Mean total N input, offtake and N balance (kg ha⁻¹ year⁻¹), apparent N recovery (%) and estimated relative fertiliser N equivalence (FNE) for slurry N efficiency, for plots of hybrid ryegrass treated with inorganic N or slurry from lambs offered different silages, (N = 4).

a,bDifferent superscript letters denote significant differences between means (P<0.05). #relates to means for slurry treatments only (1)Sum of inorganic N, slurry N plus atmospheric N deposition at a rate of 25 kg ha−1 year−1[52]. (2)The N balance was calculated by subtracting offtakes, summed over the entire period (five cuts) from total N input [53]. (3, 4)Apparent N recovery (ANR) was calculated for each plot within each replicate block according to the method of Kanneganti et al., [18] as N offtake relative to 0N (3) or 100N (4), expressed as a percentage of the difference in total N applied. ANR = ((NTRT-NCON)/NTOT)*100 where NTRT is N offtake, NCON is N offtake from control and NTOT is total N applied, all measured in kg ha−1 yr−1. (5)Estimated by reverse interpolation assuming a quadratic diminishing response in DM yield across the three inorganic N treatments (including 0 N treatment).