Performance of cowpeas cv 'Black-eye' in Guyana as afected by phosphorus and potassium

Abstract

The effect of P (0, 15, and 30 kg/ha) and K (0, 27.5, and 55 kg/ha) on yield, its components, and nodulation of the canpi, Vigna unguiculata (L) Walp. cr 'Blackeye', was studied in a soil species present in two vegetation types, savanna and forest. The effect of applying these elements at different times of crop development was also studied at the savanna location. In the savanna soil, P was the limiting factor, whereas in the forest soil, K was the limiting factor for both yield and nodulation. In both locations, however, both elements were required for optimal yields. With P, application at the beginning of the crop was preferable, whereas the timing of K application was not important for grain production.