| dc.description.abstract | Soil electrical conductivity (EC) can be used as a parameter to assist agricultural producers
in making economically important management decisions. Since particular crops and crop
varieties respond dynamically to soluble salt levels in relation to crop growth stage and
soil moisture content, many management decisions regarding crop type and variety must
be made prior to planting. Some crop stress factors could be removed or mitigated if a
handheld EC meter could be implemented during the growing season. The objectives of
this research were to 1) determine the accuracy of four handheld EC meters for
measuring soil EC across a range of environmental temperatures of 15, 20 and 25° C, soil
clay concentrations of 10.2, 17.8, 19.3, 32.3 and 50.4 %, and salt solutions containing NaMg-
SO4 or Na-Mg-Cl at concentrations of approximately 0, 1, 2, 4 and 8 dS m-1 under
controlled laboratory conditions; 2) identify functional differences of the meters that
might pose problems for in-field use; and 3) determine if meter price is related to
accuracy. The EC values provided by three of the handheld EC meters were significantly
different than the standard meter at all treatment levels. Measurements at different
temperatures of the standard KCI calibration solution (known EC 1.413 dS m ·1
) varied by
±0.15, -0.01 to +0.16, -0.14 to -0.03, and ±0.03 dS m-1, for the Hanna Black (Hl993310),
Hanna Blue {Hl98331), Field Scout, and SenslON 5 meters, respectively. When salinity was
3 dS m-1 or greater the difference between the test meters and standard meter (EC Response} was larger. Test meter measurements for the salinity by clay interaction were
different than the standard meter by ±0.5, ±1, and -2.5 to +1.5 dS m-1, for EC levels of less
than 3, 3 to 4, and greater than 4 dS m-1, respectively. The SenslON 5 handheld was the
only meter tested that was not significantly different than the standard meter {p::; 0.48}.
Test meter accuracy was highly dependent on temperature. Therefore, the most
important criteria for selecting a portable meter for in-field EC measurements is the
accuracy of the specific meter's temperature measurement and temperature
compensation model. | en_US |
