A bioassay of nitrogen availability in soils amended with manure from cattle fed dried distiller grains with solubles: effects of construction and demolition waste and peat moss

The use of construction and demolition waste (CDW) and peat moss as bedding in beef cattle feedlots may affect the amount of plant-available nitrogen (N) in manure. Such an effect, however, may differ between manure from cattle fed a regular grain diet (RM) and those fed dried distiller grains with solubles (DGM). We used five 40 d crop cycles in a greenhouse bioassay to determine the effects of RM and DGM manure containing CDW or peat moss on canola (Brassica napus L.) growth and N uptake in a Black Chernozem (loam, Typic Hapocryoll) and a Brown Chernozem (sandy clay loam, Aridic Haploboroll) with or without the addition of a nitrification inhibitor (nitrapyrin) in each cycle to minimize nitrate (NO3) leaching. Our results showed that the presence of CDW in DGM and RM manure depressed (P < 0.05) cumulative dry matter yield (CDMY) and N uptake in canola relative to manure without CDW, whereas the presence of peat increased (P < 0.05) CDMY and N uptake. Results suggest that it may be necessary to supplement CDW-amended DGM and RM manure with synthetic N fertilizer to supply adequate available N for plant uptake because the addition of CDW decreases organic N mineralization.