石灰的施用對強酸性土壤鉀固定及鉀有效性的影響

The Effect of CaCO3 Addition on K Fixation and K Availability in the Strongly Acid Soils

陳仁炫(Jen-Hshuan Chen) ； 王怡雯(Yi-Wen Wang)

《土壤與環境》 2卷4期 (1999/12) Pp. 333-345

https://doi.org/10.30058/SE.199912.0005

摘要

強酸性土壤為本省最大宗的問題土壤，而石灰施用為增進強酸性土壤生產力的重要對策之一。鉀在酬壤中的行為深段土壤pH和其他陽離子（如鈣，鎂，鈉，鋁）的影響，當以施用石灰來增進強酸性土壤生產力時，勢必引起土壤中鉀行為的變化，進而影響鉀在土壤中的有效性及鉀肥的利用率，故宜對其所衛生的鉀行為變遷予以探討，以作為鉀肥管理的依據，此即為本研究的主要目的所在。本試驗選用四種不同風化程度及成因的強酸性土壤，分別添加不同量的石灰(CaCO3)以調整土壤至目標pH（分別為原始pH、5.5、6.5及7.5），嗣於25℃下培育30天後測定各處理土壤之pH、EC、溶液性及交換性鉀、鈣、鎂、鈉、鋁濃度，非交換性鉀沔度，及土壤鉀固定能力指標，並繪出各處理土壤的鉀量度-強度（O/I）圖，以求出個別的PBCK（鉀潛勢緩衝能力），藉以瞭解石灰施用對供試之強酸性酬壤的鉀固定及鉀有效性之影響。試驗結果顯示，石灰的添加會使得強酸性土壤之pH提昇而降低交換性及溶液鋁的濃度，且增加土壤對鉀的固定能力，由於石灰的添加，造成陽離子的競爭作用，使得土壤溶液中之鉀、鎂和鈉離子濃度由於鈣離子濃度的增加而有降低的趨勢；同時，由於鈣離子的增加而競爭表面吸附位置，致使交換性鉀濃度降低。藉由鉀量度-強度關係圖，可知石灰的添加會造成土壤鉀潛勢緩衝能力增加，此表示土壤維持溶液鉀濃度的能力越強，且由鉀的活性比(ARK)之數值大小顯示，脫附的鉀主要位於邊緣及平面吸附位置，石灰添加造成該兩吸附位置鉀之釋出，提升了土壤的PBCK值。唯由土壤特正吸附的鉀濃度值(ExKs)隨著石灰的添加而昇高的現象，顯示石灰的施用確實具有增進土壤鉀固定的效應。藉由Barber-Cushman養分吸收模式的評估效果，証實在四種供試強酸土壤中可為作物吸收的鉀量係隨石灰施用量的增加而降低，再度證實石灰的施用會降低土壤的鉀供應能力。

關鍵字

鉀固定 ； 鉀有效性 ； 強酸性土壤 ； 石灰的施用

並列摘要

Strongly acid soil is the major problem soils in Taiwan, however, liming is one of the important practices in promoting the productivity of acid soils. The behaviors of potassium(K) in soils are affected by soil pH and others actions, such as Ca, Mg, Na and Al, so the availability of K and the efficiency of K fertilizers will be altered when acid soils were limed. It is necessary to determine the changes ok K behaviors in order to develop the suitable management of K and the efficiency of K fertilizers will be altered when acid soils were limed. It is necessary to determine the changes of K behaviors in order to develop the suitable management of K fertilization as acid soils were limed. Four strongly acid soils with varying degree of weathering, and four rates of CaCO3 were added to adjust soil pH (original pH, pH5.5, pH6.5 and pH7.5), then the soils were incubated at 25℃for 30 days and analyzed for pH, EC, solution (K, Ca, Mg and Al), nonexchangeable K, and K fixation index of the treated soils. The potassium quanity-intensity (O/I) plots were made and their PBCK (potassium buffer capacity) values were determined to study the effects of liming on the K fixation and K availability in these strongly acid soils.
Results showed that liming not only would increase soil pH and decrease the concentration of exchangeable and solution Al, but also increased the K fixing capacity of the soils. The concentration of K, Mg and Na in the soil solution decreased with increasing Ca concentration as CaCO3 was added. In addition, the concentration of exchangeable K decreased resulted form the surface competition by Ca. The PBCK of the soils increased with liming based on the results of Q/I relationship plots, it indicated that a better ability of soil to maintain the intensity of K in the soil solution will be as PBCK increased. Based on the values of ARK (activity ration of K), K was mainly desorbed form the edge and planar positions. Therefore, PBCK values increased as a result of the release of K from these two sites caused by liming. Results also showed that liming did increase the K fixing capacity of the soils according to the fact that the values of ExKs (specific adsorption concentration of K) increased with liming. The data of predicted K uptake by maize calculated by the Barber-Cushman nutrient uptake model decreased with increasing lime addition, it indicated that the K supplying power of acid soils did decrease as liming.

並列關鍵字

K fixation ； K availability ； strongly acid soil ； liming