Search results
Results from the WOW.Com Content Network
A simple soil moisture sensor for gardeners. Soil moisture sensors measure the volumetric water content in soil. [1] Since the direct gravimetric measurement of free soil moisture requires removing, drying, and weighing of a sample, soil moisture sensors measure the volumetric water content indirectly by using some other property of the soil, such as electrical resistance, dielectric constant ...
Volumetric water content, θ, is defined mathematically as: = where is the volume of water and = + + is equal to the total volume of the wet material, i.e. of the sum of the volume of solid host material (e.g., soil particles, vegetation tissue) , of water , and of air .
A study of a single winter rye plant grown for four months in one cubic foot (0.0283 cubic meters) of loam soil showed that the plant developed 13,800,000 roots, a total of 620 km in length with 237 square meters in surface area; and 14 billion root hairs of 10,620 km total length and 400 square meters total area; for a total surface area of ...
where A is the area of a given leaf or all leaves of a plant, and M L is the dry mass of those leaves. Typical units are m 2 /kg or mm 2 /mg. Leaf mass per area (LMA) is its inverse and can mathematically be decomposed in two component variables, leaf thickness (LTh) and leaf density (LD): [4] = =.
It is necessary to measure temperatures of both the condensation and evaporation, because the dew point is the equilibrium temperature at which water both condense and evaporate at the same rate. When cooling the mirror, the temperature keeps dropping after it has reached the dew point thus, the condensation temperature measurement is lower ...
Schematic drawing of a hydrometer. The lower the density of the fluid, the deeper the weighted float B sinks. The depth is read off the scale A. A hydrometer or lactometer is an instrument used for measuring density or relative density of liquids based on the concept of buoyancy.
Stomatal conductance, usually measured in mmol m −2 s −1 by a porometer, estimates the rate of gas exchange (i.e., carbon dioxide uptake) and transpiration (i.e., water loss as water vapor) through the leaf stomata as determined by the degree of stomatal aperture (and therefore the physical resistances to the movement of gases between the air and the interior of the leaf).
where V = the chamber volume in liters, p = the density of carbon dioxide in mg cm −3, FSD = the carbon dioxide concentration in ppm corresponding to the change in carbon dioxide in the chamber, t = the time in seconds for the concentration to decrease by the set amount. Net photosynthesis per unit leaf area is derived by dividing net ...