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- Vestergren, Johan, 1968-, et al.
(författare)
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Effect of Trees on Forms of Soil Phosphorus in an Agroforestry Parkland in Burkina Faso
- 2014
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Phosphorus is commonly a limiting nutrient for crop production, especially in highly weathered tropical soils. In two semi-arid areas in Burkina Faso with high and low aluminum and iron content respectively, we studied the effect of scattered trees within cropping fields (an agroforestry system called “parklands”) on soils from two areas with high and low aluminum and iron content, respectively. The study focused on different P forms using liquid-state 31P NMR, and their relation to soil chemical properties, determined by XRF. We hypothesized that i) There is generally a difference in P forms between under canopies and in openings outside canopies due to higher input and turnover of organic material close to trees; ii) Close to trees there are more P forms of microbial origin due to the increased activity of the microbial community; iii) This difference is more pronounced in the area with higher content of aluminum and iron. We took topsoil samples under tree canopies as well as outside tree canopies. Our results showed that there were generally low levels of organic carbon and P, but under the canopies of the scattered trees the levels were higher. 31P-NMR showed that soil P was composed of similar ratios of inorganic and organic P as has been observed in other ecosystems, and that the organic P pool was composed of P species commonly observed in soils. NMR also revealed that areas outside the canopies had a less diverse P composition. In the area with high Al/Fe content, microbial activity under trees had a more pronounced effect on the soil P composition, by significantly increasing the amounts of P species of biological origin. In conclusion, the study confirmed the importance of soil organic matter and trees for P availability in semi-arid tropical ecosystems.
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