The Experiment on the Introduction of Pinus sylvestris var. mongolica in Secondary Saline Soil of Northwestern Irrigation Area

Through using the methods of digging ditches for salt extraction, growing sweet clover for green manuring and spreading plastic film on the surface above root, Pinus sylvestris var. mongolica Litv. was introduced in the arid and semiarid area. After 9 years' growth, the average height of the trees was 4.25m, the average diameter at breast height was 7.0cm. The salt content of soil decreased from 0.26% to 0.11%. When the salt content of soil was 0.17%, the growth of P. sylvestris var. mongolica slowed down significantly. The salt content of soil in Hetao Region of Northwest China is 0.12%, P. sylvestris var. mongolica can be used for the plantation in this area.