Food Processing Residuals
Nontraditional Soil Amendments
FOOD PROCESSING RESIDUALS
Food processing residuals (FPR) cover a wide array of by-product organic materials generated from processing agricultural products into human food or animal feed products. FPRs can include materials such as fruit and vegetable peels, seeds, pits, cheese whey, bone, hide, hair, feathers, process wastewater, and process wastewater treatment sludges. The primary agronomic benefits of most FPRs are a source of plant nutrients and organic matter. Process wastewater treatment sludges can be very similar to biosolids, except they generally will not contain trace element contaminants or pathogens. As with any by-product material, chemical analysis of the product is very important. Farmers need to know how much of what nutrients and in what form are being supplied by the FPR. Most nitrogen in FPRs will be in an organic form and may be released very slowly as organic matter is mineralized.
Farmers using FPRs may face a number of management issues. Some may be highly putrescent and create immediate odor problems. Some may be difficult to handle and spread with conventional equipment. Some may have high carbon-to-nitrogen ratios (greater than 30:1) and cause temporary immobilization (unavailability) of soil nitrogen. Some, such as milk and cheese processing by-products, may have a very high oxygen demand because they decompose so rapidly. Over-application of such materials could cause anaerobic conditions to develop in the soil and literally smother crop roots. Careful investigation and chemical analysis is essential in making a decision to use an FPR.