Page 64 - Ilmu Tanah

The Chemistry and Fertility of Soils under Tropical Weeds 51

physiological characteristics and effectiveness towards weeds. In 2008, there were
1.082 trademarks of pesticides among which 200 were trademarks of herbicides
with more that 30 active substances (Komisi Pestisida Indonesia, 2008). Therefore,
to accurately determine herbicides to apply, knowledge on weed types and on the
method to choose accurate herbicides are of great importance. It is also important
to determine accurate herbicide dose and concentration as recommended in
herbicide label. Lower doses may lower herbicide effectiveless, while higher dose
may waste herbicide and may also contaminate the environment (Sriyani, 2010).
Herbicides must also be applied in time. In general, the best time to apply
herbicides is during weed growth phase at which weeds are most vurnerable at
suitable environmental condition. In general it needs several hours (about 2-5
hours) for herbicides to enter plant tissues, therefore, farmers must avoid raining
time to apply herbicides. Herbicide is generally applied most accurately in a clear
sunny morning with no wind. Herbicides must also be applied with an approriate
technique using appropriate application tools for particular land condition and
weed types and is also affected by the skills of operators in operating application
tools so that the herbicide applied is evenly distributed.
It is obvious that the success and safety of chemical weed control using
herbicides is dependent on various things all of which are related to the knowledge
and skills of farmers and also farmers awareness to control safety aspects in
applying and handling herbicides. However, based on experience, farmers like
completely clear lands and, therefore, they tend to apply herbicides repeatedly
more that actually needed. Miscalculation of herbicide dose and concentration,
low understanding of the working mechanism of herbicides and of the negative
effect of herbicides on land quality, crop productivity, and the probability of weed
resistance on herbicides are some of the weaknesses in applying chemical weed
control (Sriyani, 2009). Therefore, efforts must always be conducted to educate
farmers on the importance of safety and the negative effects of herbicides on
human life, and enviromental quality in using herbicides without sacrifying land
and crop productivity.
Efforts to ban farmers not to use herbicides is not possible because there is
condition where applying herbicides is the last choice to help farmers. Therefore,
the best approach is to manage the use of herbicides wisely by enhancing
knowledge and skills among farmers. Thereby, farmers may control weeds more
effectively by using various herbicides combined with other methods of weed
controls so that the effectiveness of weed control stays high and at the same time

Abdul Kadir Salam and Nanik Sriyani – 2019