64
S. Ambreetha et al.
1 Paddy as Microhabitat
Rice (Oryza sativa L.) serves major population in the world as a staple food crop
cultivated with the area of 160 million ha which meets dietary requirement of nearly
half the globe [24]. However, the global rice production falls under both irrigated
and rainfed conditions, they are predominantly cultivated in flooded systems. Rice
still stands as a dynamic model for number of ecological and environmental studies
besides their sustainability and nutrient recycling capacity [8] and regarded globally
as largest man-made wetland system. Prolonged flooded condition for the cultivation of crop is a fore runner for organic matter accumulation and carbon management. Growing population puts pressure on land to multiply the yield to feed them
which sets step for numerous management practices which paved way for intensive fertilization. Driven towards the desire for greater yields, imbalanced and over
fertilization posed series of environmental concerns [49] like decreased nutrient use
efficiency, adverse effect on soil microbial biomass and community composition
[35] etc., Input nutrient utilization and recycling by active microbes in the soil serve
as a reason making the system productive. Redox process under flooded system
governs nutrient availability, their cycling and transformations, and ecological functions which is an add-on reason for holding unique functions. On comparison with
upland crop, lowland paddy systems are conquered by distinct biotransformation of
carbon and nitrogen mediated by microbial communities [34]. Over the last decades,
there is a substantial increase in rice yield with the use of various N fertilizers [68]. On
the other hand, microbial soil processes affect N dynamics and therefore it is important to study their interrelation with microbial community. Microbial flora which
embodies healthy soil is affected by various management practices in which fertilization plays pivotal role. In a study in long-term permanent manurial experimental
plot, the fractions of soil organic carbon, microbial biomass carbon, culturable microbial counts and dehydrogenase and β-glucosidase activities increased significantly
in green manure amended soil. Further higher nitrifier population was evident in
inorganic or integrated organic and inorganic fertilizer [73].
1.1 Soil Characteristics
Rice cultivation under flooded condition exhibits distinct physico-chemical properties and encounters diversified microflora responsible for numerous biochemical
activities. They serve as an excellent model for acquiring insights on soil ecological
processes [103]. The biological changes endowed with them paves way for typical
succession of chemical transformations. The soil under submergence creates condition reducing the oxygen supply into the soil whose diffusivity in water is 10,000
times lower than in air [43]. Meanwhile, organic matter and photosynthates accumulation [115] contribute for reduction process in soil and oxidation of organic matter
S. Ambreetha et al.
1 Paddy as Microhabitat
Rice (Oryza sativa L.) serves major population in the world as a staple food crop
cultivated with the area of 160 million ha which meets dietary requirement of nearly
half the globe [24]. However, the global rice production falls under both irrigated
and rainfed conditions, they are predominantly cultivated in flooded systems. Rice
still stands as a dynamic model for number of ecological and environmental studies
besides their sustainability and nutrient recycling capacity [8] and regarded globally
as largest man-made wetland system. Prolonged flooded condition for the cultivation of crop is a fore runner for organic matter accumulation and carbon management. Growing population puts pressure on land to multiply the yield to feed them
which sets step for numerous management practices which paved way for intensive fertilization. Driven towards the desire for greater yields, imbalanced and over
fertilization posed series of environmental concerns [49] like decreased nutrient use
efficiency, adverse effect on soil microbial biomass and community composition
[35] etc., Input nutrient utilization and recycling by active microbes in the soil serve
as a reason making the system productive. Redox process under flooded system
governs nutrient availability, their cycling and transformations, and ecological functions which is an add-on reason for holding unique functions. On comparison with
upland crop, lowland paddy systems are conquered by distinct biotransformation of
carbon and nitrogen mediated by microbial communities [34]. Over the last decades,
there is a substantial increase in rice yield with the use of various N fertilizers [68]. On
the other hand, microbial soil processes affect N dynamics and therefore it is important to study their interrelation with microbial community. Microbial flora which
embodies healthy soil is affected by various management practices in which fertilization plays pivotal role. In a study in long-term permanent manurial experimental
plot, the fractions of soil organic carbon, microbial biomass carbon, culturable microbial counts and dehydrogenase and β-glucosidase activities increased significantly
in green manure amended soil. Further higher nitrifier population was evident in
inorganic or integrated organic and inorganic fertilizer [73].
1.1 Soil Characteristics
Rice cultivation under flooded condition exhibits distinct physico-chemical properties and encounters diversified microflora responsible for numerous biochemical
activities. They serve as an excellent model for acquiring insights on soil ecological
processes [103]. The biological changes endowed with them paves way for typical
succession of chemical transformations. The soil under submergence creates condition reducing the oxygen supply into the soil whose diffusivity in water is 10,000
times lower than in air [43]. Meanwhile, organic matter and photosynthates accumulation [115] contribute for reduction process in soil and oxidation of organic matter