Onion Cull Disposal
Author: Howard F. Schwartz and Michael E. Bartolo
Thousands of tons of onion culls are discarded each year due to the effects of pests, off grades and/or poor markets. When cull onions are improperly disposed in and near next season's onion fields, insects and plant pathogens contaminate the new onions and seriously threaten productivity and quality. Therefore, it is vital that proper sanitation be exercised each season to clean up processing facilities by removal of all onion waste and residual soil, and proper treatment of onion culls before the new onion crop becomes established in early spring.
Onion culls can be disposed of in various means according to Mike Thornton of the University of Idaho. One ton of cull onions contains approximately 215 gallons of water, 180 pounds of organic matter, three pounds of potassium, two pounds of nitrogen, two pounds of sulfur, 0.9 pounds of iron, 0.8 pounds of phosphorus, 0.6 pounds of calcium, and trace amounts of other minerals.
Idaho and Oregon personnel have successfully disposed of onion culls by:
1) Burial beneath a few to many inches of soil in pits and landfills; however, regulations regarding water quality are making it more difficult and expensive to utilize landfills.
2) Chopping, spreading and incorporation at four to six inches into marginal soils (80 tons per acre) that will not be planted to onions.
3) Feeding chopped or crushed onions to sheep and beef cattle but not finishing cattle at rates up to 10 to 25 percent of the diet.
4) Composting with wheat straw and other organic material for at least 30 days with adequate aeration and moisture.
The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.