Reclamation on Organic Matter Content and Structural Properties in Steppe Soil of Northeast Songnen Plain

In view of the problem of reduction in soil aggregate stability by reclamation in the steppe of Northeast Songnen Plain,the organic matter content and soil structural properties of soil reclaimed for different years were studied.The results showed that compared with fencing for mowing,7 years' cultivation(Cult-7),15 years' cultivation(Cult-15),33 years' cultivation(Cult-33) significantly decreased(P0.05)soil organic matter content in 20 ~30 cm depth by 20.5%,40.0% and 55.7%,respectively,and mean weight diameter(MWD) by 22.9%,35.8% and 44.0%,respectively.Meanwhile,the reclamation significantly increased(P0.05)soil bulk density,and significantly decreased(P0.05)soil porosity.It was concluded that decrease in aggregate stability and porosity in soil and increase in soil bulk density were all related to reduction in soil organic matter content by cultivation.