UC Cooperative Extension will offer a virtual Alfalfa IPM Workshop on December 3rd and 4th. The workshop will run from 9am to 12pm on each day. Registration is required, and there is a $25 fee to help cover our costs of delivering a workshop virtually. Continuing education credits will be offered. (5 "Other" credits from DPR and 4 "IPM" credits for CCAs.)
Day 1. December 3 (9 am - Noon PST) Weed and Pest Management Strategies
- Price & Acreage Trends -- Josh Callan, The Hoyt Report, Twin Falls, ID
- California Regulatory Update--Dennis Albiani, Ag. Management, Sacramento, CA
- Key Agronomic Strategies for Pest Management--Dan Putnam, UC Davis
- Poisonous Weeds of Concern in Alfalfa--Larry Forero, UCCE, Redding, CA
- Weed Control Strategies for Establishment and Production -- Earl Creech, Utah State University, Logan, UT
- Recent Weed Control Trials in Alfalfa--Tom Getts & Giuliano Galdi, UCCE, Susanville and Yreka, CA
- Weed Mangement Strategies for Pastures--Josh Davy, UCCE, Redding, CA
Day 2. December 4 (9 am-Noon PST) Insect, Disease Management Strategies
- Process of Pesticide Regulation in California--Aron Lindgren, DPR, Sacramento, CA
- On-Line Tools for Pest Management Information--Jose Luiz Carvalho de Souza Dias, UCCE, Merced, CA
- Management of Insecticide Resistance in Alfalfa--KEvin Wanner, Montana State Univ.
- Biological Insect Control in Alfalfa: A Case Study--Ian Grettenberger, UC Davis
- Update on Low Desert Forage Insects--Michael Rethwisch, UCCE, Blythe, CA
- Summer Worm Management--Rachael Long, UCCE, Woodland, CA
- Potential Use of Drones for Insect Management--Ken Giles, UC Davis
- Key Diseases and Management in Alfalfa--Deborah Samac, USDA-ARS, St. Paul, MN
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Date: September 23, 2020
Time: 8:30 AM - 12:00 PM
Location: Zoom Meeting
Registration: Click here to register.
Registration fee: $9.23
What: UC Cooperative Extension will provide updates on applied research in alfalfa variety, irrigation, and pest management; sorghum and its use in dairy feeding; sugar beets and safflower as winter forages; and personal protective equipment in a time of Covid-19.
Who should attend: California alfalfa and forage growers, consultants and allied industry.
Continuing education units: Applied for California Department of Pesticide Regulation (DPR), Certified Crop Adviser (CCA), and Nitrogen Management credits
Full agenda: Click here for full agenda.
For more information, please contact:
- Julia Kalika, UC ANR Program Support Unit, (530) 750-1361, firstname.lastname@example.org, for registration logistics questions
- Michelle Leinfelder-Miles, email@example.com; Nick Clark, firstname.lastname@example.org; Joy Hollingsworth, email@example.com; or Anthony Fulford, firstname.lastname@example.org, for program content question
This event is open to the public. Our programs are open to all potential participants. If you require special accommodations, please contact Julia Kalika, UC ANR Program Support Unit, (530) 750-1361. The registration fee covers the technological costs of providing a virtual meeting. If the fee prevents your participation, please contact email@example.com for a fee waiver./h2>
Soil health has been described as the ability of soil to function and is characterized by biological, chemical, and physical soil properties that are sensitive to changes in management. Studies have shown that reducing tillage, increasing rotational crop diversity, and employing cover crops during the fallow season can improve soil health characteristics. In turn, improvements in soil health may enhance various soil functions, like improving crop productivity, reducing input costs, and buffering plant health from living and non-living stresses.
Over the last year and a half, I have been working on a project to characterize a suite of soil health properties in alfalfa receiving full and deficit irrigation. When I was developing the project, I had two hunches. The first was that alfalfa production may improve certain soil health characteristics. Alfalfa provides soil coverage for several years. Alfalfa is also a deep-rooted crop that can scavenge water and nutrients deep in the soil profile. Additionally, alfalfa has been shown to provide a nitrogen benefit to subsequent crops. For reasons like these, I hypothesized that certain soil health characteristics might improve over the years of an alfalfa stand.
My second hunch, however, was that deficit irrigation could negatively impact soil health properties. In recent years, California alfalfa production has received negative press for water usage that exceeds that of other crops. Alfalfa does represent an important footprint in California's agricultural water use. Alfalfa has a high water demand (i.e. crop evapotranspiration, ETc) that is directly related to yield. All else being equal, as ETc increases, alfalfa yield also increases up to maximum ETc. Studies conducted by UC Alfalfa and Forage Specialist, Dan Putnam, have demonstrated, however, that alfalfa is resilient under water deficit conditions. While alfalfa may be resilient under deficit irrigation, water facilitates soil microbe functioning and nutrient availability. Therefore, I also hypothesize that soil health may degrade under deficit irrigation. This is critical knowledge to develop not only for deficit irrigation strategies but also in the event of drought, where growers may be asked to sacrifice crop irrigation for water transfers to other uses. Such knowledge could demonstrate how prioritization of water uses may impact soil conservation outcomes.
This project is being conducted at UC Davis on a Yolo silt loam and was initiated in Spring 2019. The treatments, which are replicated four times, are: 1) full irrigation (100 percent ETc), 2) full irrigation at the beginning of the season with a sudden cutoff toward the end of the season (60 percent ETc), 3) gradual deficit where each irrigation imposes restriction (60 percent ETc), and 4) more-severe gradual deficit (40 percent ETc). The treatments are applied using overhead irrigation – an 8000 series Valley 500 feet, four span linear-move system. The site allows us to observe soil characteristics under different levels of deficit, imposed at different stages of the cropping season. Soil sampling occurs twice each year – in the spring before irrigation begins and in the fall after the last irrigation. We are testing a comprehensive nutrient analysis, organic matter, total carbon and nitrogen, salinity, compaction, bulk density, N mineralization, and particulate organic carbon.
