The effect of soil moisture on mineral nitrogen, soil electrical conductivity, and pH
2002
Zhang, R. | Wienhold, B.J.
Inorganic nitrogen in the soil is the source of N for non-legume plants. Rapid methods for monitoring changes in inorganic N concentrations would be helpful for N nutrient management. The effect of varying soil moisture content on soil mineral nitrogen, electrical conductivity (EC), and pH were studied in a laboratory experiment. Soil NO3-N increased as soil water-filled pore space (WFPS) increased from 0 to 80 cm3 cm-3. At soil moisture levels greater than 80 cm3 cm-3, NO3-N concentration declined rapidly and NH4-N concentration increased, likely due to anaerobic conditions existing at higher WFPS levels. Soil pH did not change as soil moisture increased from 100 g kg-1 to 400 g kg-1 and increased from 6.2 to 6.6 at higher levels of soil moisture. Soil EC was correlated with soil mineral N concentration when measured in situ with a portable EC meter (R 2=0.85) or in the laboratory as 1:1 soil water slurries (R 2=0.92). Results suggest that EC can be used to rapidly detect changes in soil inorganic N status in soils where salts and free carbonates are not present in large amounts.
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