Combination of Organic Ameliorants is More Benefits for Improving Ecosystem Multi-Functionality by Enhancing Soil Health and Crop Productivity in Saline Soils

Abstract

Globally, soil salinity is among major threats to agricultural production in arid and semiarid regions. Although organic ameliorants have profound impacts on saline soil health, how soil quality index (SQI), crop productivity, and related ecosystem multi-functionality (EMF) respond to the combination of organic ameliorants remains unclear. Herein, we conducted a 3-year field experiment to investigate the impact of different combinations of organic ameliorants (manure, biofertilizer, and humic acid fertilizer) on sunflower yield and multiple soil attributes associated with soil health, including biophysical properties and enzyme activities. Organic ameliorants increased soil quality by 9-58% in year 2022, which was due to the reduced soil EC (electric conductivity) and increased soil fertility (available nutrients and SOC) as well as enzyme activities. This was confirmed by the Random Forest which indicated that SOC, available nutrients, and C acquisition enzyme (C-acq) were the major factors influenced SQI. The improved saline soil health conditions further increased sunflower yield by 20-40% under the addition of humic acid fertilizer and manure in 2020-2022. Soil biochemical properties explained the variance of crop productivity by 67.86-81.35%. Interestingly, the combination of humic acid fertilizer and manure was favorable for crop growth indices, including yield. Furthermore, the improvement of SQI and yield increased EMF, while the effects of SQI on EMF was stronger than yield on EMF. Compared to control, EMF under the combination of humic acid fertilizer and manure was increased by 131%. In summary, we provide experimental evidence to support that the combined use of humic acid fertilizer and manure management can help maintain saline soil health, crop production, and ecosystem functions.

Keywords: Saline soil, Soil health, Crop productivity, Ecosystem multi-functionality, Manure, humic acid fertilizer and biofertilizer