By Jon Frank, International Ag Labs

For years International Ag Labs has been preaching the merits of potassium sulfate in place of potassium chloride i.e. potash. Here are 7 quick reasons I came up with to support that claim.

1) More Energy for the Money

Commercial fertilizers are concentrated packages of energy. This energy is looked as either producing growth/vegetation or as reproductive/producing seed. Let’s never forget that energy is what grows a crop. Energy is associated with the elements in the fertilizers. Here is the bottom line: One dollar spent on potassium sulfate (K2SO4) will purchase less fertilizer by weight than will one dollar spent on potassium chloride (KCl) but the one dollar spent on potassium sulfate will buy significantly more crop growth energy. Here's why: 47% of potassium chloride is chloride and useless as an element for crop production. In contrast 100% of potassium sulfate  is useable by the plant.

2) Lower Salt Index

The salt index is an easy way to judge how damaging a fertilizer is to plant roots and its impact on germination. The higher the salt index the more it can damage roots and kill emerging seedlings resulting in a lower plant population. Potassium sulfate at 46 is less than half of potassium chloride at 116.

3) Better Uptake of Potassium

Proper uptake of potassium requires it to be in the phosphate of potassium form. When there is an excess of chlorides the bonding of potassium with phosphate is blocked. The end result is less potassium uptake into the plant in the preferred form. The high level of chlorides in the soil solution following an application of potassium chloride undermines the very reason it was applied for. The sulfate form does not overwhelm the soil solution with chloride ions and consequently more potassium is taken up by the plant in the phosphate of potassium form.

4) Microbial Stimulation vs. Microbial Suppression

Sulfates have a stimulating effect on the microbial system in the soil, whereas chlorides at high levels are very hard on soil biology and is never recommended by International Ag Labs. In defense of chlorides I must say that a very small amount is actually beneficial for soil microbes. This modest requirement is easily met by the small amount of chlorides present in potassium sulfate.  Chlorides usually run 1-2% in potassium sulfate. High rates of chlorides destroy soil carbons.

5) Plants and Soils Need the Sulfur

Most intensely-farmed soils are sulfur deficient. In the past rainfall picked up sulfur out of the air and continuously supplied sulfur with every precipitation. Today with stringent environmental codes and cleaned up smoke stacks the free sulfur is a thing of the past. In order for plants to make oils and sulfur bearing amino acids such as cysteine and methionine the plants need an adequate supply of sulfur in the sulfate form. This is exactly what potassium sulfate supplies.

6) Better Palatability

Forages, vegetables, and fruit taste poorly when the potassium comes from potassium chloride. This happens because, like it or not, chlorides are also taken up by the plants. Apples regularly sprayed with calcium chloride taste like ____. Instead use Amaze for calcium.

7) Less is More

The application of 100 lbs. of potassium sulfate will give a greater plant response than 200 lbs. of potassium chloride. We have found that 100 lbs. of potassium sulfate is quite sufficient for most crops. The only exception to this is high-value, potassium-loving crops such as tomatoes, potatoes, pumpkins, and melons where 200-300 lbs. are used per acre.

One of our suppliers is offering a “low odor” composted chicken manure that is naturally high in calcium. The calcium will help flocculate soils and create a better environment for enhanced root development. The analysis of available NPK is at the rate of 2-4-3.

Healthy soils are the key to producing high yields and this organic composted chicken manure provides the nutrients and organic matter to help improve soil tilth. It really is a great way to reintroduce biologically active organic matter into the soil!

It is OMRI certified and a pretty easy product to spread with a relatively low odor compared to other manures. It is also available in a pelletized form as well as non-pelletized. The pellets cannot be left outside.

Guaranteed Analysis: 
Nitrogen 2%
Available Phosphate 4%
Soluble Potash 3%
Calcium 9%
Sulfur 1%
Also contains traces of Mg, Zn, Iron

Derived From: Aerobically Composted Chicken Manure (ACCM), this product is a natural source of high grade nutrients designed to replenish primary and secondary soil requirements. It is rich in organic matter. The screened compost (SS243) is available but usually not on short notice. It is not pelletized. This product is organic. The lead time on this product is a few weeks out. Keep in mind this supplier is only able to produce around 1200 to 1500 tons annually. During Fall & Spring seasons this material gets tight, however and I would anticipate prices going up not down in the future.

Here is what I have learned about spreading blends in a spreader:

The SGN of the turf grade we are offering in the blend is actually 220 SGN, not 140 SGN, so it is a bit bigger but not as big as the ag granular which is 320 SGN. So when combined in a spreader, the two blends will tend to separate somewhat because the MAP will spread up to 40 ft while the smaller SOP granule of the turf grade will only spread about 30 ft. The solution is to drive every 20 ft. rather than every 40 ft. & spread twice. It is good stuff, but it won’t spread as uniformly as if it were the ag granular size.

Any further questions on spreading can be taken by Wendell at 507-235-6909, he is a farmer and knows more than I do!