Page 83 - Ilmu Tanah Book

70 The Chemistry and Fertility of Soils under Tropical Weeds

and exchangeable K were significantly higher in the secondary forest and the
plantation than that in the intensively cultivated land like the cassava and the
paddy fields. For example, the organic C and CEC in the forest of Mulyasari were
-1
-1
-1
36.6 g kg and 14.3 cmolc kg while those in the cassava plantation were 9 g kg
-1
and 4.9 cmolc kg , about 25% and 34%, respectively. The land-use conversion in
Tulung Boho Central Lampung also showed similar pattern (Table 4.9). The soil pH,
Organic C, CEC, and Exchangeable K were higher in the secondary forest than those
in the other land-use systems. The organic C and CEC in the cassava plantation
were much lower than those in the secondary forest, about 53% and 18%,
respectively. Salam et al. (1999a) also report that the soil CEC and exchangeable K
are well correlated with the soil Organic C with r = 0.68 and 0.63, respectively,
indicating the importance of soil Organic C.

Table 4.8. The changes in some soil properties by land-use conversion
in Mulyasari Central Lampung*.

Organic C CEC Exch. K
Land-Use pH
-1
-1
-1
(g kg ) (cmolc kg ) (mg kg )
Secondary Forest 5.2 36.6 14.3 73.4
Rubber 5.0 20.9 12.5 38.4

“Sengon” 4.4 11.7 5.6 29.5

Mixed Graden 4.5 21.4 6.8 58.1

Cassava 4.3 9.0 4.9 8.42

Cassava and Corn 4.5 13.8 5.7 29.5

Paddy 4.4 13.4 5.1 8.42

*Adapted from Salam et al. (1999a)

Abdul Kadir Salam and Nanik Sriyani – 2019