Improving sweet corn fertilizer-N efficiency promotes a more vigorous and healthy crop, rewards the grower with greater profits, and protects our water resources from nitrate-N pollution. Two areas of research that have the potential to improve the efficiency of fertilizer-N applications are the Minolta SPAD 502 chlorophyll meter and the presidedress soil N test. The SP meter is a rapid and nondestructive technique for assessing sweet corn leaf levels, and SP readings have been correlated to leaf N concentration. A presidedress soil N test measures the amount of soil N that will be available to the plant during the remainder of the growing season. SP meter readings combined with presidedress soil N analyses may be used to determine crop N needs and fertilizer-N sidedress application rates. Basing fertilizer-N sidedress application rates on actual crop N needs will reduce excess fertilizer-N applications and the resulting leaching of nitrates.
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