Effect of Swine Manure Application on Atrazine Mineralization, Biomass Carbon and Atrazine Degradation

Abstract

The effect of swine manure application on atrazine degradation and fate was investigated in two soils (Kennebec and Floyd) sites near Treynor and Nashua, IA. The Kennebec soil has a history of continuous corn and continuous atrazine application while the Floyd soil has a history of corn and soybean rotation. The half life of atrazine in Floyd was longer (55 days) than in Kennebec soil (7 days). The biomass carbon in both soils increase up to day 7 then decreased with time. Mineralization of UL-ring-¹⁴C atrazine (¹⁴CO₂ production) was faster in the Kennebec soil than in Floyd soil. Although swine manure increased microbial carbon over time in untreated soils, manure inhibited atrazine mineralization in the Floyd soil. In Kennebec soil, application of manure equivalent to 448 kg N/ha inhibited the atrazine mineralization during the first 35 days of incubation. Nitrogen from the manure may have inhibited cleavage of the atrazine ring. The differences between soils in trazine degradation and mineralization probably resulted from the continuous application history at Treynor site, which may have increased the population of atrazine degrader.