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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
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