Phosphorus Runoff from Two Water Sources on a Calcareous Soil
- J.K. Aase,
- D.L. Bjorneberg and
- D.T. Westermann *
Phosphorus (P) in irrigation runoff may enrich offsite water bodies and streams and be influenced by irrigation water quality and antecedent soil surface conditions. Runoff, soil loss, and P fractions in runoff using reverse osmosis (RO) water or mixed RO and well water (RO/Tap) were studied in a laboratory sprinkler study to evaluate water source effects on P transport. A top- or subsoil Portneuf silt loam (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid), either amended or not amended with manure and/or with cheese whey, with Olsen P from 20 to 141 mg kg−1 and lime from 108 to 243 g kg−1, was placed in 1.5 × 1.2 × 0.2-m-deep containers with 2.4% slope and irrigated three times from a 3-m height for 15 min, applying 20 mm of water. The first irrigation was on a dry loose surface, the second on a wet surface, and the third on a dry crusted surface. Surface (ca. 2 cm) soil samples, prior to the first irrigation, were analyzed for Olsen P, water-soluble P (Pws), and iron-oxide impregnated paper–extractable P (FeO-P) analyses. Following each irrigation we determined runoff, sediment, dissolved reactive phosphorus (DRP) in a 0.45-μm filtered sample, and FeO-P and total P in unfiltered samples. Soil surface conditions had no effect on P runoff relationships. Water source had no significant effect on the relationship between DRP or FeO-P runoff and soil test P, except for DRP in RO runoff versus water-soluble soil P (r 2 = 0.90). Total P in RO runoff versus soil P were not related; but weakly correlated for RO/Tap (r 2 < 0.50). Water source and soil surface conditions had little or no effect on P runoff from this calcareous soil.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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