*2.3.1.1. Shrimp/prawn production*

Shrimps are grown in brackish water, whereas prawns grow in freshwater. The shrimp production is done with the fields of holding salty water located in west coast and deltaic areas of eastern India where the salt-resistant rice varieties are grown. Due to limited availability of salt water, only one crop (integrated rice-shrimp farming) is grown mostly in the months of July to September every year. The channels are arranged to control the water supply into the field or pond during harvesting of rice, and the shrimp is protected in the ponds/trenches. At this stage, rice field consists of substantial number of shrimp larvae having less water. The shrimp harvesting in this case is usually done after 3 months of rice harvest. To clearly say the method followed to culture rice and shrimp is through alternative system (semi-intensive monoculture) with few modifications and balanced diet supplied during the culture. The average production rate of shrimp per hectare in this method is 1440 kg. *Penaeus monodon* is the most common species grown in this type of culturing. *Penaeus merguiensis, Penaeus indicus* and *Metapenaeus ensis* are alternative species to grow in this type of system.

specific time of spray at which crabs stay in burrows. Proper water management prevents the crab from escaping from rice fields. The average crab protein produced in rice-crab system is approximately 600 kg/hectare. The systematic management of crab culture changes the farmers socioeconomic status than the shrimp/prawn culture alone [39, 40] in addition, these crabs are more eco-friendly and grow easily in polyculture with other species [41, 42]. The only limitation in crab culture is limited availability of wild seed and is overcome by establishing crab hatchery industry to protect natural broodstock for continuous supply of seed [43]. The sequential or synchronous farming is the adaptable system for rice-crab

Integrated Rice and Aquaculture Farming http://dx.doi.org/10.5772/intechopen.78062 21

Similar to crabs, crayfishes are the strongest crustaceans that tolerate unfavorable conditions than other species. The most common species used in rice-crayfish integrated system are *Procambarus clarkii* and *Cherax quadricarinatus*. The rice-crayfish culture is common in Southern United States (*Procambarus clarkii*) and in Australia (*Cherax quadricarinatus*). The adult crayfish is used as broodstock to get seed in the ponds. The broodstock is released into field after 1 week of rice seedling implantation. On the other hand, the crayfish seed is also obtained from hatcheries. Besides this the seed also obtained from the rice-crayfish integrated system after harvesting, where the adult crayfish produce juveniles which are used as seed for immediate culture. Unlike other crustaceans rice-crayfish culture is also done with sequential farming. In this system before 2 weeks of harvesting the rice, the water is drained to facilitate crayfish to make burrows [44]. Watering the field after harvesting leads to growth of ratoon crop (occurrence of regrowth from rice stubbles) and facilitates the growth of insects, zooplankton, worms and molluscs, which promotes the direct growth of flushed out crayfish from the burrows [45]. The optimum weight for harvesting crayfish is about 15–60 g. The

Many other aquatic species can be integrated with rice culture. The typical integration of

The profit of rice-aquaculture integrated culture created a scope for betterment of social-economic status of farmers. Using this as a concept, the farmers tried to integrate other livestock with RAF. There are many systems evolved in this way and mentioned in **Table 1**. However,

Individually the rice and aquaculture systems are separate entities but are mostly holding common requirements. Because of commonality in system management, the integrated RAF is prospective and profitable. However this integrated system has conflict in requirements and their management from one system to other. The modified interventions are required to overcome these problems at each and every aspect and step of system management. Besides selection of species (both rice and aquatic species) explained earlier, integrated system

aquaculture with rice system followed in Asian countries is presented in **Figure 6**.

the livestock rearing with RAF is in primitive stage and has its own limitations.

requires many other factors to manage and is explained hereunder.

culture, which depends on type of crab species growing.

average yield of crayfish in this system is about 1960 kg/hectare [46].

**2.4. Rice-aquaculture farming with livestock**

**2.5. Management of rice-aquaculture farming**

*2.3.1.3. Crayfish production*

The most popular species of freshwater prawn grown in the integrated rice-prawn culture is *Macrobrachium rosenbergii* (*M*. *rosenbergii*). The monoculture of *M. rosenbergii* in the rice fields is in practice in North Kuttanad, where almost 248 hectares are cultivated integrated riceprawn culture in a year [34]. Like rice-shrimp farming, the alternative system of culturing is adapted for rice-prawn culture (semi-intensive monoculture). The productivity of prawn monoculture with rice is around 700 kg/hectare. On the other hand, the polyculture of prawn (*M. rosenbergii*) along with fish (*Catla catla*, *Labeo rohita* and *Ctenopharyngodon idella*) in the rice fields is also in practice, where the productivity of prawn is 285 kg/hectare, which has almost two times less production of monoculture of prawn in the integrated system. The yield of *Penaeus monodon* with mixed cultures in the rice fields is about 2135 kg/hectare [35].
