The Delta trial was planted on November 15, 2018 and consisted of 38 common wheat varieties and 10 triticale varieties in three replicate blocks. Following a tomato rotation, the trial was planted on 60-inch raised beds, and no nitrogen fertilizer was applied to the field ahead of planting small grains. Neither was irrigation applied during the season, as rainfall amounted to approximately 22.5 inches over the season (Staten Island CIMIS station).
Trial results can be viewed interactively from the Agronomy Research and Information Center Small Grains page. Regional summaries are based on 3 years of trial data across multiple locations. The Delta location is grouped with the Sacramento Valley. These multi-year, multi-environment summaries are what we recommend using for making variety selection decisions because any unusual circumstances in a single year (as from weather) can have a tremendous influence on variety performance.
Single-site summaries are also available and provide data across multiple years. These summaries allow more customized exploration of the data and also allow users to examine genotype by environment patterns in the data. (See heat map below.)
Both interactive sites have features that allow users to view, filter, and sort information. For the best experience, we recommend viewing these sites using a laptop or desktop computer with an up-to-date version of Firefox, Chrome, or Microsoft Edge web browser. (Microsoft Explorer will not work.) All results can also be viewed and downloaded as static tables and figures, with additional information about site characteristics and crop management here.
As we usher the 2019 harvest season, the 2019-20 small grains season is upon us. Don't forget to attend the Delta corn and small grains field meeting on October 15th. I wish everyone fruitful harvest and planting seasons!
- Author: Michelle Leinfelder-Miles
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
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.
Methods: The trial is a randomized complete block design (approximately 4.5 acres) with three replicates of each treatment. The soil type across the trial is a Valdez silt loam. Baseline soil samples were collected in July 2018 following wheat harvest but prior to tillage. Soil was sampled from 0-6, 6-12, 12-24, and 24-36 inch depths. On July 30, 2018, a cowpea cover crop (Vigna unguiculata cv. ‘Red Ripper', Figure 1) was inoculated with Rhizobium and planted after a pre-irrigation. Pre-irrigation was only applied to the cover crop plots. The cover crop was drill-seeded at 7-in row spacing with a planting density of approximately 50 pounds of seed per acre. A second irrigation was applied approximately one month after planting. End-of-season soil sampling (0-6 and 6-12 inch depths) occurred on October 23, 2018, prior to cover crop termination. Soil properties of interest include bulk density, soil moisture, salinity, pH, total nitrogen (N), and total carbon (C). Soil properties were analyzed by the following methods: pH from the soil saturated paste, salinity by the saturated paste extract, and total N and C by combustion method.
Preliminary Results: Soil properties are presented for the baseline condition (Table 1) and for the end of the first cover cropping season (Table 2). Bulk density averaged 1.0 g/cm3 across sample timings, depths, and treatments. Soil moisture (% by volume) was observed to increase from the baseline condition in the cover crop (“CC”) treatment. At baseline sampling, salinity increased with depth from 0.47 to 2.44 dS/m. After one cover cropping season, salinity increased in both treatments, but increased more in the no cover crop (“No CC”) treatment, averaging 1.22 dS/m from 0 to 12 inches. Soil was acidic, which is typical for the region. The pH averaged 5.5 across sample timings, depths, and treatments, but there may be a trend for cover cropping to increase the pH. Total N and C decreased with depth at the baseline sampling. After one cover cropping season, there was little change from the baseline condition in both treatments.
Summary: 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. Cover cropping is not a typical practice in the annual crop rotations of the region, and summer cover cropping is particularly rare. After the first year of a three-year study, cover cropping had no observed effect on bulk density, Total N, and Total C. Cover cropping may have slightly raised the pH in the top 12 inches, compared to dry fallow. The cover crop treatment, having received two irrigations, had lower salinity in the upper layers of soil compared to dry fallow. We also observed that the 2018-2019 triticale crop that was planted in the field germinated roughly five days earlier in the cover crop plots compared to the fallowed plots. Thus, it appears that summer cover cropping with a legume has the potential to improve soil tilth at a time of year when the field would otherwise be fallowed and dry with no soil cover, and there could be agronomic benefits to subsequent crops. We will continue to monitor these soil properties in 2019 and 2020, and additionally, we will monitor small grain yields and greenhouse gas (CH4, N2O) emissions.
We would like to thank Dawit Zeleke and Morgan Johnson (Staten Island), Tom Johnson (Kamprath Seed), and Margaret Smither-Kopperl and Valerie Bullard (USDA-NRCS) for their cooperation on this trial. We would like to acknowledge the California Climate Investments program for funding, and our UC colleagues who are cooperating on this grant in other parts of the state (Jeff Mitchell, Will Horwath, Veronica Romero, Sarah Light, Amber Vinchesi-Vahl, and Scott Stoddard).
