Fig. 5. The relationship between denitrification rate (DR) and water filled pore space (WFPS) in no-tillage irrigated maize during 1996–1997 and 1998–1999 growing seasons. Full and empty symbols correspond to fertilization at planting (P) and at the six leaf stage V6, respectively. 0–N is the control; 70 and 210 eqauls kg N ha^-1.