Currently, the second highest populated country in the world is India. Though China is occupying the first place in highest population in the world, it is expected that India may become the highest populated country by as per World Population Data Sheet of The size of the population depends on its number and the ratio of available bearable resources. The population size also is contingent on the way resources are used and disseminated between the populations.
To meet the demands of forever growing human population, major agricultural fertile lands are getting converted into residential areas. The total available land area in India occupies 2. Added fertile land area exists in India than any other country except the USA and Canada, which are holding more water area [ 1 ].
Because of the availability of more arable land and water, India became an agriculture-based country. From ancient days, major Indian populations live in villages and revolve mostly around agriculture and allied activities. It is well exemplified with the statistics of Indian population since ; it is tripled due to improvised and sub-standard conditions in India [ 2 ]. However, due to enormous increase in population along with increased poverty, modernization and more effectively globalization and medication, majority of the adjacent villages of small towns and all most all large and moderate villages located around cities were urbanized.
Urbanization caused drastic conversion of arable agricultural land into modern housing.
The food scarcity is the predominant factor that influences the growth and economy of the overpopulated country. Supplementation of nutritious food to the forever growing human population in a nation like India or overall worldwide is at most target of governments or World United Nations.
Though the agricultural land area is getting reduced due to overpopulation in the world, it is the focus to produce sufficient or more amount of nutritious food to meet the demands of population. The conventional methods of agriculture may not produce or increase the food productivity. Alternative methods are in focus to produce high amount of food by using available agricultural land.
Since ancient days the traditional cultivation methods were contributed for the food and living safety throughout the world. But at the present day, farming is completely linked to high yield by usage of many varieties of pesticides. This type of farming certainly pollutes the environment and drags the farmer into debits due to high investment on crops in the case of crop failures, which ultimately cause suicides of the farmers and their families in developing countries like India. One of the reasons for this is majority of the farmers are focusing only on one crop at time where there is a high degree of uncertainty.
Efficiency of bioaugmentation in the removal of organic matter in aquaculture systems
Besides this, the usage of excess amounts of pesticides and fertilizers causes imbalance in ecosystem and alters the natural environment, which ultimately influences the flora and fauna of that area, including soil microbiota [ 3 ], which may cause drastic change in the livelihood and may also be one of the responsible factors causing severe change in natural cycle and seasons such as reduced rainfall, increase in the temperatures and short or prolonged yearly seasons besides health hazards in the consumers. To overcome the above circumstances, integration of various agricultural enterprises, viz.
The usage of expertise of conventional methods in combination of modern methods is well explained in many studies [ 4 , 5 , 6 ].
The conventional methods of agriculture are completely successful and are developed by farmers for different environments which maintain rich biological diversity [ 4 , 5 , 6 ]. According to Csavas [ 7 ] the livestock integrated system was started in between fourteenth and seventeenth centuries by growers. The motivation overdue in integrated rice-aquaculture farming RAF is to diminish unused matter from several subsystems on the farm.
The unused products generated during farming of subsystems were secondhand as contributions to other subsystems to progress the yield and minimize the cost of productivities for the several subsystems [ 8 ]. In this series, many methods were coming into picture to produce quality food. Best examples are the terrace farming, zero-acreage farming [ 9 ], mixed cropping, mixed farming, integrated farming, etc.
The integrated rice-fish co-culture is not a new method of producing food; for centuries, it has been in practice and is designated as globally important agricultural heritage system [ 10 ]. Due to its importance in many Asian countries including India, the present chapter deals with various aspects of integrated RAF. Integrated culture is not new and exists naturally. The natural ecosystem itself is a big example for integrated culturing where a number of flora and fauna living together in the same area of land.
Coming to the natural integrated system in the rice fields, besides fish species coming from outside through water, crabs grow by making burrows within the field. The best well-known natural example for integrated rice and aquatic species ASp is rice and freshwater crab culture. The freshwater crab Oziotelphusa Oziotelphusa senex senex enormously grow naturally in rice fields in India.
This crab is a good source of protein and is available throughout the year with no cost. Though the farmers do not focus on naturally occurring integrated rice systems like crab within the rice fields for commercial purpose, they understand the importance of more than one culture within the same field. One more thing that the farmers focused on is commercially important species and benefit out of its yield along with the main crop.
The culturing of ASp in the rice fields is originated from the farmers, who were experienced with fish along with prawns, crabs and other invertebrates grown naturally ASp moves from ponds to rice fields through irrigated water in the rice fields without adding any ASp seed in the irrigated field. The observation takes the farmers to culture ASp in the rice fields initially without any selection of the ASp. Later farmers are motivated to grow selected ASp with rice by following conventional methods based on the conditions of the local environment.
In the ancient days, the farmers tasted the yield of integrated rice-ASp culture. The uncontrolled entry of outside ASp into the integrated culture field and leaving the cultured ASp to outside the field are problems even today, but capture system of rice-ASp culture was introduced to overcome this problem [ 16 ].
