- Author: Drew Lyon
- Posted by: Gale Perez
In my previous position as the Extension Dryland Cropping Systems Specialist with the University of Nebraska Panhandle Research and Extension Center in Scottsbluff, I focused my research efforts on intensifying and diversifying the winter wheat-fallow cropping system. The addition of summer crops into the rotation was a first step. Inserting summer crops such as proso millet, sunflower, or corn reduced the frequency of summer fallow from every other year to once every three years. Summer crops also helped in the management of winter annual grass weeds such as downy brome, jointed goatgrass, and feral rye. As I looked for ways to eliminate summer fallow from the rotation, my attention turned to forage crops.
Forage crops are typically harvested at about 50% heading (grass crops) or flowering (broadleaf crops). This is often six or more weeks earlier than if the crops were harvested for grain. This earlier harvest provides a couple of benefits. First, it decreases soil water depletion. Water use by crops is typically greatest from the boot or flower bud stage through early grain fill. By harvesting the crop shortly after the start of this heavy water use time, valuable soil water is conserved for the following grain crop, which in western Nebraska, was often winter wheat. The earlier harvest also prevented seed production in many weeds growing in the forage crop. Taken together, these two benefits made forage crops a good alternative for summer fallow. However, there were obstacles to the use of forage crops such as a lack of forage harvesting and handling equipment and limited local markets.
When I arrived in Pullman, WA in 2012, the focus of my program shifted to weed management in wheat production systems. One of the first new weed species I learned about was Italian ryegrass. Italian ryegrass biotypes have developed resistance to eight different herbicide modes of action, which makes managing Italian ryegrass with herbicides very difficult. Some growers have turned to forage crops to help them manage Italian ryegrass.
At a Washing State University (WSU) Weed Science Field Day a few years back, we had a grower tell us that one of his approaches for managing Italian ryegrass was to plant forage barley and harvest the forage barley and Italian ryegrass before they headed and sell it in small bales to horse owners. Italian ryegrass is an excellent forage, and the bales fetched a good price. I thought that was an excellent out-of-the-box approach for managing this very troublesome weed. I could see a similar approach working for feral rye or wild oat management.
I have also noticed that some growers with Italian ryegrass issues have planted alfalfa to manage the problem. Here, Roundup Ready alfalfa could help in the establishment year, but after that, the simple act of harvesting the alfalfa before Italian ryegrass sets seed is all that would be needed. A perennial crop like alfalfa also brings other crop rotation benefits for weed control. Once established, alfalfa competes strongly with annual weeds. The seed of most annual grasses do not survive long in the soil, so keeping alfalfa in for just three or four years will significantly decrease the soil seedbank of annual grass weeds and allow a return to annual cropping with much lower grass weed pressure.
Despite the obstacles to the adoption of forage crops in our dryland cropping systems, forage crops do offer several benefits for weed management. As herbicide resistance becomes more problematic throughout the region, non-chemical approaches to weed management will become more important. I would love to hear how you have used forage crops in your rotation to manage weeds. Please leave a comment so that others can learn from your experience.
Thanks!
Dr. Drew Lyon
Endowed Chair Small Grains Extension and Research, Weed Science
Washington State University
(drew.lyon@wsu.edu)
Original source: Weeders of the West blog | April 25, 2024
- Author: Trina Kleist, UC Davis
One more reason to adopt sustainable cultivation
California wheat farmers could both maintain their yields and improve soil health by growing annual wheat without tilling the soil year after year.
This could be one more encouragement to farmers to adopt a sustainable practice commonly called conservation tillage, no-till or minimum-till cultivation, impacting how we grow a grain that supplies about 20 percent of the calories and protein for people around the world.
A new study, by a team led by Mark Lundy, University of California Cooperative Extension specialist in UC Davis' Department of Plant Sciences, offers new insight for decades-long discussions around soil conservation, sustainable agriculture and climate-warming emissions related to growing our food. The study has been published in the journal Soil and Tillage Research. For the first time, researchers have shown that annual wheat that is not tilled each year is better for stashing carbon in the soil than perennial wheatgrass, while still yielding more crop in Central California.
