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The fraction of water held back in the aquifer is known as specific retention. Thus it can be said that porosity is the sum of specific yield and specific retention. Specific yield of soils differ from each other in the sense that some soil types have strong molecular attraction with the water held in their pores while others have less.
These properties are storativity (S), specific storage (S s) and specific yield (S y). According to Groundwater , by Freeze and Cherry (1979), specific storage, S s {\displaystyle S_{s}} [m −1 ], of a saturated aquifer is defined as the volume of water that a unit volume of the aquifer releases from storage under a unit decline in hydraulic head.
In agriculture, the yield is a measurement of the amount of a crop grown, or product such as wool, meat or milk produced, per unit area of land. The seed ratio is another way of calculating yields. Innovations, such as the use of fertilizer , the creation of better farming tools, new methods of farming and improved crop varieties , have ...
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.
In its early stages of development, soil loss tolerance rates were inconsistent because they were obtained based on rough estimates. From 1961 to 1962, several groups of soil in the United States were designated with T rates ranging from 2 to 6 tons per acre per year. The rate was subsequently adjusted to 1 to 5 tons per acre per year. [5]
Additionally, the method cannot collect accurate data for weak soil layers for several reasons: The results are limited to whole numbers for a specific driving interval, but with very low blow counts, the granularity of the results, and the possibility of a zero result, makes handling the data cumbersome. [5]
The opposite situation, i. e. when the void ratio is relatively small (dense soils), indicates that the volume of the soil is vulnerable to increase (swelling) under unloading – the smectite (montmorillonite, bentonite) partially dry clay particles present in an unsaturated soil can swell due to their hydration after contact with water (when ...
While individual products are usually measured by weight, which is known as crop yield, varying products make measuring overall agricultural output difficult. Therefore, agricultural productivity is usually measured as the market value of the final output. This productivity can be compared to many different types of inputs such as labour or land.