Microbial inoculants improve growth and yield of spring maize in saline-alkali soil

【Background and Objective】 Saline-alkali soil is characterized by excessive salt and alkali content, poor physical and chemical properties. Efficient utilization, improvement and development of saline-alkali soil resources is important for food security. Microbial amendments are a green and efficient method for improving saline-alkali soil. This study is to explore the efficiency of microbial inoculants in improving the properties and productivity of saline-alkali soils. 【Method】 Salt-tolerance critical contents in different growing stages of spring corn in the saline-alkali soils were obtained first in 2022 before soil amendment. In 2023, the saline-alkali soil was amended by building drainage ditch, organic fertilization and drip irrigation. The soils were further amended by microbial inoculants applied in different ways: i) applying 600 kg/hm2 of solid microbial amendments as base, ii) applying 300 kg/hm2 of solid microbial amendment as base coupled with applying 75 L/hm2 of liquid microbial inoculants at the jointing stage and the heading stage, respectively, iii) applying 300 kg/hm2 of basal solid microbial amendment coupled with applying 75 L/hm2 of liquid microbial inoculant dynamically based on the critical salt tolerance contents measured in 2022. The control was soil without microbial amendment. 【Result】 The salt tolerance critical content at the seedling stage, jointing stage, heading stage and filling stage were 1.77, 2.28, 5.07 g/kg and 5.27 g/kg, respectively. Compared to 2022, amending the soil in 2023 increased seedling emergence rate by 34.4% to 70.1%, and grain yield by 4.20 t/hm2 to 8.62 t/hm2. Compared to the control, microbial amendment increased plant height, leaf area index, above-ground dry matter mass and relative chlorophyll content of the leaves by 9.9%-17.1%, 38.4%-56.1%, 26.7%-32.0% and 9.2%-11.2%, respectively, and grain yield by 30.6%-36.0%. Dynamically applying microbial amendment based on soil salt content significantly increased the seedling emergence rate, growth index and grain yield. 【Conclusion】 Our results show that combining drainage ditches, organic fertilization and microbial amendments can substantially improve productivity of the saline-alkali soil for spring corn. Specifically, applying 300 kg/hm2 of solid amendments as base coupled with dynamically applying 150 L/hm2 of liquid microbial inoculants based on salt tolerance critical content was most effective to improve productivity of the soil.