Study On The Mechanism Of Fertilization In Black Soil Taking Into Account The Stability And Activity Of Organic Matter

Soil organic matter（SOM）is an important index to measure soil quality,which can be divided into physical and chemical groups by different separation methods.According to the different decomposition efficiency,each component is divided into active and stable organic matter.In recent years,the fertility of black soil has declined,and the addition of exogenous organic matter has become the main means of fertilization.The application of corn straw is a common way to supplement active organic matter.Due to the low temperature in Northeast China and the slow decomposition of corn straw,the stable organic matter can not be replenished in time.Peat contains a lot of humic acid,which can increase the content of SOM after being applied to the soil.The results showed that the mixed application of corn straw and peat could increase the content of SOM,but the effect of different proportion of corn straw and peat on SOM activity and stable organic matter content was not clear.In this paper,micro-field experiments on different ratios of corn straw and peat were carried out from 2021 to 2022.Five treatments were set up:control（CK）,all corn straw（0P）,1:2 corn straw and peat（1/3P）,2:1 corn straw and peat（2/3P）,and whole peat（P）.By studying the changes of SOM activity and stable organic matter,HA structure characteristics,soil physical and chemical properties and maize yield,the responses of different ratios of corn straw and peat to soil fertility characteristics were discussed,and finally the fertilizer ratio of organic materials which could give consideration to both active and stable organic matter was selected.The main results are as follows:According to the comprehensive two-year data,SOM and E_SOM of corn straw and peat were the highest when applied at 1:2,SOM or E_SOM which increased by 11.33%,12.89%and 59.93%,64.32%,respectively,compared with the control.With the increase of the proportion of peat,SOM and E_SOM increased gradually.Among the soil physical components,corn straw and peat were applied at 1:2,the POM content increased by 24.15%and 31.97%,compared with the control,and the MAOM content increased by 7.44%and 7.96%.Through the analysis of Chinese and foreign literature data,it is concluded that the average value of POM/MAOM is 0.28.Corn straw and peat were closest to the average value when applied at 1:2,which could take into account both active and stable organic matter.With the increase of the proportion of peat,the proportion of POM in SOM decreased gradually,while the proportion of MAOM and SOM increased.Among the soil chemical components,the contents of EOM and FA were the highest when corn straw and peat were applied at 2:1.When corn straw and peat were applied at 1:2,the HA and PQ values were the highest.Compared with the control,the HA and PQ values increased respectively by 44.57%,39.46%and 13.49%,13.93%.With the increase of the proportion of peat,the content and proportion of EOM,DOM and FA to SOM gradually decreased,while the content and ratio of HA and HM to SOM gradually increased.Compared with 2021,the content of physical and chemical components of SOM decreased in 2022,but the proportion of SOM and PQ value increased.The addition of corn straw could increase the aliphatic and alkoxy carbon content of soil HA molecules,and the aromaticity and stability of HA increased with the increase of peat application ratio.When corn straw and peat were applied at 1:2,the IR2920/1720 ratio of HA was 0.295 and0.219,the exothermic ratio of high/medium temperature was 1.318 and 3.572,the FI values of B peak was 154 and 156,C peak was 118 and 121,H/C was 0.95 and 0.89,alkyl carbon/alkoxy carbon,aromatic carbon/aliphatic carbon and hydrophobic carbon/hydrophilic carbon respectively were 0.51,49.13 and 1.53,0.95 and 0.89.The suitable ratio of hydrophobicity to hydrophilicity of HA.With the increase of peat ratio,soil bulk density,compactness and p H decreased gradually,while AN,AP,AK,plant height,stem diameter and grain yield increased gradually.When corn straw and peat were applied at 1:2,the corn grain yield was the highest,which increased by 22.43%and 29.83%compared with the control.The results showed that the application of corn straw and peat at 1:2 was more beneficial to soil fertilization and corn growth..Comprehensive analysis shows that when corn straw and peat are applied at 1:2,it can take into account both active and stable organic matter in black soil,maintain a suitable ratio of HA hydrophobic to hydrophilic,reduce soil bulk density and compactness,increase soil moisture content,and effectively increase crop yield.