SINGLE SUPERPHOSPHATE DEPRESSES MOLYBDENUM UPTAKE AND LIMITS YIELD RESPONSE TO PHOSPHORUS IN GROUNDNUT (ARACHIS-HYPOGAEA L) GROWN ON AN ACID SANDY SOIL IN NIGER, WEST-AFRICA
Fp. Rebafka et al., SINGLE SUPERPHOSPHATE DEPRESSES MOLYBDENUM UPTAKE AND LIMITS YIELD RESPONSE TO PHOSPHORUS IN GROUNDNUT (ARACHIS-HYPOGAEA L) GROWN ON AN ACID SANDY SOIL IN NIGER, WEST-AFRICA, Fertilizer research, 34(3), 1993, pp. 233-242
The effect of phosphorus (P) fertilization on dry matter production an
d nitrogen (N) uptake of groundnut (Arachis hypogaea L.) was studied d
uring the growing seasons of 1989, 1990 and 1991 under rainfed conditi
ons on an acid sandy soil in Niger, West Africa. Annual application of
16 kg P ha-1 as single superphosphate (SSP) failed to increase the to
tal dry matter production significantly in all three years. Fertilizat
ion with SSP increased the concentrations of P and sulfur (S) in shoot
s from deficiency to sufficiency levels. It decreased the already very
low concentrations of molybdenum (Mo), especially in the nodules, and
also the N concentration in the shoot dry matter. With SSP applicatio
n, total N uptake declined over three years. Foliar application of P a
nd soil application of triple superphosphate (TSP) enhanced dry matter
production, N and Mo uptake. Although these acid sandy soils are know
n to be deficient in P and S, care must be taken in using SSP in groun
dnuts as it may induce Mo deficiency, unless supplementary Mo is appli
ed.