Micronutrients in the Kootenai river valley of Northern Idaho. I. Effect of soil chemical properties on micronutrient availability |
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| Abstract: | Abstract Crops grown on soils of the Kootenai River Valley of northern Idaho are showing an increasing tendency for micronutrient deficiencies. These soils are generally high in organic carbon (OC) and slightly alkaline. Soil pH has been increasing at the rate of 0.2 units every 10 years for the last 30 years. Normal soil sampling and testing procedures have failed to identify potential deficiencies of micronutrients prior to planting crops. Consequently, a different way to predict the tendency of micronutrient deficiencies is desired. The objectives of this study were to: (1) evaluate the effects of soil pH and OC on DTPA‐extractable Cu, Mn, and Zn, (2) establish relationships between pH, OC, Cu, Mn, and Zn and soil mapping units and geographic areas (drainage districts), and (3) predict tendencies for deficiencies or sufficiencies of evaluated micronutrients. One hundred fifty‐four soil samples were collected from the surface 30 cm of fields in the Kootenai River floodplain during 1989 and 1990. Six soil mapping units and eleven drainage districts were sampled. Soil pH, OC and DTPA‐extractable Cu, Mn, and Zn were determined on each sample. AU collected data were analyzed with the GLM procedure of SAS and quartile reference was used to separate the data. Manganese availability was negatively correlated with pH and OC. Significant correlations were also found between Cu and soil pH, and Zn and OC. The pH x OC interaction significantly affected both Mn and Zn availability. Soil pH, OC, and DTPA‐extractable Cu, Mn, and Zn were used to categorize soil mapping units and drainage districts into low, medium, and high tendencies for micronutrient availability. This categorization can be used as a tool for growers and consultants for soil micronutrient management |
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