Verification of the Effect of Fully Ripened Chicken Manure Fertilizer on the Growth of Asari Clam, Ruditapes philippinarum

Abstract

A test was conducted to cultivate Asari clams using fertilizer on an artificial tidal flat located in Urasaki-cho, Onomichi City, Hiroshima Prefecture. A numerical simulation model was constructed to calculate the material circulation including water and mud, and the data obtained in the field test were explained well. It was found that the limiting factor of benthic microalgae (BMA) , which is the main food of Asari clams, changes with the season: phosphorus in autumn, water temperature and solar radiation in winter, and nitrogen from spring to summer. It was also found that growth inhibition in terms of the food requirement of Asari clams occurs significantly in spring. For this reason, it is recommended to time fertilization before the spring growth period. It was shown that the use of a large amount of fertilizer materials results in larger individuals, higher sales prices, and better cost₋benefit performance. However, considering the risk of hydrogen sulfide generation in bottom mud, it was concluded that the appropriate amount of fertilizer applied is approximately 0.4 pieces m^-2 (distance of approximately 2 m between fertilizer pieces) .