Fig. 6 Percentages (%) of the net soil nutrient storage, total N, P and K surplus and total N, P and K crop uptake out of total N, P, K input during the past 25 years in Wugong and Meixian counties. Note: 0-2 m nitrate means nitrate accumulated in the 0-2 m soil layers; 2-5 m nitrate means nitrate accumulated in the 2-5 m soil layers; Other N means N losses through NH3, N2 and N2O emissions and into deep soil profiles and groundwater.