If the combination of straw interlayer and irrigation water reduction maintained sunflower yield by boosting soil fertility and improving bacterial community in arid and saline areas

Abstract

Limited water resources have severely restricted saline soil amelioration and utilization in the Hetao irrigated area, China. Burying straw interlayer is an effective management for salt-affected soil amelioration. However, little is known whether the straw interlayer could boost soil fertility and improve bacterial community, while reducing irrigation water consumption by 10% in the third and fourth years after application. Therefore, the legacy effect of the combination of straw interlayer and irrigation water reduction was investigated following the three treatments: (i) no straw interlayer plus 100% irrigation (CK); (ii) straw interlayer plus 100% irrigation (SI+W100), and (iii) straw interlayer plus 90% irrigation (SI+W90). SI+W90 significantly increased 0–40 cm soil organic carbon (SOC) content and soil SOC/TN (C/N) ratio than CK by 12% and 13%, respectively. In addition, SI+W90 significantly decreased 0–40 cm soil total nitrogen (TN) and SOC contents by 10% and 8% respectively, but significantly increased 0–40 cm soil C/N ratio by 9%, compared to SI+W100. Furthermore, SI+W100 and SI+W90 significantly increased the relative abundance of Proteobacteria, Bacteroidetes, and Nitrospirae than that of CK, while SI+W90 significantly decreased the relative abundance of Acidobacteria compared to SI+W100, and these bacterial phyla were significantly correlated with 0–40 cm SOC content. Notably, there was no significant correlation between crop yield and soil parameters in 2018 with the relatively low yield, while crop yield was significantly correlated with 0–20 cm SOC content and the relative abundance of Proteobacteria and Firmicutes in 2019 with relatively high yield. These results indicated that both soil fertility and certain bacterial phyla may contribute to yield variation. Therefore, SI+W90 maintained crop yield in the two years. In conclusion, the combination of straw interlayer and irrigation water reduction may be more recommended for agricultural sustainable development under the condition of limited irrigation water supply in the arid and salt-affected regions.