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JoEllen Turner
<br />970 - 864 -7682 p.4
<br />8orch Environmental Pollution Consulting LLC October 2, 2012
<br />In agreement with my concerns about salinity (EC) impacts on crop yield, Mr. Dunker concluded
<br />in his recent (2011) paper that, "soil electrical conductivity data reveal substantial differences in
<br />inherent soil properties across the 0.6 ha comprising the Morrow Plots. While evidence of the
<br />central (N alley is visible, there is little indication that observed differences reflect long -term
<br />rotation or soil amendment effects. The lowest (EC) readings, indicated by the lighter areas of
<br />the map, are in the plots 4SA and 4SB, the plots that produced the highest yields in the corn -
<br />soybean rotation during the past four decades. Plots 3NC, 3ND, and 3SD, among the lowest
<br />yielding plots in continuous corn, have the highest ECa values in that rotation. In the corn -oat-
<br />hay rotation, the MLP plots (5SC and 5SD) show the highest ECa values, the highest
<br />SOC values, and yet did not produce the highest yields. Inherent soil properties dearly influence
<br />the yield levels in the Morrow Plots, and represent a source of confoundment that renders the
<br />effects of rotations and treatments impossible to isolate. " from Nafziger, B. D.; Dunker, R. E.,
<br />Soil organic carbon trends over 100 years in the morrow plots. Agron. I. 2011, 103, 261 -267.
<br />This peer - reviewed paper was later found to contain calculation errors but I hope I interpreted
<br />this part of the manuscript correctly and that Mr. Dunker did not include other errors in his
<br />paper:
<br />'The authors (Nafziger and Dunker) greatly appreciate the assistance of
<br />Dr. Ken Olson, University of Illinois, who found the errors in the paper
<br />and made suggestions for correcting them. The authors regret the errors
<br />and apologize for any inconvenience this causes to the readers."
<br />b) It also worries me that Zone I and Zone 2 will contain Bench 1 subsoil substitute
<br />within the upper 40 inches because of its high rock content (average percent coarse (rock)
<br />fragments >3" = 6.37), salinity, and the fact that its productivity is unknown. Specifically, as
<br />Mr. Dunker is well aware, high rock content will impact the soils physical and chemical
<br />characteristics. Cousin et al. 2003 wrote "the presence of rock fragments modifies (i) the soil
<br />physical properties: available water content, infiltration and runoff susceptibility, for example;
<br />(ii) the soil chemical properties: carbon content or nitrogen content; and (iii) the agronomical
<br />characteristics like the yields. Most studies dealing with stony soils usually do not take into
<br />account the rock fragments, even if their abundance cannot be neglected. As a consequence, the
<br />soil properties are not correctly evaluated, overestimated or underestimated, when only the fine
<br />fraction of the soil is considered (Ugolini et al., 1998). "Rytter concluded that although the
<br />relative volumes of stones and gravel were small, at most 8 %, neglecting the volume occupied
<br />by rock fragments led to an overestimation of C and N stocks by 8 -9 %.
<br />Cousin, I., Nicoullaud, B., Coutadeur, C., Influence of rock fragments on the water retention and water
<br />percolation in a calcareous soil. Catena 2003, 53, 97 -114.
<br />Rytter, R. -M., Stone and gravel contents of arable soils influence estimates of c and n stocks. Catena 2012,
<br />95, 153- 159.
<br />Ugolini et al., Under- and overestimation of soil properties in stony soils, 16th World Congress of Soil
<br />Science, Montpellier, France (199S)
<br />c) It is also very difficult to predict if the reclaimed soil will have the same soil
<br />strength ( "a measure of soil compaction ") and hydraulic properties as the original soil. In fact,
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