| Summary: | 碩士 === 國立中興大學 === 土壤環境科學系 === 89 === Abstract
The content of organic matter can be regarded as the index of soil fertility. It also can be used to evaluate the productivity of soil. Therefore using organic fertilizer is the most directly and significantly way to increase the soil organic matter content.
Several methods have been used to measure the organic matter content in the organic fertilizer, however, all of them still have some disadvantages and them affect the accuracy of measurement. The objectives of this study were to (1) compare and evaluate the suitability of dry ash method, wet oxidation method and elemental analysis method in determining the content of organic matter of organic fertilizers; (2) study the effect of the temperature of ashing on the values of organic matter content by using the dry ash method; and (3) evaluate the contents of organic matter of compound fertilizers containing organic matter affected by adding with chemical fertilizers.
The dry ash method was found to be the most appropriate method to measure the organic content in the pure organic fertilizer due to the amount of sample is large, however, some disturbing matters of the chemical fertilizers should be filtered out when the organic matter content in the compound fertilizer containing organic matter was measured with this method. For the elemental analysis method, the variance of measurement tends to increase because of small sample size. Therefore elemental analysis method was not suitable to be used to measure the organic carbon content in the compound fertilizer containing organic matter. The results of using wet oxidation method to measure the organic carbon content were similar to those of using elemental analysis method. Their relationship was also very significant when the temperature and time were controlled well. The results also showed that chemical fertilizers had little impact on the measurement values of wet oxidation method. In this study, all the disturbing matters in the compound fertilizers containing organic matter were washed out in order to lessen their effects on the measurement of the dry ash method. Although the disturbing matters can be washed out by water, some water soluble organic fertilizers were also eliminated.
In the future, the research may focus on how to create the best reaction environment when wet oxidation method is used to measure the content of organic carbon in compound fertilizers containing organic matter. Meanwhile if using water to filter out the disturbing matters in the compound fertilizers containing organic matter, and effectively decrease the water soluble organic content, then the dry ash method should be suggested to be used to measure the content of organic matter in the compound fertilizer containing organic matter.
Key words: fertilizer, organic matter content, organic carbon, compound fertilizer.
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