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Dissolved Phosphorus from Undisturbed Soil Cores

Related to Adsorption Strength, Flow Rate, or Soil Structure?

M. Saleem Akhtar, Brian K. Richards, Pedro A. Medrano, Maarten deGroot and Tammo S. Steenhuis^*

Dep. Bio. and Env. Eng., Cornell Univ., Ithaca, NY 14853

View larger version (85K): [in a new window]   Fig. 1. Blue dye staining of four of the five soils examined. The rainfall/dye intensity was 0.2 cm h-1, stopped after a total accumulation of 0.5 cm for the Hudson soil and after 2.5 cm for other soils.

View larger version (25K): [in a new window]   Fig. 2. Chloride concentration in drainage water in response to a Cl- pulse. The arrow indicates Cl discontinued in rainfall: (a) unsaturated flow (0.2 cm h-1 application rate, one replicate each of Hudson, Arkport, and Genesee soils); and (b) saturated flow (water applied under ponded conditions resulting in flow rates of 17.6 and 6.8 cm h-1 for Hudson and Genesee soils, respectively). Symbols are observed values. Lines are convective-dispersive equation best fits; parameter values are given in Table 3.

View larger version (31K): [in a new window]   Fig. 3. Soil P adsorption isotherms: (a) surface soil layer (A, Ap) and (b) subsoil (Bw, B/E horizon). Inserted figures depict the whole range of values. Symbols represent the average of three replicates. Lines are fitted Langmuir isotherms for Arkport (lower) and Genesee (upper); fitted lines for other soils fell between those shown.

View larger version (28K): [in a new window]   Fig. 4. Baseline ortho-P concentrations in the outflow water under an application rate of 0.2 cm h-1 for one replicate of each soil.

View larger version (45K): [in a new window]   Fig. 5. Ortho-P concentrations in outflow water under unsaturated flow (0.2 cm h-1 flow rate). Shaded areas indicate periods when phytate P was added.

View larger version (25K): [in a new window]   Fig. 6. Ortho-P concentrations in outflow water under ponded conditions: (a) Hudson, (b) Genesee, and (c) Honeoye. Arrows indicate when the applied solutions were switched back to water.

View larger version (50K): [in a new window]   Fig. 7. Organic P concentrations in outflow water under unsaturated flow (0.2 cm h-1 flow rate). Shaded areas indicate periods when phytate P was added.

View larger version (57K): [in a new window]   Fig. 8. Phosphorus concentration in outflow water for Hudson columns under unsaturated flow (0.2 cm h-1 flow rate): (a) Total P, (b) Ortho P, and (c) Organic P. Shaded areas indicate periods when phytate P was added.