麦苗发黄的原因及防治缺氮发黄主要出现在土地瘠薄、底肥不足或追肥不及时的麦田，其特征是麦苗均匀褪色变黄，且下部茎叶重于上部新叶，叶片狭小，分蘖减少。应及时追施腐熟的人粪尿、碳铵、尿素等速效氮肥。缺钾发黄常发生在砂质土壤里，且四周重于畦中，一般从老叶叶尖... The causes and prevention of yellowing of wheat seedlings Nitrogen deficiency and yellowing mainly appear in the barren land, lack of fertilizer or top dressing is not timely wheat field, which is characterized by uniform yellowing wheat seedling discoloration, and lower stems and leaves heavier than the upper new leaves, narrow leaves, reduced tillers . Should promptly topdressing manure urine, ammonium bicarbonate, urea and other quick-acting nitrogen fertilizer. Potassium deficiency yellow often occurs in the sandy soil, and four weeks in the Langzhong, generally from the old leaf tip ...