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A survey of wildfire ash impacts on California's forage crops.

B. Karle



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A survey of wildfire ash impacts on California's forage crops.
B. Karle*1, L. Forero2, J. Davy3, J. Harper4, D. Macon5, J. Heguy6, N. Clark7, J. Stackhouse8, T. Schohr9, D. Lile9, E. DePeters10, D. Meyer10, R. Poppenga11. 1University of California Cooperative Extension Orland, CA, 2University of California Cooperative Extension Redding, CA, 3University of California Cooperative Extension Red Bluff, CA, 4University of California Cooperative Extension Ukiah, CA, 5University of California Cooperative Extension Auburn, CA, 6University of California Cooperative Extension Modesto, CA, 7University of California Cooperative Extension Hanford, CA, 8University of California Cooperative Extension Eureka, CA, 9University of California Cooperative Extension Quincy, CA, 10University of California Department of Animal Science Davis, CA, 11University of California Animal Health and Food Safety Laboratory Davis, CA.

The potential impacts of wildfire ash deposition on crops harvested for livestock feed are largely unknown, especially relative to burned structures containing unknown levels of contaminants from household products, vehicles, businesses and residential chemicals. In 2018, several devastating fires plagued California, resulting in ashfall with an unknown toxicological makeup. A survey of 26 irrigated pastures, 20 hay piles, and 16 corn silage piles from locations either affected or not affected by wildfire ash was conducted. All samples were analyzed for heavy metals and a subset (n = 38) were analyzed for toxicological compounds by gas and liquid chromatography—mass spectrometry organic chemical screens. Toxicological compounds in harvested forage were detected in 6 fields (4 affected by ash, 2 not affected by ash). To determine the effects on heavy metal levels, a type 3 sums of squares multiple ANOVA was run using factors of forage source (irrigated pasture, hay, silage), impact of ash (Y/N), and their interaction. Lead, mercury, arsenic and cadmium were not detected in any samples. Models were run individually for copper, manganese, zinc, and iron. Multiple range tests used Fisher's least significant difference test. Table 1 shows the least squares means metal levels by forage type and impact of ash. Copper was not significantly affected by forage type (P = 0.07), but was higher in fields not affected by ash (P = 0.03). Zinc was affected by forage source (P < 0.01), but not by the impact of ash (P = 0.32). Manganese was significantly impacted by forage source (P = 0.04), but not by ash (P = 0.12). Iron was impacted by forage source (P = 0.02), but not by the impact of ash (P = 0.19). These results indicate that forages affected by wildfire ash deposition are safe for livestock to consume.Table 1. Least squares means mineral levels by forage source and impact from ash

ItemCU, ppmZn, ppmMn, ppmFe, ppm
Forage source
Impacted by ash
a,bWithin a column, levels with the same letter are not different at 0.05.

Keywords: wildfire, forage quality, toxicology.