Distribution of sugars, root enclosed, in the soil following corn and sorghums and their effects on the succeeding wheat crops
1938
Conrad, J.P.
Samples taken with a soil tube from beneath corn and sorgo rows showed from 20 to over 200 times as much sugars as sucrose in the soil beneath the crowns of sorgo than under those of corn. By taking larger soil samples with a spade in such a way as perhaps to be more representative of the condition sampled, than with the tube, the residual sugars expressed as sucrose were shown to occur both vertically and horizontally in highest concentrations near the crowns of the plants. Vertical slices to a depth of 1 foot, exceeding 100 p.p.m. of sugars, were not encountered over 6 inches from row centers while at the sorgo row center some were over 4,000 p.p.m. Horizontal 1-inch layers in the row and extending 4 inches on each side of it, ranged from over 12,000 p.p.m of sugars in the first such layer to less than 10 p.p.m. in the 10th inch layer. Rows of wheat parallel to the previous crop rows showed marked and statistically significant decreases adjacent to and over the row centers of sorgo and milo, while the slight decreases adjacent to previous corn rows were not significant.
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