Abstract:
To investigate the effects of different tillage modes on the structural stability, the degree of alkalization and maize yield, a 2-year field experiment of different tillage methods combined with straw returning was carried out in West Liaohe Plain. Five treatments were set up in the experiment, namely conventional tillage (CK treatment), deep turning tillage (DT treatment), powder ridge tillage (ST treatment), deep turning-straw returning tillage (DST treatment), and powder ridge-straw returning tillage (SST treatment). The experimental results showed that compared with CK treatment, other tillage treatments significantly increased the soil macro-aggregate content (
R0.25) by 75.9%-334.7%, and significantly decreased the soil micro-aggregate content (< 0.25 mm) by 6.1%-24.8% (
P < 0.05). The change in aggregate composition effectively improved the stability of the soil structure in soda saline soils, making the soil more conducive to root growth and water-air circulation. Regarding the average mass diameter (MWD) of soil water-stable aggregates, it was determined that the value in the tillage layer (0-20 cm) was higher than that in the maize root layer (20-40 cm) and the subsoil layer (40-60 cm). Compared with CK treatment, MWD of soil water-stable aggregates with DST treatment was the largest in the tillage layer, which increased by 85.1%. The MWD with SST treatment was the highest in maize root layer, which increased by 104.7%. The MWD with SST treatment was the largest in the subsoil layer, which was significantly higher than that treated with other treatments by 10.4%-48.9% (
P < 0.05). The soil sodium adsorption ratio (
SAR), a crucial indicator of soil alkalization, increased with increasing soil depth. Following maize harvest, the soil
SAR of CK treatment was not significantly different from the background value (
P > 0.05), suggesting a high risk of soil alkalization under conventional tillage. However, the
SAR of the other treatments decreased by 0.4%-10.3%, which could alleviate soil sodicity to some extent. Among these, the SST and DST treatments were more effective, suggesting that the combination of tillage and straw return could play a role in reducing soil alkalinity. Compared with CK treatment, the average maize yield of these four treatments (DT, ST, DST, and SST treatment) for 2 years increased by 37.8%-65.7% and water use efficiency (WUE) increased by 46.7%-91.7% (
P < 0.05) , and DST treatment had the best effect. This showed the possibility for water-saving agriculture in soda-saline-alkaline regions in addition to demonstrating the beneficial effects of various tillage patterns on maize yield. The correlations between different components were further illustrated using correlation analysis. MWD in the rhizosphere and
R0.25 in the tillage layer had a substantial and positive correlation with maize yield (
P < 0.05), suggesting that high-yield maize production benefits from well-structured soil in these regions. In the 10-20 cm soil layer, it was also strongly and negatively linked with SAR (
P < 0.05), indicating that high soil alkalinity in this layer may prevent maize from growing. In the tillage layer, WUE had a substantial and positive correlation with
R0.25 and MWD (
P < 0.05), while in the rhizosphere, it had a significant and negative correlation with SAR (
P < 0.05). In conclusion, a thorough examination of the experimental data suggested that the deep turning-straw returning tillage was the suitable cultivation mode for soda saline-alkali land. In the soda-saline-alkaline soils of West Liaohe Plain, the deep turning-straw returning tillage could help stabilize the soil structure and guarantee high yield and high-efficiency maize production. It offered a scientific foundation for the long-term growth of agriculture in comparable regions.