Agriculture Reference
In-Depth Information
nutrient solution, maintenance of oxygen demands, and pH are factors that need
attention while using this method of nutrient delivery. Supporting materials (sand,
gravel, etc.) are also employed in certain commercial application. In this case,
nutrient solution is flushed from one end and old solution is removed from the other
end. The disadvantages with this method are frequent pathogen attack and high
moisture rates which may cause over wilting of soil-based plants.
4.5.2
In Vivo Methods
4.5.2.1 Soil Application
Soil application is the most common method of nutrient supplement using chemical
and organic fertilizers. The factors that need attention while choosing this method
of fertilizer applications are how long the fertilizer will last in the soil, soil texture,
soil salinity, and plant sensitivities to salts, salt content, and pH of the amendment.
It is well known that negative soil particles affect the adsorption of mineral
nutrients. The anion exchange capacity of most agricultural soils is small compared
to cation exchange capacity. Among anions, nitrate remains mobile in the soil
solution and is susceptible to leaching by water moving through the soil. Phosphate
ions bind to soil particles containing aluminum or iron because the positively
charged Fe
2+
,Fe
3+
, and Al
3+
have OH
group that exchanges with phosphate. As
a result, phosphate can be tightly bound, and its mobility and availability in soil can
limit plant growth (Taiz and Zeiger
2010
).
4.5.2.2 Foliar Application
In this method, liquid fertilizers are directly sprayed onto leaves. It is generally used
for the supply of trace elements. Foliar application can reduce the time lag between
application and uptake by plant during the rapid growth phase. It can also circum-
vent the problem of restricted uptake of a nutrient from soil. Uptake of iron,
manganese, and copper may be more efficient with this method as compared to
soil application where they get adsorbed on soil particles and hence are less
available to root system (Taiz and Zeiger
2010
). As stomata and leaf epidermal
cells are majorly involved in nutrient uptake, foliar application method can have
agronomic advantage if used for nano-fertilizers. However, damage to the leaves
must be minimized in such cases by standardization of application protocol. The
shortcomings of this method include specific time (morning and evening) of
spraying because the stomata open during these time periods only. Another disad-
vantage is the possibility of plant damage if correct concentration of chemical
(fertilizer) is not applied.
