Agriculture Reference
In-Depth Information
nanoparticle is a particle with at least two dimensions below 100 nm, nanofertilizers
could soon offer a technological solution to the nutrient-loss problem, thereby aiding
technologically-minded farmers and subsistence farming. Nanofertilizers refer to
nanoscale-dimension products that deliver nutrients to crops. These nutrients can be i)
encapsulated inside nanomaterials such as nanotubes or nanoporous materials, ii) coated
with a thin protective polymer film, or iii) delivered as particles or emulsions. It has been
reported that nanoparticles and nanotubes in numerous crops (sunflower, common bean,
and maize, among others) have enhanced germination and seedling growth, physiological
activities including photosynthetic activity and nitrogen metabolism, mRNA expression
and protein level, and positive changes in gene expression, indicating their potential use
for increasing crop yields. Nevertheless, additional research is necessary in order to
understand the effect of nanofertilizers on the genetic, physiologic, and morphologic
changes in crops, as well as their effect on soil microbial communities, symbioses,
physicochemical soil properties, and pollution. One may speculate that the creation and
improvement of fertilizers at nanoscale dimensions could have a profound impact on
energy, the economy and the environment. Speculation notwithstanding, the scientific,
technical, and agricultural projects linked with nanofertilizers must include side effects in
order to accurately determine progress and shape a sustainable future.
Keywords:
Nanomaterials, crop yield, nanofertilizers, soil fertility, plant nutrition
I
NTRODUCTION
Although no clear definition of
nanofertilizer
exists, it is commonly defined as those
materials of nanoscale dimensions (i.e., < 100 nm) and specific function, which are added to a
soil to supply one or more plant nutrients essential to the growth of plants. It is well known
that 16 nutrient elements are required to grow crops (Table 1). Three essential nutrients,
known as structural elements [carbon (C), hydrogen (H), and oxygen (O)], are absorbed from
atmospheric carbon dioxide and water. The other 13 nutrients are absorbed from the soil;
these are usually grouped as primary nutrients, secondary nutrients, and micronutrients.
Additionally, as shown in Table 1, seven elements [Nickel (Ni), Selenium (Se), Vanadium
(V), Sodium (Na), Silicon (Si), Cobalt (Co), and Aluminium (Al)] are known as beneficial
elements for plants, i.e., they are not required by all plants but can promote plant growth and
may be essential for particular taxa (Hawrylak-Nowak, 2009; Pilon-Smits et al
.
, 2009; Sae-
Lee et al., 2012; Saco et al., 2013). However, the beneficial effects of low doses of Al, Co,
Na, and Se have received little attention compared to the toxic effects that typically occur at
higher concentrations (Pilon-Smits et al., 2009).
The primary nutrients are nitrogen (N), phosphorus (P), and potassium (K); these are
commonly found in blended fertilizers or equivalent grades. Indeed, crops utilize primary
nutrients more frequently than other nutrients; therefore, primary nutrients are applied at
higher rates than secondary nutrients and micronutrients. Secondary nutrients are calcium
(Ca), magnesium (Mg), and sulfur (S); these are required by crops in smaller amounts. The
least frequently used nutrients are the micronutrients: iron (Fe), manganese (Mn), zinc (Zn),
copper (Cu), boron (B), molybdenum (Mo), and chlorine (Cl).
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