Agriculture Reference
In-Depth Information
Fig. 11.5 Kinetic curves of controlled desorption of urea (mg/g) for (a) pure spherical urea and
(b) different hydrogels at pH 9.0. Reprinted (adapted) with permission from Bortolin et al. (
2013
),
copyright 2014 American Chemical Society
11.3 Controlled- or Slow-Release Systems Applied
to Pesticides
The use of agricultural pesticides is an essential practice for the protection of crops
against pests, diseases, and weeds because they compete with crops for water, light,
nutrients, and space, thereby reducing crop production. Weeds can also host pests
and diseases (Ratnadass et al.
2012
). Pesticides are substances or mixture of sub-
stances intended to prevent, destroy, repel, or mitigate any pest. Agriculture will
always have to deal with crop losses caused by these biotic stresses. In this way,
during the last 50 years, the use of pesticides has contributed to improve the
production and productivity of crop harvest, providing a better quality of crops
and supplies and thus contributing to the promotion of human health (Soane
et al.
2012
).
According to Arias-Est´vez et al. (
2008
), 60-70 % of pesticides used in agri-
cultural fields do not reach the target surface, and these fractions are lost in the
environment. Therefore, pesticides have become one of the most important organic
pollutants found in water and soil, generating concerns about their effects to the
environment and human life (Canle et al.
2001
). The controlled release of agricul-
tural pesticides could be a promising strategy to reduce the applied amount of these
agrochemicals, reducing their impact on the environment and human health and
reducing farming costs (Fern´ndez-P´rez et al.
2004
; Sopen˜ et al.
2007
; Bessac
and Hoyau
2013
).
The application rates for conventional formulations of herbicides are generally
higher than the minimum dosages required, allowing losses by degradation,
leaching, volatilization, and adsorption (Muro-Su˜´ et al.
2005
). In addition to
the significant increase in costs of agrochemicals per application, super dosages are
sources of environmental contamination. Pesticides have become one of the largest
organic pollutants of water and soil, generating worries related to their effects on
the environment and human life (Canle et al.
2001
; Giacomazzi and Cochet
2004
;