Previous studies have looked at annual wheat that is tilled each year, annual wheat that is not tilled, and a cousin species, perennial intermediate wheatgrass (trademarked Kernza), which also is not tilled. But until now, no one has looked at all of the benefits and trade-offs together. Most importantly, “no one has ever controlled for tillage,” Lundy said. “And, no one has compared annual wheat to perennial intermediate wheatgrass over multiple years in a Mediterranean climate, which is what we have in California.”
This study also is unique because it delves into the deeper question of what is going on in the soil that drives the different results for carbon there. Soil carbon reflects various processes linked to plant activity and soil health. Measuring the different forms of soil carbon may also signal whether a farming system is accumulating carbon in the soil over time – a plus for reducing climate-warming gases in the atmosphere.
“Measuring soil carbon is complex and nuanced,” said Kalyn Taylor, the lead author on the paper. “We started this experiment because we wanted to know whether and how plant activity and tilling or not tilling would affect the carbon story belowground in California's climate.”
“When we started this study, we thought the crop being perennial or annual would drive the differences in carbon storage in the soil,” Lundy added. Specifically, they had expected perennial wheatgrass would lead to more carbon in the soil because of its deeper, better-established root system. “But that's not what we found,” he went on. “What we found was, it was the lack of tillage, plus the level of productivity of common annual wheat, that made the difference in soil carbon here in California.”
Soil carbon in annual vs. perennial grain
In 2017, Lundy, then-graduate-student Taylor, UC Davis Professor Emeritus Kate Scow and others on the team started measuring different forms of soil carbon in test plots at Russell Ranch, west of campus. Plots were planted with annual wheat that was tilled each spring, annual wheat that was not tilled and perennial intermediate wheatgrass (Kernza) that also was not tilled.
Each year, the researchers measured the carbon present in the soil, the amount of soil organisms (which have carbon in their bodies) and the amount of material the plants created.
At the end of three growing seasons, they found that land planted with no-till, common, annual wheat had the highest amount of soil organisms, measured as biomass, of the three treatments.
The researchers also found soil carbon is more likely to remain stable in the no-till, annual plots, compared to both tilled wheat and wheatgrass.
In addition, the no-till, annual wheat produced plant material more consistently than the perennial wheatgrass across the three years, which saw variation in rainfall.
“Overall, annual wheat grown without soil disturbance or tillage had both higher productivity and higher potential for storing carbon in the topsoil than perennial wheatgrass in our Mediterranean climate,” Lundy said.
Related research
“No-till annual wheat increases plant productivity, soil microbial biomass, and soil carbon stabilization relative to intermediate wheatgrass in a Mediterranean climate,” is online now and will be published in the January 2024 edition of Soil and Tillage Research.
The team also found that tilled annual wheat vs. Kernza stores total carbon at different depths in the soil profile and hosts distinct soil fungal communities, primarily in the root zone and topsoil: Taylor, K., Samaddar, S., Schmidt, R., Lundy, M. and Scow, K., 2023. Soil carbon storage and compositional responses of soil microbial communities under perennial grain IWG vs. annual wheat. Soil Biology and Biochemistry, p.109111.
Previous work comparing the perennial grain known as intermediate wheatgrass (trademarked Kernza) to annual wheat had not distinguished the extent to which soil health benefits are a function of the perennial nature of the crop. Read the story here.
This story was originally published on the UC Davis News site.
/h3>/h3>/h3>- Author: Konrad Mathesius
Overview
Three years of data indicate that liquid-injected biosolids-based fertilizers (LBF, using 'Lystegro' from Lystek) are a viable alternative to conventional forms of nitrogen (N) fertilizer on a total N basis in wheat rotations in the southern Sacramento Valley. Lab data comparing LBF, pelletized biosolids-based fertilizers (PBF), and urea provide additional insight into soil phosphorous (P), salinity (EC), soil pH, and N mineralization responses after additions of the treatments.
