Soil and plant tissue testing for nitrogen management in carrots

Abstract

Carrots (Daucus carota L.) were grown in mineral soils with one of several nitrogen (N) programs during two years. Nitrogen management based on the available soil N content (nitrate plus ammonium) in the top 30 cm was compared with increasing amounts of N applied in multiple applications. Available soil N was monitored throughout the growing season. Nitrate‐N concentration in the petiole sap and in the root tissue was measured while the roots were sizing. In both years, total and marketable carrot yields were maximized with the N program which accounted for available soil N in the top 30 cm in mid‐June. Applying more N increased top biomass and nitrate‐N concentration in the carrot root which resulted in higher residual soil nitrate‐N after harvest in 1993. Insufficient N resulted in a greater incidence of foliar disease in the late fall. The nitrate‐N content of the expressed petiole sap related directly to the amount of N applied. An accounting of N inputs and plant accumulation indicates that carrots are very effective in utilizing indigenous and applied N.

Notes

Contribution of the Michigan State University Agricultural Experiment Station. This research was in part funded by the Michigan Carrot Committee.