| Autor: |
Wolfgang Zech, M. Tchienkoua |
| Rok vydání: |
2003 |
| Předmět: |
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| Zdroj: |
Agriculture, Ecosystems & Environment. 100:193-200 |
| ISSN: |
0167-8809 |
| DOI: |
10.1016/s0167-8809(03)00195-6 |
| Popis: |
Phosphorus (P) is one of the main limiting plant nutrients in most tropical soils. Acquiring quantitative information on soil P status is essential for evaluating its sustainable management in agroecosystems. The objective of this study was to evaluate how land-use shifts from semi-permanent food crop systems (CF) to plantations of tea (Camellia sinensis) (TP) and Eucalyptus grandis (EP) impact on both organic and inorganic P species. Determination of phosphorus status combined a P sequential fractionation procedure and 31 P nuclear magnetic resonance (NMR) spectroscopy. Sequentially extracted pools included available P by 0.5 M NaHCO3, Al/Fe-P by 0.1 M NaOH, Ca-P by 0.5 M HCl and residual P by 0.5 M H2SO4 after ignition at 550 °C. Soil total P (STP) varied significantly across land uses (P 31 P NMR revealed that 88–89% of P compounds in NaOH extract were organic with monoester-P accounting for 59.1–60.8%. This was followed by diester-P (9.8–12.4%), teochoic acid (8.4–10.1%), orthophosphate (8.8–9.7%), unknown compounds (7.4–8.4%), pyrophosphate (1.1–4.6%) and phosphonate (0–1.3%). EP had higher diester-P and no phosphonate compound whereas CF had substantial amount of pyrophosphate (4.6%) and less orthophosphate and teochoic acid. These results indicate that these last P compounds are easily mineralizable P forms participating actively in plant P nutrition. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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