Impact of changing crop rotation to continuous wheat on soil characteristics in semiarid areas

-3 was significantly (P< 0.01) lower than continuous wheat cropping (T1) and wheat-fallow-wheat-wheat-wheat (T3) treatments with BD of 1.29 g cm -3 . Water aggregate stability (WAS) in T4 became significantly (P<0.01) greater than other rotations. Saturated water content ( θs) of T1 and T3 (0.39 cm 3 cm -3 ) was significantly (P< 0.01) lower than T2 and T4 (nearly equal to 0.55 cm 3 cm -3 ). The lowest saturated hydraulic conductivity (K S) of about 2.0 cm h -1 occurred in T1 and T3, and the highest (5.27 cm h -1 ) in T4. Soil moisture content ( θm) in T2 and T4 during GS21 growth stage significantly exceeded those of T1 and T3. Biological yields in T2 and T4 were nearly equal (3.05 t ha -1 ) and were significantly (P< 0.05) greater than T1 and T3 (1.5 t ha -1 ). During growth stages of GS54 and GS87, θm and other measured properties were not significantly affected by crop rotations. It appears that substitution of wheat-follow or wheat-chickpea rotations by continuous wheat cropping would gradually degrade the soils and thus should be abandoned.