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Research was conducted with sweet corn ( Zea mays L.) to evaluate the presidedress soil NO 3 test (PSNT) originally developed for use on field corn on a wide range of New Jersey soils. Soil NO 3 -N concentrations reflected differences in N availability due to manure or preplant N application. The relationship between soil NO 3 -N concentration and relative yield of marketable ears was examined using Cate–Nelson analysis to define the PSNT critical level. Soil NO 3 -N concentrations >25 mg·kg –1 were associated with relative yields at ≥92%. The success rate for the PSNT critical level was 85% for predicting whether sidedress N was needed. Including NH 4 -N in the soil analysis did not improve the accuracy of the soil test for predicting whether sidedress N was needed. Although the PSNT is quite accurate in identifying N-sufficient sites, it appears to offer only limited guidance in making N-fertilizer rate predictions. The PSNT is most useful on manured soils, which frequently have sufficient N. The test likely will help decrease the practice of applying “insurance” fertilizer N and the ensuing potential for NO 3 pollution of the environment.