PROBLEM TO BE SOLVED: To provide a lightweight chaff-made seedling mat substituting for nursery bed compost which prevents the failure to join the rear end of a lightweight chaff-made rolled-seedling mat substituting for nursery bed compost which is spread on the planting face of a rice transplanter (seedling stand), to the front end of the added chaff-made seedling mat, when spreading out a chaff made seedling mat on the planting face of a riding type rice transplanter.SOLUTION: Provided is a lightweight chaff-made seedling mat substituting for nursery bed compost, in which two sheets of chaff-made seedling mats are spread in a long seedling box 1 having a length a little shorter than two conventional seedling boxes, the end of a short side contacting a long seedling box 1 is cut by a few to ten-odd cm and a nursery bed compost 3 is filled and leveled so that the chaff made seedling mat 2 and the surface become in the horizontal position, humic materials to be sowed are spread and fixed on these surfaces, and the end of the humic materials is shaped and reinforced by wrapping the chaff-made seedling mat 2 and the nursery bed compost 3.SELECTED DRAWING: Figure 1【課題】籾殻苗マットを乗用田植機の植え付け面（苗のせ台）に展開した場合、田植機の植え付け面に展開した苗代培土代替軽量苗籾殻マットロール苗の後端部と、追加した籾殻苗マット前端部との接合が不良となるのを防ぐ苗代培土代替軽量籾殻苗マットを提供する。【解決手段】在来の育苗箱２枚分弱の長さになるロング育苗箱１に籾殻苗マット２を二枚を敷きこみ，ロング育苗箱１と接する短辺の端を数～十数ｃｍ切除し育苗培土３を充填し籾殻苗マット２と表面が水平になるよう均し、これらの表面に播種し腐植する資材を敷き固定し、腐植する資材の端は籾殻苗マット２、育苗培土３の端部を包み整形・補強した苗代培土代替軽量籾殻苗マット。【選択図】図１
