N Fertilization Dependent Bacterial and Archaeal …
75
5 Impact of Optimum N Fertilization Over Paddy
Microflora
Although public agitations on chemical fertilizers are rising up, scientific results
emphasis the positive effect of optimum N fertilization on paddy microbial community structure. Low N application coupled with high N use efficiency is achieved by
one time addition of zeolite along with inorganic N amendments [105]. Balanced
N (ammonium nitrate) fertilization has recorded increased rhizo-carbon deposition
by paddy roots thereby recruiting higher diversity of soil microbiome than the plant
grown without fertilizer application. Specifically, the population of Gram positive
bacteria in rhizosphere and bulk soil significantly increased on stable application of
ammonium nitrate based fertilizers [61]. Application of inorganic fertilizers rapidly
increased the potential nitrification rate in paddy ecosystem by rising up ammonia
oxidizing bacteria and archaea in comparison with N and NK applications [61]. The
significance of balanced N and P for regularity of nitrification process is evident from
the above said report. Yet another report depicts the synergistic effect of long-term
balanced chemical fertilizer and compost application in improving C sequestration
in light and heavy fraction of Korean paddy fields [52]. Remarkably, it has been
identified that optimum application of ammonium sulphate or lime nitrogen during
fallow season, improves paddy straw decomposition by shooting up the population
of decomposing microbes. This facilitates stable release of nutrients from paddy
straw thereby contributing to high soil fertility prior to next cropping season [90].
As described by Fierer et al. [31] , N fertilization exhibits little effect over bacterial
diversity but major effect over their community composition ultimately creating a
positive phylogenetic shift in paddy microbiota. However, optimal application of N
based chemical fertilizers exerts many positive effects over microbial community
structure and their functionality.
6 After-Effects of Imbalanced N Fertilization Over Paddy
Microflora
Agricultural systems globally prefer high fertilizer responsive varieties to achieve
higher grain yields to feed the growing population. This attitude gradually led to
dumping of huge quantity of fertilizers to rapidly increase the yield potential of food
crops such as rice. Imbalanced application of N fertilizers, more specifically the
higher dose may severely impart negative effects over paddy associated microbial
life and pollutes the soil and water ecosystem. China being the largest producer of
rice has reported that application of N fertilizers in most of the rice field exceeds the
environmentally optimum N rate by 45% and the rate of N application is 10% higher
75
5 Impact of Optimum N Fertilization Over Paddy
Microflora
Although public agitations on chemical fertilizers are rising up, scientific results
emphasis the positive effect of optimum N fertilization on paddy microbial community structure. Low N application coupled with high N use efficiency is achieved by
one time addition of zeolite along with inorganic N amendments [105]. Balanced
N (ammonium nitrate) fertilization has recorded increased rhizo-carbon deposition
by paddy roots thereby recruiting higher diversity of soil microbiome than the plant
grown without fertilizer application. Specifically, the population of Gram positive
bacteria in rhizosphere and bulk soil significantly increased on stable application of
ammonium nitrate based fertilizers [61]. Application of inorganic fertilizers rapidly
increased the potential nitrification rate in paddy ecosystem by rising up ammonia
oxidizing bacteria and archaea in comparison with N and NK applications [61]. The
significance of balanced N and P for regularity of nitrification process is evident from
the above said report. Yet another report depicts the synergistic effect of long-term
balanced chemical fertilizer and compost application in improving C sequestration
in light and heavy fraction of Korean paddy fields [52]. Remarkably, it has been
identified that optimum application of ammonium sulphate or lime nitrogen during
fallow season, improves paddy straw decomposition by shooting up the population
of decomposing microbes. This facilitates stable release of nutrients from paddy
straw thereby contributing to high soil fertility prior to next cropping season [90].
As described by Fierer et al. [31] , N fertilization exhibits little effect over bacterial
diversity but major effect over their community composition ultimately creating a
positive phylogenetic shift in paddy microbiota. However, optimal application of N
based chemical fertilizers exerts many positive effects over microbial community
structure and their functionality.
6 After-Effects of Imbalanced N Fertilization Over Paddy
Microflora
Agricultural systems globally prefer high fertilizer responsive varieties to achieve
higher grain yields to feed the growing population. This attitude gradually led to
dumping of huge quantity of fertilizers to rapidly increase the yield potential of food
crops such as rice. Imbalanced application of N fertilizers, more specifically the
higher dose may severely impart negative effects over paddy associated microbial
life and pollutes the soil and water ecosystem. China being the largest producer of
rice has reported that application of N fertilizers in most of the rice field exceeds the
environmentally optimum N rate by 45% and the rate of N application is 10% higher