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The Chemistry and Fertility of Soils under Tropical Weeds   35















                           Chapter 3


                           The Important Facts about Tropical

                           Weeds




                                                                          3.1  The Concept of Weeds
                                                                     3.2  Weeds as Pioneer Vegetation
                                               3.3  General Effects of Tropical Weeds on the Soil Environment
                                                                        3.4  Methods of Weed Control
                                                                                    Key Questions



                           H
                                 uman life has never been free from the presence of weeds that directly or
                                 indirectly disturb the human activities.  The most important direct negative
                                 effects of weeds may include the decrease in the quantity and quality of
                           crop  products  that  may  cause  direct  negative  effects  on  the  farmer’s  economy.
                           Some other negative effects are the presence of weed allelopathy that may poison
                           the main crops, the difficulties in manual and mechanical crop harvesting, the role
                           of weeds as hosts of plant pests and diseases, as well as the decrease in land values
                           due  to  weed  infestation  (Sembodo,  2010).    Weeds  may  also  disturb  lands  for
                           conservation  and  recreation,  lower  land  esthetics,  decrease  the  environmental
                           quality, and disturb the animal, human, and wildlife health and existence.



                                                          Abdul Kadir Salam and Nanik Sriyani  – 2019
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