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| From an economic/agronomic standpoint, if soil Mg levels are adequate for any crop to be grown, then why spend money on more Mg? And with the higher the Ca content of high cal lime (say 38% vs 19%) then the less lime product is needed to achive the target Ca level....assuming equivalent particle size distribution....a ton of 38% is 760 lb Ca....a ton of 19% is 380 lbs Ca = 380 lb Ca difference.
From a soil function standpoint, too much Mg can precipate excess soil water, low soil oxygen, and poor percolation.....so why add to a detrimental soil/crop condition with high Mg lime? It is also likely that if you live near to the quarry your native soil was already sufficent in Mg, but years of farming and nitrate-N leached(s) the Ca.
An analogy would be, if you had soil P test of 437 ppm would you still apply phosphate fertilizer or 'farm down' the levels then apply phosphate later as needed?
Advantages we see in pasture yield from improved Ca status are improved drought tolerance and drought recovery and legume yield.....native soil Mg levels were inherently adequate or problematic but low Ca and high Al Fe and Mn.
3 or more years to see the full effect of lime several inches below the surface.
Improved soil surface tilth (reduced crusting/hardness) within in the first year, but this effect is also complimented by sufficient OM at the surface.
Edited by southernokie 2/26/2013 11:53
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as a guy who produces aglime who can tell me......
