The effects of NH 4 + −N, NO 3 − ‐N or urea‐N addition on N uptake by perennial ryegrass ( Lolium perenne ), 15 N recovery and pH of four limed and unlimed soils were determined in a pot experiment over 10 weeks. The best form of N in terms of herbage N uptake and fertilizer recovery differed between the soils. Recovery of applied 15 N in herbage was greatest for the soil with the lowest pH and highest organic matter content, and overall recovery in the soil–plant system was influenced more by soil type than by N form. There was always an apparent mineralization of soil N when perennial ryegrass was present. Soil pH changes ranged from +0·11 to −0·58 units for the unlimed soils and from +0·03 to −1·06 units for the limed soils. The use of NO 3 − ‐N rather than NH 4 + ‐N or urea‐N avoided further acidification. Lime increased herbage N only from the soils with the lowest pH values. Although the acidifying effect of NH 4 + ‐fertilizer was alleviated, liming may increase nitrification and possibly N loss via denitrification and/or leaching in the field. The major influence of soil type on herbage N uptake, pH response to the treatments and fertilizer recoveries implies that liming and fertilizer N management decisions should consider soil characteristics, such as organic matter, clay contents and pH.