Irrigated Wheat on a Calcareous Soil as Affected by Application of Nitrogen, Phosphorus, Potassium, and Zinc: II. Analysis of the Young Plant in Relation to Yield1

Abstract The base of the plant was suitable for diagnosis of N, P, K, Zn, and Mn nutrition of wheat at the three‐leaf stage. The critical level of nitrate‐N was 2,300 ppm, and 2,800 ppm or more appeared to be excessive. Desirable levels of P and Zn were related to the amount of tillering needed to produce the optimum number of heads for the potential yield. At a normal seeding rate, excess P and Zn resulted in overstimulation of tillering and reduced yields. Where low seeding rates are desirable as with expensive hybrid wheats, application of P and Zn at or just prior to the tillering stage in the right amounts as determined from plant analysis may be one means of compensating for the low initial plant population.