Fertilizer Studies with Groundnuts on the Brown Sands of Guyana. II. Effect of Nitrogen, Phosphorus, Potassium, and Gypsum and Timing of Phosphorus Application1

Abstract

AbstractThe effects of N, P, K, and gypsum and timing of application of P on the performance of groundnuts (Arachis hypogoea L.), grown on the Brown Sands of Guyana, were studied. Generally, 15 kg N/ha gave optimum production. However, in a dry season on the coarser textured soils and during all seasons on a finer textured soil 32 and 48 kg/ha of N were needed, respectively. Application of up to 30 kg P/ha increased yields on all soils found under savannah vegetation except the finest textured one. P did not increase yields of groundnut on the soil occurring under forest vegetation. Potassium within the range tested (124‐164 kg/ha) had no effect on yield. Application of up to 495 kg gypsum/ha increased yield and reduced the number of “pops.” Application of all the P at planting produced higher yields than when the application was split, and this effect was greater during periods of stress and at low rates of gypsum. Timing of P applications had no effect on the number of “pops.”Both P and K increased in all four soils with repeated applications of the respective fertilizers. The amounts accumulated however, were small relative to the quantities applied. Potassium accumulation increased with the clay content of the soils. Total N increased in two soils only.