Looks like nitrogen deficiency. Upper leaves yellow. Moderate Early season yellowing patches that disappears with crop growth and root extension. Low No visible symptoms. On sandy ground, plants appear to suffer drought stress by early heading.
Tillers fail to fill.
Leaf disease may be more prevalent. Yield response to other nutrient applications disappointing. No visible symptoms. Leaf and root disease may be more prevalent. In severe cases a leaf spotting not related to obvious leaf diseases is evident.