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ARS Home » Pacific West Area » Pullman, Washington » WHGQ » Research » Publications at this Location » Publication #397056
Research Project: Ecology and Genomics of Soilborne Pathogens, Beneficial Microbes, and the Microbiome of Wheat, Barley, and Biofuel Brassicas

Location: Wheat Health, Genetics, and Quality Research

Title: Canola rotation effects on soil water and subsequent wheat in the Pacific Northwest USA

Author
item SCHILLINGER, WILLIAM - Washington State University
item Hansen, Jeremy
item Paulitz, Timothy

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: In previous a previous 6-year study in the intermediate precipitation area, we documented a yield decline in spring wheat after winter canola, which was not due to water use, herbicide, nutrition, or disease. We did measure a decrease in fungi and arbuscular mycorrhizal fungi, using phospholipid fatty acid analysis. We then did another 6 year study in a drier area of the state, looking at spring wheat following winter canola, but also following winter wheat, winter triticale, spring barley and continuous spring wheat. In this case, water explained the yield decrease. Winter canola has less residue and traps less snowfall, compared to winter wheat, so there was less winter and spring recharge of the soil profile. Soil microbiome studies are pending to see what effect the rotation crops have on the subsequent wheat microbiome.

Technical Abstract: Farmers in Mediterranean climate regions are increasingly growing canola (Brassica napus L.) in wheat (Triticum aestivum L.)-based systems to break soil-borne pathogen disease cycles, control weeds, and enhance crop marketing opportunities. A 6-yr rainfed cropping systems experiment was conducted near Ritzville, WA from 2015-2021 to compare performance of canola, winter triticale (X Triticosecale Wittmack) (WT), and winter wheat (WW) and measure their effects on soil water dynamics and subsequent performance of spring wheat (SW). Overwinter soil water gain in canola stubble was significantly reduced compared to water gain in WT and WW stubble. The more winter precipitation, the greater the differences in soil water among treatments in early spring. There was a trend in all years for diminished overwinter soil water gain in canola stubble. Averaged over years, grain yield of SW was 1940, 2340, and 2210 kg/ha grown on canola, WT, and WW stubble, respectively (p=0.045). Coefficients of determination from regression analysis conducted each year showed a high correlation between water content in the 180-cm profile in early spring and SW grain yield, except in one year of extreme drought. This paper provides a first report in a Mediterranean region of decline in wheat grain yield after canola versus after a cereal crops, primarily due to reduced overwinter soil water storage.