Aggregate composition of carbonate chernozem from South Banat

Abstract

In order to estimate the aggregate composition of carbonate loamy chernozems on the loess of South Banat, utilized as cultivated and pasture, fractionation was performed of individual categories of structural aggregates according to their size and also the determination of structure coefficient, mean weight diameter and geometric mean diameter of the dry structural aggregates. Laboratory analyses involved soil samples of the humus, i.e. arable (0-20-30 cm) and subarable horizons (20-40 and 40-60 cm) from 24 profiles of cultivated land and the samples of surface (0-20-30 cm) and subsurface layers (20-40 and 40-60 cm) of the humus horizons of 4 pasture profiles. The results of the investigations showed that beside favorable, mainly crumby-beady structure there appeared also significant differences in aggregate composition, both between various profiles, in dependence on the utilization mode of the soil, and between various depth zones of the humus horizon. The content of agronomical most valuable aggregates fraction (0.25-10 mm) in all depth zones of the humus horizon of the investigated profiles is >60%, which is, according to the classification by ŠEIN et al. (2001), a characteristic of good-structured soil. According to the values of structure coefficient and the mentioned classification, the cultivated soil profiles (1.5-2.42) show good, and those from pasture (1.15-1.70) satisfactory structure. In cultivated soil profiles, mean weight diameter and geometric mean diameter of the dry aggregates is significantly higher than in those from the pasture, and when they are larger, the structure of the soil is better and vice versa. .

U cilju ocene agregatnog sastava karbonatnih ilovastih černozema na lesu Južnog Banata, pri njivskom i pašnjačkom načinu korišćenja, izvršeno je frakcionisanje pojedinih kategorija strukturnih agregata prema njihovoj veličini i određivanje koeficijenta strukturnosti, srednjeg masenog i srednjeg geometrijskog dijametra strukturnih agregata. Laboratorijskim analizama obuhvaćeni su zemljišni uzorci humusnog, odnosno oraničnog (0-20-30 cm) i podoraničnog horizonta (20-40 i 40-60 cm) iz 24 njivska profila i uzorci površinske (0-20-30 cm) i podpovršinskih proba (20-40 i 40-60 cm) humusnog horizonta iz 4 pašnjačka profila. Rezultati istraživanja pokazali su da pored povoljne, pretežno mrvičasto-graškaste strukture postoje i znatne razlike u agregatnom sastavu kako među raznim profilima, u zavisnosti od načina korišćenja zemljišta, tako i u raznim dubinskim zonama humusnog horizonta. Sadržaj agronomski najpovoljnijih agregata (0.5-10 mm) u svim dubinskim zonama humusnog horizonta istraženih profila je > 60%, što je, prema klasifikaciji Šein-a et al. (2001), karakteristika zemljišta dobre strukture. Prema vrednostima koeficijenta strukturnosti i navedenoj klasifikaciji njivski profili (1.5-2.42) pokazuju dobru, a pašnjački (1.15-1.70) zadovoljavajuću strukturnost. U njivskim profilima prosečni maseni i geometrijski prečnik agregata znatno je veći nego u pašnjačkim, a kada su njihove vrednosti veće struktura zemljišta je bolja i obratno. .