Studies On The Control Of Soil N Supply And N Availability For Tomato Under The Incorporation Of Straw With High Carbon/Nitrogen Ratio In Greenhouse

High soil nitrogen residue and Nitrate pollution in ground water was popular in intensive vegetable cropping region due to excessive chemical nitrogen and manure with low C/N ratio. Incubation experiment in situ and soil column experiment combined with15N isotope technique was used to study the influence on the incorporation of sticky corn with high C/N ratio on soil N residue, soil N supply and N availability for tomato. The results were listed as fallows:(1) Compared with controls (without any organic matter addition), organic matter addition significantly increased soil CO2emissions. The order is:sticky corn straw harvesting at silking stage combined with chicken manure> sticky corn straw harvesting at silking stage> sticky corn straw harvesting at maturity stage>chicken manure>Control. Soil mineral N was’significantly increased by chicken manure while it was significantly reduced by the addition of sticky corn straw. The combination of sticky corn straw and chicken manure significantly increased tomato dry matter and fresh fruit yield, and it can reduce soil N residue at harvest in0-15cm soil layer in contrast with the treatment just applying chicker manure.(2) The addition of sticky corn straw with high C/N ratio significantly improved soil organic carbon content, soil light fraction, but it reduced soil inorganic nitrogen and its15N content. Accordingly, N uptake from soil was reduced by the addition of sticky corn straw. It indicated the addition of sticky corn straw could redcue N availablility from soil.(3) The addition of sticky corn straw and chicken manure together decreased C/N ratio compared with just adding sticky corn straw and promoted the decomposition ablility of microbial to adding material. At the end harvest of tomato,9.40%of15N fom sticky straw was uptake when sticky corn was applied independly.9.30%of15N from sticky straw was uptake when sticky com was applied with chicken manure together. The addition of just sticky corn straw kept more15N from sticky corn straw in0-15cm soil layer, especially in the form of organic15N. It indicated the combination of sticky corn straw and chicken manure increase the tomato N uptake from soil and chicken manure.In conclusion, the addition of sticky corn straw with chicken manure could not only weaken the immobilization of soil inorganic nitrogen by microorganisms, but also could reduce the N mineralization when chicken manure was added separately. Therefore, the combination of straw with high C/N ration and chicken manure was a better N management practice to both improve vegetable yield and reduce N loss.