was significantly higher in locations where annual K application was 300 kg ha−1 K2O, which were also the areas that had a wheat/maize rotation; however, the annual K budgets and balance indexes of K were not well correlated with annual K application (Table 5). Annual K absorption by crops averaged 99.0 kg ha−1 in the northeast region, 181.2 kg ha−1 in the north-central region, and 220.9 kg ha−1 in the northwest region. The northwest region the highest regional annual K deficit (−67.7 kg ha−1 K2O), followed by the north-central region (−41.4 kg ha−1 K2O), followed by the northeast region (−31.4 kg ha−1 K2O). Potassium balance index ranged from 0.59 in Changji to 1.00 in Linfen.