High-altitude integrated rice-fish culture system of the Apatani Plateau

UNESCO’s tentative heritage site

Dr Rajashree Saikia & Dr Dipankar Debnath

Teaching Associate, Dept. of Environmental Science, Gauhati University

Department of Ecology and Environmental Sciences, Assam University, Silchar (kripashree@gauhati.ac.in)

The rice field fishery of Apatani plateau was captured fishery before 1956. In 1960, the Department of Fisheries in Arunachal Pradesh took the initiative to develop systematic pond farming practises, and in the process, Apatani farmers also adopted the culture system. Apatani farmers have been habituated to raising rice and fish together in their mountain terraces since 1960. The potential areas of rice-fish culture on the Apatani plateau are Napping, Yachuli, Ziro-II, Palin, and Koloriang. Apatani used to do mono-cropping of rice in their fields. They principally use three varieties of rice, namely, Emeo, Pyape, and Mypia. The total area of the Apatani Plateau is 10,135 km2, where rice-fish culture is undertaken on approximately 592.0 ha of irrigated rice lands out of 715.7 ha. The Apatani Plateau is a land of miscellaneous cultures. The major festivals of Apatanis are the Myoko, Dree, Yapung, and Murung. The Apatani people believe that these traditional festivals ensure better cultivation of agricultural crops and the well-being of the local inhabitants. The climate of the Apatani Plateau has a humid subtropical to temperate type of climate. So, this plateau receives an adequate amount of rainfall during the summer season. Interestingly, the weather condition in this region depicts that the coldest months (December and January) are extremely cold whereas the warmest months (July and August) are very pleasant. The permeability and water-retaining capacity of clayey loamy soil favour the Apatani rice-fish culture system.

This rice-cod-fish cultivation is a low-input and environmentally friendly practice. The stocked fish practically depend on the natural food sources of the rice fields, so farmers hardly use any supplementary fish feed. The farmers sometimes use household and agricultural wastes and the excreta of domestic animals like pigs (Sus scrofa scrofa), cows (Bos taurus), mithuns (Bos frontalis), and goats (Capra aegagrus hircus) in the fields as energy subsidies and to make such farming more sustainable and organic in nature. Moreover, Azolla and Lemna are allowed to grow in the field water as nitrogen fixers. The organic food formed in the field may play an important role in the detrivorous habitat of the stocked fish. The sources of water in these high-altitude rice fields are the diverted mountain streams and trickle-down rainwater of the monsoon season. The bamboo pipes are being used to distribute water from the networks of earthen irrigation channels using two outlet pipes. One outlet is fitted angularly at the upper level through the dyke to maintain the water level, and another outlet is fitted at the bottom of the dyke to the exterior and is used for dewatering the field at harvest.

Men and women separately have different farm duties during field preparation for the cultivation of rice and culture of fish while the women folk mainly participated as the major work force. Ancient and old-fashioned agricultural technologies are being utilised for cultivation practices. Modern implements like tractors, power tillers are not affordable as well as inaccessible to the farmers. They mostly use agricultural implements such as the dao (sickle) and dibble sticks in most of their agricultural practices. They transplant a maximum of 2–3 healthy rice plants at an average distance of 26 cm from each other after completing field preparation activities.

Fish refuges are excavated inside the fields. Three species of common carp, viz., Cyprinus carpiospecularis, Cyprinus carpio communis, and Cyprinus carpionudus, are used to stock the tanks just after 10 days of rice transplantation into the fields. The stocked fish are harvested twice in a season. The first and second or final harvests of stock fish are done in the middle of July and October, respectively. But the rice is harvested from the end of September until the middle of October, i.e., once a season. The four cultivars of rice, namely, Amo, Ambo, Mypia, and Pyapee, were cultivated along with the fish species Cyprinus carpio L (Common Carp). The total productivity ranges 300-500 kgha-1season-1of fish and 3000-4000 kg of rice ha-1season-1. The fish enhanced rice productivity (10–15%) by controlling the growth of algae, weeds, and injurious insects, providing nutrient input through fish excreta, and promoting tillering of the rice through movement of the fish inside the field. Further, the mineralization process of organic matter, puddling of mud, and soil aeration by other benthos caused a better yield of rice in such fish-culture wet fields of the Apatani people in Arunachal Pradesh. The yield records of rice and fish for each of the rice fields were obtained from the farmer (owner) through personal interview of the study plots.

The field dyke at higher elevations and at lower elevations is constructed with a height of 0.9 m to 1.5 m and 0.4 m to 0.6 m, respectively, where they also cultivate various nitrogen-fixing vegetables and millets for enhanced productivity. In addition to this, the dyke is also used for complete drying of field water during harvesting of rice and fish. Bamboo fencing is done to avoid the escape of fish through the pipes. This eco-friendly and economically beneficial farmer’s practise has made the system unique in the context of aquatic resource utilization.

The zooplankton and algal life forms show abundant populations, a typical population attribute, particularly during the rice growing season. These organisms serve as natural food sources for the fishes concurrently in the flooded rice fields to enhance unit land aquatic productivity. This ecosystem service, in turn, indirectly maintains healthy man-made swamps with better livelihood options for tribal framers. Field water depth being the limiting factor, the population structure of such planktonic organisms persisted under the rice canopy till the complete recession of the water with seasonality. All the agro-inputs in this ecosystem, including organic manures, decomposed rice stubbles, and macrophytes, along with other biotic and abiotic factors, regulate the various population properties in the inundated rice fields. For growth and development, the stocked fish in the rice field may have utilised and assimilated available aquatic biomass along with zooplankton through trophic interactions.

Therefore, high-altitude flooded environments enriched with such natural fish feeds hold sufficient scope to raise fish alongside a concurrent crop of rice in the same field. In the context of plankton and other fish food organisms, the wet rice fields are still data-deficient. The water quality parameters as well as the community structure and population dynamics of algal life forms under the rice canopy were favourable for the growth and abundance of zooplankton, which actually exerted a great bearing on the fish yield. Therefore, such a unique integrated aquaculture agriculture system requires special attention for its better productivity and improved management protocol, which will lead to greater profitability for the small-scale rural farmers in Assam and other north eastern hill states.