Purpose <p>Losses of phosphorus (P) and carbon (C) from livestock farming impair downstream water quality, requiring a better understanding of their leaching processes. The aim of the study was to examine how leaching of P (total dissolved P – TDP; dissolved reactive P – DRP; dissolved organic P – DOP) and dissolved organic C (DOC) was affected by soil type, chemical property and amendment.</p> Methods <p>Leaching experiments with simulated rain were conducted on five different mineral and organic soils before and after a manure or mineral fertilizer application, respectively. The soils were: Fluvisol, Stagnosol, Umbrisol, Histosol (Ruptic), and Histosol. Profile-long soil columns were used, and chemistry of soil and water samples were studied.</p> Results <p>Before the P addition, the Histosol (Ruptic) soil with high P and organic matter contents but low sorption in the subsoil had significantly greatest flow-weighted mean concentrations (FWMCs) of TDP (315 versus 33‒48&#xa0;µg L<sup>‒1</sup>), DRP (215 versus 5‒26&#xa0;µg L<sup>‒1</sup>), DOP (101 versus 19‒33&#xa0;µg L<sup>‒1</sup>) and DOC (46 versus 8‒25 mg L<sup>‒1</sup>) in drainage water among all soils. Leaching of DOC varied more than TDP, DRP and DOP across most soils. The manure application significantly elevated FWMCs-TDP in three soils than before the application and led to greater FWMCs-TDP in all soils and FWMCs-DOC in most soils than mineral fertilizer did. The ratios of DRP to DOP and to TDP were significantly correlated to whole-profile degree of P saturation (DPS) of the soils (R<sup>2</sup> &gt; 0.9, <i>p</i> &lt; 0.05).</p> Conclusion <p>Sorption/desorption characteristics of subsoils greatly affected concentrations and loads of P and DOC in drainage, as well as the ratios of DRP to DOP and to TDP. Therefore, sorption/desorption characteristics and DPS of subsoils should be included in the work of assessing dissolved P and DOC leaching and developing nutrient mitigation measures.</p>

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Leaching of dissolved phosphorus and carbon and phosphorus fractionation in drainage: effects of soil type, chemical characteristics and amendments

  • Jian Liu,
  • Hilmar Tor Sævarsson,
  • Marianne Bechmann,
  • Tore Krogstad,
  • Tomas Persson,
  • Anne Falk Øgaard

摘要

Purpose

Losses of phosphorus (P) and carbon (C) from livestock farming impair downstream water quality, requiring a better understanding of their leaching processes. The aim of the study was to examine how leaching of P (total dissolved P – TDP; dissolved reactive P – DRP; dissolved organic P – DOP) and dissolved organic C (DOC) was affected by soil type, chemical property and amendment.

Methods

Leaching experiments with simulated rain were conducted on five different mineral and organic soils before and after a manure or mineral fertilizer application, respectively. The soils were: Fluvisol, Stagnosol, Umbrisol, Histosol (Ruptic), and Histosol. Profile-long soil columns were used, and chemistry of soil and water samples were studied.

Results

Before the P addition, the Histosol (Ruptic) soil with high P and organic matter contents but low sorption in the subsoil had significantly greatest flow-weighted mean concentrations (FWMCs) of TDP (315 versus 33‒48 µg L‒1), DRP (215 versus 5‒26 µg L‒1), DOP (101 versus 19‒33 µg L‒1) and DOC (46 versus 8‒25 mg L‒1) in drainage water among all soils. Leaching of DOC varied more than TDP, DRP and DOP across most soils. The manure application significantly elevated FWMCs-TDP in three soils than before the application and led to greater FWMCs-TDP in all soils and FWMCs-DOC in most soils than mineral fertilizer did. The ratios of DRP to DOP and to TDP were significantly correlated to whole-profile degree of P saturation (DPS) of the soils (R2 > 0.9, p < 0.05).

Conclusion

Sorption/desorption characteristics of subsoils greatly affected concentrations and loads of P and DOC in drainage, as well as the ratios of DRP to DOP and to TDP. Therefore, sorption/desorption characteristics and DPS of subsoils should be included in the work of assessing dissolved P and DOC leaching and developing nutrient mitigation measures.