土壤水分境況對強酸性土壤磷吸著與有效性的影響

Effects of Soil Moisture Regime on the Sorption and Availablility of Phosphate in a Strongly Acid Soil

陳仁炫(J. H. Chen) ； 劉有祥(Y. H. Liu)

《土壤與環境》 2卷1期 (1999/03) Pp. 45-57

https://doi.org/10.30058/SE.199903.0005

摘要

磷在土壤中的行為包括吸附、脫附、沉澱、溶解、固定、淋洗及被植物吸收等作用，而該等作用的相對改變程度會因土壤水分境況的不同而異。本試驗即針對土壤水分境況及乾溼效應對強酸性土壤磷吸附和磷有效性的影響進行探究。本試驗選取強酸性的大肚山洪積母質紅壤，分別施用二種劑量的KH2PO4（0, 200 mg P／kg土)，並分別於不同水分含量（-33 kPa勢能之水分）的60%，100%及150%處理下，於恆溫生長箱中予以培育。在培育過程中又將土樣分成經乾溼交替與不經乾溼交替（即濕土培育）兩種處理。四週後，分別測定各處理土樣的pH，磷吸附能力各種型態磷酸鹽，及四種磷有效性指標(溶液磷、陰離子交換樹脂磷、Olsen磷及Bray 1磷)之濃度。實驗結果顯示，以一般實驗室慣用之溼土培育方式對磷有效性和磷吸附特性的影響，與模擬田間之乾溼交替方式所得者並不一致。一般而言，在土壤中磷的吸附能力及脫附能力均隨水分含量的增加而增加，而磷有效性指標的測值則隨水分含量的增加而降低。同時，土壤經乾溼交替處理者雖然磷吸附及磷脫附能力均低於濕土培育者，但土壤中含難溶性磷酸鹽的量郤較高，故乾濕交替處理之土壤的磷有效性指標測值比溼土培育者低。

關鍵字

土壤水分境況 ； 磷吸附能力 ； 磷脫附能力

並列摘要

The phosphorus (P) behavior in soil, including adsorption, desorption, precipitation, dissolution, fixation , leaching, and uptake by plants, is supposed to be affected by the soil moisture, The purposes of this research were to study the effects of soil moisture and drying-wetting cycles on the adsorption, desorption and availability of P in an acid soil.Acidic Dai-Du Shan soil was collected in this study, then applied with two levels of KH2PO4 (0, 200 mg P/kg) respectively, and then incubated in a growth chamber at three levels of soil moisture (60%, 100% 及150%) of water content (-33kPa potential). The incubations were made by wetting, or drying-wetting cycles. After four weeks, the capacities of P adsorption, the forms of phosphste and the P availability index (solution P, anion exchange resin P, NaHCO3-P, and Bray-1P) were determined for each treatment.The results obtained from wet incubation in laboratory were found to be different from those of drying-wetting cycles that simulated the moisture status in the field. In addition, the desorption capacities of P increased with the increasing soil water content. The values of P availabilities in the soil were showed to be as a result of the changes of capacities of P sorption, soil pH, organic P mineralization, and phosphate dissolution that induced by soil moisture regime. In general, the capacities of adsorption and desorption of P increased and P availability decreased with increasing soil moisture in acid Dai-Du Shan soil. In addition, the P availability and the adsorption and desorption of P were a little bit lower in drying-wetting incubation than in wet incubation.

並列關鍵字

Soil moisture regime ； Adsorption capacity ； Desorption characteristics