The Research Of Reclamation Of Saline-Sodic Soil In Songnen Plain

Songnen Plain,which is an important area for agriculture and pasture,is also one of the three distribution area of saline-sodic soil in the world.Due to irrational reclamation in recent years,soil salinization and sodification in Songnen Plain have become more serious,which impede the sustainable development of ecomomy,society and ecology.In order to searching for effective measures of saline-sodic soil reclamation with low cost and wide application,Four studies were conducted,namely,vegetation restoration on bare sodic patch through laying cornstalks,ridge and furrow system(RFS)and raised bed and furrow system(RBFS),as well as reclamation dry land by sand mulching,respectively.We researched the effects of these methods.The study discovered:Laying cornstalks on bare sodic patches significantly promoted vegetation restoration,but there is no significant differences in vegetation restoration among different amount and laying directions of cornstalks.The composition of restored vegetation and trend of indicators for vegetation restoration among treatments varied among years.Soil water content(SWC)increased significantly from ridge to furrow in 0-10 cm in RFS.p H in 0-10 cm was lowest.On the ridge and slope,EC decreased with depth,however,EC increased with depth in the furrow.EC presented a decreasing trend from ridge to furrow.RFS can promote vegetation restoration on bare sodic patches to some extent,but differences of restoration effects were not significant among treatments.SWC on the top and slope of RBFS increased as depth increased,but that at the bottom and in the furrow decreased with depth.In general,SWC increased from top to furrow in 0-10 cm.On the top and upper slope,EC decreased as depth increased,but increased with depth at the bottom and in the furrow.Generally,EC significantly decreased from top to furrow,with the lowest EC appearing in H30.Salt accumulation generally occurred in RBFS.RBFS promoted vegetation restoration on bare sodic patches,with no significant differences occurring among indicators of restoration for different treatments.Vegetation restoration status of RBFS also showed high variability among years.Sand mulching significantly affected SWC.SWC increased with depth first,then decreased,with highest SWC appearing in boundary of sand and sodic soil.SWC decreased as thickness of sand increased in 0-20 cm.p H and EC were also significantly affected by sand mulching.p H and EC increased with depth,and p H and EC in sand layer were significantly lower compared with those in sodic soil layer.p H and EC in the same layer decreased with increasing sand thickness in 0-40 cm.Sand mulching also significantly promoted growth and yield of maize as well as sunflower.Generally speaking,most indicators reflecting growth and yield of maize and sunflower consistently increased as sand thickness increased,with more significant effect of sand mulching on maize compared with that on sunflower.Sand mulching imposed significant effect on the yield of alfalfa;however,sweet clover was not significantly affected by sand mulching.Sand mulching with a thickness of at least 20 cm was required for cultivating maize.The optimal sand thickness for cultivating alfalfa was 30 cm.