Two stories in crop production refers to a tree crop grown above and an annual crop below.

Two stories from J. Russell Smith's, Tree Crops: A Permanent Agriculture (1953), and their elaboration throughout this elegant book, were material to Fox Valley Berkshire adopting the two story practice.

"I stood on the Great Wall of China high on a hill near the borders of Mongolia. [...] The slope below the Great Wall was cut with gullies, some of which were fifty feet deep. As far as the eye could see were gullies, gullies, gullies- a gashed and gutted countryside.  The little stream that once ran past the city was now a wide waste of course sand and gravel which the hillside gullies were bringing down faster than the little stream had been able to carry them away. Hence, the whole valley, once good farmland, had become a desert of sand and gravel, alternately wet and dry, always fruitless. [...] Its sole harvest now is dust, picked up by the bitter winds of winter that rip across its dry surface in this land of rainy summers and dry winters."

"Again I stood on a crest beneath a spreading chestnut tree, and scanned a hilly landscape. This time I was in Corsica. Across the valley I saw a mountainside clothed in chestnut trees. [...] The expanse of broad-topped, fruitful trees was interspersed with a string of villages of stone houses. [...] These grafted chestnut orchards produced an annual crop of food for men, horses, cows, pigs, sheep, and goats, and a by-crop of wood. Thus, for centuries, trees upon this steep slope had supported the families that lived in the Corsican villages. The mountainside was uneroded, intact, and capable of continuing indefinitely its support for the generations of men."

Hillside or lake bed, the point is to produce both high and seasonally multiple yields with the least of erosion.

Photo 1:  From Smith, above, Fig. 46, North Carolina, c.1953

Photo2: Young, still very light bearing Mulberry trees, North paddock, Fox Valley Berkshire, 5 March, 2011