Seasonal Availability of N from Composted Cattle Manure and Poultry Manure in Field and Incubation Studies

ABSTRACT

Seasonal availability of nitrogen (N) from composted cattle manure (CCM) and poultry manure (PM) was studied in incubations and in fields with a crop of iceberg lettuce and leeks at two sites in Sweden during two seasons. Release of N from CCM was delayed for about 8 weeks in incubated soil and in soil with a crop of leeks, and N availability remained at the mineral N content of CCM at application. After 8 weeks, available N in CCM increased. However, in soil with a crop of iceberg lettuce, available N increased earlier and available N from CCM, as well as from PM, peaked during rapid crop growth. Available N from PM, both in the field and in incubated soil, dropped to a minimum after about two weeks and then increased during the season. N availability decreased at the end of the cropping period for both crops and both manures. The traits of the course of seasonal N availability were similar in the field and in incubated soil for both manures. However, the rapid increase of available manure N during growth of iceberg lettuce differed markedly from incubated soil. Initial losses of N from PM, possibly by volatilization, were higher in incubated soil.