ИСТИНА

Valley soils of humid areas are comprised of various peat and sandy soils of alluvial or lacustrine origins. These soils are located in subordinated positions in a landscape and accumulated high amounts of organic matter and mineral nutrients. Fluctuation of the river bed in space often causes highly complex soil cover in a valley. Studying those soils with conventional methods of soil mapping is very time and resource consuming. Therefore, we tested the electrical geophysical methods of multi-frequency electromagnetic scanning (AEMP-14) and electrical resistivity mapping (LandMapper ERM-01) for mapping peat and mineral alluvial soils formed in the glacial valley of Yachroma river. This area has been drained and used in intensive vegetable production for over 100 years. The distinction in botanical structure of peat and hydrology conditions at the different zones of the valley causes distinction in physical and chemical properties of sedge-mossy, grass-woody, and mineral-peat layered soils. The sedge-mossy peat typically has lower ash content and bulk density, and higher water content, than the grass-woody peat. Electrical resistivity of sedge-mossy peat soil is minimal (<20 ohm m) in comparison with resistivity of grass-woody (30-40 ohm m) and mineral-peat layered soils (50-60 ohm m). Based on the distribution of different peat and mineral deposits, an optimal plan of agricultural usage was proposed. Mineral-peat layered soils were recommended to use under intense vegetable production. The rest of the area in fields 1, 2, and 3, especially where seeping groundwater is close to the soil surface, could be used for grass pasture. The whole territory of field 4 and 5 could be used either for pasture or crop rotations of vegetables and grasses. Although such management scheme would reduce usage of soils for high cost vegetable crop, it decreased the cost for reclamation of these soils and service of drainage systems.