Above: Application of LysteGro (Liquid-Injected Biosolids-Based Fertilizer, LBF) in Solano County
Introduction
As more California municipalities begin to prioritize the diversion of waste products from landfills into agricultural systems, it is pressing for growers to understand how to utilize new inputs such as liquid-injected biosolids-based fertilizer (LBF) in their operations.
Biosolids-based fertilizers can generally provide subsidized and therefore cost-effective sources of N for small grains and other agronomic crops. However, while there have been long-term biosolids studies using materials derived from biosolids, near-term performance needs to be understood and documented to improve grower confidence and capacity in the utilization of these products.
Figure 1: Yield and protein data from field trials over three site years in the Southern Sacramento Valley. Conventional N fertilizer treatments are indicated in blue. Shades of green represent biosolids treatments, with higher rates represented by progressively darker shades of green. N equivalents are represented numerically in each of the labels (i.e. LBF_57 is 57 pounds of N per acre as Liquid-Injected Biosolids-Based Fertilizer). Letters above each column indicate whether there is a significant difference between treatments. Columns with the same letter are not significantly different from one another.
Figure 2: Yield and protein data from the trials across 3 years modeled at 60, 90, and 120 pounds of total N applied per acre. Differences in predictions are insignificant, indicating that both materials appear to perform similarly in terms of total N applied per acre.
Methods
The objective of this research was to evaluate the yield and protein performance of LBF as an N source in small grains relative to conventional forms of N fertilizer. Lab incubations were intended to provide information on the response of soil P, N, pH, and EC to different treatments over a period of 12 weeks.
Field trials took place over the course of three planting seasons (Table 1). Wheat was typically planted in late November to early December. LBF and nitrogen (as UAN 32 or anhydrous ammonia) were added to fields pre-plant. LBF and anhydrous ammonia treatments were injected six-inches deep. UAN 32 was added prior to incoming rain. No in-season additions of N were added in these trials because biosolids cannot be injected mid-season and the objective of the trial was to make an apples-to-apples comparison based on the type of material.
Table 1: Information on three growing sites/ years where trials took place.
Laboratory incubations were also carried out to examine the behavior of the LBF relative to a pelletized biosolids-based fertilizer (PBF), and conventional N fertilizers (as urea).
Results and Discussion
Results from the field trials indicate that LBF produces generally equivalent yield and protein results in small grains when compared to conventional forms of fertilizer as an N source (Figure 1) when used in pre-plant applications. Other findings indicate that there may be some ancillary benefits associated with the use of LBF as an N source by way of providing a source of P (Figure 3), carbon, micronutrients, and water.
Lab incubations reflected some of the patterns witnessed in the field: Increases in P, slower N mineralization rates, and otherwise similar soil chemistry outcomes relative to that of conventional fertilizer, particularly after 12 weeks (Figure 3).
Organic matter was not seen to increase significantly in-season, but the fact that the LBF material is 10% solids, and those solids are roughly 30% carbon from organic matter means that additions of carbon, micronutrients, and water could be advantageous to crop growth.
Incubations
Figure 3: N mineralization, available phosphorous, salinity (as electrical conductivity, EC ), and pH results from 12-week lab incubations at 70 degrees F, comparing LBF, PBF, and pelletized urea mixed into a Yolo loam at 90 lbs N / acre. Significant difference between treatments is indicated within a given week by different letters.
Conclusion
Small grain growers working in the southern Sacramento Valley or in similar climates should feel confident that LBFs will likely perform as well as conventional sources of N when applied at similar rates of total N. LBFs may also provide additional benefits to growers in the form of increased P, micronutrients, or additional soil moisture. Growers should also consider the combined use of biosolids and in-season conventional N additions when needed. As always, good N-management and monitoring can greatly improve grower capacity for success.
