Leaf Tissue Testing and Soil and Plant Tissue Relationships for Nitrogen Management in Carrots

Abstract

Nitrogen (N) management in carrot (Daucus carota L. var sativus) production systems is critical for increasing efficiency of crop production, decreasing costs, and decreasing nitrate leaching losses to groundwater. Leaf tissue testing may be an appropriate method to monitor and meet carrot N requirements. A field trial was conducted in three locations to 1) determine if “critical tissues” identified in previous research are appropriate for leaf tissue testing in N management of carrots, 2) determine the effects of various N regimes on soil and tissue N concentrations, 3) describe the relationships among soil N concentrations, tissue N concentrations, and yield for several N regimes, and 4) study the effects of N regimes on growth, yield, and recovery of marketable grades of carrots. Nitrogen critical tissues for leaf tissue testing were not useful in N management. Overall, results showed no significant differences in soil and tissue N levels due to increasing N regimes. Correlations among soil, tissue, and yield differed at each harvest but most were not significant. N concentration was higher in soils at a depth of 0–15 cm compared to 15–30 cm. Total N concentrations in tissues decreased over sequential harvests. No clear relationships emerged comparing tissue NO3‐N to soil N measurements over the entire growing season. There were no significant differences in growth and yield of carrots in response to N regimes. Interestingly, a N rate of 0 kg/ha had significantly more fancy‐grade carrots than a N rate of 200 kg/ha. There were no significant differences in culls due to increasing N application.