Survey: We would also like to alert readers of a cover cropping survey that is being conducted by the Contra Costa County Resource Conservation District. The survey is found here. The purpose of the survey is to learn more about cover cropping practices and barriers to adopting cover cropping on-farm. Even if you farm in another county, please consider filling out the survey, which should take about 10 minutes. The survey is open through the end of June. Your responses will help inform CCC RCD and UCCE programming. Thank you for your participation.
- Author: Michelle Leinfelder-Miles
The annual UC Davis Small Grains and Alfalfa Field Day will take place on Wednesday, May 15, 2019 at the Agronomy Field Headquarters (2400 Hutchison Drive, Davis, CA 95616). Registration opens at 7:30am, and lunch is provided between the small grains morning program and alfalfa afternoon program. The event is free and open to the public, and continuing education credits will be available. Directions are as follows:
The field day is located on Hutchison Drive, just west of Davis. Take the Hwy. 113 exit north from I-80, or Hwy. 113 south from Woodland. Exit west on Hutchison Drive. Take a right at the first roundabout, a left at the second roundabout, and the Agronomy Headquarters is about ¼ mile down in a clump of trees and buildings on the left.
The agenda is as follows:
8:00am – Noon: Small Grains Program
8:00 Welcome and Opening Remarks
8:20 Depart for field (travel to breeding trials)
8:35 Malting Barley & Oat Breeding: Alicia del Blanco, UC Davis
8:45 Barley Breeding for Food, Feed and Forage: Allison Krill-Brown, UC Davis
9:00 New Wheat Varieties: Oswaldo Chicaiza, UC Davis
9:15 Breeding Triticales for Bread and Forage: Josh Hegarty, UC Davis
9:25 Increasing Grain Size and Number: Alejandra Alvarez, UC Davis
9:35 A New Gene Controlling Number of Grains Per Spike: Saarah Kuzay, UC Davis
9:40 Balancing Source and Sink to Increase Yield: Jorge Dubcovsky, UC Davis
10:00 Herbicide Programs for Barley and Wheat: small grain herbicides and maximizing efficacy for control: Lynn Sosnoski, UC Cooperative Extension
10:20 Italian Ryegrass: Updates on Cultivation vs Herbicide Trials: resistance and methods for control: Konrad Mathesius, UC Cooperative Extension
10:30 Warm-season legume cover crop between winter small grains: Michelle Leinfelder-Miles, UC Cooperative Extension (This project was supported by the California Climate Investments program.)
10:45 Using Nitrogen Rich Reference Zones to Guide Wheat Topdress Decisions in the Sacramento Valley: Sarah Light, UC Cooperative Extension
10:55 Yield and Protein Stability for Wheat and Triticale Varieties Grown under N and Terminal Drought Stress: Mark Lundy, UC Cooperative Extension
11:05 Updates on UC Statewide Small Grain Trials: Seasonal conditions, pests and diseases, nitrogen management, and extension efforts: Mark Lundy, UC Cooperative Extension
11:15 Comments from breeders with entries in UC Statewide Small Grain Trials
11:30 UC Statewide Small Grain Trial Observations
11:50 Return for lunch
12:00 BBQ Lunch: Many thanks to the California Crop Improvement Association for the complimentary lunch!
12:30 - 4:00: Alfalfa/Forages Program
12:40 Welcome and Introductions: Dan Putnam, UC Cooperative Extension/UC Davis
12:45 Depart for field tour
12:55 Managing Alfalfa in a Wet Year- What are the Diseases? How to Keep your Fields Healthy: Rachael Long, UC Cooperative Extension
1:10 IPM and Managing for Weevil Resistance in Alfalfa: Ian Grettenberger, UC Davis
1:25 Evaluation of N Stabilizers in Corn: Michelle Leinfelder-Miles, UC Cooperative Extension
1:40 Forage Sorghum as a Summer Option: Controlling Sugarcane Aphid in Sorghum/Sudangrass: Nick Clark, UC Cooperative Extension
1:55 Innovations in Overhead Irrigation – How that might improve Water Use Efficiency: Isaya Kisekka, UC Davis
2:10 Fun with Drones –Detecting Pest and Diagnosing Problems with Aerial Photography: Umair Gull, UC Davis
2:25 Controlling Difficult Weeds in Alfalfa: Lynn Sosnoskie, UC Cooperative Extension
2:50 Alternative Crops Research: Kura Clover, Switchgrass, Hemp: Dan Putnam, UC Davis
3:05 Reduced Lignin Alfalfa Varieties and Interactions with Harvest Scheduling: Brenda Perez, UC Davis
3:20 Analyzing Alfalfa Varieties for Pest Resistance (Nematodes, Insects, Diseases) and other characteristics: Dan Putnam, UC Davis
3:35 Alfalfa and Tall Fescue Breeding Programs at UC Davis: Charlie Brummer, UC Davis
3:50 Test your Weed ID IQ: Weed Identification: Brad Hanson, UC Davis
4:15 Return to Headquarters