在酸性水田土壤添加稻桿生物炭對磷物種分布之影響

Speciation of Phosphorus in Acidic Paddy Soil as Affected by Rice-Straw Biochars

張琇妍(Hsiu-Yen Chang)

指導教授 ： 王尚禮

國立臺灣大學/生物資源暨農學院/農業化學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202000427

摘要

酸性土壤廣泛存在於世界各地，而此類土壤的強酸性及高鐵鋁含量使得磷之植物有效性低而導致稻米的產量降低。本實驗藉由添加兩種不同溫度(350℃及600℃)之稻桿生物炭於兩種不同質地之酸性土壤(平鎮系及台南系)，預期提高酸性土壤之pH、增加氧化還原電位變動之範圍及釋出磷，以提高酸性土壤之磷有效性；並藉由尼龍網袋將生物炭及土壤區隔，以釐清在還原階段及再氧化階段生物炭及土壤之磷含量和磷物種之變化。結果顯示，添加生物炭可提高土壤pH且增加Eh變動之幅度。在還原階段，生物炭之可溶性磷及可交換性磷隨孵育時間減少，350℃生物炭主要磷物種由可溶性磷轉變為鐵鋁磷，600℃生物炭主要磷物種由可溶性磷轉變為鈣磷。在再氧化階段，生物炭可溶性磷及可交換性磷含量則持續減少。在還原及再氧化階段添加生物炭處理之土壤與對照組相比可溶性磷含量顯著增加，指出添加生物炭之酸性土壤可有效改善土壤之磷有效性。

關鍵字

酸性土壤 ； 還原反應 ； 生物炭 ； 磷有效性 ； 磷物種

並列摘要

Acidic soils occur extensively worldwide and most of them are being used for paddy rice cultivation. However, due to strong acidity, high Fe/Al toxicity, and low P availability, the rice yield from these soils is usually limited. To investigate the effect of biochar amendment on the P availability in acidic paddy soils, this study added rice-straw biochars produced at two different temperatures (i.e. 350RS and 600RS) to two soils with different textures. The content and speciation of P in soil and biochar during soil reduction and reoxidation were determined. The results indicated that adding biochar to acidic soil can increase soil pH and change soil Eh. During soil reduction, the amounts of soluble P in biochars gradually decreased. The soluble P in biochars was transformed into the labile-P associated with Fe/Al and into the apatite-like P in 350RS and 600RS respectively. During soil reoxidation, the amounts of soluble P in biochar continuously decreased. The amounts of soluble P in biochar-amended soils showed a marked increase during soil reduction, and this result demonstrated that adding biochar to acidic soils can improve the P availability in the soils.

並列關鍵字

acidic soils ； redox ； biochar ； phosphorus availability ； phosphorus speciation

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