Growth Response and Phosphorus Uptake by Groundnut in Calcareous Soil in Relation to Applied Phosphorus under Varying Soil Moisture Conditions

The effect of soil moisture (25, 50 and 75% available soil moisture: ASM) and phosphorus (0, 25, 50 and 75 kg P₂O₅/ha) on available P and growth response and uptake of P by groundnut was studied in a field. The results showed that 75% ASM significantly outyielded the other levels with respect to growth, kernel production, shelling percentage, oil content and P uptake by the crop, but its effect over 25% ASM was more pronounced at later growth stage than the earlier one.

Application of P up to 50 kg P₂O₅/ha produced significantly favourable effect on all the above parameters except shelling percentage. Available P increased significantly in surface and sub-surface soils with level of irrigation but only in surface layer due to P doses. Irrespective of treatments, the highest level of available P was noted during pod development. The available P in surface soil was significantly correlated with dry matter yield and P uptake at all growth stages, but with sub-soil it showed significant relationship with haulm and pod yield and P uptake by haulm.