Study On The Distribution Characteristics Of The Composition And Properties Of Black Soil Humus With Two Parent Materials

Studying the difference of humus composition between two black soil profiles developed on laterite parent material and loess parent material has important theoretical significance for revealing the formation and development law of highly weathered laterite parent material under temperate climate conditions,and also provides scientific basis for improving and fertilizing black soil.Based on the study of clay mineral composition,the profile soil of black soil developed on different parent materials in Jilin Province were selected as the test soil,and the profile distribution characteristics of humus composition and properties were studied.The results are as follows:First,the clay content of laterite parent black soil is high,and the clay content varies greatly with the depth of soil profile.The clay content of loess parent black soil has no obvious change compared with laterite parent black soil.With the deepening of soil profile,the content of amorphous iron oxide(Fe_o)in laterite parent material black soil decreases and the change trend is obvious,however,the amorphous iron oxide in Loess parent material black soil has no obvious change rule.The content of free iron and aluminium oxides(Fe_d,Al_d)in Loess parent material black soil is lower than that in laterite parent material black soil.Moreover,the change trend of free iron and aluminum oxides in Loess parent material black soil is not as obvious as that in laterite parent material black soil.Second,the total carbon content of the laterite parent material black soil is between 0.812 and 16.7g/kg,the content of the organic carbon of heavy fraction is between 0.802 and 13.6g/kg;The total carbon content of the Loess parent material black soil is between 2.87 and 11.4g/kg,the content of the organic carbon of heavy fraction is between2.5 and10.5g/kg.The content of total organic carbon and recombinant organic carbon in laterite parent material black soil is higher than that in Loess parent material black soil,the carbon sequestration capacity of Loess parent material black soil is not as high as that of laterite parent material black soil.Third,with the deepening of soil profile,the content of humus carbon and carbon in each component of the two parent black soil decreased,and the difference was significant(P<0.05).The E4/E6 and log K values of laterite parent material black soil increased at first and then decreased gradually,while the E4/E6 and log K values were the lowest in layer C.The E4/E6 and log K values of Loess parent material black soil increased gradually,and the E4/E6 and log K values were the highest in layer C.Fourth,the distribution of the loosely combined humus content in the profile of two parent materials black soil is basically the same.The distribution of the stably combined humus content in the profile is obviously different.There are also obvious differences in the distribution of the content of compact humus in the profile.Two parent materials black soil,there are different HA,FA and HA/FA in the loosely combined humus and the stably combined humus.Fifth,among the organic mineral complex,the complexes at all levels contents of the two parent materials black soil have different trends.Laterite parent material black soil,in the surface soil,fine sand complexes are the main,followed by clay-size complexes,and silty-size complexes are the least.With the deepening of soil profile,the clay-size complexes are the most,followed by silty-size complexes and the fine sand complexes are the least.Loess parent material black soil,the main soil layers are fine sand complexes,followed by clay-size complexes and silty-size complexes are the least.Sixth,the content of macroaggregates in two parent materials black soil decreases with the deepening of the profile,while the content of macroaggregates in layer C is very low.The content of macroaggregates in laterite parent material black soil decreased gradually,and increased at BC2 layer.The content of macroaggregates in Loess parent material black soil decreased sharply with the deepening of the profile.In Microaggregates,the change rules of the two parent materials black soil are the same.In powder-clay aggregates,laterite parent material first increases and then decreases with the deepening of the profile.The black soil of Loess parent material is on the rise all the time,therefore,the C layer content of Loess parent material is obviously higher than that of laterite parent material.