Soil pH is a key factor in farmland as it controls availability of nutrients, microbial activity and crop productivity. Before delving into what causes soils to become acid and the steps to take to treat and correct acidic soil, we must first establish what is considered an optimal pH for crop production.

For most prairie crops, a soil pH range of 6.0 to 8.0 is suitable for optimal growth and development. Soils with pH ranging from 5.6 to 6.0 are considered moderately acid, while strongly acid and very strongly acidic soils have pH ranging from 5.1-5.5 to <5.0, respectively. Crops have difficulty establishing and show a decline in productivity and yield in soils with a pH below 6.0.

What Causes Soils to become Acid?

Multiple factors can be at the origin of soil acidity:

Consequences of Soil Acidity

Soil acidity can be improved, and the pH of the soil increased, by the addition of calcium and/or magnesium. This can be in the form of calcic or dolomitic lime, wood ash, CKD or other calcium carbonate-derived amendments. Each of these amendments has both benefits and drawbacks in terms of effectiveness, purity, speed of action and cost.

Lime is most effective at neutralizing acidity when it is incorporated or tilled into the soil to the full depth of the root zone. The amount of lime material required depends on the following factors:

The more carbonate equivalent in the lime amendment, the less product is needed; timing of application depends on the selected source of lime.

Figure 4. Effect of liming in improving soil pH and reducing the impact of aluminum on root system of barley.

OMEX Has the Solution

OMEX has developed several products that complement liming and can help mitigate the effects of aluminum toxicity.

Pulse Primer, Pulse Pak and Primer Soybean – Applied to seeds prior to sowing, these calcium-based seed primers protect the emerging radicle from the toxic effect of aluminum, encourage nodulation, and provide a sufficient amount of molybdenum unavailable in acidic soils.

TPA – This in-furrow liquid Starter improves efficiency of phosphorus, diminished due to aluminum or iron tie-up. TPA is formulated with a patented Thermo Poly Asparte molecule with a higher CEC that breaks the bonds between aluminum/iron and phosphorus, rendering the latter more available to the plants.

In addition, we offer various sources of calcium and magnesium to help increase soil pH, and humates that can be used to improve soil’s organic matter content and biological activity.

Whether or not you have acidic soils, your OMEX representative can guide you in the selection of the right products for your crop’s needs. Your rep can provide you with a nutrient management strategy that incorporates our wide range of seed-applied Primers, in-furrow Starters, in-crop Foliars and other specialty products to help you meet your yield goals, under a wide range of conditions.