- Author: Konrad Mathesius
Join us next week for a workshop that will cover some basic wheat fertilization strategies and focus on how to use the Nitrogen Fertilizer Management for California Wheat Webtool.
Yolo County: Wednesday, October 11th 2023, 9 a.m. – 11:00 a.m.
70 Cottonwood Street, Woodland, CA
Register: click here
Given the high cost of Nitrogen (N) fertilizer and a tendency to apply the majority of N prior to planting, growers stand to potentially leave a lot of money on the table by failing to optimize their N-management in small grain systems. For example, early, heavy rains last year flushed a lot of nitrate out of the soil profile before wheat could take it up during the rapid growth phase. In-season applications provide an opportunity to take account of the water year, and the crop status before deciding on a season-long N fertilizer budget.
The Nitrogen Fertilizer Management Webtool for California Wheat offers in-season insight on whether and how much N to apply given the seasonal conditions. While the use of the webtool is pretty straightforward, we have found that it is helpful to offer workshops to help CCAs and growers become more familiar with its use. These two-hour trainings offer an introduction to principles of N-management in wheat and use/ interpretation of the webtool.
Agenda Below:
YOLO COUNTY
Small Grains Nitrogen Management Webtool Training
Wednesday, October 11th 2023, 9 a.m. – 11:00 a.m.
70 Cottonwood Street, Woodland, CA
Please RSVP using QR code or click here
Presented by:
Konrad Mathesius, UCCE Agronomy Advisor, Yolo, Sacramento, and Solano
Who should attend: CCAs and other crop consultants specializing in crop nutrient management.
Growers, Ag Industry, and the general public are also welcome
8:40 a.m. Registration, light refreshments
9:00 a.m. Welcome and Introduction
9:10 a.m. Principles of N fertilizer use in California small grains
9:40 a.m. Measuring field data pre-plant and in-season
N-rich reference zones
Soil sampling for nitrate
10:00 a.m. Soil nitrate quick test demonstration and data interpretation
10:15 a.m. Webtool example and case studies
10:25 a.m. Webtool walkthrough
10:45 a.m. Crop Consultant/ CCA forum, survey, feedback, troubleshooting, and discussion
11:00 a.m. Adjourn and Lunch, Please RSVP using the link or QR code above.
CE Credits
CCA: 2 (pending)
INMP/Cures: 2 (pending)
- Author: Konrad Mathesius
Summary Review
Results from this year's Italian ryegrass (IR) herbicide trials helped quantify differences in herbicide resistance among IR populations within the southern Sacramento Valley. The trial took place in Bird's Landing, CA (near Rio Vista), and was replicated farther north in Esparto, CA.
- Trials from this year suggest that Osprey-resistant IR populations often associated with the area around Dixon, CA could extend at least as far south as Bird's Landing with only 26% control of IR by Osprey in the trial site.
- The Osprey-resistant population appears to also be moderately resistant to Simplicity, another herbicide in the same chemical family, which only provided 60% control at the Bird's Landing site.
- Axial (an ACCase inhibitor) worked well at controlling IR in Bird's Landing (92% control).
- In Esparto, IR in the trial was somewhat more susceptible to ALS inhibitors. IR control was only around 80% with Simplicity.
Introduction
For a few years I've heard PCAs mention that Italian ryegrass (IR) populations around Dixon are showing resistance to Osprey (an ALS inhibitor herbicide), but quantification of differences in weed control can help provide a better understanding of what growers are dealing with. IR is notorious for its capacity to develop herbicide resistance to multiple modes of action (MoA). As an obligate outcrossing plant, IR must cross-pollinate in order to produce viable seed. This means that genetic material is regularly exchanged during pollination, which allows populations to respond to environmental pressure. Development of herbicide resistance in IR over the years has caused increasing concern for small grain growers, who are limited in their options for control.
This study is part of a wider range of studies examining different options available to growers for IR control in small grains. This study quantifies the efficacy of various available herbicides on IR populations in small grains both in the northern parts of Yolo County and the southern parts of Solano County.
