GENESIS AND DEVELOPMENT OF ARGILLIC HORIZON IN ULTISOL CLIMOSEQUENCEMakhrawie, M. Lutfi Rayes, M. Munir and Sudarto
This soil research on 5 Ultisol pedons was aimed to investigate various processes and factors influencing the genesis and development of the argillic horizon. The results of the research showed that the Clay Iluviation Index (CII) and the depths of the E, Bt and Bt-E horizons relatively increased and the Argillic Development Index (ADI) relatively decreased with increasing rainfall. The total clay ratio of Bt/A or Bt/E horizons for the 5 pedons showed a value of >1.2. The fine clay to total clay (FC/TC) ratio in Bt horizon ofthe P1 and P2 pedons was higher than that in horizons above and below the Bt horizon, whereas the FC/TC ratios in the P3, P4, and P5 pedons were only higher than that in the A horizon, respectively. The difference of the highest with the lowest FC/TC ratio was in the P2 pedon (0.53), indicating that the ADIwas quite large. The P3 pedon showed the largest thickness of Bt, Bt-E and Bt / E ratio horizons. There were varying percentages of clay coating (3.61 - 28.18% vol.), showing evidence of the argillic formation.