Academic Journals Database
Disseminating quality controlled scientific knowledge

Variable Charge of Ultisols due to Phosphate Application and Incubation Time

ADD TO MY LIST
 
Author(s): Muhammad Mahbub

Journal: Jurnal Tanah Tropika
ISSN 0852-257X

Volume: 15;
Issue: 2;
Start page: 103;
Date: 2010;
Original page

Keywords: Negative variable-charge | pHo | phosphate | salt (CaCl2) concentration | Ultisols

ABSTRACT
The laboratoryexperiment was conducted to study the effect of phosphate (P) application and its incubation time on pHo (pH at thepoint of zero charge) and variable charge of ultisols . The determined parameters were pHo and variable surfacecharges.Soil samples were added by 0, 375 and 1,125 mg P kg-1 (or 0, 50 and 150% of the P sorption maximum,respectively). Then, they were incubated for 2, 4, 6 and 8 weeks. The variable surface-charges and pHo weredetermined by using the activity of potential determining ions (H+ and OH-) within two salt concentrations as counterions (0.1N and 0.001N CaCl2) through a potentiometric titration method. The results were indicated that the high Psorption and 766 mg P kg-1 in maximum sorption were due to high contents in clay fractions and aluminum as well aslow pH of experimental soil. Application of P and incubation time were able to decrease pHo and to increase negativesurface-charges. Additionals of 375 and 1.125 mg P kg-1 incubated for 8 weeks gave the value of pHo 2.86 and 2.69;as well as the magnitude of negative charges 14.48 and 16.76 cmol(-).kg-1, respectively (both for 0.001N CaCl2).For pH > pHo (the characteristic of variable charge soils), the higher the salt (CaCl2) concentration and pH solution,the higher the negative surface-charge.
Save time & money - Smart Internet Solutions      Why do you need a reservation system?