Progress 04/01/15 to 09/30/18
Outputs
Target Audience:
Nothing Reported
Changes/Problems:The primary PI died before the conslusion of the study, so there was a major delay in completing some of the writing and analysis. This has now been finished, and a draft of the manuscript has been completed, and will be submitted soon. What opportunities for training and professional development has the project provided?1 M.S. degree was awarded with this study as the thesis project. How have the results been disseminated to communities of interest?1 peer-reviewed article is in preparation. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Soil-applied herbicides are important for controlling weeds in many crops, as they offer a broadened control spectrum and chemical diversity when POST-applied herbicide options are limited. However, if soil-applied herbicides persist for an extended time, there is risk for damage to susceptible rotational crops in succeeding years. As herbicide degradation in the soil is dependent on water, among other factors, needs to reduce agricultural water use in the future could lead to limited herbicide degradation and a greater risk for carryover. This project seeks to understand how limited irrigation affects dissipation of soil-applied herbicides in irrigated crop rotations. A field study was undertaken by applying 8 soil-applied herbicides to dry bean and corn. Three irrigation treatments (100, 85, and 70% of crop evapotranspiration) were applied with an overhead sprinkler. Soil samples taken 0, 1, 7, 14, 21, 28, 42, 56, 70, 84, 112, and 140 d after application were analyzed for herbicide level using gas or liquid chromatography and mass spectrometry. Results were regressed over time to produce a degradation curve and soil half-life estimate for each herbicide and irrigation treatment. Reduced irrigation never significantly increased soil half-life of any herbicide tested for both study years. Growth and yield of rotational crops planted one year following herbicide application supported these results, as reduced irrigation did not increase the risk of carryover. Instead, carryover was primarily determined by the inherent persistence of individual herbicides. Imazethapyr (0.1 kg ai ha-1) injured rotational sugar beet, corn, and sunflower. Isoxaflutole (0.1 kg ai ha-1) injured rotational dry bean and sunflower. Pyroxasulfone (0.2 kg ai ha-1) injured rotational sugar beet in one of two years. Atrazine (2.0 kg ai ha-1), saflufenacil (0.1 kg ai ha-1) + dimethenamid-p (0.6 kg ai ha-1), ethalfluralin (0.8 kg ai ha-1), trifluralin (0.6 kg ai ha-1), and pendimethalin (1.1 kg ai ha-1) did not injure rotational crops.
Publications
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Progress 10/01/16 to 09/30/17
Outputs
Target Audience:
Nothing Reported
Changes/Problems:The originalPI for this project died in a tragic motorcycle accident. We are doing the best we can to bring this project to completion but things have fallen behind the original schedule. Dr. Sbatella left big shoes to fill. What opportunities for training and professional development has the project provided?An M.S. student completed his degree with this project as his thesis. How have the results been disseminated to communities of interest?Data has been presented to scientists at professional society meetings. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Field study was finished in 2017, final data has been collected, but is still being analyzed.
Publications
- Type:
Conference Papers and Presentations
Status:
Awaiting Publication
Year Published:
2017
Citation:
Adamson et al. (2017) Dissipation of Soil-Applied Herbicides under Limited Irrigation. Proc. Western Soc. Weed Sci. 129.
- Type:
Conference Papers and Presentations
Status:
Awaiting Publication
Year Published:
2017
Citation:
Adamson et al. (2017) Crop Response to Soil-Applied Herbicide Carryover. Proc Western Soc. Weed Sci. 37.
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Progress 10/01/15 to 09/30/16
Outputs
Target Audience:The study area was visited by college students and Ag professionals, in order to show the effects of herbicide carryover in rotational crops. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Grad student is learning the laboratory procedures for determining herbicide residues in soil. The study area was visited by college students and Ag professionals, in order to show the effects of herbicide carryover in rotational crops. How have the results been disseminated to communities of interest?Partial results have been shared to growers and interested public in field days, and to other prefessionals in professional meetings. What do you plan to do during the next reporting period to accomplish the goals?In 2017, the field bio-assay portion of the second study will be completed, and all soil samples will be processed to determine herbicide degradation.
Impacts
What was accomplished under these goals?
The field study initiated in 2015, continued during the 2016 growing season at the Powell Research and Extension Center. During this season the portion of the study initiated the previous years was planted to sugarbeet, corn, sunflower or dry beans as a field bioassay, to evaluate the effects of herbicide carry over under different irrigation regimes. Crops were evaluated for injury during the growing season and harvested for yield determination. In an adjacent field, a second run of the study began in 2016, with same methodology used in 2015. In fall of 2016, all soil samples collected from both studies, are being process to determine herbicides levels remaining in soil. The objective is to determine degradation rates of the tested herbicides under different irrigation levels.
Publications
- Type:
Other
Status:
Published
Year Published:
2016
Citation:
G. Sbatella and A. R. Kniss. 2016.Effects of Limited Irrigation on Herbicide Efficacy and Herbicide Carryover.Field Days Bulletin 2016, Wyoming Agricultural Experiment Station. Pg 75-76.
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Progress 04/01/15 to 09/30/15
Outputs
Target Audience:During the year 2015 a field study was initiated at the Powell Research and Extension Center where four different soil-applied herbicides were applied to dry beans and corn respectively. Crops were grown under three irrigation regimes (100, 80, and 69 % of crop evapostranspiration), and soil moisture was monitored using GS1 soil moisture sensors. Volumetric soil water content of the three irrigation treatments averaged 22%, 18% and 17% throughout the growing season. Crop yields decreased as irrigation was reduced. Soil samples were collected at regular intervals following herbicide application and will be analyzed in the lab in the year 2016 to determine herbicide levels remaining in the soil. A second set of soil samples was collected in fall of 2015 and will be used in 2016 to perform a greenhouse bioassay to determine crop response to residual herbicide. These results will be compared to crop response in the field during the 2016 growing season, when sugar beet, sunflower, and dry bean or corn will be planted over the original plots and assessed for herbicide damage. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Graduate students have become familair with soil-water content monitoring techniques, irrigation techniques, herbicide applications, data collection. How have the results been disseminated to communities of interest?Preliminary results from the first year have been presented by the graduate student at the University Wyoming and in professional meetings (Western Society of Weed Science). What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Data was collected from the 2015 field study to compare with 2016 observations which will allow preliminary conclusions regarding the major goals for the project.
Publications
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