A long term experiment was conducted to investigate the impact of different tillage and fertilization on the N mineralization
potential of soils in
rice based cropping system. The results showed that the nitrogen release potential in both of tilled and no tilled soils at the depth of 0 to 5cm was relatively lasting. The nitrogen release potential of tilled soils at the depth of 5 to 15cm revealed greater than no tilled soils. Fallowed soils at the depth of 0 to 5cm had remarkable higher No and N mineralized in short period (N m) in no tilled soils (NT) than tilled soils (CT). But no evident differences of No and N m in soils at the depth of 5 to 15cm and 15 to 30cm between these two tillage methods were found . There was a trend that No and N m in soils of treatments CF (only chemical fertilizer),PM (pig manure +chemical fertilizer) and CS (crop straw+chemical fertilizer) were higher under NT than under CT. No and N m in no tilled soils at the depth of 15 to 30cm were greater than tilled soils. While the No and N m between no tilled and tilled soils at the depth of 15 to 30cm did not differ significantly. N uptake by 25 crops in PM and CS treatments under NT was almost the same as that under CT, but in CK (no fertilizer) and CF treatments N uptake for NT was less than for CT. Under no tillage system, No and N m in soils with combined fertilization (PM and CS) kept higher than CF and CK treatments while CK treatment was the lowest one, however, under fallow condition, No and N m in soils normally showed very high;under tilled system , No and N m for PM and CS were the highest among the all fertilization treatments. These differences mainly existed in the soils of the depth of 0 to 5cm.