Based on the long-time location exeriments

accumulation and distribution of available sulfur in soil of different cropping systerms under the condition of 22 years' continuous application of NP chemical fertilizer in Loess Plateau were studied.The results showed that there are two peaks of available sulfur in soil profiles.The first peak occurred in 60-80 cm soil depth with the values of 27.07 mg/kg

25.42 mg/kg

24.23 mg/kg

22.61 mg/kg

16.56 mg/kg and 15.14 mg/kg in maize-wheat(2 a) millet rotation

pea-wheat(2 a) millet rotation

wheat(2 a) millet-maize rotation

pea-wheat(2 a) maize rotation

wheat succession and sainfoin-wheat(2 a) rotation respectively.The second peak occurred in 120-180 cm soil depth and the values in maize-wheat(2 a) millet rotation

pea-wheat(2 a) millet rotation

pea-wheat(2 a) maize rotation

sainfoin-wheat(2 a) rotation

pea-wheat(2 a) maize rotation and wheat succession were 34.20 mg/kg

32.16 mg/kg

31.00 mg/kg

30.32 mg/kg

29.16 mg/kg and 26.22 mg/kg

respectively

which were higher than the first available sulfur peak value.The accumulation of available sulfur in soil profiles(0-200 cm) in maize-wheat(2 a) millet rotation

wheat(2 a) millet-maize rotation

pea-wheat(2 a) millet rotation

pea-wheat(2 a) maize rotation

wheat succession and sainfoin-wheat(2 a) rotation were 559.64 kg/hm2

538.88 kg/hm2 514.34 kg/hm2

489.58 kg/hm2

432.75 kg/hm2 and 423.68 kg/hm2

respectively.The results also showed that long-time application of P fertilizer was the principal factor influencing the distribution of available sulfur in soil profile at different cropping systerms.Additionally

available sulfur transported to deep soils in this study.The results suggest that the difference of sulfur uptake and utilization caused by different crops and cropping styles had effected accumulation and distribution of available sulfur in soil profiles.