Effects of rotational tillage on soil properties and water use efficiency in a wheat-maize cropping system on north china plain

Many studies have found excessive soil tillage is one of the most important indicators of soil degradation. Soil tillage pattern determines the soil physical properties and crop growth. No-till coupled with subsoiling has been widely accepted. Although it could alleviate soil compaction, it can't solve the problem of soil organic matter concentration on the topsoil after long-time no-till. Hence, from 2011 to 2016, a field experiment was carried out in Pingdu County, Qingdao City, Shandong Province, China. The treatment included three different tillage practices: no-till (NT) with straw cover each year; rotational tillage (RT), deep plow tillage in the first year, followed by two years no-till, and deep plow tillage in the fourth year, crop straw mulching each year; deep plow tillage (DPT), deep plow tillage with straw remove each year. Variables of soil bulk density, soil water stable aggregates, soil organic matter and soil water use efficiency were measured. The results showed that a 0~30 cm mean soil bulk densities under DPT and RT treatments were significantly decreased by 8.5% and 10.1% respectively, compared to NT treatment; while soil bulk densities under DPT and RT treatments increased by 1.8%, 2.4% at 30~40 cm soil layer. The NT and RT treatments increased the soil water stable macro-aggregate at 0~40 cm soil layer, compared to DPT treatment, and increased by 31.8% and 31.5%, respectively. At 0~40 cm, the mean SOM, under RT and NT, increased by 55.0% and 53.3% in 2013, and increased by 119.4% and 114.8% in 2016 respectively, compared to DPT treatment. The average yield of winter wheat treated with NT and RT increased by 2.2%, 24.2%respectively, while WUE increased by 11.3%, 13.4%, compared to DPT treatment during 2011~2016. Average yield of summer maize increased by 4.25%, 7.6% respectively, while WUE increased by 3.7%, 5.6%, compared to DPT treatment in 2011~2016. The result showed that rotational tillage is a good method to resolve the problems of long-time no tillage, and further research is required to reveal the deep tillage interval under conservation tillage, with the aim of developing the most appropriate rotational tillage system. © 2019, Asian Association for Agricultural Engineering. All rights reserved.