In Japan, the other key point to the flowering of peasant agricultural productivity was the fixed land tax rate for most of the Edo period.  As changing the taxes was too politically difficult for all but the first few shoguns, peasants on the Shogun's land were able to keep most any productivity improvements they made, be they from crop diversification to fertilizer to new rotations.  Over time, this led to

1. increasing integration of the countryside into national networks of production and distribution, as peasants sold their leftover stuff to wholesale distributors in Osaka and Edo.

2. a rural consumer revolution, as the money was used to buy stuff, replacing plain material want/crude homemade goods with superior product.

3. the growth of rural industries, as farm families looked to plug their labor supply into these new market systems through handicraft production in a variety of traditional industries.

All this resulted in Japan having a rather highly developed capitalist economy over much of its territory well before the country was opened to the West.  Already having such an economy made it possible for Japan to adapt to the global markets of the 19th century.