Influence of conservation tillage practices on soil properties and crop yields for maize and wheat cultivation in Beijing, China

Conservation tillage is becoming increasingly attractive to farmers because it involves lower production costs than does conventional tillage. The long-term effects of sub-soiling tillage (ST), no tillage (NT), and conventional tillage (CT) on soil properties and crop yields were investigated over an 8-year period (2000-07). The study was conducted in a 2-crop-a-year region (Daxing) and a 1-crop-a-year region (Changping) of the Beijing area in China. At 0-0.30 m soil depth, water stability of macro-aggregates (> 0.25 mm) was much greater for ST (22.1%) and NT (12.0%) than for CT in Daxing, and the improvements in Changping were 18.9% and 9.5%, respectively. ST and NT significantly (P < 0.05) improved aeration porosity by 14.5% and 10.6%, respectively, at Daxing and by 17.0% and 8.6% at Changping compared with CT treatment. Soil bulk density after 8 years was 0.8-1.5% lower in ST and NT treatments than in CT at both sites. Soil organic matter and available N and P followed the same order ST approximate to NT > CT at both sites. Consequently, crop yields in ST and NT plots were higher than in CT plots due to improved soil physical and chemical properties. Within the conservation tillage treatments, despite similar economic benefit, the effects on crop yields for ST were better than for NT. Mean (2000-07) crop yields for ST were 0.2% and 1.5% higher than for NT at Daxing and Changping, respectively. We therefore conclude that ST is the most suitable conservation tillage practice for annual 2-crop-a-year and 1-crop-a-year regions in the Beijing area.