The benefits of soil liming are manifold. Let's organize them: the primary and most important objective is to reduce soil acidity, known as soil pH. Every farmer should know how to test pH and what doses to apply for specific crops. This knowledge is essential nowadays, and reliance solely on fertilizer manufacturers' information should be avoided as it is usually too generic. Some plants are very sensitive to liming, and knowing how to prepare the soil for specific crops can result in yield increases of up to 20-60%. The correct soil structure is the second very important benefit of liming. The key parameters include: improving (creating) the granular structure of the soil, better aeration, increasing porosity and the balance of microbiological systems and living organism activities, better water circulation and organic substance exchange, and enhancing the availability of mineral nutrients. All these processes have a positive effect on soil well-being and help to prevent its biodegradation processes.

Just 20-30 years ago, scientists recommended identifying soil acidity levels in fields using so-called bioindicators. These are some species of wild plants that prefer highly acidic soils. However, recent research has revealed the significant inaccuracy of this method. Reliable determinations can only be made through laboratory methods to establish soil acidity. The test results allow for a fairly precise determination of the range and timing for optimal liming of fields or sowings. The pH range for most crops in Poland should oscillate around pH 5.5 to 6.5. For pH-sensitive plants, it should be between 6.0 to 7.0. Particularly recommended is the implementation of a systematic and intelligent liming system for individual fields and crops. This requires systematic monitoring of soil acidity (pH) and flexible determination of the amount of lime preparation. Detailed dosage tables are always included in the manufacturer's informational materials. The result of such an approach will be achieving and maintaining plant well-being – thus also increasing yields and farmer satisfaction.

Testing soil acidity is not a complicated task. However, not everyone has the knowledge and time to conduct such tests independently. As for pH measuring devices, caution should be exercised. While such devices are available on the market, their reliability is highly questionable; only higher-end devices that can be calibrated may demonstrate accuracy in measurements. Experiments conducted with cheap devices of this kind have shown their complete inconsistency with the actual pH of the soil. A better solution is to commission such tests to a specialized laboratory – for example, at the nearest District Chemical-Agricultural Station.

The method of liming depends on the crop. The best time to spread lime is between harvests and late autumn, or even winter. The post-harvest period is usually characterized by good soil moisture, which directly facilitates the dissolution of lime in the soil. Another significant aspect is the lime activation period, which is longer during this time as it extends from crop harvesting to planting or sowing. As you can see, this extended period allows for soil testing, and careful selection of the appropriate fertilizer, resulting ultimately in the correctness of the entire procedure. Granular fertilizers are particularly recommended here. They do not require as intensive mixing with the soil and can also be used in winter and early spring (recommended for winter grains, rapeseed, perennial plantations, and permanent green areas). Granular fertilizer is also the best form of lime for top dressing – to save the yield. In such cases, the sowing time may coincide with the plant's growth phase.

The dosage of lime is influenced by many environmental and agrotechnical factors. Therefore, it is not possible to determine unequivocally, without additional research, what amount of lime will be sufficient to achieve satisfactory results. An important factor, for example, is the soil pH and the type of lime fertilizer used. Oxide, carbonate, or chalk lime have different applications for different soils and varying reaction times. The method of liming itself also has an impact. Many farmers believe that it is sufficient to lime fields every few years with large doses of fertilizer. This is not necessarily true. Recent scientific studies indicate that the best results can be achieved by subjecting fields to systematic, annual liming treatments – using smaller doses. By maintaining such a strategy of agrotechnical treatments, for most types of soils and plant varieties, doses ranging from 400 to 1200 kg per hectare will be sufficient. These doses increase for acidic heavy soils; in such cases, lime requirements can be estimated at around 800 to 2000 kg per hectare per year. Note: when using oxide lime, do not excessively acidify with large doses, as this can lead to over-liming or drying out the soil!

It all depends on the liming system and the soil pH. Spreading granular lime fertilizers is often part of an annual plant fertilization system. Hence, lower doses are applied – producers assume that the soil pH is stabilized. The lime preparation is used to introduce the necessary dose of calcium – somewhat "incidentally," it also maintains the proper soil pH. In the case of powdery carbonate lime fertilizers, a dose is often given to acidify the soil for 4-5 years. Therefore, the dose is correspondingly larger. The size of the dose also depends on the chemical composition of the preparation. One rule applies here: the better the fertilizer, the smaller the doses. In the case of oxide lime, the differences in the recommended doses also result from the content of CaO, which can range from 40 to 80%.

In the case of calcium oxide, there is a risk of soil over-liming because an excessive amount of calcium hydroxide, which forms as a result of contact with water in the soil, can damage crops. However, over-liming with calcium carbonate is not practically possible. This is a natural product, and its absorption is controlled by the plants themselves – taking the appropriate amount of product from the soil. A good example is soils from areas with shallow limestone rocks. Calcium carbonate can constitute even 20-30% of the soil mass, i.e., in soil with a 1-hectare field area, about 1000-1500 tons constitute lime! At the same time, only about 1% of the calcium present in the soil actively participates in soil processes related to plant nutrition.

Regarding the effectiveness of using lime as a spray, opinions are divided and often contradictory. This mainly stems from the confusion between two types of lime: artificially produced oxide lime (quicklime, building lime) and natural lime, namely carbonate lime. Using oxide lime as a spray can have very serious and adverse consequences for plants. Incorrect dosage selection can even result in burning vegetables or trees. On the other hand, carbonate lime is absorbed to a limited extent through the leaves of plants. In cases where intervention is necessary for lime plants during their growth phase, it would be more effective to spread granules to allow for a faster reaction in the soil.

