The effect of oxidation-reduction potential on plant growth
1939
Volk, N.J.
A study was undertaken for the purpose of determining the effect of oxidation-reduction potential, within certain limits, on plant growth when oxygen was not a limiting factor. Thirteen different crops were tested using sand cultures and constant flow nutrient solutions of different Eh values but of constant nutrient value and in equilibrium with the air. No attempt was made to study changes in the state of oxidation or reduction, or other changes that might accompany changes of Eh in soils. In all tests it is believed that Eh was the only variable present. The results show that for the plants tested, a change in Eh from about 525 millivolts to about 325 millivolts did not affect plant growth. An Eh of 325 millivolts is approximately 100 to 150 millivolts below the lowest Eh reached by 48 arable Alabama soils tested throughout the year 1937. Oxidation-reduction potentials below 325 millivolts have not been studied by the method described herein.
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