سنجش پتانسيل معدني شدن و شاخص قابليت جذب نيتروژن توسط برخي ويژگي هاي بيولوژيك خاك

چكيده انگليسي :

132 Assay of N Mineralization Potential and Availability index by Some Soil Biological Properties Elham Mirparizi e mirparizi@ag iut ac ir 14 December 2011 Department of Soil Science Collage of Agriculture Isfahan University of Technology Isfahan 84156 83111 IranDegree Sc Language Farsi Dr F Nourbakhsh farshid@cc iut ac ir AbstractNitrogen N is the most required element for plants In soil ecosystem N is one of the limiting factors forthe plants growth Nitrogen mostly exists in the soil in the form of organic molecules which due toamidohydrolases activity is transformed into inorganic form so that it can be absorbed by plants Moreinformation of the mechanisms and indicators of N mineralization is needed to better use of fertilizers and toprevent contamination of surface and groundwater In order to evaluate the relationship between Nmineralization process and N uptake by the plant Lepidium sativum with some soil biological parameters 22soil samples from different geographical regime of Iran were selected and their physiochemical propertiesdetermined The N pools were determined by measuring inorganic N nitrate and ammonium solution organicN SON hot kCl extractable ammonia potentially mireralizable N under either aerobic or anaerobic condition The microwave induced N mineralization was also measured The activities of L asparginase L glutaminase and urease were determined basal respiration arginine ammonification microbial biomass N and absorption of280nm in extracts were studied as biological indicators The results showed that all soils were calcareous andsome of them were saline The simple linear regression between the physical chemical characteristics of thesoils N pools biological indicators and the plant indexes and also regression equations were calculated Theincrease of organic N improved amount of mineralized N enzymes activities and plant N uptake andconcentration Based on the cluster analysis results the soils can be divided into three major categories One ofthe samples was categorized separately after omitting this soil from statistical analysis stronger correlationswere observed The results of Principle Component Analysis PCA demonstrated that the vectors related topotentially minreralizable N under aerobic and anaerobic conditions the activity of urease enzyme organiccarbon and arginine ammonification had the same direction and showed the stronger correlation between thesevariables The particle size distribution and soil enzyme activities were not associated The result of PCA highlysupported the results obtained by regression methods In order to find out the best model for estimatingpotentially mireralizable N under aerobic and anaerobic conditions and the test plants N uptake andconcentration stepwise multivariate regression analysis was performed In multiple regression models for Nmineralization process in both aerobic and anaerobic condition organic carbon and ultraviolet absorption werethe most important parameters entered into the model The measurement of ultraviolet absorption is not acommon method in soil science labs therefore after deleting these parameters from statistical analysis nitrateand inorganic N were entered respectively into the models of N mineralization both under aerobic and anaerobicconditions The activity of L glutaminase played the largest role in the multiple regression models for the plant N uptake and concentration Key words amidohidrolases arginine ammonification potentially mireralizable N plants nitrogen uptake

ميرپاريزي، الهام

سنجش پتانسيل معدني شدن و شاخص قابليت جذب نيتروژن توسط برخي ويژگي هاي بيولوژيك خاك

آميدوهيدرولازها , آمونيفيكاسيون آرجينين