Deficiency of magnesium in maize (Zea mays L.) induced by high potassium level in a micaceous soil of Kumaon region of Uttarakhand, India

Abstract

A field observation was undertaken in a farmer’s field sown with maize at Mukteshwar, Uttarakhand to record whether K rich micaceous soil can cause Mg deficiency. The crop was fertilized with nitrogen and phosphorus only. The visible effect of Mg-deficiency initiated after 20-25 days of maize sowing as interveinal chlorosis in older leaves along the margins running the full length of the leaves parallel to the veins. In later stage, necrosis of older leaves occurred particularly at the tip of the leaves. The leaf and soil sample collected at 45 days after sowing (DAS) revealed an extremely low content of Mg in soil (4.32 mg kg^-1) and plant (0.11%). The soil analysis also revealed that the soil was acidic in nature (pH 5.07) with low cation exchange capacity (9.7 cmol kg^-1). However, the soil was having a very high level of water soluble (18.2 mg kg^-1), exchangeable (262.3 mg kg^-1) and available K (280.5 mg kg^-1), which has resulted in an imbalanced exchangeable K: Mg ratio (60.7:1) rendering reduced uptake of Mg by maize. Therefore, it was concluded from the study that magnesium deficiency can occur in maize in conditions like acidic, sandy, mica rich soils with high level of K combined with low Mg content, even without K fertilization. Hence, the farmers may use dolomitic lime and/or Mg-containing fertilizers to correct Mg deficiency under such conditions for sustainable agricultural production systems.