Use in-season soil or plant analysis to determine the nutrient status of the growing crop. If the N status of the crop is low or growing conditions appear to be above average, apply additional N with the next irrigation. Suggested P rates are for band application. Placement of P fertilizers in the root zone is important because P is not mobile in soil. Incorporate broadcast applications of P fertilizers into the soil prior to planting.
Sunflower seed is sensitive to salts in fertilizers.
Most Colorado soils are relatively high in extractable K, and few crop responses to K fertilizers have been reported. Broadcast application incorporated into the soil prior to planting is the usual method. Suggested potassium rates for dryland and irrigated sunflowers. 0 Other Nutrients Most Colorado soils contain adequate levels of available S, and soil tests for available S are not routinely performed. Some deep well waters are low in SO 4 -S, so analyze water samples if soils are low in organic matter content and you suspect S deficiency.