Agrochemical and physicochemical properties of the soil of virgin dark serozems of the Aktau mountain range of Nurata district of Navoi region

In this article, we present the main geomorphological indicators of virgin dark serozems common on the slopes of the Aktau mountain range of the Nurata mountains. The relief of the territory of the studied soils is formed on mountain slopes with a dissected relief. The lands of these territories are used for grazing. Soil-forming rocks are alluvial-deluvial, rubble deposits formed on the destruction products of various bedrocks. Dark serozems are common in a temperate, humid climate, characteristic of the upper zones of the serozem belt. A significant annual input of organic substances into the soil determines the increased humus content of the soils, the greater thickness of the humus horizons. Increased moisture determines a deeper washout of carbonates. In the profile of virgin dark serozems, the following genetic horizons are distinguished: a humus-accumulative horizon of dark gray color, reaching a thickness of 16-20 cm with good turfiness; the structure of the upper horizons is plastic, turning into lumpy. The horizon B is 40 to 80 cm thick and contains insect chambers covered with limescale. The coloration is lighter with a brownish tint. An important feature of the soils of the belt of dark gray soils is their skeletal structure. The degree of skeletonity is different and depends on the depth of gravel deposits. The maximum hygroscopicity in virgin dark gray soils ranges from 2.746 to 4.819 % of the weight of absolutely dry soil. Fluctuations in the content of maximum hygroscopicity depend on the amount and composition of absorbed bases and soluble salts in the soil. The thickness of the humus horizon in virgin dark gray soils is 60-90 cm, the maximum content of humus is on the upper horizon at 6-7 cm. Its amount in the arable horizon is 2.66 -3.34 %. The content of mobile forms of phosphorus in the soil - 8.5-9.0 mg/kg of soil, the availability of exchangeable potassium is medium and high - 276.9-361.2 mg/kg. Dark serozems are richer in colloid-silt fractions, and organic colloids play a more significant role in their composition than in typical and light serozems. Therefore, their absorption capacity is higher.

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