Soil reaction is a measure of acidity or alkalinity. It is important in selecting crops and other plants, in evaluating soil amendments for fertility and stabilization, and in determining the risk of corrosion. In general, soils that are either highly alkaline or highly acid are likely to be very corrosive to steel. The most common …Continue reading “Iowa Soil pH Maps [gSSURGO]”
Saturated hydraulic conductivity (Ksat) refers to the ease with which pores in a saturated soil transmit water. The estimates are expressed in terms of micrometers per second. They are based on soil characteristics observed in the field, particularly structure, porosity, and texture. Saturated hydraulic conductivity is considered in the design of soil drainage systems and …Continue reading “Iowa Soil Saturated Hydraulic Conductivity (Ksat) Maps [gSSURGO]”
Clay as a soil separate consists of mineral soil particles that are less than 0.002 mm in diameter. The estimated clay content of each soil layer is given as a percentage, by weight, of the soil material that is less than 2 mm in diameter. The amount and kind of clay affect the fertility and …Continue reading “Iowa Soil Clay Content Maps [gSSURGO]”
Sand as a soil separate consists of mineral soil particles that are 0.05 mm to 2 mm in diameter. In the database, the estimated sand content of each soil layer is given as a percentage, by weight, of the soil material that is less than 2 mm in diameter. The content of sand, silt, and …Continue reading “Iowa Soil Sand Content Maps [gSSURGO]”
Water content, -15 bar, is the amount of soil water retained at a tension of -15 bars, expressed as a volumetric percentage of the whole soil material. Water retained at -15 bars is significant in the determination of soil water-retention difference, which is used as the initial estimation of available water capacity for some soils. …Continue reading “Iowa Soil Water Content – 15 Bar Maps (wilting point) [gSSURGO]”
Bulk density, one-third bar, is the oven-dry weight of the soil material less than 2 mm in size per unit volume of soil at water tension of -0.33 bar (-33 kPa), expressed in grams per cubic centimeter. Bulk density data are used to compute linear extensibility, shrink-swell potential, available water capacity, total pore space, and …Continue reading “Iowa Soil Bulk Density – 1/3 Bar Maps [gSSURGO]”
Organic matter is the plant and animal residue in the soil at various stages of decomposition. The estimated content of organic matter is expressed as a percentage, by weight, of the soil material that is less than 2 mm in diameter. The content of organic matter in a soil can be maintained by returning crop …Continue reading “Iowa Soil Organic Matter Maps [gSSURGO]”
Available water storage (AWS) is the total volume of water (in centimeters) that should be available to plants when the soil, inclusive of rock fragments, is at field capacity. It is commonly estimated as the amount of water held between field capacity and the wilting point, with corrections for salinity, rock fragments, and rooting depth. …Continue reading “Iowa Available Soil Water Storage Maps [gSSURGO]”
Available water capacity (AWC) refers to the volume of water held per volume of soil that is available for plant uptake. This water typically occurs between suction levels of ~ -10 kPa (field capacity) and -1,500 kPa (wilting point). The capacity for water storage is given in centimeters of water per centimeter of soil for …Continue reading “Iowa Soil Available Water Capacity Maps [gSSURGO]”
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