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CC BY-NC V4.0, Open Access
Thesis
ON-FARM COVER CROP TRIALS IN THE DRYLAND WHEAT FALLOW REGION OF NORTH-CENTRAL WASHINGTON
Washington State University
Master of Science (MS), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004481
Handle:
https://hdl.handle.net/2376/125317
Abstract
Cover crops have been associated with increased soil health in many parts of the world. In low-rainfall dryland cropping regions, soil moisture depletion and resulting yield reduction are a concern for many producers as potential soil health benefits of cover crops are intangible. An on-farm, large scale study was conducted to compare three cover crop timing of establishment treatments to a low-disturbance chemical fallow control treatment in the northern wheat producing areas of central Washington. Eighteen farms participated in the study, conducted over a 4 year period, resulting in a total of 40 single replicate trials, not all comparison treatments were present in each trial. Cover crop mixtures were multi-species grass and broadleaf blends suited for each season. Successive cash crop yield, gravimetric water content and soil indicators were compared to assess the viability of cover crops in the dryland wheat-fallow production system. Data was analyzed using PC-Ord using non-metric multidimensional scaling. Wilcoxon Rank Sum and correlation coefficients between treatments were run to understand impact of each treatment compared to chemical fallow control.
Cover crops in wheat-fallow rotations reduced gravimetric water content by an average of 2 to 5 % depending on treatment; subsequent crop yield was reduced by an average of 13% when compared to the control. Soil NO3-N decreased by an average of 5 mg kg-1 after fall, and 9 mg kg-1 after spring and summer cover crops. Soil pH increased in all treatments from 5.55 in the Control to 5.61 in Fall treatments, 5.73 in Spring, and 5.72 in Summer. Cover crop treatments had varying impacts on micronutrients, OM, SOC, POXC, and NH4-N. Fall treatment had positive effects on the most soil health indicators and the highest percentage of plots which yielded above the control. However Fall had less than half the number of plots than other treatments
Cover crop treatments appear to alter certain soil health indicators, especially pH, while reducing yield in the low rainfall region of north central Washington. Producers need more information on the value of the change in soil characteristics to balance against the expected yield loss using cover crops.
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Details
- Title
- ON-FARM COVER CROP TRIALS IN THE DRYLAND WHEAT FALLOW REGION OF NORTH-CENTRAL WASHINGTON
- Creators
- Leslie Michelle Michel
- Contributors
- Lynne Carpenter-Boggs (Advisor)Ian C Burke (Committee Member)Doug P Collins (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 99
- Identifiers
- 99900882138501842
- Language
- English
- Resource Type
- Thesis