Impact of Conservation Tillage on Some Soil Physical Properties and Soybean Yields(Glycine max L. Merrill)

The great challenge in north Songnen Plain,China is soil degradation and dry period and sandstorm attacking during soybean planting season.The objective of this work is to assess the effects of no-tillage and reduced tillage systems on soil temperature,soil water storage,soil compaction and its effects on soybean yields in a productive soil.The determinations were carried out in 2008.Notillage(NT) showed higher water storage than both reduced tillage(RT) and conventional tillage(CT) during the soybean planting season.Mean soil temperatures were lower under NT than under both RT and CT,and similar between RT and CT during the initial period.Thermal amplitude was lower under NT than under both RT and CT,and was similar between RT and CT during the first growing stage(June 4 to June 19).Bulk density was higher under NT than under CT at 5-20 cm depth,and no different between RT and NT at 10-20 cm soil depth.Penetration resistance performed differences between tillage systems,being higher under NT than under RT and CT at 0-20 cm depth.Grain yields showed no significant differences between tillage systems.Results suggested that application of NT/RT at local climatic and soil conditions could reduce soil water deficiency/sandstorm-attacking during soybean growing season without affecting soybean grain yields in short terms of conservation tillage.