**2.2. Rice and aquaculture**

RAF had been in practice since years due to the constant profits of integrated culture. However, the generally practised rice-aquaculture is categorized into three major types [19],

**Figure 1.** Perimeter-type rice field used for rice-aquaculture integrated farming.

from outside. However, continuum in the transition from pure capture culture to a capture-

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

Certain criteria should be followed while selecting the site (land) for integrated rice-aquaculture. The selected area (place) should have an optimum rainfall of 80 cm in a year; the lands with uniform contour and high water retaining capacity of land are considered for site selection. 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

The topography and contours of the land will make the difference in preparation of rice field.

**a.** *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. The middle of

**b.** *Central pond-type field*: the pond is prepared in the middle of the rice field. This is the easiest way to produce trench for integrated aquaculture and rice production (**Figure 2**). **c.** *Lateral trench-type field*: trenches were prepared on one or both sides of rice slopes (**Figure 3**).

Besides these three types, there are many types of trenches prepared for integrated riceaquaculture. Different other types of trenches in the rice field are presented in **Figure 4**. The ideal ratio for making an integrated RAF is explained well, for example if a 1 hectare of land of integrated system is about 125 m × 125 m. In this, 0.67 hectares is the area to be used for rice, i.e. 102.5 m × 102.5 m, whereas 7.5 m × 440 m for four sides of the field which is equal to 0.21 hectares were used for aquaculture (fish, crustacean and other aquatic animal culture). About 0.12 hectares of area, i.e. 3.75 m × 485 m, will be used as embankment area. The other area of

RAF had been in practice since years due to the constant profits of integrated culture. However, the generally practised rice-aquaculture is categorized into three major types [19],

based production system is gradual and is described by Halwart [17].

countries and some of the African countries.

loam with silty clay are most preferable for RAF [18].

There are three types of rice fields identified such as:

the land is the growing area for rice (**Figure 1**).

about 0.04 hectares is used for planting fruits.

**2.2. Rice and aquaculture**

**2.1. Site selection**

14 Aquaculture - Plants and Invertebrates

*2.1.1. Rice field selection*

**Figure 2.** Rice field with central pond system for rice-aquaculture farming.

namely, (1) synchronous/combined/simultaneous farming, (2) sequential/rice-aquaculture rotation/alternate farming and (3) relay farming.