This project is ongoing, but we have interesting preliminary results. One example is with particulate organic carbon. Particulate organic carbon (POC) is a biological indicator of soil health because it is the fraction of soil organic matter that is readily available as an energy source for soil microorganisms. Though not statistically significant (Fig. 1, P = 0.066), there is a trend for the higher irrigation rates – and sustained irrigation throughout the season – to have higher POC. Between the two irrigation treatments providing approximately 60 percent of ETc, the third treatment which provides a sustained deficit throughout the season tends to have higher POC than the 60 percent ETc treatment that has a sudden cut-off of water about two-thirds of the way through the season. These results suggest the importance of water in sustaining soil biological activity.
Likewise, there is a similar trend for higher irrigation rates and sustained irrigation through the season to result in lower soil compaction readings (Fig. 2, P = 0.2691). At the 6-inch depth, the full irrigation rate trended toward having the lowest compaction, followed by the 60 percent sustained deficit treatment. All treatments, however, had average readings below 300 psi, which is the pressure above which root growth is believed to be constrained.
These are preliminary results. We will soil sample again this fall, and hopefully again next spring and fall, to see if these trends continue. I want to acknowledge my UC Davis collaborators on this project: Dan Putnam, Isaya Kisekka, Daniel Geisseler, Umair Gull, and Veronica Romero. I also want to acknowledge the South Delta Water Agency for funding support.
Figure 1. Average particulate organic carbon (top 12 inches) across four irrigation treatments and three seasonal readings (Spring 2019, Fall 2019, Spring 2020).
Figure 2. Average soil compaction at 6-inch depth across four irrigation treatments and three seasonal readings (Spring 2019, Spring 2020, Summer 2020).
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
- Author: Michelle Leinfelder-Miles
- Author: Dan Putnam
- Author: Rachael Long
A question came to me from a crop consultant. His alfalfa grower asked him how he could increase crude protein (CP) in his alfalfa. The buyer of the alfalfa, for the most part, is happy with the hay. For example, the buyer is happy with the total digestible nutrients (TDN), but he would like to see a little higher CP. The consultant said that the grower is generally on a 28-day cutting cycle and is generally cutting the hay pre-bloom. He wondered if nitrogen (N) fertilizer would help to improve CP.
The best way to improve CP is to: 1) cut early, 2) choose a more dormant variety (but give up yield), and 3) manage the harvest to retain the leaf fraction. Since this grower is already cutting pre-bloom, and since the grower is not yet replanting, that would leave option 3. Retaining the leaf fraction is important because the protein content of the leaves is higher than that in the stems. Trying not to rake the hay when it is especially dry might help to retain the leaves.
Let's now focus on the consultant's question of whether N fertilizer could help to improve CP. The UC Irrigated Alfalfa Management production manual states that N fertilizer has resulted in higher CP in some instances but that an equal or higher number of trials showed no improvement to CP with N fertilizer. Dan Putnam, Rollie Meyer, Vern Marble, and other forage researchers have, for a long time, recommended against fertilizing alfalfa with N. This is based upon field data, economics, and logic!
1. Forage Quality. While N fertilizers can (in some cases) increase the apparent CP of the forage by a point or two, this "protein" is not actually well utilized by ruminants. N fertilizer usually results in a higher non-protein nitrogen content (NPN) which is NOT protein, but free N in various forms (e.g. nitrate or free amino acids), which is immediately released into the rumen upon ingestion and forms ammonia. The ammonia must be excreted by the animal at a metabolic cost (ATP), so it is actually costing feed energy. It also results in excess urea in the manure. So, even though it looks like the protein is a little higher, it isn't actually. Remember, CP is measured N content (not just protein) multiplied by 6.25.
2. Economics. Small differences in yield are sometimes (not always) observed with applied N; however, those are rarely economically advantageous. Remember that the uptake levels of alfalfa are very high. A 10-ton Central Valley alfalfa crop will remove about 700 lbs of N, which with losses, one would need to apply close to 1,000 lbs N/year to meet the N needs of the crop. One could never cost-effectively fertilize to satisfy this need.
3. Losing your free N. N applications or high soil N have the tendency of suppressing N2 fixation by making the Rhizobium lazy. Fertilizers would mostly just replace fixed N. Atmospheric N contributions to alfalfa growth are a major environmental benefit, and it's a shame not to take advantage of it.
4. Weeds. N applications encourage weeds, especially grasses. This negatively impacts quality.
5. Trade-off with Energy. Keep in mind that some alfalfa hay crops that have low N and low CP also have high TDN (energy values) such as the well-managed Intermountain spring cut hays grown under cool temperatures. This is due to dilution - if carbohydrates accumulate in the leaves, (e.g. 5-8 percentage points higher), then CP (and NDF/ADF) will be lower. When something goes up, something else goes down. Since energy tends to be more valuable in the marketplace, however, this is a good thing!
Having said all of this, there are some rare situations where N fertilization may be helpful to get the crop going after the roots have been compromised, but even these are unusual. Rachael Long detailed this in the blog When is N fertilization to alfalfa beneficial? Almost Never!
Dan Putnam does have a lingering question about applying N fertilizer in alfalfa and that is whether very small amounts (e.g. via drip irrigation) might be effective at hastening regrowth after each cutting. Growers using drip have done this, and Dan thinks it could work with overhead sprinklers or with buried drip lines where the N can be 'spoon fed' and carefully managed. We need data, however, to prove whether or not this would be effective. Dan suspects the differences would be minor.