Agriculture Reference
In-Depth Information
relentless efforts. The nutrients that are left in the soil may enter into the aquatic
environment causing eutrophication. In addition to the low nutrient efficiencies,
agriculture in developing countries including India is facing a problem of low
organic matter, imbalanced fertilization, and low fertilizer response that eventually
caused crop yield stagnation (Biswas and Sharma 2008 ). The fertilizer response
ratio in the irrigated areas of the country has decreased drastically. It has been
reported that 27 kg NPK ha 1 was required to produce one ton of grain in 1970,
while the same level of production can be achieved by 109 kg NPK ha 1 in 2008.
The optimal NPK fertilizer ratio of 4:2:1 is ideal for crop productivity, while the
current ratio is being maintained at 6.7:3.1:1 in India due to the excessive use of
nitrogenous fertilizers. In order to achieve a target of 300 million tons of food grains
and to feed the burgeoning population of 1.4 billion in the year 2025, the country
will require 45 Mt of nutrients as against a current consumption level of 23 Mt. The
extent of multi-nutrient deficiencies is alarmingly increasing year by year which is
closely associated with a crop loss of nearly 25-30 %. The extent of nutrient
deficiencies in the country is of the order of 90, 80, 50, 41, 49, and 33 % for N,
P, K, S, Zn, and B, respectively. Thus, from all sources, the country will be required
to arrange for the supply of about 40-45 Mt of nutrients by 2025 (Subramanian and
Tarafdar 2009 ).
Nanotechnology deals with particles measuring a dimension of one-billionth of a
meter or one-millionth of a millimeter. This enables atom-by-atom manipulation,
and thus processes or products evolved from nanotechnology are very precise and
hardly possible to achieve through conventional methods. This fascinating field of
science has been exploited widely in engineering, health, electronics, and material
sciences, and agricultural scientists have begun to use it as a tool to improve the
input use efficiencies by integrating nanotechnological approaches in the conven-
tional production system. In this context, there would be greater importance of the
information about how to increase the NUE of fertilizers by nanotechnology in the
coming years.
In this chapter, current status of understanding of nano-fertilizer formulations
and its associated effects on crop production systems has been narrated.
3.1.1 Nano-fertilizers
Nano-fertilizers are nutrient carriers of nano-dimensions ranging from 30 to 40 nm
(10 9 m or one-billionth of a meter) and capable of holding bountiful of nutrient
ions due to their high surface area and release it slowly and steadily that commen-
surate with crop demand. Subramanian et al. ( 2008 ) reported that nano-fertilizers
and nanocomposites can be used to control the release of nutrients from the
fertilizer granules so as to improve the NUE while preventing the nutrient ions
from either getting fixed or lost in the environment. Nano-fertilizers have high use
efficiency and can be delivered in a timely manner to a rhizospheric target. There
are slow-release and super sorbent nitrogenous and phosphatic fertilizers. Some
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