In this system, cultured ASp purely depends on the naturally available feed in the field. But in general, farmers supplement feed for growing organism from outside. However, continuum in the transition from pure capture culture to a capture-based production system is gradual and is described by Halwart [ 17 ]. Integrated rice and aquatic species culture have lot of scopes and achievements of high productivity in terms of carbohydrate and protein with proper management methods and controlling systems.
The selection of culture species plays a crucial role in productivity, besides environmental conditions and proper management at the time of culturing. However, the farmers are in practice to cultivate the integrated rice and aquaculture in many areas of Asian countries and some of the African countries. Certain criteria should be followed while selecting the site land for integrated rice-aquaculture. The site selection for rice cum aquaculture farming is low lying area where water flows easily and is available at any time in needs.
The fertile soil rich in organic manure and with high water holding capacity is used for rice fields. In general, soils with medium texture and loam with silty clay are most preferable for RAF [ 18 ]. The topography and contours of the land will make the difference in preparation of rice field.
There are three types of rice fields identified such as: Perimeter-type field : the field in this type prepared with a moderate elevation and ground sloping on all sides into perimeter trenches which facilitates easy drainage. Central pond-type field : the pond is prepared in the middle of the rice field. Besides these three types, there are many types of trenches prepared for integrated rice-aquaculture.
In this, 0.
About 0. The other area of about 0. Different types of trenches in usage for rice-aquaculture integrated farming. A Diagonal trench, B crossed trench, C Y-shaped trench, D peripheral and one central longitudinal trench, E two equidistant transverses with peripheral trench and F latticed trenches. RAF had been in practice since years due to the constant profits of integrated culture. In this type, the rice and aquatic culture species are grown simultaneously in the same field. Both the rice and cultured species are harvested at the same time.
The synchronous rice-aquatic farming method has its own importance since it produces aquaculture protein with no additional cost; the cultured aquatic species secretes ammonia for rice growth besides destroying the weeds, tillering, enrichment of minerals digging activity and utilization of unused aquatic feed by the crop plant. This method of integrated culture is an old one and is familiar in the Asian countries. The stocking time after transplantation of rice seedlings varies from aquatic cultural species to species. The stocking procedure differs with the type of aquatic species growing fingerlings or fish or prawn or crab or mollusk or any other aquatic species.
Moreover, the number of crops produced every year is two in this case.
Beneficial Microorganisms in Agriculture, Aquaculture and Other Areas
Since having drawbacks in simultaneous rice-aquaculture farming, it was modified and established as alternative farming. Rice-aquaculture rotation is a simple method of farming where aquatic species were grown after harvesting of rice in the flooded fields without removing the rice stubbles.
The water levels were shallow in the case of rice, whereas for aquatic species, water depth is raised. In this method more than one ASp were raised [ 19 ]. The depth for growing aquatic species in the field is raised well before the transplantation of rice seedlings with a moderate height of external dyke. However, the pesticides used for rice production degrades during interval between harvesting of rice and stocking of aquatic species.
The rice stubbles in the water at the bottom of the field facilitate the growth of decomposing microbes which served as food for aquatic cultural species. The decomposition of stubbles enriches the water and soil with natural fertilizer utilized by the next cycle of rice where it helps to produce high yield. Besides this, sequential rice-aquaculture farming has many advantages such as i no limitation for depth of water neither in rice cultivation nor in aquatic species culture, ii maintenance of adequate water levels provides sufficient dissolved oxygen and water temperature, iii rice stubble decomposition facilitates microbial food for aquatic species and fertilizer for the next cycle of rice for improved production, iv useful for mono- and polyculture of aquatic species and v reduced attack of insect pest on rice fields due to interruption in their life cycle in rotation farming.
The relay farming is a complicated system compared to synchronous and alternative rice-aquaculture farming and is a combination of these two methods [ 19 ]. In this farming rice and aquatic species were started like synchronous farming, but the aquatic species are not harvested while rice species are harvested.
It means that relay farming requires longer period for aquaculture. It means this method requires additional rearing facility for transferring fish at the time of rice harvesting. Relay farming provides high amount of aquatic protein with high yield of rice crop with short duration. The drawback in this method is more investment and labor. The carp and prawn species are the most commonly used to produce protein in relay farming. Worldwide integrated farming of aqua with irrigation is becoming popular to produce more yield and makes the farmers economically strong.
It is well practised in the rainfed areas mainly in countries producing rice. Various types of aquaculture in the rice fields are in practice. The major aquatic species that come under finfish and shellfish are the cultural species used for integration with rice fields. Among finfish and shellfish, the two types of cultures brackish and freshwater species have importance to grow in RAF. But the selection of this species purely depends on the variety of rice growing. It is very particular that only certain rice species are productive in brackish water.
The rice varieties of holding salinity tolerance and floating-stem long-stemmed were preferred for brackish water RAF.