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Background and Aims <p>Historical manure applications on the Delmarva Peninsula created legacy soil phosphorus (P) accumulation, yet winter wheat (<i>Triticum aestivum</i> L.) often faces early-season P deficiency due to fixation in acidic soils. This study evaluated whether reactive silica (Si) amendments mobilize legacy P across three scales: laboratory chemical desorption, in-field pot plant uptake, and field trial yield.</p> Methods <p>A tiered approach used three legacy P soils. A 154-day incubation screened the desorption potential of silicic acid, Ca-Mg silicate slag, and switchgrass char. An in-field pot study isolated Si effects from liming effects using pH-balanced applications of silicic acid, silica gel, and slag. Finally, a field trial compared Ca-Mg silicate slag against standard lime and starter P practices.</p> Results <p>In the incubation, silicic acid and slag chemically mobilized P, while switchgrass char reduced water extractable P (WEP). In the pot study, reactive Si increased soil WEP by up to 70% and nearly doubled tissue Si, but did not enhance biomass or P uptake. Similarly, slag applied in-field did not alter soil P availability, though it significantly increased grain yield compared to standard management (8.25 vs. 7.58&#xa0;Mg&#xa0;ha<sup>−1</sup>).</p> Conclusion <p>We hypothesize that pH-induced secondary Ca-P precipitation overrode Si-driven P mobilization. Furthermore, because yield improved without altering P nutrition, we hypothesize this field benefit was driven by Si-mediated stress resilience. Ultimately, while reactive silica chemically mobilizes legacy P, it cannot reliably replace starter P fertilizers. Heavy metal testing is recommended before applying slag in forage systems.</p>

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Legacy phosphorus mobilization by reactive silica amendments: from laboratory mechanisms to agronomic effectiveness in winter wheat

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月23日

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  • Zhixuan Qin,
  • Sapana Pokhrel,
  • Angelia L. Seyfferth,
  • Lauren R. Mosesso,
  • Amy L. Shober

摘要

Background and Aims

Historical manure applications on the Delmarva Peninsula created legacy soil phosphorus (P) accumulation, yet winter wheat (Triticum aestivum L.) often faces early-season P deficiency due to fixation in acidic soils. This study evaluated whether reactive silica (Si) amendments mobilize legacy P across three scales: laboratory chemical desorption, in-field pot plant uptake, and field trial yield.

Methods

A tiered approach used three legacy P soils. A 154-day incubation screened the desorption potential of silicic acid, Ca-Mg silicate slag, and switchgrass char. An in-field pot study isolated Si effects from liming effects using pH-balanced applications of silicic acid, silica gel, and slag. Finally, a field trial compared Ca-Mg silicate slag against standard lime and starter P practices.

Results

In the incubation, silicic acid and slag chemically mobilized P, while switchgrass char reduced water extractable P (WEP). In the pot study, reactive Si increased soil WEP by up to 70% and nearly doubled tissue Si, but did not enhance biomass or P uptake. Similarly, slag applied in-field did not alter soil P availability, though it significantly increased grain yield compared to standard management (8.25 vs. 7.58 Mg ha−1).

Conclusion

We hypothesize that pH-induced secondary Ca-P precipitation overrode Si-driven P mobilization. Furthermore, because yield improved without altering P nutrition, we hypothesize this field benefit was driven by Si-mediated stress resilience. Ultimately, while reactive silica chemically mobilizes legacy P, it cannot reliably replace starter P fertilizers. Heavy metal testing is recommended before applying slag in forage systems.