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Modeling Magnesium Uptake from an Acid Soil. II. Barber‐Cushman Model
Author(s) -
Rengel Z.,
Robinson D. L.
Publication year - 1990
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/sssaj1990.03615995005400030028x
Subject(s) - lime , lolium multiflorum , ultisol , chemistry , loam , lolium , nutrient , agronomy , magnesium , zoology , environmental chemistry , soil water , soil science , environmental science , poaceae , geology , biology , paleontology , organic chemistry
A better understanding of the processes that are involved in the absorption of Mg may lead to improved management practices to avoid high grass tetany potential of forage. Two ryegrass ( Lolium multiflorum Lam.) cultivars were grown in a greenhouse on an acid Stough soil (a coarse‐loamy, siliceous, thermic Fragiaquic Paleudult) amended with three rates each of CaO and MgCl 2 . Linear, lime‐rate‐dependent relationships between exchangeable and soil‐solution Mg were found. The slopes of these relationships (Mg buffer power) were 0.68, 1.31, and 1.21 for lime rates 0, 1, and 3 g kg −1 , respectively. The Barber‐Cushman nutrient‐uptake model consistently overpredicted observed Mg uptake by 1.15 to 1.70 times, depending on the Mg application rate. Model calculations showed accumulation of Mg at the root surface. Sensitivity analyses revealed that large values of maximal net Mg influx ( I max ) were the reason for overprediction of Mg uptake. Using input parameters based on soil‐solution Mg activities lowered the overprediction to 1.10 to 1.61 times the observed uptake. A major obstacle to using the Barber‐Cushman model for predicting Mg uptake is the lack of information about kinetic parameters of plant uptake from soil solution.