Phosphorus runoff from two water sources on a calcareous soil

Area of Science:

• Environmental Science
• Soil Science
• Water Quality

Background:

• Phosphorus (P) in irrigation runoff can lead to eutrophication of water bodies.
• Irrigation water quality and soil surface conditions are potential factors influencing P transport.
• Understanding P runoff dynamics is crucial for managing agricultural impacts on water quality.

Purpose of the Study:

• To evaluate the effect of irrigation water source on phosphorus (P) transport in runoff.
• To assess the influence of antecedent soil surface conditions on P runoff.
• To investigate P fractions in runoff under different irrigation and soil scenarios.

Main Methods:

• Laboratory sprinkler study using Portneuf silt loam soil amended with manure and/or cheese whey.
• Irrigation with reverse osmosis (RO) water or mixed RO and tap water on varied soil surface conditions (dry loose, wet, dry crusted).
• Analysis of runoff, sediment, and various P fractions (dissolved reactive P, FeO-P, total P) in collected samples.

Main Results:

• Soil surface conditions did not significantly affect P runoff relationships.
• Water source generally had no significant effect on the relationship between P runoff and soil test P.
• A strong correlation was observed for dissolved reactive P (DRP) in RO runoff versus water-soluble soil P (r² = 0.90).
• Total P in RO runoff showed no relation to soil P, and weak correlation for RO/Tap water.

Conclusions:

• Water source and soil surface conditions exhibited minimal influence on P runoff from the studied calcareous soil.
• The findings suggest that for calcareous soils, factors other than irrigation water source and surface conditions may be more dominant in controlling P runoff.
• Further research may be needed to explore other soil properties or management practices affecting P transport in such environments.