Soil microbial diversity in banana plantation soils as influenced by long-term organic and conventional farming

• Main Authors: Yu-Meng Chou, 周于盟
• Other Authors: 沈佛亭
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/25002357629166423977

碩士 === 國立中興大學 === 土壤環境科學系所 === 103 === Chemical fertilizers and chemical pesticides are commonly used to increase soil fertility and reduce plant pathogen in conventional farming. To achieve agricultural production in a more sustainable way, integrated managements instead of overdose use of agricultural chemicals are adopted to obtain high quality and yield of crops meanwhile maintain soil quality. The distribution of microbes which participate in nutrient transformation may be changed spatially or temporally in a dynamic soil ecosystems. In the present studies soil microbial diversity as influenced by long-term organic and conventional farming were evaluated in banana plantation soils. Soil samples were collected from the established fields in Taiwan Banana Research Institute during 2011-2014. Basic properties of soil such as water content, pH, EC and organic matter content were determined. Approaches to study metabolic and population diversity in banana plantation soils were conducted. These included the culture-dependent and culture-independent methods to obtain viable number of different bacterial groups, community level of physiological profiles and microbial community structure under different long-term farming systems. The results demonstrated that water content, pH and organic matter content were the highest in 17-year organic farming soils and lowest in long-term conventional farming soils. Metabolic potentials of fast-growing microbes in 7-year organic farming soils were generally higher than that in 17-year organic farming soils or conventional farming soils, as revealed by richness, average well color development and diversity index. The SAWCD value demonstrated that carbohydrates were well utilized by fast-growing microbes in soils under organic farming than that under conventional farming. α-Malic acid, β-Methyl-D-Glucoside, D-Cellobiose, L-Serine and N-Acetyl-D-Glucosamine were positively correlated with organic farming, while L-Asparagine and Pyruvic Acid Methyl Ester were positively correlated with conventional farming, which were verified by principle component analysis. Soils under organic farming harbored slight higher number of heterotrophs, free-living nitrogen fixers and tricalcium phosphate solubilizers than that in conventional farming soils. Members belonging to the phylum Firmicutes were dominated in all the three farming soils, and diverse Bacillus lineages at species or strain level were resolved by cultivated-based method. Microbial community structure of soils under three farming systems was compared through 16S rDNA clone library construction and sequence analysis. The 17-year organic farming soils have the highest percentage of unclassified bacteria (at the phylum level) while members belonging to Proteobacteria were dominated in 7-year organic farming soils and conventional farming soils. A higher percentage of clones was occupied by the phylum Acidobacteria in conventional farming soils, which may be related to soil deterioration.