Combined organic ameliorants is benefits for improving ecosystem multi-functionality in saline soils

Globally, soil salinity is among major challenge for agricultural production in arid and semi-arid regions. Although organic ameliorant has profound effects on saline soil quality, how soil quality index, crop productivity, and ecosystem multi-functionality respond to combined organic ameliorants remains unclear. Herein, a 3-year field experiment was conducted and included six treatments (no organic ameliorant, humic acid, biofertilizer, manure, combination of humic acid and manure, combination of biofertilizer and manure) organized into a randomized complete block design. In relative to other organic ameliorants, combination of humic acid and manure improved soil quality index by 29–74 % and sunflower yield by 7–34 % in 2020–2022, with soil quality indexes explained the variance of crop productivity by 67.86–81.35 %. The improved soil quality and yield further increased ecosystem multi-functionality, while the effects of soil quality on ecosystem multi-functionality was stronger than yield on ecosystem multi-functionality. Compared to other organic ameliorants, ecosystem multi-functionality under combination of humic acid and manure increased by 51–87 %. Besides, the effects of combined humic acid and manure on SQI and EMF were higher than the sum of that under humic acid and manure alone. In conclusion, the combined humic acid and manure was more beneficial to improve ecosystem multi-functionality by enhancing soil quality and crop production in saline soils, and contributed to agricultural production in arid and semi-arid regions.