Changes in Soil Organic Carbon, Nitrogen and Phosphorus in Modified and Native Rangeland Communities (Case study: Sisab Rangelands, Bojnord)

Abstract

Converting the native rangelands to simplified agronomic communities causes<br />some changes in soil carbon, nitrogen and phosphorus. Establishing of perennial plant<br />communities on formerly cultivated rangelands is expected to stabilize soil properties and<br />increase the amount of C, N, P stored in rangeland soils, but there is little information on what<br />plant communities are the most effective for improvement of soil C, N, P reserves. The<br />purpose of this study was to compare soil C, N, and P pools in ungrazed native rangelands<br />with plant community of Festuca-Centurea with those ungrazed pastures established by<br />sowing non-native perennial grasses (Agropyron elongatum and Agropyron desertorum),<br />shrubs (Kochia prostrata), and wheat cultivation in continuous dry land farming system.<br />Study site was located in Sisab Research Station in North Khorasan Province, Iran. The<br />results showed that the total C, N and P contents in the soils under modified plant<br />communities were less than that for native rangeland. Soils under A. elongatum, A.<br />desertorum and K. prostrata tended to have higher values for total C, N and P than soils<br />cultivated annually in wheat-fallow systems. The total C and N content of soils under K.<br />prostrata were near as native rangeland which suggests that K. prostrata can increase the soil<br />C and N contents much more rapidly than the other perennial communities.