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Northwest A&F University (2021)

The Study of Decaying Characteristics of Plant Residues in Desert-Oasis Ecosystem

孙本华

Titre : The Study of Decaying Characteristics of Plant Residues in Desert-Oasis Ecosystem

Auteur : 孙本华

Grade : Master 2021

Université : Northwest A&F University

Résumé partiel
Desert and oasis ecosystem are the main ecosystems in arid area. Studying the characteristics of decaying process, decaying remainders and soil humic acids can accumulate the first hand data for studying the accumulation and decomposition of soil organic matter, the situation of soil fertility, substance cycling and energy flowing in desert-oasis ecosystem, and has the great significance on desert ecosystem restraint and oasis ecosystem extension. Using corn straw and soybean straw, the characteristics of the decaying process and the remainders, the difference of soil fertility status and soil humic acids character in different using ways are studied by normal analysis combined with energy analysis, thermal analysis (DTA, TG, DIG) and infrared spectrum analysis (FTIR). The main conclusions were as follows :(1) The residues decayed quickly at 0-3 months, slowly at 3-6 months, and kept constant at 6-13 months basically. The decaying rate of corn straw adding N was higher than that of soybean straw, and the decaying rate in oasis ecosystem was higher than in desert ecosystem.According to the changes of the amounts of decaying remainders and the decomposition rate of organic C, the decaying process could be divided into 3 stage : the fast decomposition stage → the slow decomposition stage → the stage tending to be stable.The C/N ratios of corn residues and soybean residues still kept at 26-29, 29-36 at the end of experiment respectively, and were much higher than that of soil humus. It showed that the humification didn’t complete after 13 months’ decaying at the end of experiment.(2) The results obtained by using oxygen-bomb calorimeter showed that the changes of the caloric value (Qv) of corn residues presented as "saddle -shape", and the soybean residues presented as "bow-shape" basically. According to the Qv changes of two kinds of residues, the decaying process could be divided into 3 stage : the fluctuating and rolling stage →the stage tending to be stable→ the fluctuant reducing stage. The 3 stages divided by Qv, the changes of remainders amount and organic carbon decomposition rate were different on the beginning to ending time and the sequences .It showed that the changes of remainder amounts only reflected the weight loss of residues, but the Qv changes reflected the changes of component and character of residues.

Mots clés : Desert-oasis ecosystem ;Residue decay ;Caloric value ;Thermal analysis ;Infrared spectrum ;

Présentation (CNKI)

Page publiée le 23 février 2022