Statut organique et respiration microbienne des sols du nord de la Tunisie

Abstract

Organic status and microbial respiration in Northern Tunisian soils. The soil organic matter content is an important characteristic of soils fertility. It is also a characteristic more and more wanted in a global context of climate change, where the storage of the carbon in soil is a serious alternative to limit the CO2 emissions into atmosphere. Thirty-five soils located in North Tunisia (25 cultivated soils and 10 forest soils) were sampled. Soil organic matter was characterized by measuring total organic carbon content and total nitrogen content and the biodegradability of soil organic matter determinated by measuring the microbial respiration during 28 days of incubation at 28°C. The soil organic carbon content and total nitrogen content of the studied soils vary from 0.8 to 3.2% and from 0.07 to 0.45%, respectively. The forest soils have the largest contents in carbon and in nitrogen. At the end of the incubations, the quantity of C-CO2 emitted by the 35 soils varies between 213 and 853 mg C-CO2 .kg-1 dry soil. The easy mineralizable pool varies between 1.6 and 7.6% of the total organic carbon of soils. The quantity of resistant carbon was estimated by means of the Van’t Hoff law; it varies between 92 and 99% of the total soil organic carbon.

Keywords

• Land use
• arable lands
• forests
• soil organic matter
• total nitrogen
• microbial activity
• Tunisia