通过野外定位观测和室内分析,探讨了松嫩平原盐渍化区土壤的微域特征.结果表明:研究区由高平地、微坡地、洼地边缘和洼地4种微地貌单元组成.洼地发育均腐土,洼地边缘、微坡地和高平地发育碱积盐成土.高平地土壤的碱土碱化层出现在15～30 cm,碱化度(ESP)60％.微坡地土壤表层的ESP最大可达75％.洼地边缘的ESP分布在10～30 cm土层,最大为30%～40%.洼地的土壤几乎没有碱化层.研究区不同微地貌部位发育的土壤水分特征曲线存在明显差异.微坡地土壤饱和含水率最大仅为25%,而洼地土壤0～10 cm饱和含水率高达45％.不同微地貌单元的冻融过程存在明显的差异.微坡地和洼地的最大冻结深度分别为157和136 cm.冻结期,洼地土壤表层含水率由冻结前的20％增加到50％.微坡地土壤表层含盐量变化在4个微地貌单元中最明显;冻融前后微坡地土壤表层含盐量增幅达80%.
The study by the methods of in situ observation and laboratory analysis showed t
hat the micro-relief in salinization area of Songnen Plain area was composed of
flat land, micro-slope land, depression margin, and depression. Isohum
usols distributed in depression, while alkalic halosols distributed in depressio
n margin, micro-slope land, and flat land. The exchangeable sodium percent (ESP
)
in alkalized layer (15〖KG-*2〗-〖KG-*7〗30 cm) of alkaline soil in flat land w
as 60%, and the ma
ximal ESP in surface soil layer in micro-slope land could reach to 75%. The alk
a
lized soil layer in depression margin was mainly at the depth of 10〖KG-*2〗-〖K
G-*7〗30 cm, where
the maximal ESP could reach to 30%〖KG-*2〗-〖KG-*7〗40%. Nearly no alkalized la
yer was found in t
he soil profile in depression. The soils developed on the four micro-relief uni
t
s had obvious differences in their water retention curves. The maximal saturatio
n moisture content in the soils of micro-slope land was only 25%, while that of
0〖KG-*2〗-〖KG-*7〗10 cm soil layer in depression reached to 45%. The freezing
-thawing process in
different micro-relief units differed markedly, with the maximal frozen depth
i
n micro-slope land and depression being 157 and 136 cm, respectively. The su
r
face soil moisture content in depression increased from 20% before freezing to 5
0% during freezing period. Among the four micro-relief units, micro-slope land
h
ad the most obvious variation of surface soil salt content during freezing-thaw
ing, with the increment after thawing being as high as 80%.