Nitrogen and Phosphorus Losses from Organic Soils

The nutrient content of drainage water from Histosols located in New York was monitored from June 1975 through July 1977. Continuous flow records and nutrient concentration data obtained from daily composite samples were used to calculate annual nutrient outputs which ranged from 0.6 to 30.7 kg/ha for PO 4 − ‐P, 39.2 to 87.5 kg/ha for NO 3 − ‐N, and <1.0 to 1.9 kg/ha for NH 4 + ‐N. Nutrient concentrations in the drainage water increased with increasing flow, so that the greatest output of nutrients was during late winter and spring high‐flow events. Maximum observed concentrations were 35 mg/liter for NO 3 − ‐N and 10 mg/liter for PO 4 3− ‐P. The amount of N lost in drainage water was similar at all sites and was about 10% of that mineralized; the remainder was presumed to be denitrified. The fiftyfold variability in phosphorus output appeared to be related to interactions within the soil profile rather than fertilizer practices, although these probably contributed to the generally high levels found. It was concluded that fertilizer nitrogen additions were unlikely to affect the quantity of NO 3 − leached. The study showed that organic soils can contribute to N and P in land runoff in much greater proportions than indicated by their area.