Section 5
Chapter 4,509

Calcium sulphate versus lime as fertilizer filler: effects on ammonium and nitrate uptake by perennial ryegrass

Kirkpatrick, T.; Bailey, J.S.

Communications in Soil Science and Plant Analysis 37(5/6): 733-750


ISSN/ISBN: 0010-3624
DOI: 10.1080/00103620600563978
Accession: 004508430

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The recovery of 15N-labelled nitrogen (N) by perennial ryegrass can be significantly increased by mixing gypsum (CaSO4 . 2H2O) into soil rooting medium at rates equivalent to 0.7t ha(-1). Similar improvements in fertilizer N efficiency might be achieved, at less cost and more conveniently, by applying smaller amounts of CaSO4 anhydrite more strategically to fertilizer microsites as a fertilizer filler or diluting agent, in calcium ammonium nitrate (CAN), in place of CaCO3. With this in mind, two complementary pot experiments were conducted under simulated spring conditions in a controlled environment chamber. Use of CaSO4 as diluting agent, in place of CaCO3, appreciably enhanced (>30%) the uptake of labeled N by perennial ryegrass plants within the second week of regrowth, but thereafter, because losses of 15N-labeled NO3(-)-N from pots by denitrification or leaching had been minimal, plants in both treatments eventually recovered equal amounts of this N form from the soil.

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