New Zealand Journal of Agricultural Research abstracts
The calcium requirements of pastures in New Zealand: A review
D. C. Edmeades
agKnowledge Ltd
P.O. Box 9147
Hamilton, New Zealand
K. W. Perrott
AgResearch Ltd
Private Bag 3123
Hamilton, New Zealand
Abstract Calcium (Ca) plays a vital role in the structural
integrity of soils, plants, and animals. This review considers the Ca status
of New Zealand pastoral soils and examines the Ca requirements of pastures
and animals. Against this background the diagnostic criteria used to assess
Ca requirements for pastures are reviewed. It is concluded that the current
Ca concentrations in New Zealand topsoils are more than adequate for optimal
pasture and animal production and that this situation is sustainable, based
on Ca budgets, given a continuance of the traditional fertiliser practices
of superphosphate and liming. For a set of 97 pastoral topsoils, covering
all the major soil groups in New Zealand, it was found that soil pH was not
related to either exchangeable Ca or Ca saturation (exchangeable Ca/CEC at
pH 7). In addition it was found that Ca saturation based on CEC underestimated
the Ca saturation calculated from the effective CEC (ECEC). It is likely
therefore that soil Ca requirements based on the former would be overestimated.
From this and other evidence it is concluded that soil pH should be used
as the sole criterion for determining lime requirements.
Keywords animals; calcium; diagnosis; pasture nutrient
requirements; soils; sustainability
A02062;
Received 27 September 2002; accepted 13 August 2003; online publication
date 26 February 20043
New Zealand Journal of Agricultural Research, 2004, Vol. 47: 11-21
0028-8233/04/4701-0011 © The Royal Society of New Zealand 2004
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