土壤有機質對木麻黃林地磷肥吸附之影響

Effects of Organic Matter on the PhosPhate Sorption of Casuarina Forest Soil

陳明義(Ming-Yih Chen) ； 林昭遠(Chao-Yuan Lin) ； 呂金誠(King-Cherng Lu)

《中華水土保持學報》 19卷1期 (1988/05) Pp. 80-88

https://doi.org/10.29417/JCSWC.198805_19(1).0007

摘要

本研究旨在於瞭解木麻黄林地土壤有機質對磷肥吸附之影響，藉以探討木麻黃海岸林生態系中磷肥之循環情形。兹將結果摘述如下：1.台中港木麻黃防風林內，土壤團粒之有機質含量高達8.88％，其中腐植酸佔2.42％，黃酸佔3.20％。由於有機酸之影響，土壤團粒之pH值僅爲4.35。2土壤中各營養元素以有效性磷之含量（2.5 ppm）最爲貧瘠，土壤經高溫處理後，所栽植之木麻黃幼苗對土壤養分之吸收量較未處理者多。於高溫處理區，木麻黃單株對氮，磷，鉀吸收量之增幅大小依序爲氮（724.6 μg），鉀（458.6 μg），磷（42.9 μg）3.土壤團粒經H_2，O_2，處理後，有機質含量以及對磷肥之吸附量均會減少。若再添加NaOH處理後，團粒對磷肥之吸附量將可提高。4團粒對磷肥之吸附量係隨溶液pH之不同而異，添加NaOH處理時，溶液中之Na離子濃度並不影響磷吸附量，磷吸附量之改變主要是受OH^-濃度所影響。5.溶液pH對磷有效性之影響最主要是決定於各參與反應之諸陽離子，土壤溶液中大量之陽離子極易因pH之變化而影響磷之吸附量。6.腐植酸溶於鹼不溶於酸，當溶液pH＞ 5.5時，添加腐植酸處理者，溶液中磷被固定量幾乎爲零，但於pH ＜5.5時，腐植酸將逐漸發生沉澱，溶液中之磷將隨之發生共沉。7.以腐植酸改良土壤增加磷肥之有效性，於強酸性土壤時，先添加腐植酸再施磷肥之效果將比先施磷肥後再施腐植酸之效果好。8.黃酸之分子較腐植酸爲小，單位重量之表面積較腐植酸者爲大，故共沉時對磷之吸附量較腐植酸大。

關鍵字

有機質 ； 木麻黃林 ； 磷肥吸附

並列摘要

Effects of organic matter on the phosphate sorption of Cesuarina forest soil as well as the phosphorus cycling of coastal Cesuarlna windbreak ecosystem at Taichung Harbour were studied. The results obtained are summarized as follows: 1. The contents of organic matter, humic acid and fulvic acid in soilaggregates of Casuarlna forest were 8.88%, 2.42%, 3.20%, respectively. Owing to the effects of organic acids, soil pH was only 4.35, 2. Among the nutrients measured, available phosphorus content (2.5ppm) was the poorest. Nutrient uptaklng of Cesuarina seedlings planted on heated soils was more than that on untreated soils. The increments of N. K and P uptakes of one seedling on heated soil were 724.6μg, 458.6μg, and 42.91μg, respectively. 3. Both organic matter content and phosphate sorption of aggregates decreased following H_2O_2 treatment. If NaOH was added, phosphate sorption of aggregates would be enhanced. 4. Phosphate sorption of aggregates was pH-dependent. After adding NaOH, phosphate sorption was changed mainly by OH not by Na^+concentration. 5. Effects of solution pH on phosphate availability were mainly controlled by reacted cations. Phosphate sorption could be effected by the abundant cations in soil solution under changing pH values. 6. Humic acid was soluble in alkalis but insoluble in acids. After adding humic acid, phosphate In solution was almost solved under pH＞5,5. When the solution pH＜5.5, humic acid gradually coprecipitated with phosphete. 7. For improving the phosphate availability in strongly acid Soils, adding humic acid firstly and then phosphate would be better than the opposite operation. 8. Having lower molecular weight and larger specific surface, fulvic acid induced larger amount of coprecipitation with phosphate than humic acid did.

並列關鍵字

Organic matter ； Cesuarlna forest ； Phosphate sorption