March 2006

 

The issue of soil pH and how to correct it is a topic of ongoing debate.  I see more and more tanks of acid (one form or another) along side irrigation pumps.  It's common to see piles of sulfur waiting to be spread.  Any remedy, or attempted fix ends up adding an expense to your budget.  I'm all for expenses that result in an increase in profit, otherwise why spend it?  Make sure you're getting the most “bang” for your buck!   Consider the following.  In the top 8” of soil (the active root zone) of an acre there is about 2 million pounds of soil.  Our soils contain a high percentage of calcium carbonate (lime).  A 1% lime rate equals 20,000 lbs or 10 tons of lime in the top 8” of soil!  When we attempt to acidify the soil by adding sulfur the following reaction occurs.   Sulfur breaks down into sulfuric acid.  This dissolves the calcium carbonate, producing carbon dioxide as a by product that dissipates.  The remaining calcium combines with sulfate from the sulfuric acid to make gypsum (calcium sulfate).  It takes 1 ton of sulfur to neutralize 3 tons of lime. This means you need 3.25 tons of sulfur to convert the 10 tons of lime in the top 8” of soil.  This process doesn't happen overnight, but for discussion purposes lets say it happens all at once.  You now are at zero so to speak and there's still not been a change in pH!  You now need to add more sulfur to move the pH downwards.  To compound the problem, if you're irrigating out of the Orchard Mesa canal, with each acre foot of water you're adding back approximately 600 lbs of calcium carbonates!  OK, what's the point?  Make sure that your program is going to hit it's target, that it's going to profit you. 

 

 

Good  advice is free when it's taken, and paid for when it's not!