Fertilizer potential of thin stillage from wheat-based ethanol production

Abstract

Accumulation of thin stillage (TS), a byproduct resulting from ethanol production, has led to a need to explore all possible means of its utilization. The objective of this research was to evaluate the effectiveness of TS derived from wheat (Triticum aestivum L.)-based ethanol production plant as a fertilizer. The experiment was conducted over a 2-year period in east-central Saskatchewan, Canada. Treatments included three rates of TS: 50, 100, and 200 kg N ha−1 using two methods of application: broadcast, and incorporation and injection. For comparison, conventional fertilizer urea (46-0-0) was applied at the same rates of N as the TS. Responses of crop yield (wheat and canola (Brassica napus L.), N and P uptake, and apparent N recovery were measured over two growing seasons on a Black Chernozemic soil. For both seasons, at equivalent N rate, the TS produced similar or greater crop yield and nutrient recovery compared to urea fertilizer, especially when injected. This is caused by the presence of other plant nutrients, such as P and S in TS, and its relatively high plant-available NH4 +-N content. The injection of TS appears to be a more effective application method compared to broadcasting, likely through reducing volatile N loss and placing nutrients closer to the growing crop roots when injected in bands in soil. The TS did not show any adverse effect on measured crop parameters even at the high rate of application. The results of this study suggest that land application of TS can be an effective solution for TS management that recycles nutrients in the feedstock grain for the ethanol production.