Improment Effect Of Different Organic Material Additions On Saline Alkali Soil In The Western Songnen Plain

Soil salinization is a worldwide environmental problem and one of the main aspects of soil degradation.Soil salinization has seriously affected regional ecological environment and food production.The Songnen Plain is one of the three major soda saline soil distribution areas in the world,located in the agricultural and animal husbandry ecotone,and its ecosystem is quite fragile.In the past 30 years,due to the increasing population,the pressure on human survival has increased,and people’s irrational use of grasslands(overgrazing,mowing,reclamation,etc.)has become increasingly intense.As a result,the salinization area of the soil in the Songnen Plain continues to increase,and the degree of salinization continues to intensify.The improvement of saline-alkali soil has become an urgent task.Returning organic materials to the field can reduce atmospheric pollution caused by straw burning,increase production and fertilizer,improve soil quality,and promote crop growth.At present,the effect of organic materials on improving saline-alkali soil is still unclear.This study was conducted in the Mongolian Autonomous Region of Durbert County,Daqing City,with different organic material return modes(straw pulverization,ammoniation,combined application of nitrogen fertilizer,biochar,etc.)set up.The decomposition of straw was analyzed using nylon bag method;Select 12 soil physical and chemical indicators for measurement and analysis,establish a soil quality indicator system,screen appropriate evaluation indicators through principal component analysis,establish a minimum dataset,and calculate their soil quality index.The research results show that:(1)There are differences in straw decomposition rates among different treatment groups,among which the treatment group treated with ammoniated crushed rice straw has the best straw decomposition effect,with the decomposition rates of 87.13% and81%(the first year),82.83% and 81.10%(the second year)in the non growing season and the growing season,respectively.(2)After returning different organic materials to the field,the soil p H,soluble salt content,and electrical conductivity significantly decreased,while the water content significantly increased during the growth season;The content of soil organic carbon and active organic carbon increased,while the content of soil dissolved organic carbon decreased;The content of total nitrogen and ammonium nitrogen in soil increased,while the content of nitrate nitrogen decreased;Both soil catalase activity and alkaline phosphatase activity have been improved,indicating that returning organic materials to the field can effectively improve the physical and chemical properties of soil,improve soil structure,and improve soil quality.(3)The minimum dataset consists of four indicators: soil p H,soluble salt content,dissolved organic carbon content,and alkaline phosphatase activity.The results of soil quality index analysis showed that the ammoniated crushed rice straw treatment group had the best improvement effect.The crushed rice straw combined with nitrogen fertilizer can effectively improve soil structure and improve soil physical and chemical properties,and it is easy to obtain in daily life and easy to promote.