The Effect of Acidic Amendments on the Behaviors of Potassium in Calcareous Soils

酸性改良劑的添加對石灰質土壤鉀行為的影響

洪建民(Chien-Min Hung) ； 陳仁炫(Jen-Hshuan Chen)

《臺灣農業化學與食品科學》 44卷3期 (2006/06) Pp. 143-156

https://doi.org/10.6578/TJACFS.2006.017

摘要

石灰質土壤因含碳酸鹽，尤其是CaCO3，以及高pH值之緣故，致土壤中K/Ca比太小而使植物不易利用土壤中的鉀。以酸性物質之添加來降低土壤pH值，為改良石灰質土壤的方法之一，唯有關以酸性物質改良石灰質土壤時，對鉀行為影響之研究仍有限，誠需予以探討及評估。本研究之目的在探討以硫磺粉與硫酸鋁降低石灰質土壤pH值時，對土壤中鉀行為的影響。選取碳酸鈣含量差異大之五種石灰質土壤，分別添加不同劑量之硫磺粉與硫酸鋁，並於25℃，-33kPa水分勢能下進行培育試驗，使各供試土壤pH值降低至約7.0及6.5。培育期間測定土壤pH值、各型態鉀含量，培育後測定pH值、各型態鉀、鈣、鎂含量及鉀的量度－強度(Q/I)關係。結果顯示，硫酸鋁改良五種黏板岩石灰性土壤初期可獲得較施用硫磺粉者釋出較多的土壤溶液鉀，培育八週後仍能保持高量的溶液鉀。添加酸性改良劑於土壤可促進土壤非交換性鉀的釋出，但非交換性鉀含量較低，風化程度較高之員林土壤則出現鉀的固定作用。酸化石灰質土壤促使土壤鉀的平衡活性比(AR(下標 K)°)下降至1×10^(-3)(mol/L)(上標 1/2)甚至更低，會使土壤鉀之供應不利於植物短期吸收利用，然而高的鉀潛勢緩衝能力(PBC(下標 K))值顯示可減少鉀肥的施用頻率及增加鉀肥的施用量。

關鍵字

石灰質土壤 ； 硫磺 ； 硫酸鋁 ； 鉀的潛勢緩衝能力PBC(下標 K) ； 量度－強度Q/I關係

並列摘要

Carbonates, particularly CaCO3, in calcareous soils with a high soil pH, result in a K/Ca value that is very small and the plants cannot efficiently use the potassium (K). One way to improve calcareous soil is to lower its pH value by applying acidic amendments. However, research on the effect of the acidic amendments on the behaviors of K in calcareous soils is limited and further assessments are required. The objectives of this study were to investigate the behavior of K when sulfur(S) and aluminum sulfate[Al2(SO4)3•14H2O] were applied to reduce the pH of calcareous soils. Five calcareous soils with different CaCO3 levels were examined. Incubation was performed while different amounts of S and Al2(SO4)3•14H2O were applied to the soil until the soil pH was lowered to 7.0 and 6.5 under the condition of 25℃ and -33kPa water potential. The pH values, and the concentrations of different forms of K in the soils were measured throughout the incubation period. The pH values, various concentrations of forms of Ca, Mg and K as well as the quantity/intensity (Q/I) relationships of K were measured after the incubation. The result of applying acidic amendments to five types of soils indicated that more solution K was released than S when applying Al2(SO4)3•14H2O during the initial stage. A rich concentration of solution K was retained in these five types of soils, even after being incubated for eight weeks. The addition of acid amendments promoted the release of non-exchangeable K in slate calcareous alluvial soils. Nevertheless, a fixation did occur for soils with a lower non-exchangeable K content and that experience severe weathering such as the Yuanlin soil. Acidification of calcareous soil lowered the AR(subscript K)° to be as low as 1×10^(-3)(mol/L)(superscript 1/2) or less. This result did not improve the soil supply of K to the plants over the short term. However, the high potential buffering capacity of K (PBC(subscript K)) indicated that the frequency of using K fertilizer should be reduced, and a large amount of K fertilizer should be needed.

並列關鍵字

Calcareous soils ； Sulfur ； Aluminum sulfate ； Potential buffer capacity of potassium PBC(subscript K) ； The relationship of quantity/intensity Q/I