Monday, 7 November 2005
13

Chlorophyll Meter: a Diagnostic Test for Predicting Nitrogen Status in Corn Production.

Noura Ziadi, Athyna Cambouris, and Michel Nolin. Agriculture and Agri-Food Canada, 2560 Hochelaga Blvd., Sainte-Foy, QC G1v 2J3, Canada

In corn (Zea mays L.) production, accurate nitrogen (N) management tools are required to optimize growth and economic return as well as to minimize negative environmental impact. The chlorophyll meter (CM) is one of the potential techniques/tools that can be used to evaluate corn N status and determine if additional N fertilizer is needed. The general objective of this research was to study the accuracy of the CM to evaluate corn N status and to predict N fertiliser requirement. The study was conducted on a 15-ha field near Montreal, Quebec, Canada, for three years (2000-2002). During each spring, soil samples (n = 150, 0-20 cm) were collected on a systematic nested design (6, 14, 50, 70 and 100-m grid interval). Six N fertilizer rates (0-250 kg N ha-1) were applied at the 6-leaf stage. The CM test was performed using a Minolta SPAD-502 CM (Spectrum Technologies Inc.) at 6-leaf stage (V6) and at beginning of the flowering stage (BF). Among the three years experiment, N fertilizer rates have a significant effect (P < 0.001) on CM measurements which varied between 36.9 in the control and 55.2 when 250 kg N ha-1 was applied. These results are due to the high soil N-availability as indicated by soil nitrates measurements. Significant relationships were obtained both between CM measurements at BF and corn grain yields (0.60 < R2 < 0.98), and CM measurements at BF and corn N uptake (0.51 < R2 < 0.98). These results demonstrate that CM measurements taken at BF can be a suitable test to estimate corn N status.

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