摘要
红树林及由红树林沼泽发育的酸性硫酸盐土在我国约有１０．６万公顷。红树的主要生化特点之一是其化学组成中硫含量很高，平均达０．４％左右，大大高于同地带其它灌木（０．１％左右），这一特征深刻地影响着土壤发生及其性质。当红树林残体被埋藏而分解后，有大量的硫进入土壤，从而使土壤具有含硫层。该层全Ｓ含量多在０．３％以上，表层土壤也在０．２％左右，而一般热带地区酸性土只有０．０４％左右。土壤地下水中约为入海河口海水中的１０—２０倍，也是这类土壤硫主要来源于红树林等生物体对海水中硫的富集的一个佐证。当土壤围垦而脱水后，硫化物遭氧化而生成大量硫酸，致使土壤呈强酸性，含Ｓ层最低ｐＨ值可达２．２，大量的铝活化析出，严重危害作物生长。我们把红树埋藏层（含硫层）作为诊断层，并根据本研究结果对该诊断层的指标进行了修改。按照其埋藏深度、ｐＨ和含Ｓ量将这类土壤续分为上位（＜２５ｃｍ）、中位（２５—４５ｃｍ）和下位（４５—７０ｃｍ）三种类型。为改善这类土壤的生态条件，保护生态环境，可针对硫在不同氧化还原条件下的化学行为进行改良，如垦植种稻，泡水压“酸”，蓄淡洗“酸”等；也可针对合硫层浅、土镶易酸化的特点进行改良，如填土隔“酸”，施石灰或磷矿?
angrove and acid
sulphate soils developed from mangrove swamp are about106,000 ha in China. One of the
main characteristics of mangrove is the high Scontent in its chemical composition (generally 0.
2%-0.6%, 0.4% on average, muchhigher than the 0.1% of tropic shrub). The characteristic greatly
influences tbe ge-nesis and nature of the soils. When the remains of mangrove are buried and
decom-posed, a large amount of S enters the soil, making the kind of soil contain the bu-ried
mangrove layer with a high S content. In general, the surface soil is about 0.2%in the content of
total S, and the buried mangrove layer is mostly over 0.3%, whileother acid soils of tropic
region are only about 0.04%. Besides, SO content of theunderground water in this kind of soil is
10-20 times as much as that of the seawaters of estuary. And it can also prove that S of the soil
chiefly comes from theS of sea water accumulated by mangrove. After the swamp is enclosed
and reclaim-ed, the soil water goes off. Sulphides produce a large amount of sulphate due
tooxidization, so the soil reveals strong acidity-the lowest pH can reach 2.2, and lotsof Al are
activated and separated out. This is very harmful to the growth of plants.We consider the
buried mangrove layer (the S-bearing horizon) as the diagnos-tic horizon (total S is 0.3% or
higher, the pH of dried soil is 3.8; jarosite colorvalue is ≥ 2.5 Y) and sub divide the soil into
three types according to the appea-ring depth of the borizon: the shallow (<25cm), the middle
(25-45cm) and thedeep (45-70cm).In order to improve the ecological condition of this kind of
soils, protect eco-logical environrnent and develop economy, we should take some measures
to reducethe acidity (Al toxicity) and to prevent acidification of tlie soils, such as storingfresh
water to wash acid, adding soil to separate acid layer, liming to neutralizeacid, cboosing
acid-resisting variety, and applying suitable fertilizers, especially gro-und phosphate rock, as
well as developing suitable planting in line with local condi-tions (coconuts, pineapples, etc.),
digging fishing pools and establishing mangroveproiective region and tourist region.
出处
《土壤学报》
CAS
CSCD
北大核心
1994年第1期86-94,共9页
Acta Pedologica Sinica
