Agriculture Reference
In-Depth Information
Fig. 2.3 The application of nanotechnology to fertilizer inputs can best be divided into three
categories: nanoscale fertilizer inputs, nanoscale additives, and nanoscale coatings or host mate-
rials. These three categories do have some degree of overlap, meaning some products may fall into
more than one category
2.2.1 Nanoscale Fertilizer Inputs
In this family, fertilizer inputs have been prepared in the form of particles or
emulsions with nanoscale dimensions. Generally, the claim is made that reducing
the size of the input leads to improved uptake and better overall release efficiency
providing better efficacy with a lesser amount required. However, many patents and
patent applications make these efficiency claims and further claims that their
formulation lacks toxicity, but in most cases, little evidence is provided to corrob-
orate these statements. Furthermore, many examples give minimal physical evi-
dence for the size and monodispersity of their input particles (e.g., microscopy,
dynamic light scattering, etc.).
Fertilizer nano-objects, including particles prepared from urea, ammonium salts,
peat, and other traditional fertilizers, fall under this category. Notably, both chem-
ical and organic-based fertilizers are represented in this category. For example, a
peat/bacteria composite granulated to the nanoscale is claimed to lead to improved
soil fertility over bulk fertilizer treatment (Wang 2008 ). Both chemical and physical
approaches have been explored for the preparation of urea nanoparticles. A chem-
ical process has been used to deposit urea on calcium cyanamide cores yielding a
nanoparticle fertilizer formulation (Wan 2004 ). A nanoparticle formulation pre-
pared by grinding a mixture of urea, bacteria, plant antibiotics, and an NPK
composite fertilizer down to nanoscale dimensions has also recently been patented
(Wang et al. 2008a ). In some instances, a mixture of physical and chemical or
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