The effect of thin stillage on the chemical and biological properties of a Chernozem in Western Canada

The aim of the current study was to assess the effects of direct application of thin stillage on soil residual available nitrogen (N) and phosphorus (P) content along with some selected soil chemical (organic carbon, pH, electrical conductivity, metals content) and biological (dehydrogenase activity and microbial biomass) properties after crop harvest in a two-year field study. The experimental treatments included injected TS, broadcasted and incorporated TS and urea fertilizer with 3 application rates equivalent to 50, 100, and 200 kg available N ha−1 in addition to a control. Overall, NO3−-N content in TS treated soil was higher in the second year, but was not significantly different from that of urea treatments. Soil available P content increased in both years, but was greater in the second year, indicating the high release of N and P nutrients through TS organic matter decomposition after application to soil. In selected treatments, microbial biomass was higher in TS than urea treatments, but not significantly different from the control. The other measured soil parameters remained unchanged for both years. This study indicates that application of TS for two years did not contribute to NO3−-N accumulation in soil beyond the year of application when compared to urea fertilizer. Further studies with longer-term need to be conducted to monitor possible build-up of NO3−-N and P in soil via carryover of unused inorganic forms and also possibly through increased microbial mineralization.