Seasonal No-Tillage Ridge Cropping System (SNTRCS)significantly ameliorated soil structure, especially improving the soil
structure in sub-surface soils (15-35cm). Compared to the controls, SNTRCS of increasing soil aggregation including water-stable structure aggregates in top soils (0-15cm)and sub-surface soils (15-35cm).The characters of organo-inorganic complex also indicated the SNTRCS
increased complex quantity by 45. 0% ,complex degree by 3. 6% within 15-35cm soil layers compared to the controls. According to successive measurements of soil bulk density within ridges for 10a (1985-1991),the soil bulk density within sub-surface layers (15-35cm) deceased and has remained less than 1. 3g/cm3 for l0a.An analysis of micromorphology on soils under SNTRCS management showed that the aeration porosity of 1. 0-0, 2mm was increased 7. 1%-21. 2% in surface layers (0-15cm) and 11. 8%-16. 2% in sub-surface layers (15-35cm) compared to the controls.According to measurements of soil nitrogen, organic matter, soil enzyme activities and microbes,SNTRCS significantly increased soil N nutrition and biological activities in sub-surface layer (15-35cm) and sub-soil layer ( 35-50cm ), but little differences in top layers (0-15cm). Total N,organic matter,total microbes,aerobic fiber-decomposing bacteria,urease activity, alkaline phosphatase, invertase were increased by 20%-80% or more in the subsurface layer and sub-soil layer. This improvement of the nutrition status in the sub-surface layers and sub-soils is significant for crop growth during it' s reprodutive period.On the basis of mentioned above,
sub-surface layers amelioration is a very important function in SNTRCS.