Topsoil properties as affected by tillage practices in North China

A study was conducted in the North China Plain during the summer maize growth season 1997, using field and laboratory measurement techniques, in order to evaluate the impacts of different tillage practices (conventional tillage (CT), no-tillage (NT) and subsoiling tillage(ST)) on the top soil physical and hydraulic properties. ST caused an important reduction in bulk density in the top 40 cm of the soil profile, a significant increase of the volume of the larger pores (>50 μm diameter) and a significant decrease of the volume of the smaller pores (<10 μm diameter). This resulted in an improvement of water transmission at high water content and in a decrease of water retention capacity at low water content. Water infiltration into the subsoiled soil was improved owing to greater macroporosity. Small differences were observed between CT and NT practices. Changes of topsoil properties induced by tillage practices were found to be subject to significant temporal variations, particularly for bulk density, infiltrability and field saturated hydraulic conductivity.