Table 3.

Evaluation indexes of degraded land in the Heihe River Basin

Assessment factors	Slight	Moderate	Moderate to severe	Severe
Soil salt in 0-30 cm (%)	0.5∼1	1.0∼1.5	1.5∼2.0	>2.0
Soil moisture in 0-100 cm (w %)	5∼12	2∼8	0.1∼5	< 0.1
Time of water logging (months)	<2	2∼4	4∼6	> 6
Area of shifting sands and sand dunes (%)	10∼20	20∼30	30∼50	> 50
Coverage of vegetation (%)	> 60	60∼40	40∼20	< 20
Grass yield (Dry kg ha-1)	800∼600	600∼500	500∼400	< 400
Slope gradient	10∼15	15∼20	20∼25	> 25