. Mass fraction of humus in accordance with GOST 26213-84, as a percentage, the lower boundary of topsoil should be: in the forest steppe and steppe zones – at least 2, in the southern taiga forest, arid, semi-desert, foothills of the desert-steppe, subtropical foothill semidesert and desert, subtropical shrub-steppe and suholesnoy, subtropical, vlazhnolesnoy, in the northern forest-steppe zone of gray forest soils, soils in mountainous areas – at least 1 in desert and subtropical desert – not less than 0.7. Mass fraction of humus in a potentially fertile soil layer, the percentage should be in the forest steppe and steppe zones – 1-2, in the dry steppe and desert zones – 0,5-1. 2.1.2. The pH of the aqueous extract of fertile soil layer should be 5,5-8,2; in podzolic soils zheltozemnyh, red earths and soils of mountain regions – not less than 4.0.
Measuring the pH of the aqueous extract is carried out according to GOST 17.5.4.01-84. The pH of the salt extract of sod-podzolic Soil should be at least 4, 5, in a peat layer – 3.0 – 8.2. Mass fraction of exchangeable sodium, percent, from the cation exchange capacity, shall be: in the mixture formed a fertile layer of black soil, dark chestnut, chestnut soils and gray soils, saline soils in the complexes – no more than 5 on feebly and srednesolontsevatyh varieties of zone and hydromorphic soils steppe and steppe zones – to 15, on a weekly and humus-poor southern species srednesolontsevatyh chernozem, brown, chestnut soil and gray soils, and hydromorphic soils semihydromorphic arid and semi-arid zones – up to 10. Determining cation exchange capacity is carried out according to GOST 17.4.4.01-84. Water-soluble toxic salts in the fertile soil layer should not exceed 0.25% by weight of the soil, limit the allowable number of water-soluble toxic salts in the fertile soil layer can be increased to 0.5% when used in irrigated sites. Measurement and calculation of the amount of toxic salts produced according to GOST 17.5.4.02-84.
Mass fraction of soil particles less than 0.1 mm should be in the range – 10 to 75% on the floodplain, oxbow, deltaic sands and sandy sediments priarychnyh – 5.10%. Large-scale soil maps should be used to establish the model, podtipovoy, genera and species belonging soils. Optionally set the standard removal of topsoil with the structure of the soil cover on the soil of northern, northwestern, north-eastern provinces, territories and autonomous republics, with tundra, permafrost taiga soils, as well as in the taiga-forest zone of podzolic soils in large parts And the Central Asian republics of Kazakhstan, located in the desert, foothill desert-steppe, subtropical desert zones. Do not set the standard removal of topsoil in the case of a discrepancy it GOST 17.5.3.05 and soils to a great extent gravelly, strongly and very, very stony, weakly, moderately and heavily washed sod-podzolic, brown forest, gray and light gray forest, moderately and severely eroded dark gray forest, dark chestnut, sod-calcareous, yellow soils, red earths, gray soils.