Seasonal Changes in Carbon Content, and Dehydrogenase, Phosphatase, and Urease Activities in Mixed Prairie and Fescue Grassland Ah Horizons

Abstract

Total C, water-soluble C, and 3 soil enzymes associated with Ah horizons under ungrazed mixed prairie and fescue grassland ranges were assessed over a 23-month period. Generally, total C was higher in samples from heavily grazed sites than in those from ungrazed sites and was higher over the winter months than during the summer. Water-soluble C was generally higher in soil from mixed prairie than in soil from fescue grassland except for short periods during the winter. Enzymatic activities are highest in samples from the fescue grassland site regardless of grazing intensity. Enzymatic activities of both sites increased during the winter months. Grazing intensity affected enzymatic activities differently at the 2 sites. A working hypothesis is proposed to account for organic matter breakdown during the winter and spring months.