Study On The Improvement Effect Of Acidified Biochar Combined With Saponified Slag On Soda Alkaline Soil

Soil degradation caused by land salinization seriously affects the quality of cultivated land and crop production.Traditional improvement methods mainly include desulphurizing gypsum and other Ca modifiers,replacement of Na combined with soil colloid,and leaching to remove Na ions in surface layer.However,nowadays,the waste saponified residue from the production of epoxy propane by chemical plants need to occupy a large amount of land resources,and the accumulation of waste residue is also easy to cause environmental pollution.But high Ca content in saponification slag is a kind of material,so this test is to soda solonetz of songnen plain as the research object,by biochar and acidification biochar under the premise as main ingredients,match with saponification slag instead of desulfurization gypsum,with the method of indoor culture and soil column leaching,research with the effects of acidizing biochar and saponification residue on the composition of main basic cation,salt leaching and soil physical and chemical properties of soda solonetz,to explore the feasibility of saponification residue in soda solonetz improvement.The main research results are as follows:(1)Biochar addition is beneficial to improve soil fertility and reduce the content of Na in soil,and the higher the amount of biochar added,the more obvious the effect will be.In the waterlogged culture experiment,when 4% biochar was added,the soil water-soluble Na salt content decreased by 7.92%compared with CK treatment.In the soil column leaching test,the leaching amount of Na salt in the 4%biochar added treatment was 13.98% lower than that in the CK treatment,indicating that Na was fixed by biochar.Acidification biochar contributes to the increase of soil alkali-hydrolyzed nitrogen content,and its adsorption effect is stronger than general biochar,and its adsorption of exchangeable Na in soil is also stronger.In the waterlogging test,the water-soluble Na salt content treated with 2% acidified carbon was23.08% lower than that treated with CK.(2)The combination of biochar and calcium carbide saponification residue can achieve better results.In the waterlogging test,the content of water-soluble Na with high additive amount(4% biochar +1.2%calcium carbide saponification residue)was 15.07% lower than that with low additive amount(1% biochar+0.3% calcium carbide saponification residue).Moreover,the treatment with high additive amount has a good effect on reducing the total alkalinity of soil.Among them,the total alkalinity of soil treated by4%+1.2% was 25% lower than that treated by CK.In the soil column leaching experiment,soil salt leaching was better under the treatment of low additive amount(2% biochar +0.6% calcium carbide saponification residue).(3)Acidified biochar and calcium carbide saponified residue have stronger adsorption capacity.The content of exchange sodium in soil decreased,and the decrease of total alkalinity of soil was the most obvious.In the flooding test,the total alkalinity of the treatment with high additive amount(4% acidified carbon +1.2% calcium carbide saponification residue)was 43.68% lower than that of the CK treatment.The content of Na in soil reached 2.98mg/g,and the content of water-soluble salt was also the lowest.In the soil column test,the leaching amount of Na ions was also significantly lower than that of CK treatment.(4)Acidified biochar and lime saponification residue have better synergic effect,and stable improvement effect.The soil porosity and soil bulk density were increased,and the effect increased with the addition of improver.In the soil column test,the leaching amount of Na ions with high additive amount(4%acidified carbon +1.2% lime saponified residue)was 12.8% higher than that with CK treatment,and the leaching amount of total salt was 57.4% higher.In the flooding test,due to the adsorption effect of acidifiedbiochar on soil Na,its content and water-soluble salt content showed a trend contrary to that of the soil column test.The combination of the two treatments significantly increased the content of alkaline hydrolysis nitrogen in soil,among which the content of alkaline hydrolysis nitrogen in the group with high dosage(4% acidified carbon +1.2% lime produced saponification residue)was more than twice that of the CK treatment.