The results of the 2019 UCCE Delta field corn variety trial (Fig. 1), located on Tyler Island, are presented in Table 1. Three replicate blocks of fourteen varieties were planted on May 7th by air planter. The fourteen varieties included 11 varieties submitted by seed companies and three submitted by the grower. All varieties were glyphosate tolerant. Each plot consisted of four 30-inch beds on an average row length of 1300 feet. Seed was planted approximately two inches deep and six inches apart down the row. The soil is a Rindge mucky silt loam with approximately 20 percent organic matter in the top 15 inches of soil. The Rindge series is a mucky peat soil down to about 60 inches, and approximately 55,600 acres in the Delta are described by the Rindge classification. The previous crop in the field was corn. Subsurface irrigation by “spud ditch” was employed twice. Anhydrous ammonia was applied pre-plant (115 units N/acre), and 8-24-6 with ½ percent of zinc was knifed in at planting (additional 33 units N/acre). Weed control was by cultivation and glyphosate herbicide program, and Onager miticide was applied. The field was harvested on October 21^st.

Stand counts were made approximately two weeks after planting. The stand was assessed in the center two rows of each four-row plot, counting the plants along a 10-foot length. Bloom was assessed over the week of July 15^th. We monitored disease incidence and plant lodging in late September. Disease incidence, particularly Fusarium ear rot, was lower in 2019 compared to 2018. A sign of Fusarium ear rot is white fungal mycelium around the kernels. The disease is usually introduced to the ears by corn earworm or by thrips that travel down the corn silks at pollination. Incidence may be reduced in varieties with longer or tighter husks that prevent insect infestations. Planting earlier in the season may also reduce incidence, as the crop may reach pollination before insect pests are prevalent. Head smut, a disease that replaces ears with dark brown spores, had low incidence this year. These two diseases are generally managed by variety selection.

The table presents mean values for the three replicates. The statistical method used to compare the means is called the Tukey's range test. Varieties were considered statistically different if their P value was less than 0.05, or 5 percent. What this means is that when differences between varieties exist, we are 95% certain that the two varieties are actually different; the results are not due to random chance. Differences between varieties are indicated by different letters following the mean. For example, a variety that has only the letter “a” after the mean yield value is different from a variety that is followed by only the letter “b”, but it is not different from a variety whose mean value is followed by both letters (“ab”). Similarly, a variety whose mean yield is followed by the letters “ab” is not different from a variety whose mean yield is followed by the letters “bc”. Eight varieties have a letter “a” following their mean yield, which means that those eight varieties all performed similarly in the trial. In other words, based on this research, we cannot attribute numerical differences to varietal differences.

In addition to yield, there were also statistical differences among varieties in days to bloom, Fusarium ear rot, head smut, ear height, grain moisture, and bushelweight. The CV, or coefficient of variation, is the standard deviation divided by the mean, or a measure of variability in relation to the mean. For the diseases, the variability among the three replicates was very high.

For a printable version of this report, please see: https://ucanr.edu/sites/deltacrops/Corn/. Special thanks go to the cooperating growers, Gary and Steve Mello, and the participating seed companies.

Results from the statewide UC small grains variety testing program are now available for the 2018-19 season. The Delta trial location was on Staten Island on a Valdez silt loam soil. Approximately 25,000 acres of soil in the Delta are characterized by the Valdez classification, which generally has less than one percent organic matter in the top foot of soil and can be poorly drained.

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!

 

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.