*2.5.2. Fertilizers and chemicals*

Organic and inorganic chemicals and fertilizers are essentially required for the growth of both rice and aquatic species. Besides nourishment of rice, external supplementation of reasonable amount of nutrients raised the levels of phyto- and zooplankton, which serve as food for aquatic cultural species. Aquatic species in the rice field enrich the soil fertility, which ultimately reduces the external supplementation of fertilizer and reduces the production cost [55]. This proves that RAF requires less usage of fertilizers than rice alone [56]. Alternatively yield of rice increases by the supplementation of nitrogen fertilizers at the time of land preparation instead of applying at the time of farming [57]. Addition of ammonia during farming causes damage to ASp as it acts as toxicant in the water, whereas no change has been seen with phosphorus fertilizer application in soil and water [56].

Organic fertilizers benefit for the growth of both rice and ASp. Moreover, the additional supplementation of animal manure helps for the better growth of aquatic species at the time of land preparation [58], and in this way, any toxic effects of these manure to the aquatic species are avoided [57]. Nevertheless, integrated rice-aquatic culture farming is good for poor and unfertilized soils where the aquatic culture species play the greatest role in making them fertile [24].

Besides fertilizers and nutrients, the control of pest and fungal diseases of rice is another task for production of higher yield of rice which usage is not at all good for the growth of ASp. In addition to reduced yield, the uncontrolled usage of pesticides and fertilizers declines the biodiversity. Prolonged misuse of pesticides and fertilizers over the years has also halted the development of inland fisheries and aquaculture [59–62].

In an attempt to reduce pesticide use, important changes have taken place in strategic approaches to plant protection. Integrated pest management (IPM) methods have brought ecological principles and social scientific perspectives into traditional crop management. These ecology-based pest control methods have resulted in markedly improved rice farming systems, which are not only higher yielding but also more sustainable [63–66]. In addition to this, increased adoption of rice-fish farming, with fish as a natural control agent of pest organisms, provides a promising alternative for further developing ecological sound management strategies of the rice field environment [61, 67–69].
