| This paper took Huaxi reservoir in Huaxi District,Guiyang,the South Campus of Guizhou University,three typical Karst limestone-developed soil in Zhen Shan Village as materials,applied the Dry&Wet Screening Method to compare the stability and grain gradation distribution of limestone-developed soil aggregate under different vegetation forms,and then analyzed the distribution characteristics and the stability of soil aggregate under different vegetation forms.Moreover,by comparing the changes of organic carbon after leaching ion different forms' s ions,it analyzed the protection mechanism of various grain gradation aggregate to organic carbon.Research Results as followings:(1)Among the limestone-developed soil aggregate,the grain gradation content of 0.5-0.25 mm and <0.25 mm was the lowest,and the sum of the two grain gradation accounted for about 10%of aggregate total quantity,which showed that the large aggregate(>0.5mm)was the main form of aggregate in the zone of limestone-developed soil.The average content of the dry screening aggregate > 5mm,5-2mm,2-1mm,1-0.5mm,0.5-0.25 mm,and < 0.25 mm reduced in turn;Limestone soil aggregate each grade after wet-screened is given priority to with the corresponding aggregate water stability,soil breaking into a new aggregate,the amount of aggregate continuously decreased with the decrease of graded.(2)Among the limestone-developed soil aggregate,> 0.25 mm of water stable aggregate and water soluble calcium,aluminum,ion state of calcium,magnesium,aluminium,carbonate combined with calcium,magnesium,iron,aluminum plasma has significant negative correlation.Among the limestone-developed shrub soil,> 0.25 mm of water stable aggregate and water soluble calcium,magnesium,ion state of calcium,magnesium,carbonate combination state of magnesium,iron,aluminum,organic material combination state of magnesium,iron,aluminum has significant negative correlation.Among the limestone-developed arbor soil,> 0.25 mm of water stable aggregate and water soluble state of calcium,iron,aluminum,ion state of calcium,magnesium,carbonate combination state of calcium,iron,organic material combination state of calcium was significantly negative correlation.(3)limestone soil,carbonate combined with metal ion has been the biggest influence on > 5 mm graded aggregate stability,5-1 mm graded aggregate stability influence factors are different under different vegetation types,mainly by the carbonate combined with state,ion state and organic material in combination with metal ion,1-0.25 mm graded aggregate stability is mainly affected by the organic material in combination with metal ion.(4)The grassland soil > 1 mm(> 5 mm,2 mm,5-2-1 mm)graded total organic carbon after the protection of the carbonate combined with ion leaching aggregate is strongest,1-0.5 mm fraction is strongest after ion leaching of water soluble states aggregate protection of organic carbon,0.5-0.25 mm fraction in aggregate after ion ion-extraction the protection of organic carbon is strongest.Shrub soil > 5 mm fraction in strongest protective effect of organic carbon after the organic material in combination with metal ion leaching aggregate;Grade 5-0.5 mm has the strongest protection of organic carbon after the carbonate combined with ion leaching aggregate.0.5-0.25 mm fraction has strongest protective effect of organic carbon in aggregate after ion ion leaching.Arbor soil > 5 mm graded aggregate has the strongest protection of organic carbon in the organic material after combination with metal ion leaching,5-2 mm and 2-1 mm graded aggregate's protection of organic carbon is strongest after ion ion leaching,1-0.5 mm fraction in the carbonate combined with ion leaching aggregate after the protection of organic carbon is strongest,0.5-0.25 mm in the leaching of water soluble metal ion aggregate after the protection of organic carbon is strongest.(5)In strong oxidizing(1/3KMn O4)grassland soil aggregate of ion and water soluble ion leaching,> 5 mm and 5-2 mm graded aggregate for the protection of organic carbon is the strongest;After carbonate combined with ion extraction in 2-1 and 1-0.5 mm graded protection of organic carbon is strongest;After organic material combined with metal ion leaching,> 5 mm graded for maximum protection of organic carbon is strongest.2-1 mm graded protection of organic carbon is strongest in shrub soil after three ion extraction of water soluble state and ion state and carbonate combination state;After organic material combined with ion extraction > 5 mm graded has the strongest protective effect of organic carbon.After water soluble metal ion extraction,the 2-1 mm graded arbor soil's protection of organic carbon is strongest;After ion ion-extraction,2-1 mm and 5-2 mm graded's protection of organic carbon is strongest;After carbonate combined with metal ion leaching,1-0.5 mm graded'sprotection of organic carbon is strongest;After organic combination of ion extraction >5 mm grained's protection of organic carbon was the strongest.(6)under the condition of weak oxidizing(1/30 KMn O4),the grassland soil water soluble state and carbonate combined state after ion leaching,1-0.5 mm graded protection of organic carbon is strongest;After ion ion-extraction > 5 mm graded protection of organic carbon is strongest;After carbonate combined with metal ion leaching,1-0.5 mm graded protection of organic carbon is strongest;After organic material combination of ion extraction,2-1 mm fraction of the protection of organic carbon is strongest.Shrub soil water soluble ion leaching,5-2 mm fraction of organic carbon has the maximum protection;after extraction 2-1 mm and 1-0.5 mm graded protection of organic carbon is strongest by the ion state,carbonate state and organic material in combination with metal ion.The arbor soil ion leaching by the water soluble state and ion state,2-1 mm grained protection of organic carbon was the strongest;After carbonate combined with metal ion leaching,1-0.5 mm fraction of organic carbon has the maximum protection;After organic combination of ion extraction,> 5 mm graded given priority to protection. |
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