<jats:p>This article investigates the amount and forms of humus in the major soil types of the flat areas of Kashkadarya region. The study reveals that the quantity and composition of humus vary significantly depending on natural-climatic conditions, irrigation levels, and agrotechnical practices. In irrigated sierozem (gray) soils, humic acids bound with calcium dominate, while in saline soils, fulvic acids and
unstable forms of humus prevail.</jats:p>