FIG. 1.

Effects of plant species and plant age on the number of culturable bacteria (A) and dehydrogenase activity (B) in soil sampled from the rhizosphere of L. perenne (▴) or T. pratense (▪) or in nonplanted controls (•). Soils were fertilized on days 87 and 106 with NH₄NO₃ and KH₂PO₄ to give 35 μg of N g⁻¹, 25 μg of P g⁻¹, and 30 μg of K g⁻¹. Open symbols, fertilized treatments. Error bars, standard errors.