Abstract: 【Objective】To investigate the improvement effects of single or combined application of corn straw biochar and electrolytic manganese industrial residues（ammonium magnesium manganese sulfate,electrolytic manganese residue and its arsenic-removed product）on saline-alkali soil,and to provide a reference for the resource utilization of such industrial residues.【Methods】The typical moderately alkaline soil from the Yinbei Plain in Ningxia was selected and the soil incubation and leaching experiments were conducted. The following treatments were set up：1% corn straw biochar（BC）,0.1% ammonium magnesium manganese sulfate（AMS）,1% electrolytic manganese residue（EMR）,1% arsenic-removed electrolytic manganese residue（EMRQ）,1% corn straw biochar+0.1% ammonium magnesium manganese sulfate（SBC）,1% ammonium magnesium manganese sulfate co-pyrolyzed biochar（SBCG）,1% corn straw biochar+1% electrolytic manganese residue（EBC）,and 1% corn straw biochar+1% arsenic-removed electrolytic manganese residue（EBCQ）,with no amendment treatment as the control（CK）. The effects of each treatment on soil pH value,sodium adsorption ratio,exchangeable sodium percentage,organic matter content,available nutrient contents and the leaching dynamics of base cations were analyzed.【Results】The AMS treatment exhibited the most obvious effect on reducing soil pH value,with a decrease of 5.0% compared with CK;the sodium adsorption ratio of each treatment was significantly lower than that of CK（P<0.05）,with the EMR treatment and AMS treatment showing reductions of 67.7% and 65.3%,respectively;the exchangeable sodium percentage of the BC treatment was the lowest,with a decrease of 55.0% compared with CK. The BC,SBCG,SBC,EBC and EBCQ treatments significantly increased soil organic matter content（P<0.05）,with increases ranging from 69.1% to 125.2% compared with CK. In terms of available nutrients,the EBCQ treatment exhibited the highest available phosphorus content,which increased by 35.4% compared with CK;the BC,SBCG,SBC and EBCQ treatments significantly increased the content of available potassium（P<0.05）,with increases ranging from 61.3% to 109.7% compared with CK;all treatments significantly increased the content of alkali-hydrolyzable nitrogen（P<0.05）,with the EBCQ treatment showing an 11.4% increase compared with CK. The leaching experiment showed that the concentrations of leached cations of the EBCQ treatment significantly increased,with Ca²⁺ and Mg²⁺ concentrations being higher than those of CK by 1 756.4% and 1 247.3%,respectively.【Conclusions】The combined application of biochar and electrolytic manganese industrial residues can effectively improve the nutrients of saline-alkali soil and regulate the composition of base cations. The comprehensive effects of 1% corn straw biochar+1% arsenic-removed electrolytic manganese residue treatment is the best.

Key words: Saline-alkali soil improvement, Biochar, Electrolytic manganese residue, Ammonium magnesium manganese sulfate