本研究係於溫室進行,將多量磷肥(500ppm P)分四次同時施入本省十二種不同土壤中,每次施入後,即經浸水、風乾處理約一個月,以摸擬田間情況。四次共歷時五個月。處理過的土壤(每土壤均包括一不施磷之對照)再進行Neubauer法磷效應試驗,種值作物爲小麥。目的爲探討及比較原土壤中磷素與施肥磷素之聚積型態;化學測定法有效磷值與真正有效磷值間之關係,及施肥聚積磷素之同收率。其結果摘述如下: 1.原土壤中之磷幾乎全以Fe-P及Ca-P型態存在,前者在十二土壤中平均佔53.2%,後者佔44.8%,而以Al-P型態存在者僅佔三者總量之1.9%。在施用多量磷肥(500ppm P)後之土壤中Al-P所佔的百分率升高爲42.8%(十二土壤平均),Ca-P減低爲17.6%,Fe-P減低爲41.3%。又本試驗資料顯示施用磷肥5500ppm P後土壞中的磷絕大部分(84%)以Al-P及Fe-P型態存在,二者之比約爲1:1。 2.施肥聚積磷素之囘收率(以Bray's P-1法測定者)在13.8%至62.2%之間,十二土壤平均爲35.5%。囘收率之高低與土壤之CEC,P Sorption及O.M.含量成顯著負相關關係,而與有效磷含量成顯著正相關關係,如以土壤之CEC,P Sorption及Bray's P三者共同估計磷素囘收率,其準確匪可達78%。 3.作物磷吸收量與土壤Bray或Olsen磷均有極顯著之相關關係,其相關係數依次爲0.858(上標 **)及0.866(上標 **);但與EUF法測得磷之相關關係則較差。以上結果顯示以Bray或Olsen法測得之土壤有效磷可有效代表土壤中可被作物吸收利用之磷含量,無論此磷肥係過去或新近施用者。又本研究資料顯示作物吸收之磷在原土壤中多爲Fe-P,施肥土壤中則多爲Al-P。
Phosphorus was incorporated into 12 different soils in 4 successive applications at 30 days interval in the greenhouse. After each addition, the soils were submerged for 10 days, than left until dry to simulate field conditions. A total of 500ppm P was applied while a check treatment (no P was added) was included for each soil. After this pretreatment, the soils were used for Neubauer's P test; the plants grown were wheat. Soil chemical properties were analyzed and available P was extracted by Bray's, Olsen's, and EUF methods. Distribution of inorganic P fractions were determined for both the P-treated and check soils. This study was conducted to compare the distribution of inorganic P fractions in the original soil and P-enriched soil, the extractability and availability of P applied in soil as well as the P recovery rate of these soils. The results are summarized as follows. 1. P fractionation data show that in the original soil, the inorganic P forms are dominantly Fe-P (53.2%) and Ca-P (44.8%), and only 1.9% is Al-P (the average of 12 soils), whereas in the P-fertilized soil, 84% of the inorganic P fractions are Al-P and Fe-P, with a ratio of about 1: 1, and Ca-P becomes the minor part. 2. The P recovery rate (as determined by Bray's P-1 method) of the 12 soils varies greatly from 13.8 to 62.2%, with an average of 35.5%. regression study shows that P recovery rate is negatively correlated with soil CEC, P sorption, and O. M. content, but positively correlated with soil available P. When P recovery rate is estimated by soil CEC, P sorption and Bray's P together (the multiple corrlation coefficient R=0.881(superscript **)), its accuracy is 78%. 3. Quantities of soil P extracted by Bray's, Olsen's, and EUF methods are significantly correlated with plant P uptake, while the Bray's and Olsen's methods producing the higher correlation coefficients (0.858(superscript **) and 0.866(superscript **) respectively). This significant correlation signifies that soil available P as extracted by Bray's or Olsen's method can effectively represent the amount of P in soil that can be utilized by plants, no matter it is newly applied or not.