early in May before the leaves of the trees became dense enough to affect the crop productivity. Maize
planting between rows of wheat was completed in April before the wheat havest.
Table 1 gives the layout of our two types of agroforestry systems. In the shelterbelt type, poplar
grew along the boundaries of crop plots. Each land plot is 200 m x 300 m. The treebelt consists of
three rows of trees at 5 m spacings between rows of each belt, and 4 m spacings between trees in each
row. In the intercropping system, paulownia trees were planted in the crop land on a space 40 m x 5 m.
As may be seen from Table 1, trees occupy only O.l-2.5% of the total land area of the agroforestry systems.