P,S,Mo
P,S,Co
P,Mo,Co
All of these
climate and occupation
soil and drainage
climate and natural vegetation
economic base and races
3, 1, 2, 4
1, 2, 3, 4
1, 2, 4, 3
1, 4, 2, 3
1000 m2
750 m2
500 m2
250-400 m2
Wheat
Paddy
Sugarcane
Maize