Methods
Two trials were set up: one in Bird's Landing and one in Esparto. Each plot was 15 x 100 feet and was replicated 4 times at each location. Plots were planted with wheat in late December 2022 after a burndown treatment and were treated in January of 2023 using the maximum label rate of each herbicide along with recommended adjuvants (Table 1). A 20ft x 15ft section of each plot was left unsprayed as an untreated reference. Axial was unintentionally applied at half label rate in Esparto.
Prowl was tested to see if it might improve control by by providing residual control of late germinating ryegrass that escaped preseason control efforts but did not germinate with the first fall rains. IR control was not significantly better in the Prowl tankmix vs Simplicity applied alone in this experiment.
Treatments and Rates Evaluated for Italian ryegrass Control in Two Wheat Sites in 2023 in the Sacramento Valley.
Weed counts were taken in late February in each plot (3 sub-samples). The untreated reference sections within each plot were measured once (1 representative sub-sample). Percent weed control was measured by the difference in ryegrass density within the treated and untreated areas in each plot.
Grain was hand harvested in late July using 3 x 4ft^2 quadrats in each plot. Spikes were collected by cutting the stem at the base of the spike using a sickle. Samples were then air dried. Grain yield was determined by subtracting an estimated chaff weight of 17% from the weight of the harvested spikes (McCartney et. al, 2006).
Results and Discussion
Percent control
Within each location, herbicides varied significantly in terms of the capacity to control IR.
In Bird's Landing (20 miles south of Dixon, CA), Axial provided significantly better IR control than Simplicity, Prowl + Simplicity, and Osprey. Osprey did not reduce IR populations compared to the non-treated control plots. (Figure 2)
In Esparto, a tank mix of Prowl + Simplicity provided better control of IR than Osprey but was not different than Simplicity alone (p = 0.52) or the tank mix of Axial + Simplicity (p = 0.81). Osprey provided only moderate control (58%) and was marginally different from Simplicity (p = 0.084), which provided 79% control.
The differences in control between the two ALS-inhibitor herbicides (Simplicity and Osprey) at the two locations are an indication of the variation among IR populations that are only 50 miles apart.
Yield
Yield results collected from the Bird's Landing site show trends that generally correspond with differences in weed control, although no significant differences in estimated yield were found due to the variability of the data.
Conclusion
Variations in herbicide efficacy are a good reminder that there is a lot of genetic variability in IR populations; even fields only a few miles apart could have important differences in response to herbicides. This means that grower practices can directly impact the development of herbicide resistance in their area. Growers in the Dixon area should incorporate IPM practices listed above and consider the use of Axial as an alternative weed control if they haven't already, and growers farther north should remain particularly vigilant about preserving the efficacy of their ALS inhibitor herbicides by integrating some of the IPM practices listed below.
- Using certified seed (to prevent weed seeds from hitching a ride to entirely different areas of the state)
- Thoroughly cleaning equipment, or operating equipment only within local areas to prevent the spread of weed seed to other parts of the state
- Rotating herbicides within the season and from one season to the next, where possible
- Spraying at the right time (check labels, apply on the early end of the spray window)
- Spraying the right rate (Axial applications in Esparto were sprayed unintentionally at half-rate and provided no control).
- Spraying when weeds are actively growing
- Planting wheat at the right density
- Incorporating mechanical cultivation or Harvest Weed Seed Control where possible
- Checking and calibrating spray nozzles
- Incorporate the use of pre-emergent herbicides labeled in California
- Rotating crops where possible to diversify herbicide programs
- Check for escapes and monitor fields for efficacy
Growers are also encouraged to take advantage of UC IPM resources online, and in-person through their local farm advisors.
References
McCartney, D.H.; Block, H.C.; Dubeski, P.L.; Ohama, A.J. Review: The composition and availability of straw and cha? from small grain cereals for beef cattle in western Canada. Can. J. Anim. Sci. 2006,86, 443–455.