PROBLEM TO BE SOLVED: To provide a vegetation base material containing nitrogen, phosphorus and potassium in good balance, and preferably containing the phosphorus in a shape of being easily absorbed in a plant. SOLUTION: The water-retainable composition contains bone coal, a water-absorbing polymer, and optionally an organic waste. The formulated proportion (based on the dried weight) of the water-absorbing polymer in the water-retainable composition is 20-70 wt.%, preferably 30-60 wt.% based on the whole amount, and the remainder is the bone coal (and the organic waste). The bone coal produced, for example, from an organism derived from a carcass of livestock while regulating the oxygen content at a carbonizing step and/or a cooling step after the carbonization is used as the bone coal. COPYRIGHT: (C)2005,JPO&NCIPI
