Radioisotope Laboratory, Department of Soil Science and Agricultural Chemistry Tamil Nadu Agricultural University, Coimbatore-641 003, India.
Among the nine oilseed crops, groundnut is an important edible oilseed crop of our country and edible oil economy primarily depends upon groundnut production. S, Ca and Mg requirements are highest in oil seed crops followed by pulses and least in cereals. Among the secondary nutrients, Ca deficiency causes groundnut pegs and pods to abort and reduced yield, indicating the essentiality of that nutrient for groundnut production. Application of gypsum @ 1.5 t ha–1 at flowering was found to be most effective in increasing oil content. In groundnut, the response with Mg application was ranged from 21.0 to 41.6 per cent. Sulphur is the another secondary nutrient influencing the groundnut productivity preferably in addition to N, P and K. Apart from these secondary nutrients, groundnut is also sensitive to the deficiency of micronutrients such as B, Zn and Fe. The response of groundnut to Zn ranged from 210 to 470 kg ha–1. In Zn deficient soils, application of Zn increased the nodulation, chlorophyll content and pod yield. Similarly, Fe chlorosis in groundnut is another problem of growing concern in many alkaline calcareous soils, where bicarbonate ions hinder the uptake and translocation of Fe in the plant. Boron is highly essential for proper seed setting and seed quality and also it helps in the absorption of N by groundnut crop. In red loamy soils of Coimbatore, application of ZnSO4 @ 20kg ha–1 plus 0.5 per cent foliar spray along with borax @ 25 kg ha–1 plus 0.25 per cent foliar spray recorded the highest pod, kernel and oil yield. Hence, secondary and micronutrient ferilization is essential for enhancing the productivity of groundnut crop.
