Effect of potassic fertilization on yield of fodder sorghum-sudan grass hybrid and selection of extractants for determination of plant potassium availability

Abstract

The current study was carried out to assess the effect of potassium (K) fertilization on K-uptake and yield of fodder sorghum-sudan grass hybrid and to choose extractant(s), delineating the K-availability for routine soil testing method. Hybrid sorghum-Sudan grasses were grown in three different soils (red, alluvial, and black) with 100, 50, and 0% recommended K-doses for five seasons. Seven extractants, namely, cold H2SO4, Mehlich-1, 0.1 N CH3COONa, 1 N CH3COONH4 (pH 7), 0.1 N BaCl2, and sodium tetraphenylborate (NaTPB) with 5 and 15 minutes of contact times, were evaluated for elucidating forage K-availability. Results have revealed that biomass yields from all soils were higher (p < 0.05) in K-100% than in K-0%; whereas NaTPB (5 minutes) and ammonium acetate were found as better extractants for the determination of forage K-availability.