Table 1. Concentrations of inorganic, amino acid and peptide N in the soil solution of a UK agricultural soil^a.

	N concentration (µmol N l−1)
Total dissolved N	844±30
Total dissolved N <1 kDa	746±46
Peptidic-N <1 kDa	31±2
Free amino acid N	4±0.9
NH4 +	16±4
NO3 -	655±38

^aValues are mean ± SEM; n = 4.