东北松嫩草原土壤开垦对有机质含量及土壤结构的影响

针对我国东北松嫩草原开垦引起土壤团聚体稳定性不断下降问题,对不同开垦年限土壤有机质含量和土壤结构性质进行了研究.结果表明:在我国东北松嫩平原草原上,与围栏割草场相比,开垦天然草原种植7年、15年、33年玉米以后,0～30cm深度土壤有机质含量分别降低20.5%、40.0%和55.7%,土壤结构的平均重数直径分别降低了22.9%、35.8%和44.0%.同时随草原开垦年限的增加,土壤容重显著增加,土壤孔隙度显著降低.相关分析表明,在东北松嫩天然草原开垦的情况下,土壤结构的恶化与土壤有机质含量的降低密切相关.

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 dif- ferent years were studied. The results showed that compared with fencing for mowing, 7 years' cultivation (Cuh-7), 15 years' cultivation (Cult-15), 33 years" cultivation (Cult-33) significantly decreased(P<0.05) 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 signif- icantly increased(P<0. 05)soil bulk density, and significantly decreased(P<0.05)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.