Premium
Calcium Effects on Quantity‐Intensity Relationships and Plant Availability of Ammonium
Author(s) -
Koenig R. T.,
Pan W. L.
Publication year - 1996
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1996.03615995006000020022x
Subject(s) - intensity (physics) , calcium , ammonium , environmental science , chemistry , environmental chemistry , physics , organic chemistry , quantum mechanics
Competition among cations for exchange sites in soil may influence NH 4 concentrations in soil solution adn consequently affect NH 4 availability to plants. Laboratory, greenhouse, and field experiments were conducted to determine whether Ca additions enhance NH 4 availability, thereby increasing the potential for NH 4 absorption by plants. A Shano silt loam soil (coarse‐silty, mixed, mesic Andic Mollic Camborthid) was equilibrated with NH 4 solutions ranging in concentration from 0 to 70 mg N L ‐1 with either distilled water or a 400 mg Ca L ‐1 matrix. The Ca matrix resulted in 20 mg (167%) more NH 4 ‐N L ‐1 in solution than the distilled water matrix at an exchangeable NH 4 concentration of 100 mg N kg ‐1 soil. Calcium also reduced the potential maximum quantity of NH 4 adsorbed by the soil as well as the soil buffer capacity for NH 4 . Combining Ca with NH 4 fertillzers (1:2 Ca/N molar ratio) increased NH 4 concentrations in the soil solution in subsequent greenhouse and field experiments. The influence of Ca on soil solution NH 4 concentration is attributed to preferential adsorption of Ca and the displacement of NH 4 from soil exchange sites. Mechanistic model predictions of NH 4 uptake were 22% higher for rice ( Oryza sativa L.) and 7.5% higher for corn ( Zea mays L.) when Ca was combined with NH 4 , as a result of an increase in soil solution NH 4 concentrations and the effective diffusion coefficient for NH 4 . These experimental results and model simulations indicate that in NH 4 ‐fertilized soils, the applicaiton of Ca will increase NH 4 availability and absorption by plants.