It depends on area. The guys north of broward (and in parts of broward) have pretty darn nice soil. Low (normal) rates of sulfur will probably do the trick there.
My area is a bit more dire. I used 40 50 pound bags of sulfur (2000 pounds) for a quarter acre. It's been several months with minimal effect (about a 0.4 PH drop). No detriment to vegetation, but the yellow color of the sulfur looks ugly :-).
I based my rates on an experiment done by Agvise. The soil that they experimented on actually has a lower level of free calcium than the soil we have here in parts of broward and dade, so I figured that their experiment was a good starting point for me. (Some soils in this area have free calcium carbonate percentages in the double digits!) I would have done more, but 40 bags of tiger was a hefty chunk of dough.
Agvise's conclusions were that gypsum didn't work and that sulfur had a minor effect that dissipated over the years. They also found that the cover crops experienced no detriment nor any improvement in nutrient uptake. I can't find the link to the latest in the series of follow-ups, but the PH eventually went back to the original starting point of 8.0.
In the many years that I've spent trying to combat high ph soil, and after trying nearly everything (soil drenches, sulfur, foliar mixes, compost incorporation, mulching, etc), the thing that has produced the best results has been tree trimmer mulch that slowly breaks down and builds up a layer of ph-neutral soil. The ph buffering capacity of this type of soil is pretty high, but sulfur applied to this layer can reduce ph by 0.2+. The end goal is to create 6 to 12 inches of fully composted soil. This has taken me many years, and even with this the more sensitive trees still have significant chlorosis (eg, carambola). However the impact has been fairly significant.
Below are links to Agvise's experiment:
http://www.agvise.com/educational-articles/high-soil-ph-can-we-fix-this-problem/Here is the follow-up from 2011:
http://www.agvise.com/wp-content/uploads/2012/07/John-SoilAmendments05-2011.pdfApplication Rates:
1. For 1 lb of sulfur, use 1.11 lb Tiger Organic 0-0-0-90.
2. Apply appropriate amount of Tiger Organic 0-0-0-90 according to soil amending needs recommended by a pH test and soil test to check for sodium and lime.
3. As a general guideline, apply 250 lbs/acre or up to 5 lbs per 1,000 sq ft of Tiger 90CR Sulfur and monitor soil pH levels to determine if additional sulfur applications are required.
4. One 50 lb bag should cover up to 10,000 sq ft.
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I prefer elemental sulfur. I've heard that aluminum sulfate can be harmful to plants if you go overbaord with it.
As i have stated before, Tiger Sulfur (elemental) is the best way to go to overall lower soil ph. However, if growing something acid loving such as blueberries, miracle fruit, bougainvillea, etc., it would also benefit to use something such as peat, pinebark, pine needles at the actual planting site as well as supplementing with a fertilizer for acid loving plants such as a bougainvillea or azalea /camellia blend.
bsbullie - What kinda application rates you using? My trees have a 6 feet diameter bed of organic mulch around them. Thanks for the input.
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