PHOSPHORUS UPTAKE BY BAHIAGRASS FROM SPODOSOLS - MODELING OF UPTAKE FROM DIFFERENT HORIZONS


IBRIKCI H. , COMERFORD N., HANLON E., RECHCIGL J.

SOIL SCIENCE SOCIETY OF AMERICA JOURNAL, cilt.58, ss.139-143, 1994 (SCI İndekslerine Giren Dergi) identifier identifier

Özet

Bahiagrass (Paspalum notatum Flugge), when grown on a Myakka fine sand in Florida (sandy, siliceous, hyperthermic Aeric Alaquod), did not respond to P fertilization even though Mehlich-1 extractable P was low in the surface soil horizon. Previous research suggested that the Bh horizon was a potential source of P. The objective of this study was to evaluate the plant availability of P in the Bh horizon and to determine to what degree existing nutrient uptake theories explain the uptake of P by bahiagrass under greenhouse conditions. Sod and soil samples were collected from unfertilized bahiagrass growing on a Spodosol. Sod was replanted into soil samples. Plant and root samples were collected from unfertilized bahiagrass growing on a Spodosol. Sod was replanted into soil samples. Plant and root samples were collected at 18, 36, 61, and 90 d. Selected soil and plant model parameters were estimated at each harvest period. Bahiagrass was able to extract more P from the Bh horizon material than from Ap or E horizon materials. The COMP8 computer model was used to simulate uptake of P by bahiagrass. Observed and predicted P uptake by bahiagrass followed the same relative pattern (Bh > Ap > E). There was statistically good agreement between observed and predicted P uptake for 18-d-old plants, but less agreement at 90 d (within 20%) from the Bh horizon. Predicted P uptake values from the Ap and E were statistically lower than observed values at both harvest dates. Selected extraction procedures indicated that there was no P release from the mineral forms in the Ap horizon. Data suggest the plant-induced mineralization was an important P supplying mechanism in this pot study.