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Evaluation on K availability of the major group soils in Taiwan
應予以探究之o 本論文探討 (1)本省主要土類土壤之鉀固定特性及與土壤
沸騰硝酸，中性醋酸銨，Mehlich I，Bray I，Mehlich III以及AB-DTPA
換性鉀的釋放速率恐太慢而無法及時供甘藍吸收利用，固在兼顧 "量" 的
衡量下，Mehlich III 應為最適切之鉀有效性測定方法o 在以石
Potassium (K) fixation has been suggested to be the main factor in reducing K availability in soil. Therefore, it is necessary to investigate the characteristics of K fixation in the main groups of soil in Taiwan in order to evaluate their K availabilities. The relative change in the forms and the availabilities of K in the soils could be altered by K fertilization, and the effect of each forms of K on K availability should be determined. Several methods have been used to determine K availability in soils, but their suitability needed to be evaluated. Liming is an important mean in improving the productivity of acid soils, however, its effect on K availability still confused and should be studied. The purposes of this study were to (1)study the relationship between K fixation capacity and soil properties of those main soil groups in Taiwan, (2)determine the effects of K fertilization on soil K availability and cabbage growth, (3)evaluate the suitability ofseven methods in determining K availability, and (4)investigate the effect of liming on the fixation capacity and availability of K in acid soil. Basedon the relationships between K fixation capacity and soil properties, calcareous eluvial soils had higher K fixation capacity than those of noncalcareous eluvial soils and others strongly weathered soils. It was concluded that the K fixation capacity of soils was largely governed by the kinds and the content of clay minerals and soil pH. Results also showed that theith lower K fixation capacity resulted in more readily availableK released, and the relative changes in the forms of K was not significantly influenced by the time of incubation. The results of pot experiment clearly indicated that nonexchangeable did play a very important role on the K uptake by cabbage. The boiling HNOз, neutral NH4OAC, Mehlich I, Bray I, Mehlich III , and AB-DTPA method all were suitable in determining K availability of Shan Wha soil which has strong K fixation capacity . Furthermore, the method of boiling HNOз had a best relationwith the K uptake by cabbage, but the relase rate of nonexchangeable K was too slow to provide cabbage absorption. Therefore, the Mehlich III was the most suitable method in determining K availability in soils as the quantity of K was considered. There had been a distinct increase in the K retention as liming acid soils, and surface adsorption was the main mechanism of K retention as pH below 6.0, however, K fixation was gradually important with more lime was added. According the amount of K uptake by maize calculated by using the Barber-Cushman nutrient uptake model, K availability in soils was decline with liming in the acid soils. In addition, liming caused a increase in K fixation capacity and decrease in the efficiency of K fertilization. It suggested that the changes of K availability in soils, and the adjustment of the K fertilization management need to be consider when acid soils were liming.
|Appears in Collections:||土壤環境科學系|
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