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The United States loses almost 3 tons of topsoil per acre per year. [16] 1 inch (2.5 cm) of topsoil can take between 500 [17] and 1,000 years [18] to form naturally, making the rate of topsoil erosion a serious ecological concern. Based on 2014 trends, the world has about 60 years of topsoil left.
The Universal Soil Loss Equation (USLE) is a widely used mathematical model that describes soil erosion processes. [1]Erosion models play critical roles in soil and water resource conservation and nonpoint source pollution assessments, including: sediment load assessment and inventory, conservation planning and design for sediment control, and for the advancement of scientific understanding.
Soil loss tolerance for a specific soil, also known as the T value, which can be calculated with [1] formula, is the maximum average annual soil loss expressed as tons per acre per year that will permit current production levels to be maintained economically and indefinitely. T values range from 1 to 5 tons per acre per year. [2]
The acre-foot is a non- SI unit of volume equal to about 1,233 m 3 commonly used in the United States in reference to large-scale water resources, such as reservoirs, aqueducts, canals, sewer flow capacity, irrigation water, [1] and river flows. An acre-foot equals approximately an eight-lane swimming pool, 82 ft (25 m) long, 52 ft (16 m) wide ...
Atterberg limits. The Atterberg limits are a basic measure of the critical water contents of a fine-grained soil: its shrinkage limit, plastic limit, and liquid limit. Depending on its water content, soil may appear in one of four states: solid, semi-solid, plastic and liquid. In each state, the consistency and behavior of soil are different ...
The specific heat of pure water is ~ 1 calorie per gram, the specific heat of dry soil is ~ 0.2 calories per gram, hence, the specific heat of wet soil is ~ 0.2 to 1 calories per gram (0.8 to 4.2 kJ per kilogram). [90] Also, a tremendous energy (~584 cal/g or 2442 kJ/kg at 25 °C) is required to evaporate water (known as the heat of ...
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Degraded soil requires synthetic fertilizer to produce high yields. Lacking structure increases erosion and carries nitrogen and other pollutants into rivers and streams. [8] Each one percent increase in soil organic matter helps soil hold 20,000 gallons more water per acre. [8]