A Method for Measuring Short-Term Nutrient Absorption by Plants: III. Nitrogen
1959
DeMent, J. D. | Stanford, George | Hunt, C. M.
Roots of intact, N-deficient oat plants proliferated rapidly in contact with both N-fertilized and unfertilized soils, and recovery in top growth of 10 to 40 mg. of N applied as (NH₄)₂SO₄ ranged from 67 to 38.5% after 7 days. Recovery by whole plants (tops + roots) ranged from 93 to 62%. During the same period, uptake from ureaform was about one-third that of the soluble sources. No differences in uptake from NaNO₃, (NH₄)₂SO₄, and urea in 7 days were found. Since selective absorption of NO₃⁻ and NH₄⁺ ions by oat plants was not apparent under the experimental conditions, this crop is regarded as a suitable one for evaluating relative potential availability of N sources and factors influencing N uptake by the short-term method. N uptake from fertilizer with time described a sigmoid curve. The moisture equivalent was approximately the soil moisture level at which maximum N uptake occurred from Hartsells fine sandy loam and Webster silty clay loam. A highly significant linear correlation (r = 0.98) was found between N content of whole plant and tops based on combined analysis of data obtained with 2 soils, 3 N sources, 3 uptake periods, and 4 levels of N.
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