科研之友
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摘要
Soil acidification due to N supplied from fertilizer or aerial deposition in grasslands is well recognized and documented; however, little is known about its consequences on soil P availability. This question was addressed on a long-term field experiment done on grassland in Erce (Central Pyrenees, France), where plots were treated for 6 yr with a factorial combination of mineral N added as NH(4)NO(3) (0 and 190 kg ha(-1) yr(-1)) and P (0 and 50 kg ha(-1) yr(-1)) and managed with a frequent defoliation regime (3 cuts yr(-1)). Diffusive PO(4) ion dynamics at the soil-solution interface was determined by coupling sorption studies with (32)P labeling of PO(4) ions (Pi) and dilution analysis. Results showed that the soil pH did not change in zero-N treatments (5.9 +/- 0.1) in comparison with the initial soil (5.9 +/- 0.1), whereas it decreased to 5.3 +/- 0.1 on N-treated soils. Meanwhile the cation exchange capacity and exchangeable Ca(2+) and Mg(2+) contents decreased significantly and the saturation percentage of the adsorption complex by Al(3+) increased from 2 to 15; no changes were observed for untreated soils. Furthermore, the gross amount of diffusive Pi (Pr) was accurately described as a function of the concentration of PO(4) ions in the solution (Cp) and time (t) by a Freundlich kinetic equation; these dynamics were significantly modified by N supply but not by P.
- 出版日期2011-1
