Fig. 3From: Biological and synthetic approaches to inhibiting nitrification in non-tilled Mediterranean soilsDetermination of δ15N (a) and nitrogen content (b) in sorghum leaves. Control = sorghum without fertilization; AS = sorghum fertilized with ammonium sulfate; AS + D = sorghum fertilized with ammonium sulfate + DMPP. Different letters indicate significant differences using the Duncan test (p < 0.05; n = 4)Back to article page