USE OF A CHLOROPHYLL METER TO EVALUATE THE NITROGEN STATUS OF DRYLAND WINTER-WHEAT

Chlorophyll meter leaf readings were compared to grain yield, leaf N concentration and soil NH4-N plus NO3-N levels from N rate studies for dryland winter wheat. Soil N tests and wheat leaf N concentrations have been taken in the spring at the late tillering stage (Feekes 5) to document a crop N deficiency and to make fertilizer N recommendations. The chlorophyll meter offers another possible technique to estimate crop N status and determine the need for additional N fertilizer. Results with the chlorophyll meter indicate a positive association between chlorophyll meter readings and grain yield, leaf N concentration and soil NH4-N plus NO3-N. Additional tests are needed to evaluate other factors such as differences among locations, cultivars, soil moisture and profile N status.