STRUCTURE FOR THE AGROFORESTRY SYSTEMS AT THE EXPERIMENTAL SITES
The agroforestry systems consist of trees and crops. Proper selection of tree and crop species andtheir rational temporal and spatial arrangements are crucial so that the efficiencies of utilization of solarradiation, water and nutrients can be high. Poplar (Paplus canadensis) and paulownia (Paulowniaefongaru) were chosen because the projection areas of their canopies are relatively small, and theygrow well in the local saline soils. Wheat and maize are the two crops harvested each year from thesame plots. The temporal arrangements of crops and plantations were such that wheat was harvested