Does total nitrogen/sulfur ratio predict nitrogen or sulfur requirement for corn?

Nitrogen and S can interact within the corn (Zea mays L.) plant. The objectives of this study were to evaluate in corn (i) the effect of N and S on nutrient uptake and grain yield, (ii) use of tissue total N/S ratio to predict grain yield, and (iii) the impact of applied SO₄-S on basal stalk NO₃-N concentration. Treatments were applied as a factorial design. Factor 1 consisted of 0 or 28 kg S ha^-1. Factor 2 consisted of 0, 56, 112, 168, 224, and 280 kg N ha^-1. Fertilizer N increased the concentration of N and S in corn R1 leaf tissue, N concentration in grain, relative grain yield, grain removal of N and S, and NO₃-N in the basal stalk. Fertilizer S increased R1 leaf N and S concentration, decreased basal stalk NO₃-N, and increased corn grain yield when N was applied at a rate that maximized corn grain yield. The total N/S ratio in corn R1 leaf and harvested grain were affected by N application but not by S addition. Basal stalk N/S ratio was affected by both N and S. A critical N/S ratio could not be identified to predict corn grain yield response. While the data support a general effect of N and S on the uptake of each other, fertilization with N or S should be based on potential for increased grain yield from either nutrient. Based on results, optimal N rates for corn are not affected if S is also applied.