Laterite Facts

To: aquatic-plants at actwin_com
Subject: Laterite Facts
From: Tyson Lee <tyson at phoenix_net>
Date: Fri, 2 Feb 1996 03:02:52 -0500
I recently searched "laterite" on Alta Vista just to see what it would turn up.

The following is an excerpt I found interesting and thought others would too:




The  research undertaken by the Soil Survey and Land  Use 
Organisation, Palayamkottai to develop the red and laterite  soil 
in  Tirunelveli Kattabomman district, has come as a boon  to  the 
people, particularly the farming community.

        Unlike black cotton soils, which have uniform topography, 
red  soils generally occur on gently sloping to  undulating  land 
with the gradient exceeding three per cent. The soil is found  on 
the  surface or deep below. The texture also varies  widely  from 
loamy  to clayey. However the soils are  generally  well-drained. 
They  are  often  gravelly  due to rock  or  iron  fragments  and 
secondary iron nodules are also common. The soils show acidic  to 
neutral  reaction. Due to dominance of kandite  clay  mineralogy, 
they possess low cation exchange capacity, low base and  nutrient 
status  and poor organic matter but have a higher amount of  iron 
and alumina.

{......perhaps Dupla adds something to theirs to increase the CEC?}


For further reads:

        {Laterite soils result from laterisation, the process  by 
which silice is removed leaving the soil enriched with oxides  of 
iron  and  alumina.  The  enriched soil  becomes  harder  due  to 
dehydration  and  the hardened mass  called  `plinthite'  appears 
vesicular or like a honey comb in structure. The red and laterite 
soils are generally not saline or alkaline.

        Red  and  laterite  soils  (mainly  alfisols,   altisols, 
inceptisols  and  entisols  as per soil taxonomy)  are  found  in 
China,  India,  Argentina,  Kenya,  Nepal,  Uganda,  Sri   Lanka, 
Bulgaria, the Philippines, Vietnam, Bangladesh, Africa,  Nigeria, 
Australia,  Thailand  and Pakistan. In India,  it  comprises  107 
million hectares mainly in eastern Madhya Pradesh, Bihar plateau, 
Orissa, West Bengal, Andhra Pradesh, Karnataka, Kerala and  Tamil 
Nadu.  In Tamil Nadu alfisols and inclusions of  inceptisols  and 
entisols  occur in abundance in Dharmapuri, Salem,  South  Arcot, 
North  Arcot,  Chinglepet, Madurai,  Pudukottai,  Dindigul  Anna, 
Tiruchi, Tirunelveli Kattabomman and Kanyakumari districts.}

        Red  soils originate from almost all kinds of felsic  and 
mafic  parent  material, mostly in tropical, semi-arid  to  humid 
climates  with  annual rainfall ranging from 500-4,000  m.m.  and 
mean  annual soil temperature between 16oC to 30oC. In  order  to 
categorise   the  red  soils,  the  Soil  Survey  and  Land   Use 
Organisation, Palayamkottai, undertook a reconnaissance survey of 
the red soil area and identified eight major soil sub groups. The  p73 
survey being broad based, specific management practices could not 
be advocated to the farming community.


Tyson Lee
tyson at phoenix_net
http://tyson.cet.net/~tyson