Sorption-Desorption and Solution Concentration of Phosphorus in a Fertilized Sandy Soil
- Z. L. He,
- A. K. Alva *,
- Y. C. Li,
- D. V. Calvert and
- D. J. Banks
- Univ. of Florida, Inst. of Food and Agric. Sciences, Indian River Res. and Education Center, Fort Pierce, FL 34945-3138;
Univ. of Florida, Inst. of Food and Agric. Sciences, Citrus Res. and Education Center, Lake Alfred, FL 33850-2299;
Univ. of Florida, Inst. of Food and Agric. Sciences, Tropical Res. and Education Center, Homestead, FL 33031-3314.
There has been increasing concern about drinking water contamination and accelerated eutrophication of surface water bodies. A field experiment was conducted to assess leaching potential of PO4-P in a Riviera fine sand (loamy, siliceous, hyperthermic Arenic Glossaqualf) under grapefruit (Citrus paradisi Macfad.) production that received 0 to 30 kg P ha−1 yr−1. The PO4-P concentration was measured in soil solution sampled using suction lysimeters installed above (120 cm) and below (180 cm) the hardpan (argillic horizon). Phosphorus sorption-desorption in soil samples from different depths of the soil profile was determined to understand the transport and leaching of P in the sandy soil. Phosphorus sorption capacity of the argillic horizon was much greater than the soil above and below it. The PO4-P concentrations in soil solution varied from 0.031 to 0.976 and from 0.002 to 0.083 mg P L−1 at the 120- and 180-cm depths, respectively. Solution PO4-P concentrations generally increased with P application rates. The concentrations of P in solution at the 120-cm depth were much greater than those at the 180-cm depths, due to the greater P retention capacity of and restricted flow of P through the hardpan. This study demonstrates that leaching of P into groundwater was reduced by the presence of a hardpan in the Riviera fine sand. However, the water drained from the soil above the hardpan contains phosphorus and could be a potential P source to surface waters.
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