1992/11/01 by James L. Walworth, J. L. Walworth, M. T. Panciera +2
Agricultural and Biological Sciences · Materials Science · #Soil Carbon and Nitrogen Dynamics #Plant Micronutrient Interactions and Effects #Clay minerals and soil interactions
paper · doi:10.4141/cjss92-043
Field trials were conducted on three cryic soils in southcentral Alaska to determine the local suitability of the Mehlich 3 extractant. Mehlich 3 extractable B, Cu, Fe, Mn and Zn, DTPA-TEA extractable Cu, Fe, Mn and Zn, and hot water extractable B were measured on soils from factorial experiments with variable rates of B, Cu, Mn, and Zn. Additional soil samples from two B rate and liming studies in central Alaska were included in extractable B comparisons. Forage rape, broccoli, and potato tissue samples were collected from the factorial studies to determine relationships between soil- and plant-available micronutrients. Crop yields were not affected by micronutrient applications Neither Mehlich 3 nor DTPA-TEA extractant predicted plant-available Cu or Fe. Coefficients of determination between soil and plant tissue B were comparable for extraction by Mehlich 3 or hot water and ranged from 0.11 to 0.82 Neither the Mn nor Zn tests accounted for more than 39% of the observed tissue nutrient concentration variation. The inclusion of soil PH and organic matter slightly improved estimates of available B, Mn, and Zn. Mehlich 3 extractable Fe was poorly related to DTPA-TEA extractable Fe. Copper extracted with Mehlich 3 was related to that extracted with DTPA-TEA (r 2 = 0.73); the inclusion of soil pH improved the relationship (r 2 = 0.84). Mehlich 3 extractable Mn and Zn were closely related to DTPA-TEA extractable levels (r 2 = 0.91 and 0.94, respectively). The correlation between Mehlich 3 and hot water B (r 2 = 0.57) was significantly improved by including soil organic matter content (r 2 = 0.71). Key words: Micronutrients, extractant, Mehlich 3, DTPA, hot water