The effect of surface liming on herbage production in permanent grasslands is rather uncertain. To better understand the effect of liming on the grassland, a study was made with a field experiment and a pot experiment with soil from the same field. In the field, the effects of liming and NPK fertilization on the production and composition of the vegetation were studied. In pots, the effects of liming and phosphate fertilization on different grass species were analysed. The effect of NPK fertilization (+3AE96 t ha )1 ) on the production of the original grassland was greater than that of liming (+0AE68 t ha )1 ), which was only observed (P < 0AE05) on the unfertilized plots. Liming increased the total number of species and the proportion of dicotyledons. After replacing the semi-natural community with Dactylis glomerata L., the effects of liming (+2AE37 t ha )1 ) and fertilization (+6AE52 t ha )1 ) were increased. These results, together with those of the pot trial, show the important role of phosphorus in the fertilization effect, and are interpreted as a protective effect of P against aluminium toxicity.

The Al resistance of the C-S-R species was variable and independent of their traits. S-type species, adapted to acid soils and with traits of conservative strategy, displayed Al resistance. The large difference in Al resistance between grasses may help assess Al soil toxicity by using the abundance of grasses.

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