Nitrogen Inputs and Losses in Tobacco, Bean, and Potato Fields in a Sandy Loam Watershed

Abstract

Abstract Results from a 2‐year study concerned with additions and losses of N from cropped fields in an intensively farmed sandy loam watershed in southern Ontario indicated that heavily fertilized hurley tobacco ( Nicotiana tabacum L. [Kentucky 2110]) (220 kg N/ha per year) potato ( Solanum tuberosum L. [Superior]) (165 kg N/ha per year) fields can potentially lose up to 52 and 92 kg N/ha per year, respectively, from the 75‐cm profile by leaching and denitrification. Mineral N production rates calculated from results obtained in the field over the growing season varied from 0.0 to 0.73 kg N/ha per year. The lower rate resulted from leaching losses. The monitored NO 3 ‐N profile distributions under fertilized hurley tobacco and potato crops showed definite leaching patterns. Soil water samples taken periodically from the potato field at 90 and 150 cm showed NO 3 ‐N moving through the lower profile in response to rainfall events. A plot treated with Cl showed no significant Cl leaching losses until early fall when rains moved about 45% of the added Cl below 75 cm.