Characteristics of Volcanic Ash Soil Clay-Humus Complexes in Changbaishan and Wudalianchi, Northeast China

Abstract

Characteristics of clay-humus complexes obtained by modified Tyulin's method in volcanic ash soils of Changbaishan and Wudalianchi, Northeast China, and influence of tropospheric eolian dust on composition of the clay-humus complexes were studied. Results were as follows:
1) In surface of volcanic ash soils of both the two places, clay-humus complexes were dominated by G₂. Ratios of G₀/G₂, G₁/G₂, G₀/(G₁+G₂) were low. The amount of G₁ complexes and the ratio G₁/G₂ increased with increasing influence of eolian dust. The influence of eolian dust decreased with depth of the soil pedon.
2) Both the two places, in surface of volcanic ash soils the highest amount of carbon was found in G₂ complexes. 64.0-96.2% of total carbon in Changbaishan soils and 42.7-76.9% in Wudalianchi soils were distributed in G₂ complexes. The carbon content of each kinds of complexes decreased with depth of soil pedon. Influence of eolian dust resulted in decrease of carbon content in G₂ and increase of carbon content in G₁ complexes for each horizons of a soil pedon.
3) All of fine-clay, middle-clay, coarse-clay and total clay content in complexes of the surface horizons of volcanic ash soils in both the two places showed a tendency of G₂>G₁>G₀. All the 3 kinds of complexes contained significantly higher amount of total clay in Wudalianchi soils than in Changbaishan soils. And for each horizons of a soil pedon, the clay content in G₁ complexes was determined by the clay content in soil, i. e., the clay content in G₁ complexes became high while the influence of eolian dust was strong.
4) Clay mineral composition of each complexes was as same that of soil. But the amount of 1.42 nm clay minerals and kaolinite in complexes of surface soil from Changbaishan C2 on which the influence of eolian dust was weak showed a tendency of G₂>G₁>G₀, the amount bf muscovite and/or illite, and feldspar in complexes showed a tendency of G₁>G₂>G₀. However, such tendencies became weaker with the depth of the pedon. Similar phenomenon was found up to the BC horizon of the pedon W3 which was strongly influenced by eolian dust.