| | Crop micronutrient concentrations of both vegetative tissues and grain, if applicable, were measured from 17 selected AESA Soil Quality Benchmark Sites in the fall of 2003. Entire plants (straw and grain) harvested from three, one m2, cuts at each topographic location (upper, mid and lower slope position) were analyzed using Inductively Coupled Plasma (ICP) methodologies. Micronutrients analyzed included boron, cadmium, chlorine, copper, iron, manganese, molybdenum, nickel, selenium, silicon and zinc. The purpose of this report is to provide an account of these micronutrient concentrations and to correlate them with a number of selected soil properties including soil pH, organic carbon, sand, silt and clay content, cation exchange capacity (CEC) and calcium carbonate concentrations. In addition, the uptake, translocation and importance of each micronutrient are discussed, as is a summary of the effect of micronutrient partitioning between the grain and straw fraction, the effect of landscape form (i.e., slope position) and the effect of provincial ecoregion on their concentration.
A value of r ≥ ±0.4 was used as an indication of a correlation between micronutrient concentrations and/or select soil parameters. Results indicated that there were 21 correlations to be discussed according to these criteria. Of these, many were not readily explainable, and were likely an artifact of the correlation analysis itself or attributable to a small sample size. In general, differences in plant tissue micronutrient concentration were identifiable as a result of various soil properties, ecoregions and partitioning pattern between the grain and straw components. None of the eleven micronutrients measured differed in response to topographical position.
Note that the interpretation of the straw values, as discussed in this report, is based on an analysis of the entire crop plant harvested at maturity. As such, these values may be somewhat skewed, as this is not the methodology typically employed for assessing nutrient deficiency/sufficiency at this growth stage. At maturity, nutrients are often being actively translocated from the vegetative tissues to the developing grain, and as such grain values are often more representative of nutrient concentration, and as an indication of nutrient sufficiency. |
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