Effect of straw retention and mineral fertilization on P speciation and P-transformation microorganisms in water- extractable colloids of a Vertisol
<p>Water-extractable colloids (WECs) serve as crucial micro-particulate components in soils, playing a vital role in the cycling and potential bioavailability of soil phosphorus (P). Yet, the underlying information regarding soil P species and P-transformation microorganisms at the micropartic...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-01-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/22/135/2025/bg-22-135-2025.pdf |
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| Summary: | <p>Water-extractable colloids (WECs) serve as crucial micro-particulate components in soils, playing a vital role in the cycling and potential bioavailability of soil phosphorus (P). Yet, the underlying information regarding soil P species and P-transformation microorganisms at the microparticle scale under long-term straw retention and mineral fertilization is barely known. Here, a fixed field experiment (<span class="inline-formula">∼</span> 13 years) in a Vertisol was performed to explore the impacts of straw retention and mineral fertilization on inorganic P, organic P, and P-transformation microorganisms in bulk soils and WECs through a sequential extraction procedure, P K-edge X-ray absorption near-edge structure (XANES), <span class="inline-formula"><sup>31</sup></span>P nuclear magnetic resonance (NMR), and metagenomics analysis. In bulk soil, mineral fertilization led to increases in the levels of total P, available P, acid phosphatase (ACP), high-activity inorganic P fractions (Ca<span class="inline-formula"><sub>2</sub></span>-P, Ca<span class="inline-formula"><sub>8</sub></span>-P, Al-P, and Fe-P), and organic P (orthophosphate monoesters and orthophosphate diesters) but significantly decreased the abundances of P-cycling genes including P mineralization, P-starvation response regulation, and P uptake and transport by decreasing soil pH and increasing total P. Straw retention had no significant effects on P species and P-transformation microorganisms in bulk soils but led to increases in organic carbon, total P, and available P concentrations in WECs. Furthermore, compared with mineral fertilization, straw retention caused significantly greater differences in the relative abundances of P-cycling genes between WECs and bulk soils. The abundances of <i>phoD</i> gene and <i>phoD</i>-harboring Proteobacteria in WECs increased significantly under straw retention, suggesting that the P-mineralizing capacity increased. Thus, mineral fertilization reduced microbial P-solubilizing and mineralizing capacity in bulk soil. Straw retention could potentially accelerate the turnover, mobility, and availability of P by increasing the nutrient contents and P-mineralizing capacity at the microscopic colloidal scale.</p> |
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| ISSN: | 1726-4170 1726-4189 |