The effect of potassium on performance and production of groundnut grown on Rudua series soil

Groundnut is one of potential cash crops currently being planted in Malaysia. Its cultivation requires a light-colored, light textured soil with good drainage and moderately low amounts of organic matter. Such soil is preferred since it is usually loose and friable, permitting easier penetration of roots and formation of pegs, better percolation of rainfall, and easier harvesting. In Malaysia, such suitable soil for groundnut cultivation is the BRIS soils. Even though this soil series has low cation exchange capacity (CEC), poor in water holding capacity and has low nutrient content, an appropriate fertilizer treatment can ensure a good harvest of groundnut crop. Rudua soil series was selected for the purpose of this study specifically to determine the effect of different potassium sources (both soil- and foliar-applied) on the growth performance and yield production of Margenta variety. Three potassium sources, namely, KCI, KNO3, and K2SO4 along with nitrogen, phosphorus and other soil amendments (organic fertilizer and calcium fertilizer) were applied at the recommended rates. The plants grown in polybags were laid out in a Randomized Complete Block Design (RCBD). The growth performance of the groundnut plants was monitored closely at weekly intervals beginning two weeks after sowing where records were taken for plant parameters such as dates of flower initiation, dates of peg initiation, leaf area, fresh weight of plants, number of pods, weights of pods and seeds. The analysis of variance indicated that the differences between treatment means were not significant for time of flowering, time of peg initiation, leaf area, and weight of plant biomass. So was yield where different sources of potassium did not show significant differences. Nevertheless, potassium in the form of KCI could be considered as the better treatment in terms of producing the highest fresh and dry weights of pods, number of seeds and seed weight while plants treated with K2SO4 fertilizer either soil- or foliar-applied produced the lowest pod yield (number of pods, weight of pods, number of seeds and weight of seeds). It could be concluded then that the sources of potassium fertilizer are of no consequence for the growing of the Margenta variety of groundnut in BRIS soil of the Rudua series as the yield obtained showed no significant differences. Supplementary application of potassium as foliar spray during plant growth did not bring about positive effect either on yield production.