Agriculture Reference
In-Depth Information
the help of some endomycorrhizal fungi was reported that could reduce copper
toxicity in the contaminated soils (Manceau et al.
2008
).
Increased applications of engineered carbon-based nanomaterial increase con-
cerns about their toxicity to humans and animals. Carbon nanomaterials, such as
single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes
(MWCNTs), and carbon buckyballs, also found increased applications in the field
of agriculture and food. This raised questions regarding the safety of using such
nanomaterials with crops. Various studies showed contradictory results on the
phytotoxicity of carbon nanomaterials in plants. The effects of functionalized
SWCNTs (fCNTs, functionalized with poly-3-aminobenzenesulfonic for high
dispersibility) and nonfunctionalized SWCNTs (CNTs) on root elongation of six
different crop species (cabbage (
Brassica oleracea
), carrot (
Daucus carota
),
cucumber (
Cucumis sativus
), lettuce (
Lactuca sativa
), onion (
Allium
sp.)) have
been extensively studied (Buzea et al.
2007
).
3.6 Nanocomposites
Nanocomposites have been developed in order to supply wide range of nutrients in
desirable properties. These compounds are capable of regulating the inputs
depending on the conditions of soil or requirement of crops. Zinc-aluminum
layered double-hydroxide nanocomposites have been used for the controlled release
of nutrients that regulate plant growth (Hossain et al.
2002
). In soil niches,
nanomaterials are porous and hydrated, and as such they control moisture retention,
permeability, solute transport, and availability of plant nutrients in soils. These
nanomaterials also control exchange reactions of dissolved inorganic and organic
species between the soil solution and colloidal surfaces. The physicochemical
properties in the surface of nanocomposites provide much of reactivity to soil
biological and abiotic processes (Navrotsky
2004
). Zhang et al. (
2006
) reported
that results of measurements on nutrients of wheat plant showed that in treatments
with the five kinds of bulk-blended SRFs, the contents of NPK absorbed by wheat in
shooting period were higher than that of chemical fertilizer of equal amount of
NPK, which was consistent with the rule of nutrients demanded by wheat. Liu
et al. (
2005a
) reported that the organic material was intercalated in the layers of
kaoline clays, and the natural kaoline exfoliated into nanometer-sized layers. The
organic agent and clays formed nanocomposites through hydrogen bond combina-
tion. The SEM pictures of polystyrene-starch nano-subnanocomposites showed
that many pores were present on the surface of film at sizes ranging from 10 to
20 nm. These nano-subnanocomposites were used as the cementing and coating
materials of slow-/controlled-release fertilizer.
Liu et al. (
2006
) studied the nitrogen slow-release behavior of the
superabsorbent nitrogen fertilizer (SSNF) in water and water retention capacity of
the soils with SSNF. They reported that the surface cross-linked product not only
had good slow-release property but also excellent soil moisture preservation
