Effects Of Earthworms On Soil Humus Composition And Maize Yield During Straw Return

Returning straw to the field is currently an important soil fertility measure in China.Some substances in straw can be transformed into soil humus after decomposition.Adding earthworms to the soil can effectively decompose straw,improve the decomposition rate of straw and promote the formation of soil humus.A field experiment was conducted in a mono-cropping corn field,with four treatments,are,CK（without straw and earthworms）,S（straw applied only）,E（earthworms applied only）,SE（earthworms and straw were added）.In May,July and September 2021,the effects of earthworms on soil humus components and maize yields of 0-10 cm,10-20 cm and 20-30 cm were discussed.Soil humus composition modification method was used to extract soil humus components,the main components were extracted into humic acid,fulvic acid,humin,potassium dichromate external heating method to measure soil humic acid,fulvic acid,humin carbon content.The relationship between soil humus components and soil physicochemical factors was discussed by combining redundancy analysis,and the relationship between soil humus components and soil physicochemical factors and maize yield was discussed by correlation analysis.The results show that:（1）The addition of earthworms and straw can improve the organic carbon content of soil humus components,which is conducive to improving the degree of soil humification.Compared with the addition of earthworms and straw,the addition of straw treatment significantly increased the soil humin acid carbon content and humin carbon content（P<0.05）,of which july increased the most.The addition of earthworms and straw significantly increased soil fulvic acid carbon content（P<0.05）.During the3 sampling periods,the addition of straw and the addition of earthworms and straw could improve the soil PQ values（humic acid/humic acid + fulvic acid）and ratio of humic acid to fulvic acid（P<0.05）.（2）The addition of earthworms and straw also had a greater impact on the height,stem thickness,leaf area index and yield of maize plants.Compared with the addition of earthworms and straw,the height of maize plants increased significantly after the treatment of earthworms and straw at different growth stages of maize,the thickness of maize stems increased significantly,and the leaf area index increased significantly（P<0.05）.Maize yields are highest under earthworm and straw treatment,with increased maize yields after earthworm and straw treatment compared to local farmland maize yields.The interaction of earthworms and straw can promote maize growth and increase maize yield.（3）The soil humus components and soil physicochemical factors were redundantly analyzed,and the results showed that in May,soil bulk weight,available potassium and available phosphorus significantly affected the soil humus components（P<0.05）.In July,the available nitrogen,available potassium and bulk weight significantly affected the soil humus components（P<0.05）.In September,the soil physicochemical factors had no significant effect on the humus components.（4）The results of ANOVA showed that different treatments,seasons and interactions of the two significantly affected the plant height,stem thickness and leaf area index of maize（P<0.05）.The results of the correlation analysis showed that there was a significant positive correlation between water content,humic acid,fulvic acid and humin and maize plant height and stem thickness,there was a significant positive correlation between water content,available phosphorus,available potassium,fulvic acid and leaf area index,and there was a significant positive correlation between water content,available nitrogen,available phosphorus,available potassium,humic acid,fulvic acid and humin.In summary,the addition of straw and earthworm treatment can increase the carbon content of soil humus components,promote corn growth,and improve corn yield.