ÖZETBu çalışmada; reaksiyonlarz farklı (Alka/in-Asiı) topraklardanNaHC0 3 (0.5 M, pH=8.5) ve Bray-2 (0.1 N HCl +0.03 N NH4F)çözeltileriyle ekstrakte edilmiş olan fosforun; molibdo-fosforik mavirenk esasına göre iki ayıfosfor tayin metodu (HCl-Sn ve HıS04 - Askorbik asit) ile bulunan miktarlarz birbirıeri ile mukayese edilmiş, aralarandakiilgi derecesi hesaplanmış ve uygulaması daha basit ve seriolan Sülfirik asit-Askorbik asit metodunun HCl-Sn metodu yerineikame edilme imkanı araştırılmıştır.Netice olarak; adı geçen iki metod arasında NaHC0 3 ve Bray-2ekstrakılarında % 1 seviyesinde önemli (r=0.976 ve r=0.998) müsbetilgi tesbit edilmiş ve Sülfirik asit-Askorbik asit metodunun kolorimetrikfosfor tayininde HCl-Sn metodu yerine kullanılabileceği neticesinevarılmıştır.An lnvestigation On The Applications Of Two Different Colorimetric Methods For Phosphorus DeterminationUsing NaHCO3 And Bray-2 Extracts From Alkaline And Acid Soil.Using acid and alkali soils, wehave tasted two different colonmetricmethods for determining inorganic' phosphorusin NaHCO 3 and Bray- 2extracts.The soils Wihch were used in thisexperiment were coIlected from Erzincanand Bayburt valiey alsa Rize Region.Rize soils were acid, Erzincanand Bayburt soils were alkaline inreaction.The Olsen's 0.5 M NaHCO3 atpH 8.5 eqtraction meth~ct'were appliedto six Rize and six Bayburt soils whileten surface soils each regions wereextracted according to the Bray- 2(O. IN HCl + 0.03N NH4F)Molybdophosphoric blue methodin hydrochloric acid system Jackson(1958) and H ıS0 4- Ascorbic acid methodJohn (1970) have been used ınall soil extracts.it has been found that the bothcolonmetric methods gave positif correlationwith the extractants at the levelof 1 %'However there was no differencesbetween the values obtained by thesecolorimetric methods but the H ıSO 4Ascorbicacid procedure was simpleto operate and more reproducible.