Critical Limits of Potassium in Soil and Plant and Response of Groundnut (summer)in Medium Black Calcareous Soils of Saurashtra

摘要

A pot experiment was conducted to determine the critical limits in soil and plant and response to potassium of groundnut crop by collecting medium black calcareous soil (Typic Ustochrept)from 20 sites varying in physico-chemical properties and potassium status.The samples differed in water soluble K,exchangeable K and non-exchangeable potassium concentrations.Potassium fertilization significantly increased pod and fodder yields of crop as well as concentration and uptake of K.The per cent pod yield response ranged between -0.01 to 37.59 and -2.59 to 47.03 at 25 and 50 mg K kg~(-1)levels,respectively.The yield response of groundnut to added potassium was considerably higher in low K soils than in those of medium and high K status.Bray's per cent yield was significantly correlated with neutral 1N NH_4OAc-K (r=0.687**),water soluble-K (r=0.370*)and boiling 1N HNO_3K (r=0.446*).The neutral 1N NH_4OAc-K (available K)showed higher degree of correlation coefficient (r)with Bray's per cent yield (0.687**),K concentration (0.441*)and its uptake (0.619**).Critical limits of available potassium in medium black calcareous soil for neutral 1N NH_4OAc-K was 121.0 kg K ha~(-1).The critical limit of concentration of K in groundnut at 30 DAS and maturity was found to be 0.94 and 0.46 per cent in plant,respectively.