tional crop cultivation. The application of manure and
fertilizer may increase SOC sinks (Wu et al., 2004; Xu
et al., 2006), sustain soil quality, and sequester carbon.
In the study area, corn roots are often returned to the
field, but little of the straws. Straws are mostly used as
fuel, and some are burned in-situ, and some of them are
used as forage for livestock and finally returned to the
field. The corn-straw-return-field practice is strongly
recommended to increase soil quality and carbon stock.
As for the orchard and vegetable field, manure applications
should be encouraged, while chemical fertilizers
should be used restrictively to reduce the risk of potential
non-point source pollution. At the same time, the
intense tillage in vegetable field should be reduced by
adopting more conservation tillage practices (Cambardella
et al., 2004; Al-Kaisi et al., 2005)