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African Crop Science Journal
African Crop Science Society
ISSN: 1021-9730
EISSN: 2072-6589
Vol. 4, No. 2, 1996, pp. 185-196
Bioline Code: cs96056
Full paper language: English
Document type: Research Article
Document available free of charge

African Crop Science Journal, Vol. 4, No. 2, 1996, pp. 185-196

 en Relation of some chemical properties to soil erodibility of some south western Kenyan soils
Macharia, D.W.; Moll, W. & Kamau, P.A.

Abstract

A laboratory study to investigate the effect of soil cations and dithionite
iron (Fe[d]) content on soil erodibility (K) was conducted using simulated
rainfall on ten selected Kenyan soils.  Rainfall with a simulated  intensity
of 6 mm min-1 and duration of 3 minutes was applied to soil which had been
passed through an 8-mm sieve and packed at a density of 2.5 g cm-3 in trays
of dimension 25  25 cm.  Soil loss including both splash and wash erosion was
determined under three moisture regimes (dry, field capacity (F.C.) and
moist/wet).  The relevant chemical properties of the soils were analysed and
these were correlated with the soil loss. The soils had Fe[d] ranging from
0.2 to 1.5%,  manganese (Mn[d]) from 0.31 to 0.80%, silicon (Si[d]) from 0.16
to 0.45% and sodium adsorption ratio (SAR) from 0.02 to 0.33.  The total iron
(Fe[t]) and aluminium (Alt) contents ranged from 5.9 to 12.6% and from 10 to
23.8%, respectively.  The average soil loss varied from 1.8 to 47.4 t ha-1
and the determined K-values ranged from 0.035 to 0.914.  The nomograph
K-values overestimated the erodibility of the soils high in Fe[d] and Na, but
multiple linear regression analysis confirmed that Fe[d] and Na are important
parameters in predicting soil erodibility.  About 78% of the variations in
soil loss was accounted for by CEC, Exch. Ca, Exch. K, EC and soil organic
matter (SOM), whereas 77% of the variations was explained by Ca[t], Fe[d],
Fe[t] and Na[t] contents of the soils.

Keywords
Cation content, dithionite iron, rainfall simulation

 
 fr
Macharia, D.W.; Moll, W. & Kamau, P.A.

Résumé

Une experience de laboratoire a ete effectuee en utilisant de la
precipitation simulee sur dix sols selectionnes au Kenya pour analyser
l'effet des cations de sols et de dithionite de fer (Fe[d]) sur l'erosion de
terre. Une precipitation avec intensite simulee de 6 mm min-1 et duree de 3
minutes etait donnee e des sols qui ont ete passes au tamis de 8 mm puis
presses e une densite de 2,5 g cm dans des plateux de 25-25 cm. La perte de
sols par eclaboussement ainsi que par erosion etait determinee pour trois
regimes d'humidite (sec, capacite de champ (F.C.) et mouille/humide). Les
cracaterisques chimiques utiles des sols ont ete analysees et correlees avec
les pertes de sols. Le contenu des sols en cations se rangeait de 0,2 e 1,5%
pour le fer (Fe[d]), de 0,31 e 0,80% pour le manganese (Mn[d]), de 0,16 e
0,45% pour le silicium (Si[d]) et le rapport d'absorption de sodium (SAR) de
0,02e 0,33. La teneur totale en Fer (Fe[t]) et aluminium (Alt) se rangeait de
5,9 e 12,6% et de 10 e 23,8%, respectivement. La perte moyenne de terre
variait de 1,8 e 47,7 t ha-1 et la valeur de K de 0.035 e 0.914. Les valeurs
nomographiques de K surestimaient l'erosion des sols avec beaucoup de Fe[d]
et Na, mais une regression multiple confirme que le Fe[d] et Na sont des
parametres importants pour predire l'erosion du sol. Environ 78% de la
variabilite en perte de sols est expliquee par le CEC, l'echange de Ca,
l'echange de K, EC et la matiere organique du sol (SOM), tandis que 77% de la
variabilite est expliquee par la teneur de Ca[t], Fe[d], Fe[t], et Na[t] dans
les sols.

Mots Clés
Teneur en cation, dithionite de fer, simulation de la precipitation

 
© Copyright 1996 - African Crop Science Society

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