Calcium Sulfate has been used for centuries to reclaim soils that are affected by sodium. The sodium is displaced by calcium on the exchange site creating a better soil structure. The sodium reacts with sulfate and moves with water below the root zone. More recent research by Purdue University shows that soils with high amounts of magnesium also are in a “dispersed state” after rain events, similar to high sodium soils. As a result these soils may have a slower infiltration rate and percolation rate. PRO CAL 40 added to these soils will improve the soil structure by adding calcium to displace the magnesium on the exchange sites. These soils will also hold more water with the addition of PRO CAL 40.

There is no data to suggest that over applying calcium sulfate to soils would be detrimental. There are reported applications of 25-50 tons/acre applied to some soils with no ill effect. In fact, the positive benefits in soil structure were still noticed 15 years later. In general economics will prevent over application.

Some producers who have calcium sulfate recommended for sodium affected soils are concerned whether PRO CAL 40 would have a detrimental effect if applied to soils with no sodium problem. Sodium affected soils are often localized which can make it difficult to apply calcium sulfate to just those affected area. Applying PRO CAL 40 to soils with no sodium will not have any adverse effect. Although sodium may not be a problem in those soils, internal drainage and poor soil structure may still be issues in those soils. Applying calcium sulfate can improve these conditions in those soils as well. Improving crop production in those areas will result in the alkali areas realizing even greater improvement.

Applications of calcium sulfate will generally have no effect on soil pH. It is a neutral salt. Exceptions to this would be when applied to soils with sodium and/or high pH (>7.4). These soils usually contain some carbonates and bicarbonates. By applying PRO CAL 40 to these soils you will tie up the carbonates and bicarbonates and form lime. This will, in turn, lower the pH. Also PRO CAL 40 could decrease pH in soils that are relatively dry by increasing the amount of soluble salt. PRO CAL 40 has an acid pH when it comes directly from the PGLA-1 plant due to the small amount of lactic acid present in it. After stockpiling, this lactic acid decomposes and the pH of our calcium sulfate will increase, stabilizing around 7.5. If PRO CAL 40 is applied to soils directly from the PGLA-1 it may initially lower the soil pH slightly. However, since a great amount of hydrogen is needed to lower pH in the soil plow layer and the lactic acid will decompose by bacteria quite quickly in the soil no long term effects are usually experienced.

Research has shown calcium sulfate to be more mobile than lime and in acid soils it will move into sub-soils and will supply calcium to roots that are starved of calcium and reduce aluminum toxicity. Although the pH won’t change, a liming response can be realized.

There are some naturally occurring bacteria in the soil that produce lactic acid. Research has shown that it will actually stimulate microbial activity in soils. In fact, lactic acid is used in soils for bio-remediation of some compounds. Natural occurring lactic acid bacteria are also active during ensiling processes. The lower pH from lactic acid actually increases the solubility of PRO CAL 40 in high pH soils.

It is true that PRO CAL 40 is a derivative of the processing of corn sugars into lactic acid. It does not actually come from the corn kernel, itself. The lactic acid produced is used as a food preservative. It is important for producers to understand, however, that for each ton of PRO CAL 40 they buy, they make the production of lactic acid from corn more economical, therefore, increasing the potential demand for corn.


In Iowa, PRO CAL 40 and NutraBio are registered with the Department of Agriculture as liming materials. Regulations prohibit Soil Solutions from marketing either of these products in the state of Iowa as having any other qualities or benefits other than its value as a liming material. Although this website may list other benefits and features of these products we are not allowed to market PRO CAL 40 or NutraBio based on these benefits in Iowa.

If you have any questions please feel free to contact us.

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