Why is soil liming so important?

Does the type of lime matter? Based on what to choose the type and dose of lime?

Soil liming should be an integral agronomic procedure on every farm. With this treatment, we can relatively easily improve the pH of the soil, which will make the nutrients available in the soil properly absorbed by plants.

What is worth knowing before starting soil liming?

Before starting soil liming, it is necessary to perform soil analysis, which will give us results on the soil's richness, pH and agronomic category. It is on the basis of these results that we should select the appropriate dose of lime fertilizer. Soil testing should be done regularly to monitor the pH of the soil and its changes over time.

When selecting a dose of lime, it is necessary to take into account two components that make up it and are dependent on each other. These are: the soil reaction - pH and the agronomic category of the soil.

Knowing the relevant pH value, we can evaluate the soil reaction based on it. Each pH value gives us information on how acidic a soil is. This ranges from very acidic soil to acidic soil, slightly acidic soil and neutral soil.

• Soil with a pH of 6.5 or lower is considered acidic soil. 
• Soils with a pH5.6 - 6.5 are referred to as slightly acidic soils, 
• soils with a pH of 4.6 - 5.5 as acidic soils, 
• while soils with a pH lower than 4.5 as very acidic soils. 
• Soils with a pH of 6.6 - 7.2, are neutral soils where soil liming is limited.

The next element is to determine the agronomic category of the soil. This information is obtained together with the results for nutrient content and soil pH from the laboratory. This information is so important that it determines the dose of lime. The dose of lime on light soils differs significantly from the dose of lime on heavy soils in the same range of soil reaction.

Soil acidification is most rapid in light soils, which are most prone to leaching of mineral nutrients into deeper soil layers. Consequently, lime doses are correspondingly higher compared to heavy soils. Heavy soils are much less susceptible to acidification than medium and light soils, making lime doses much smaller and lime applications less frequent.

Optimal timing of soil liming.

When to lime the soil? This is a question that many farmers ask themselves. The answer is, it depends, as there is no definite date.

However, it is best to perform the soil liming treatment immediately after harvesting the crop from the field.

Why? Because lime fertilizers should not be combined with the application of mineral fertilizers (NPK). Because lime fertilizers cause large losses of nitrogen and reduce the uptake of phosphorus by plants. The situation is similar with the use of natural fertilizers - manure, manure, slurry. We should keep an interval of at least 2 weeks between liming and the application of other fertilizers.

The above restrictions give us a relatively short window for soil liming. This makes it necessary to perform it immediately after harvesting. Theoretically, there are two periods, in late summer, right after the harvest, and in autumn, right after the potato digging and the beet and corn harvest. Thus, after the lime application, we can perform a set of post-harvest tillage, the lime will be mixed with the soil and penetrate deep into the soil profile, which makes it deacidify the soil. In the meantime, we can sow catch crops, wait for weeds to germinate and perform mineral and natural fertilization before sowing winter crops and oilseed rape.

It is recommended that soil liming for spring crops be carried out in autumn. There are no contraindications to liming the soil in early spring, but due to the amount of work and its concentration, and uncertain weather, this treatment should still be carried out in the preceding calendar year. Remember to avoid applying lime to wet soil.

How and with what to lime the soil.

Soil liming can be done with carbonate or oxide lime fertilizers. However, with what to lime?

It is assumed that carbonate lime fertilizers are more safe for the soil and the microorganisms living in it. They act more slowly, so they can be used in larger doses and are suitable for all types of soil, including ideal for light soils.

Lime and magnesium fertilizers, such as Dolomite, have a similar effect. The effect of soil deacidification with dolomite lime can be seen only 2-3 years after liming the soil, but it lasts for quite a long time. The risk of over-fertilization is very low and, in addition, we provide the soil with magnesium. When choosing this lime, do a soil test for magnesium content. In case of its low content, the use of dolomite is an ideal solution.

Oxide lime fertilizers work very quickly and should be applied judiciously depending on the type of soil. They should only be applied to heavy and medium soils because they are less likely to change the soil reaction more quickly. The dosage of these fertilizers should be very precise, as overdosing disrupts the natural microbial processes in the soil. If the pH of the soil is very acidic and we want to deacidify the soil relatively quickly, the application of oxide lime seems to be a valid option.

Lime application

The type of lime and its form will determine how it is applied. We can choose between lime in granular and loose form.

In the case of lime fertilizer in granular form, the matter is simple, the use of mineral fertilizer spreaders. However, in the case of lime in loose form, a lot depends on its hygroscopicity and where it is stored.

The most popular equipment for applying lime in loose form are spreaders. As lime application rates are relatively large (they start at 1 ton per hectare) compared to mineral fertilizer application rates, this equipment is ideal. Unfortunately, it has its downside and that is the unevenness of lime application, which is due to both the design of the spreaders and the structure of the lime.

An alternative to spreaders are lance spreaders, which are also capable of applying lime in loose form. Their great advantage is that they apply lime fertilizer evenly over the entire working width. The lime treatment with this method is the most precise. 

Unfortunately, the downside of this solution is that the lime cannot be previously stored in the field or yard. It must be delivered to the field on an ongoing basis during application in special tankers. In addition, not all lime is suitable for application with this equipment. The lime must be specially ground beforehand so that it does not block the augers in the spreader lances. This makes the method of its application require windless weather, as of the above it is most prone to drift during application.

Summary

When selecting the type of lime, we should pay attention to the % of calcium oxide content and its reactivity.

The calcium oxide content makes it possible to compare different fertilizers and calculate the amount needed. Reactivity, on the other hand, determines the percentage of calcium oxygen that dissolves and thus begins to deacidify the soil and be available to plants. Using lime with higher CaO content but lower reactivity, not only do we pay more for calcium oxide, the desired effect is much weaker.

In order to properly select the dose of lime, it is necessary to analyze a soil sample in the laboratory for soil type and reaction.

Soil liming should be performed every 2-3 years based on the current results of laboratory analysis.