Soft Rock Phosphate is an important phosphate source that is actually a byproduct from the old time hard rock mining. In order to increase the purity of the higher analysis of the hard rock, the soft rock was a clay impurity which was washed and then it was sent in this water through to a settling pond. So then it filled this settling pond up and so these are huge huge settling ponds and the surface dries out and the soft rock is skimmed off the top of the settling pond and then it can either be processed or sold as is.
Hard rock phosphate, in contrast, is mined just as it is and is a tri-calcium phosphate. Sometimes it has a little carbon. But it is extremely insoluble in the soil. It requires a hyperactive bacterial system and a tremendous amount of soil acidity in order to derive much benefit. Soft rock, on the other hand, is quite a bit more available. A lot of times we'll see availability showing up on the soil test within 1-2 years, even the first year if a soil's got some acidity.
There are a tremendous amount of trace minerals in soft rock phosphate and there's a certain electromagnetic energy or field with soft rock phosphate so that it's extremely sticky. If you get it wet, you can feel how sticky it is. This electromagnetism helps to hold calcium up in the root zone. So it's a real critical part of building the soil so that you can hold the calcium.
Soft rock is also a pretty good supplier of silicon, it has a decent amount of boron in it, and then a whole bunch of other trace minerals, about 60 trace minerals all together. And we find it to be an absolute critical ingredient in building soil phosphorus levels for organics. And any time the goal is quality, soft rock phosphate should be part of what is used to build and maintain soil phosphate levels.
We supply this from three sources. One source is from Idaho, and this is not a processed product so it's pretty much just skimmed off the settling pond and put into bulk truck loads or super sacks in powder form. And we sell it by the semi load, so either a 22-25 ton semi load in bulk, and if we ship it on a flatbed, 24 tons in super sacks. These bulk bags are not standardized in their weights, but overall the semi load will be 22-24 tons.
We also sell Florida soft rock phosphate from two sources. Both are available as either powder or granular. The granular makes it a little easier to work with since can be used in a fertilizer spreader, but it is dusty, it's not a perfect pellet and it will coat the beater blades on the back of a spreader, so even though it is granulated you still eventually have to go back and clean those blades as you're spreading soft rock phosphate. Otherwise it just builds up and coats the blades.
The advantage of the granular, of course, is that it can be spread with a fertilizer spreader. The Idaho source needs to be spread with a lime spreader and even in that situation sometimes the soft rock will still bridge in the spreader and someone's going to have to knock down those bridges so you can get it to spread. It is a little cumbersome product. Another way it could be done is if the powdered product is added to a liquid manure and then mixed in with the manure and then spread out as liquid as part of the manure. This would be a very good way to do that.
Soft rock phosphate, again, will hold the calcium, and that's really key if you want to build available calcium and also to build a soil that is capable of producing nutrient dense foods. So it's kind of a foundation point.
Soft rock phosphate is not recommended automatically, you need a soil test to determine if you need phosphates. Many soils, especially those with composted manure have excessive phosphates. And consequently soft rock phosphate is not recommended on those soils. So make sure that the soil is tested beforehand.
The Idaho soft rock has a higher carbon content, that gives it a nice chocolate brown color. The Florida sources have less carbon but have a little higher analysis of phosphorus and calcium. So they're all good products, we like them equally. They all fit into a good biological program to grow quality.
Organic Soft Rock Phosphate Powder from Idaho
Organic Granular or Powder Mineral Grow from Florida
Info Sheet (PDF)
Download Analysis (PDF)
Download MSDS (PDF)
OMRI Listed Canada (PDF)
OMRI Listed US (PDF)
Organic Granular or Powder Soft Rock Phosphate from Florida
Download Analysis (PDF)
Download MSDS (PDF)