Study on Nitrogen Supply Capacity of Three Soils in Taihu Region

[Objective] Soil nitrogen supply capacity of three main soils in Taihu Region was studied.[Method] The aerobic incubation method,submerged incubation method and chemical extraction method were used.[Results] In aerobic condition,nitrogen mineralization increased in the order:huangni soil wushan soil wusha soil.In wushan soil,mineralized nitrogen from 20-60 cm soil depth accounted for 40% of mineralized nitrogen of 0-60 cm depth.In anaerobic condition,nitrogen mineralization increased in the order:wushan soil huangni soil wusha soil.In wushan soil,soil nitrogen supply mainly derived form 0-20 cm soil depth.Rice production and rice nitrogen uptake in huangni and wusha soils were significantly higher than that in wushan soil.Hydrochloric acid-hydrolyzable nitrogen,hot KCl-hydrolyzable nitrogen and NaOH-hydrolyzable nitrogen decreased with soil depth.[Conclusions] Chemical extraction indexes could reflect soil nitrogen mineralization capacity.