Accounting soil organic carbon stock and its active components in some Iraqi soils under different land use practices using Roth-C model

الملخص EN

This Sudy was conducted to compute organic carbon stock and its components using the Roth-C model in the soils of some selected farms under different land use sy^ems comprising crop- fallow rotation including wheat- fallow, maize - fallow, Barley-fallow, native vegetation of tall grasses and forest in the mountain and marshland area.

The predominant grass species are Panicum, Coloniao and reed in the marshlands.

Ten farms were selected from different locations representing common land use that include native vegetation, bare land and cultivated land and under different climatic conditions.

General surface data were collected about all selected location and soil samples were taken to determine general soil properties using the common laboratory methods.

The results revealed the effect of land use type on the common soil properties mainly the total organic carbon( TOC).

Clay content ranged from 18.1% in the soil of babel in irrigated farm (Bab 2), to 55.9% in the soils of Erbil under dry farming system.

The results show some variations in soils properties which affect organic matter accumulation and its components.

Soils of the native vegetation show the highest content of TOC and its components.

The Roth-C model predicts that the soil organic carbon consists of 0.45 % C in RPM, 2.0 % C in DPM, 7.97 % C in IOM, 13.24 % in BIO and 76.36% in HUM.

Soils of the native vegetation show the highest content of TOC and have the highest amount of OC lost and CO2 evolved from the farms.

According to these results, the application of Roth - C model responded well to predictions for TOC and its components in some Iraqi soil under different land uses, compared with measured values of TOC in some of the farms.