Surface runoff phosphorus (P) loss in relation to phosphatase activity and soil P fractions in Florida sandy soils under citrus production
Phosphorus losses by surface runoff from agricultural lands have been of public concern due to increasing P contamination to surface waters. Five representative commercial citrus groves (C1–C5) located in South Florida were studied to evaluate the relationships between P fractions in soils, surface...
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Veröffentlicht in: | Soil biology & biochemistry 2006-03, Vol.38 (3), p.619-628 |
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Sprache: | eng |
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Zusammenfassung: | Phosphorus losses by surface runoff from agricultural lands have been of public concern due to increasing P contamination to surface waters. Five representative commercial citrus groves (C1–C5) located in South Florida were studied to evaluate the relationships between P fractions in soils, surface runoff P, and soil phosphatase activity. A modified Hedley P sequential fractionation procedure was employed to fractionate soil P. Soil P consisted of mainly organically- and Ca/Mg-bound P fractions. The organically-bound P (biological P, sum of organic P in the water, NaHCO
3 and NaOH extracts) was dominant in the acidic sandy soils from the C2 and C3 sites (18% and 24% of total soil P), whereas the Ca/Mg-bound P (HCl-extractable P) accounted for 45–60% of soil total P in the neutral and alkaline soils (C1, C4 and C5 soils). Plant-available P (sum of water and NaHCO
3 extractable P fractions) ranged from 27 to 61
mg
P
kg
−1 and decreased in the order of C3>C4>C1>C2>C5. The mean total
P concentrations (TP) in surface runoff water samples ranged from 0.51 to 2.64
mg
L
−1. Total P, total dissolved P (TDP), and PO
4
3−-P in surface runoff were significantly correlated with soil biological P and plant-available P forms (
p |
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ISSN: | 0038-0717 1879-3428 |
DOI: | 10.1016/j.soilbio.2005.02.040 |