CHLOROPHYLL METER EVALUATION FOR NITROGEN MANAGEMENT IN CORN

Precise nitrogen (N) fertilizer management in corn requires accurate and timely analysis of plant tissue N status throughout the growing season. Chlorophyll meter readings (CMR) were compared to laboratory analyzed tissue N (TN) during two growing seasons in com preplant fertilized with variable rates of N provided by cattle manure and urea. Although a positive linear relationship between CMR and TN was observed on most July and August sampling dates of the seasons, the regression coefficients varied between sampling dates. When days after planting and CMR for both years were included in a multiple regression equation, 84% of TN variability was explained. Both CMR and TN were highly correlated with final crop yield. A critical CMR value of 52 at anthesis was suggested to prevent com yield reductions. Based on the results from this study, it is evident that the chlorophyll meter may prove to be a valuable tool in fertigation management.