Evaluating phosphorus loss from a Florida spodosol as affected by phosphorus-source application methods.
Incorporating applied phosphorus (P) sources can reduce P runoff losses and is a recommended best management practice. However, in soils with low P retention capacities, leaching can be a major mechanism for off-site P loss, and the P-source application method (surface or incorporation) may not significantly affect the total amount of off-site P loss. We utilized simulated rainfall protocols to investigate effects of P-source characteristics and application methods on the forms and amounts of P losses from six P sources, including five biosolids materials produced and/or marketed in Florida, and one inorganic fertilizer (triple superphosphate). A typical Florida Spodosol (Immokalee fine sand; sandy, siliceous, hyperthermic Arenic Alaquods) was used for the study, to which the P sources were each applied at a rate of 224 kg P ha(-1) (approximately the P rate associated with N-based biosolids applications). The P sources were either surface-applied to the soil or incorporated into the soil to a depth of 5 cm. Amended soils were subjected to three simulated rainfall events, at 1-d intervals. Runoff and leachate were collected after each rainfall event and analyzed for P losses in the form of soluble reactive P (SRP), total dissolved P (TDP), total P (TP), and bioavailable P (BAP) (in runoff only). Cumulative masses (runoff + leachate for the three rainfall events) of P losses from all the P sources were similar, whether the amendments were surface-applied or incorporated into the soil. The solubility of the amendment, rather than application method, largely determines the P loss potential in poorly P-sorbing Florida Spodosols.
Agyin-Birikorang
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S
Soil and Water Sci. Dep., Univ. of Florida, 106 Newell Hall, P.O. Box 110510, Gainesville, FL 32611-0510, USA. agyin@ufl.edu
O'Connor
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GA
Brinton
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SR
D005431:Florida; D010758:Phosphorus / Q000737:chemistry*; D011786:Quality Control; D011891:Rain; D012989:Soil Pollutants / Q000737:chemistry*
D012989:Soil Pollutants; D010758:Phosphorus