This proposal is for a second year of continued funding (FY24). The project from year one (FY23) is being implemented during the 2023 growing season.
Herbicides are the primary tool used for weed management in soybean (USDA – National Agricultural Statistics Service). Difficult to manage weeds (pigweed species, ragweed species, foxtail species, common lambsquarters, kochia, horseweeed, etc.) as well as herbicide-resistant populations for many of these weeds have been selected over time across North Central US soybean cropping systems. Increasing herbicide costs and environmental concerns have only added to management challenges. Current herbicide application practices focus on broadcast applications that deliver a constant herbicide rate across an entire field. However, weed populations have great spatial variability that is influenced by factors such as weed species biology, soil type, crop rotation, and tillage and harvest practices. Previous research has evaluated site-specific weed management (SSWM) using weed species distribution maps and site-specific herbicide applications resulting in herbicide savings ranging from 23 to 89% (Gerhards et al., 2022). Despite the potential economic and environmental benefits with SSWM, current technologies have not been able to achieve this on a field scale. With recent improvements and integration of active sensors and sprayer technologies, the ability to detect and treat weeds on a real-time site-specific basis should soon become feasible. Several companies are developing smart sprayers with the ability to detect and spray weeds in real-time both in fallow (green on brown) and early-season in crop (green on green). This technology has potential to shift from broadcast herbicide applications that deliver a constant herbicide rate across an entire field to only treating parts of the field where weeds occur. This could further improve herbicide efficacy as herbicide doses could be adjusted based on weed size and weed species as detection technology improves for species identification, potentially reducing overall herbicide cost and use. This system has potential to improve weed management in soybean using technology driven SSWM.
The long-term goal of this research project is to optimize herbicide applications with a smart sprayer system in the US to stimulate the adoption of precision agriculture tools for more sustainable weed management programs.
Our research team has the skills and research equipment related to weed management and pesticide application technology to successfully complete this project. The second year of the research project (FY24) will be conducted at the University of Wisconsin-Madison (Werle), University of Nebraska-Lincoln (Proctor), Kansas State University (Dille), and the BASF Midwest Research Farm near Seymour, IL (Miller/Werle). The project collaborators have a well-established partnership with BASF (Dr. Bruno Vieira, Kalvin Miller et al.) enabling access to a small plot (mobile 10-ft tractor mounted) and large-scale sprayers (60-ft boom, located in NE) equipped with the BASF-Bosch Smart Spraying Technology. These four research sites are located in strategic soybean producing regions of the United States. Moreover, these research sites are infested with the most common and troublesome weeds that North Central US soybean growers are facing (pigweed species, ragweed species, foxtail species, common lambsquarters, kochia, horseweed, etc.). While the BASF-Bosch Smart Spraying technology will be used, inferences from this project could be applied to other similar technologies such as the John Deere-Blue River and the Greeneye sprayer systems.
This project will evaluate different configurations of site-specific herbicide applications to control weed infestations in soybean using preemergence and postemergence herbicide programs. Studies will test the BASF-Bosch Smart Spraying Technology with large-scale (studies with >40 acres) field projects in NE and small plot projects in IL, KS and WI to evaluate weed detection, targeted spray deposition, weed control, end-of season weed seed production, reduction in herbicide usage for spot-spray compared to broadcast herbicide applications, nozzle selection (broadcast vs even nozzles), target area optimization (1 vs 3 nozzle spot spray area), and soybean yield.
Multiple years are planned to be able to follow weed community response to spot-spray applications under a soybean-corn rotation with each phase of the rotation planted and evaluated each year. Plots will be established, maintained, and evaluated for multiple years with same treatments applied to each plot through time. This proposal will support a second year of funding from NCSRP but would be year 3 of a multi-year study.
A range of treatments will be evaluated in small- and large-plot studies in 2023 and are proposed to repeat for a second year in 2024.
In 2023 Werle's lab will have 2 studies with the small plot smart sprayer at Seymour IL to evaluate herbicide program efficacy. In addition, 2 studies replicated at 2 locations in WI will evaluate the effects of weed control from different nozzle types (broadcast vs even) and spot spray areas (1 vs 3 nozzles). Another study in WI will evaluate spray coverage with different spot spray nozzles and boom height configurations.
Dr Dille’s lab at KSU will have two soybean studies in 2023, one is a repeat of a trial initiated in 2022 and one is a new study evaluating spot-spray programs with different rate structures. These trials will be conducted in KS and IL on both soybean and corn.
In 2023, Dr. Proctors lab will conduct a greenhouse trial evaluating the effect of different herbicide doses across a range of weed sized to simulate different spot spraying scenarios. They will also conduct a series of spray chamber trials evaluating spray patterns of different nozzle configurations that might be utilized on a spot sprayer. Finally, they will conduct field trials evaluating weed control using different broadcast and spot spray rates and chemistries to help develop soybean and corn herbicide program recommendations with spot sprayer technologies.
There is evidence of economic gains when optimizing herbicide weed control through increased weed control efficacy and reduced herbicide load (>70% reduction) in the field and environment using smart-sprayer technologies (Zanin et al., 2022; Ruigrok et al., 2020). Knowing that weed populations most often occur in patches throughout the field highlights the opportunity to target weed control to those locations. With the newer technologies including multiple booms and tanks, we can ensure that weeds are not missed by using broadcast applications from one boom while spot spraying when weeds are detected by the sensors. Through this research, we can explore and demonstrate how to optimize efficacy of troublesome weed species occurring in soybean fields across the North Central region.
In the future, optimizing the smart-sprayer technology with other integrated weed management approaches, such as using diverse crop rotations, including cover crops, changing row spacing and planting populations, and applying multiple effective herbicide sites of action together with sensor-based weed identification, we can demonstrate at the field scale the potential economic gains for soybean farmers.