169
part of ametryn (pKa = 4.10) exists as a positively charged conjugate acid (de Paula
et al. 2016). The electrostatic interaction between the ametryn conjugate and the
ionized soil particles is enhanced resulting in a more stable structure. As a result,
ametryn is more persistent in acidic soils (de Paula et al. 2016). According to Meyer
and Heathman (2015), the soils under intensive sugarcane production in Chikwawa,
southern Malawi, have become acidic. Very high temperatures (above 35 °C) coupled with frequent irrigation or flooding may also have contributed to soil acidification through soil mineral leaching in Chikwawa. In addition, burning crop residues
removes excess positively charged ions contained in plant material, which are necessary for balancing negatively charged ions in organic molecules. This could neutralize the soil acidity upon decomposition (Rengel 2011). This scenario would
increase the probability of soil contamination and negatively affect soil-dwelling,
non-target organisms.
4 Conclusion
In summary, temperature and the timing and amount of rainfall will continue to influence degradation, sorption and transport of pesticides used in sugarcane production.
Higher temperature will negatively affect pesticide toxicity, prompting farmers to
use more and/or change pesticides. There is greater risk of pesticides contaminating
water bodies through the runoff and erosion of sorbed pesticides. The persistence of
pesticides such as ametryn and glyphosate may be higher in acidic soils. This study
highlights the need to determine the occurrence of pesticide residues in sugarcane
cropping and aquatic systems surrounding sugarcane plantations.
Acknowledgements This review was funded through the program ‘Capacity Building for
Managing Climate Change in Malawi (CABMACC)’. CABMACC is a completed collaborative
program supported by the Norwegian Government and the Government of the Republic of Malawi
and implemented by the Department of International Environment and Development Studies
(Noragric) at the Norwegian University of Life Sciences (NMBU) and Lilongwe University of
Agriculture and Natural Resources (LUANAR), Malawi.
References
Adhikari U, Nejadhashemi AP, Woznicki SA (2015) Climate change and eastern Africa: a review
of impact on major crops. Food Energy Secur 4(2):110–132
Aktar MA, Sengupta D, Chowdhury A (2009) Impact of pesticides use in agriculture: their benefits
and hazards. Interdiscip Toxicol 2(1):1–12
Bloomfield JP, Williams RJ, Goody DC, Cape JN, Guha P (2006) Impact of climate change on
the fate and behavior of pesticides in surface and groundwater – a UK perspective. Sci Total
Environ 369:163–177
Bonnett GT, Hewitt ML, Glassop D (2006) Effects of high temperature on the growth and composition of sugarcane internodes. Australian J Agric Res 57(10):1087–1095
Impact of Climate Variability on the Use and Exposure of Pesticides in Sugarcane…
part of ametryn (pKa = 4.10) exists as a positively charged conjugate acid (de Paula
et al. 2016). The electrostatic interaction between the ametryn conjugate and the
ionized soil particles is enhanced resulting in a more stable structure. As a result,
ametryn is more persistent in acidic soils (de Paula et al. 2016). According to Meyer
and Heathman (2015), the soils under intensive sugarcane production in Chikwawa,
southern Malawi, have become acidic. Very high temperatures (above 35 °C) coupled with frequent irrigation or flooding may also have contributed to soil acidification through soil mineral leaching in Chikwawa. In addition, burning crop residues
removes excess positively charged ions contained in plant material, which are necessary for balancing negatively charged ions in organic molecules. This could neutralize the soil acidity upon decomposition (Rengel 2011). This scenario would
increase the probability of soil contamination and negatively affect soil-dwelling,
non-target organisms.
4 Conclusion
In summary, temperature and the timing and amount of rainfall will continue to influence degradation, sorption and transport of pesticides used in sugarcane production.
Higher temperature will negatively affect pesticide toxicity, prompting farmers to
use more and/or change pesticides. There is greater risk of pesticides contaminating
water bodies through the runoff and erosion of sorbed pesticides. The persistence of
pesticides such as ametryn and glyphosate may be higher in acidic soils. This study
highlights the need to determine the occurrence of pesticide residues in sugarcane
cropping and aquatic systems surrounding sugarcane plantations.
Acknowledgements This review was funded through the program ‘Capacity Building for
Managing Climate Change in Malawi (CABMACC)’. CABMACC is a completed collaborative
program supported by the Norwegian Government and the Government of the Republic of Malawi
and implemented by the Department of International Environment and Development Studies
(Noragric) at the Norwegian University of Life Sciences (NMBU) and Lilongwe University of
Agriculture and Natural Resources (LUANAR), Malawi.
References
Adhikari U, Nejadhashemi AP, Woznicki SA (2015) Climate change and eastern Africa: a review
of impact on major crops. Food Energy Secur 4(2):110–132
Aktar MA, Sengupta D, Chowdhury A (2009) Impact of pesticides use in agriculture: their benefits
and hazards. Interdiscip Toxicol 2(1):1–12
Bloomfield JP, Williams RJ, Goody DC, Cape JN, Guha P (2006) Impact of climate change on
the fate and behavior of pesticides in surface and groundwater – a UK perspective. Sci Total
Environ 369:163–177
Bonnett GT, Hewitt ML, Glassop D (2006) Effects of high temperature on the growth and composition of sugarcane internodes. Australian J Agric Res 57(10):1087–1095
Impact of Climate Variability on the Use and Exposure of Pesticides in Sugarcane…