by Michiyo from Japan
we used small portion of peat moss（泥碳苔）, and as for clay, we purchased the kind
for roof tile（屋瓦）.
The reason why this type of clayball to be considered better was that, it did not melt by the extraordinary heavy rain during the winter time of that year. Other ones by concrete mixer or by hands completely melted although some seed germinated in the springtime from the ground.
Also because it has flat surface to attach better to the ground, it can stay in the middle of a steep hill.
And finally, it has a very different function from the regular clayballs, that this disc contains more seeds and they are allowed (or forced) to make a colony for plants to grow together.
To my understanding, Fukuoka came up with the idea of protecting the seeds with mud or clay, and he did not give a specific instruction on how it should be wrapped or be made, so I think that we should all keep working to find the ones that work in different climate of the world. The ones which are suited for humid areas like Japan and other Asian countries may be different from Greece and its neigboring countires whose climate, vegetation and animals are very different.