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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

 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

 
 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

 
© Copyright 1996 - African Crop Science Society

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