Evaluating phosphorus loss from a Florida spodosol as affected by phosphorus-source application methods

Area of Science:

• Soil Science
• Environmental Chemistry
• Agronomy

Background:

• Phosphorus (P) runoff is a significant environmental concern, with incorporation of P sources recommended to mitigate losses.
• Sandy soils with low P retention capacity are prone to P leaching, potentially diminishing the effectiveness of application methods.

Purpose of the Study:

• To investigate the impact of P source characteristics and application methods on P losses from sandy Spodosols.
• To compare P losses (soluble reactive P, total dissolved P, total P, bioavailable P) from surface-applied versus incorporated biosolids and inorganic fertilizer.

Main Methods:

• Simulated rainfall experiments were conducted on a Florida Spodosol (Immokalee fine sand).
• Six P sources (five biosolids, one fertilizer) were applied at 224 kg P ha⁻¹, either surface-applied or incorporated to 5 cm.
• Runoff and leachate were collected over three simulated rainfall events and analyzed for various P forms.

Main Results:

• Cumulative P losses (runoff + leachate) were similar regardless of whether P sources were surface-applied or incorporated.
• The solubility of the P source was the primary factor influencing P loss potential in these low P-sorbing soils.

Conclusions:

• For soils with low P retention, the P-source application method has minimal effect on total P loss.
• Focusing on the inherent solubility of P sources is more critical than application technique for minimizing P loss in such environments.