Elemental composition of humic acids of rendzina soils in Serbia

Abstract

The soil elemental analysis presented here focuses on humic acids in the Amo and Ap horizons of 16 profiles in different parts of Serbia that are characteristic of rendzina soils. The mass fraction of C in humic acids of rendzina soils in Serbia ranges from 50.33% to 56.81%, with the average of 52.34%. The mass fraction of H in humic acids of all investigated rendzina profiles was found to vary between 4.28% and 5.81%, and the average was 5.18%. The corresponding fraction of N was 3.34-4.96%, or 4.06% on the average. The mass fraction of O in the studied rendzina humic acids ranged from 33.81% to 39.88%, and was 38.42% on the average. The atomic C of humic acids in all renzdinas studied varied between 33.61% and 38.79%, and was 35.81% on the average. The atomic fraction of H varied between 37.38% and 45.13%, or the average 42.08%. Oxygen content in humic acids was found to be 17.11-21.69%, or 19.73% on the average, while nitrogen content was 2.02-2.83%, or the average 2.38%. The H:C ratio in humic acids was found to vary from 0.96 to 1.32, being 1.18 on the average, while the C:N ratio was 12.06-18.43, or the average 15.21. The results of this elemental analysis show that the humic acids of Serbian rendzina soils are characterized by a medium degree humification and condensation, which is consistent with the fulvate-humate type of humus in that soil.

Istraživanja elementarnog sastava huminskih kiselina rendzina Srbije imala su za cilj određivanje stepena humificiranosti i kondenzacije huminskih kiselina, a sve u svrhu proširivanja znanja o uslovima obrazovanja i evolucije ovog nedovoljno proučenog tipa zemljišta u Srbiji. Rezultati ispitivanja elementarnog sastava prikazani u ovom radu odnose se na huminske kiseline (19 preparata) iz Amo i Ap horizonta 16 profila rendzine sa različitih područja Srbije karakterističnih za ovaj tip zemljišta. Maseni udeo C u huminskim kiselinama u rendzinama Srbije kreće se od 50.33 do 56.81%, a u prošeku iznosi 52.34%. Maseni udeo H u huminskim kiselinama u svim ispitivanim profilima rendzina varira od 4.28 do 5.81%, a u prošeku iznosi 5.18%. Maseni udeo N u huminskim kiselinama rendzina varira od 3.34 do 4.96%, a u prošeku iznosi 4.06%. Maseni udeo O u huminskim kiselinama rendzina varira od 33.81 do 39.88%, a u prošeku iznosi 38.42%. Atomski udeo C u huminskim kiselinama, u rendzinama u celini, varira od 33.61 do 38.79%, a u prošeku iznosi 35.81%. Atomski udeo H varira od 37.38 do 45.13%, a u prošeku iznosi 42.08%. Kiseonika huminske kiseline rendzina sadrže 17.11-21.69%, prosečno 19.73%, dok sadržaj azota varira 2.02-2.83%, a u prošeku iznosi 2.38%. Odnos H:C u huminskim kiselinama varira od 0.96 do 1.32, a u prošeku iznosi 1.18, a odnos C:N varira od 12.06 do 18.43, i u prošeku iznosi 15.21. Rezultati elementarne analize pokazuju da su huminske kiseline rendzina Srbije srednjeg stepena humifikovanosti i kondenzacije što je u korelaciji sa fulvatno-humatnim tipom humusa ovog tipa zemljišta.