Evaluating Oilseed Meals, Distillers Grain, Anaerobically Digested Fiber, and Mint Sludge as Nitrogen Fertilizer Sources.

The new development of ethanol and biodiesel plants in the United States is creating a large, and potentially excessive, quantity of byproducts in the forms of distillers grains and oilseed meals. The organic nitrogen (N) compounds in these byproducts rapidly mineralize in soils, showing the potential to be used as a N fertilizer source to plants. The objective of this research is to evaluate the application of biofuel byproducts on yield, size distribution, and nutrient uptake for Russet Umatilla potatoes. Canola meal, mustard seed meal, dried distillers grains, and a urea fertilizer (46 %N) were hand-applied at rates of 100, 150, and 200 lb total N/acre. The lowest tuber yield for mustard meal was at the highest N rate, and may be related to the isothiocyanate concentration in the meal. Potatoes fertilized with canola meal, mustard meal, and dried distillers grains had higher tuber yields and proportionally heavier tubers at all rates, compared to potatoes fertilized with urea. It appears that the urea fertilized potatoes were suffering from a sulfur (S) deficiency, which could cause a tuber yield reduction.