hope to see you in the field!

 

10:00am          Welcome, Introductions, and Project Overview

                       Michelle Leinfelder-Miles and Brenna Aegerter, UCCE, San Joaquin County

10:20am          “Lightning Talks”

Brief presentations from organizations working on cover cropping and soil health

             Cool Season Cover Cropping: Sarah Light and Amber Vinchesi-Vahl, UCCE

             Cover Cropping Survey: Ben Weise, Contra Costa Resource Conservation District

             Climate Smart Farming Program: Sara Tiffany, Community Alliance with Family Farmers

             Cover Cropping Incentive Programs: Sonya Miller, USDA-NRCS San Joaquin County

             Summer Cover Crop Options: Valerie Bullard and Margaret Smither-Kopperl, USDA-NRCS                                               Plant Materials Center

10:45am          Caravan to field site

11:00am          Warm Season Legume Cover Cropping in the Delta – Preliminary Results from Year 1

                       Michelle Leinfelder-Miles and Brenna Aegerter, UCCE

11:15am          Viewing of plot

11:45am          Wrap-up and Evaluations

A little over a month ago, I visited some contiguous garbanzo bean fields in southern San Joaquin County, at the request of the grower. The grower observed that plants were yellowing and dying (Fig. 1) and wondered what might be causing the problem. The grower did not figure that he would be able to do anything about the problem in this year's crop, but he was thinking ahead for future cropping. He doesn't have reliable water at this site, so his cropping options (i.e. rotation options) are limited. He would consider growing garbanzos in these fields again next year unless diagnostics revealed a disease problem.

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.