The document summarizes inventory valuation methods used by three fertilizer companies - National Fertilizers Limited, Chambal Fertilizers and Chemicals Limited, and Fertilizer Corporation of India Limited. National Fertilizers Limited values raw materials, packing materials, and stores & spares at lower of weighted average cost and net realizable value. Chambal Fertilizers and Chemicals Limited also values items like naphtha, raw materials, and packing materials at lower of weighted average cost and net realizable value. Fertilizer Corporation of India Limited values raw materials and packing materials at lower of weighted average cost and net realizable value as well.