also: なえしろ
noun
rice nursery; seedling bed
A specially prepared bed where rice seedlings are grown before being transplanted to the paddy field.
春になると、農家は苗代に種もみをまく。
In spring, farmers sow rice seeds in the nursery bed.
苗代で育った苗を田んぼに植え替える。
The seedlings grown in the nursery bed are transplanted to the paddy field.
Compound of 苗 (seedling) and 代 (substitute, or in this context, a prepared plot). The reading なわしろ is a sound shift from なえしろ.