Page 69 - Ilmu Tanah Book

56 The Chemistry and Fertility of Soils under Tropical Weeds

The changes in land-uses may surely affect the land and vegetation cover
including weed types and coverage. These changes may change the microclimate
and the soil biodiversity and eventually change the soil biology and microbial
population and activities and the soil chemistry and fertility. Deforestation from
the primary forest to secondary forest and coffee plantation had been reported to
change the weed dominance (Salam et al., 1998b; Oki et al., 1999), the soil
chemistry, biochemistry, and fertility (Salam et al., 1998b; Salam et al., 1999a;
1999b; Salam et al., 2001), heavy metal solubility (Salam, 1999; Salam, 2017).
Some soil fertility indices like soil CEC, C and N contents, and enzymatic activities
were in general higher in primary forest that those in secondary forest and coffee
plantation and cultivated lands (Salam et al., 1998b).

4.1 Effects on Weeds and Other Vegetation

Changes in plant cover and microclimate may change the weed and vegetation
dominance. Salam et al. (1998b) report that the primary forest of Budi Syukur in
West Lampung was dominated by vegetation of Family Ficus like Ficus septica, F.
ampelas, and F. variegata, and those of Family Mevaceae (Hibiscus spp.). Also
found at lower frequencies and densities were Shorea spp., Hopea spp.,
Dipterocarpus sp., and Dryobalanops spp. In the primary forest of other locations
the dominant vegetation were Shorea spp., Hopea spp., Dipterocarpus sp., and
Dryobalanops spp. The dominant vegetation of the secondary forests at all
locations were Ficus septica, F. ampelas, and F. variegata, and the Family of
Mevaceae (Hibiscus spp.). Tomato, beans, and paddy were grown in the cultivated
lands.
The differences in the dominant vegetation had been reported to significantly
affect the soil chemistry and fertility of soils. This suggestion is supported by
abundant research results (Salam, 1996; Salam et al., 1997c ; Salam et al., 2001;
Rumpel et al., 2015; Baumert et al., 2018). For example, land-use change of bushes
to continuous cassava plantation in Gunung Batin North Lampung, Indonesia, also
resulted in the significantly decrease in soil CEC, organic matter content, and
available P (Table 4.2); also the decrease the availabilities of micronutrients (Salam
et al., 1997c). Treatment with cover vegetation for more than 3 years significantly
affected some soil chemical properties of coffee plantations (Table 4.3). Paspalum
conjugatum or natural vegetation caused higher values of organic C, total N,
available P, and enzymatic activities than did the control treatment with only coffee

Abdul Kadir Salam and Nanik Sriyani – 2019