Rice fish crop rotation in valley dists of Manipur

Yumnam Bedajit, Sagolsem Sumangal and Thokchom Robindro
Manipur is located in the North Eastern Hill region of India that lies at latitude of 23083’N and 25068’N and longitude of 93003’E and 94078’E having a total area of 22,347 square kilometres. It is a hill grit state where the hills constitute 90.9% area with various altitudes ranging from 2,000 to 3,000 meters above the mean sea level. Further the state capital locates in the middle of the oval-shaped valley running from north to south encompassing approximate land area of 700 square miles (2,000 km2) surrounded by deep blue mountains on all sides at an elevation of 786 meters above the sea level.
The people of North-Eastern Hill Region depend on diverse agricultural practices ranging from a variety of shifting aquaculture systems, fallow systems, home gardens and sedentary systems, such as wet-rice cultivation. In North-Eastern Hill Region, the system of raising fish in the rice fields probably borne out of rice cultivation practice itself at water logged rice fields form natural habitat for wild fish and reportedly believed to have appeared first only as the simple capture device.
Manipur being a predominant agrarian state, the area of first crop/pre-kharif/spring rice (February- March to June-July) is decreasing due to many factors. The factors are non-availability of suitable, preferred rice variety, lodging and sprouting of mature grains of the existing rice variety during harvest due to rain, out yielding of only one proper main crop to the total of two crops i.e. first and second crops, meagre area of irrigated fields, expansion of Loktak and other major lakes due to Loktak Hydel Power Project, conversion of rice fields into fish ponds. Hence, the present study was carried out to improve or alter the existing practice of rice fish rotation of the farmers.
The study was carried out for three consecutive years in the valley districts of Manipur viz. Imphal East, Imphal West, Thoubal and Bishnupur districts. 20 numbers of fish farms with an area of 0.5 ha each were selected from the valley districts of Manipur. Study was conducted during the years 2014 to 2016 in the field of twenty farmers under refined System of rice Intensification method (without ploughing, fertilizer or manure). After the harvest of fish in the month of February, rice nursery was raised. As the nursery was ready by 15-17 days (longer due to low temperature) the water from the farm is completely drained out and the soil bed is allowed to settle down. Plots were prepared and seedlings transplanted in the usual SRI manner. After the harvest of rice, fishes raised from the previous years in a separate nursery pond were stocked in the ratio of grass carp (500 nos.), silver carp (500 nos), rohu (1000 nos.), mrigal (1000 nos.) and common carp (1000 nos.) during July month with the onset of monsoon. Rice variety: PAC 807 (A short duration hybrid of 120-125 days in spring) were used. Seed rate was 5kg/ha and spacing was 25 x 25 cm. Beds/plots were prepared on the naturally levelled pond beds. Transplanting of 15 days old seedling was done on the marks made by a roller marker as usual during March month (5th March). Weeding was done twice in the season firstly with a conoweeder followed by a hand weeding.
The average Benefit Cost ratios for rice and fish are 2.51 and 2.60 respectively. This practice enabled the farmer to earn an average annual gross income of Rs. 3,48,850/ha giving rise to a B: C of 2.56. First crop/pre-kharif/spring rice (February, March – June, July) is dying down in Manipur due to many factors such as non-availability of suitable variety, susceptibility to lodging and sprouting because of rain during harvest, meagre irrigated area, submergence of shallow lake areas due to Loktak Hydel Power Project, etc. One major factor for the main low land rice is low yield of first crop and the second one is due to improper land preparation due to lack of time. In fact, one proper crop of rice out yields the total of first and second crops which is very much disappointment of the farmer. Nowadays, shallow lake areas that were once good paddy fields have been conditionally converted into fish farms. In these fish farms, farmers are trying to harvest at least one crop of short duration rice. An improvement for the existing production system in these areas was expected to revive the ever-decreasing trend of first crop. Fish production is approximately twice as high in rotational rice-fish farming systems. So, fish farming in the rice fields is officially promotes in National Aquaculture Development Plan in china. It is envisaged that a substantial amount of rice can be produced through integrated rice and fish culture, system. In India, rice-fish farming is considered particularly suitable for the less productive rainfed areas. Successive government in the state are also focusing on sustainable rural development, food security, and poverty alleviation, rice-fish farming systems received a great deal of attention in the recent past. In some rice-fish culture systems, instead of concurrent rice-fish culture, rice plantation and fish culture are conducted alternately in the same field. Rice plantation and fish culture may be conducted alternately by crop or annually. Compared with concurrent rice-fish culture systems, rice and fish do not have a close symbiotic relationship in alternate farming systems. However, alternative rice plantation and fish culture are beneficial to each other in many aspects It is worthy to note that alternative rice-fish culture is relatively easy and does nor require extensive earthwork to modify the structure of the field.
Table1. Benefit Cost ratios of Rice
Year 2014 2015 2016
Yield (MT/ha) 9.24 9.58 9.62
Gross return (Rs) 65940 77325 87925
Cost of cultivation (Rs) 26530 30930 35170
Net return (Rs) 39410 46395 52755
B:C 2.49 2.50 2.56
Average B:C = 2.51
Table 2. Benefit Cost ratios of fish
Year 2014 2015 2016
Yield (Kg/ha) 2438.8 2470.75 2436.42
Gross return (Rs) 275607 306715 332023.5
Cost of production (Rs) 104250 11574.5 131750
Net return (Rs) 171357 295140.5 200273.5
B:C 2.64 2.65 2.52
Average B: C = 2.60
Pooled B: C for rice and fish = 2.56
From this study, we can draw a conclusion that in the shallow lake areas of Manipur where paddy fields have been converted into fish farms thereby reducing the area of rice fields, farmers can profitably take up the practice of rice fish rotation and as a result standard of living of these farmers can be improved as well as area of pre-kharif rice can be increased in Manipur.

The writers are from Central Agricultural University, Imphal, Manipur-795001, Krishi Vigyan Kendra, Thoubal, Wangbal, Manipur-795138 For further details contact:- Public Relations& Media Management Cell, CAU, Imphal. Email: [email protected]