Table 5. Treatments of the field experiment.

Treatment	Nitrogen management	Straw management
N0	Zero N application	Wheat and maize straw removing
N0+S	Zero N application	Wheat straw mulching and maize straw returning
Nopt	Improved Nmin test	Wheat and maize straw removing
Nopt+S	Improved Nmin test	Wheat straw mulching and maize straw returning
Ncon	Conventional farming practice	Wheat and maize straw removing
Ncon+S	Conventional farming practice	Wheat straw mulching and maize straw returning
Mbal+S	Composted cattle manure with chemical fertilizer N based on N balance calculation	Wheat straw mulching and maize straw returning
Wbal+S	Composted municipal waste with chemical fertilizer N based on N balance calculation	Wheat straw mulching and maize straw returning