Top dressing with lime fertilizers is only possible when using carbonate lime. In the case of oxide lime (quicklime, building lime), top dressing with lime will burn plants and destroy crops. Granular carbonate lime fertilizer is particularly suitable for feeding plants during their growth phase. It is easily absorbed from the surface layer of the soil. Of course, it should be noted that not all plants react to top-dressing lime in the same way. This primarily depends on the level of sensitivity to lime. The higher the sensitivity, the more effective the treatment will be. For specific details, it is advisable to consult with manufacturers of granules.

Currently, among farmers, there is still a belief in the effectiveness of spreading lime in the form of powdered fertilizer. However, more informed users of lime fertilizers notice significant limitations of such products. These limitations are associated with problems with uniform spreading and the resulting product losses. To overcome these limitations, the process of lime granulation has been initiated, allowing for the minimization of these described losses.

For heavy, fertile soils, oxide lime, carbonate lime, or oxide-carbonate lime can be used depending on the needs. In the case of rapid soil acidification, oxide lime is best suited. However, its use should be minimized as it adversely affects the chemical and physical properties of the soil in the long run. In the longer term and for safety, it is better to use slower-acting carbonate fertilizers.

The rate of lime assimilation by the soil environment largely depends on its physicochemical properties and environmental conditions (moisture, aeration, and soil temperature). For example, oxide lime fertilizers (quicklime, building lime) react very violently and cause excessive soil drying. In the case of carbonate fertilizers, the most important factor is their pulverization. The finer the powdery particles, the faster the penetration into the soil, and the more effective the fertilizer.

The nomenclature of lime fertilizer types is regulated by the Act of July 26, 2000, on fertilizers and fertilization; Journal of Laws No. 89, item 991. The Act clearly describes and classifies lime fertilizer types. The assessment was based on the physical condition and chemical composition of lime and the methods of its extraction. From the farmer's perspective, the most profitable varieties are 04 - This class includes a total of 13 types of lime without magnesium, of which five varieties come from limestone processing, four from by-production, and the last four are recognized as minerals. Attention should be paid to varieties containing magnesium as these are usually dolomites. The most effective granulated lime is variety 04, containing over 50% CaO and over 90% CaCO3. Until now, there was no producer of this type of fertilizer in Poland; only imported fertilizer from Germany and France was sold, with prices reaching over 2000 PLN per ton. Currently, the only producer of this type of fertilizer is the POLCALC plant in Lubień Kujawski, selling the fertilizer under the trade name POLCALC III GENERATION, and the price of this fertilizer is around 450 PLN per ton.

The conversion is required by law, which mandates producers to inform about the composition of the fertilizer expressed in the amount of oxide, even though the chemical composition of carbonate lime does not contain oxide (CaO) but rather calcium carbonate (CaCO3). This solution was introduced to facilitate the calculation of the amount of fertilizer needed to lime the soil after conducting a pH test and to easily assess the fertilization value of lime.

Every producer is obliged, upon customer request, to present a certificate determining the quality of the lime fertilizer being sold. Such documents are issued to producers by the District Chemical-Agricultural Stations or by the Institute of Soil Science and Plant Cultivation in Puławy. This information should be found on the packaging of the products being sold. In case of any doubts, it is advisable to commission the testing of the product by the nearest District Chemical-Agricultural Station.

Lake chalk carbonate lime, marked as variety 06a, is a fertilizer with a very fine structure, mostly if it is dried and granulated. However, its low content of CaCO3 compared to lime fertilizers derived from limestone processing, variety 04, makes it significantly less efficient and effective.

There is also waste lime, so-called cellulose, and others; however, their agricultural usefulness is questionable, and surely, the use of such fertilizers may have a negative impact on soil and product health. It is the lime with the highest degree of contamination, which means that only about 30-50% of it is actual lime. The rest is impurities of difficult-to-determine utility. Such lime must be chemically tested because there is a high risk of contaminating field surfaces with highly toxic heavy metals. However, even such caution may be insufficient. Chemical-agricultural stations only determine the content of two basic heavy metals: cadmium and lead, in such tests! Other toxic substances are not identified in such analyses! The price of such "lime" can range from 1 PLN to 15 PLN per ton.

The simplest way is to examine the degree of calcium fineness. You can perform a simple test here. After pouring two tablespoons of limestone into a glass of water, you should obtain a kind of "milk" in suspension. Low-quality products will leave sand or other impurities at the bottom of the glass. It is also important to pay attention to the manufacturer's certification obtained from the District Chemical-Agricultural Station or the Institute of Fertilizers and Soil Science in Puławy. Good limestone should contain over 90% of pure CaCO3, which, in terms of mass conversion, corresponds to approximately 50-55% CaO.

Lime reactivity is a factor indicating the quality of the fertilizer. In other words, the higher the reactivity, the better. However, a clear distinction needs to be made between oxide lime (quicklime, building lime) and carbonate lime. In the first case, reactivity stems from the chemical composition of the preparation (CaO content). On the other hand, the reactivity of carbonate lime (CaCO3) results from the degree of fragmentation of the raw material. Naturally, the finer the fractions, the greater the reactivity.

The main advantage of granulated fertilizers is their easy assimilation by the soil substrate, which directly affects crop yields. Additionally, granulated lime is easy and cost-effective to spread, ensuring high work comfort and process accuracy in liming. Highly recommended are highly reactive, granulated lime preparations stored in big-bag sacks, which facilitate transportation and use of the fertilizer.

Distinguishing lime granules from counterfeits is quite simple. Just pour a sample of the product (e.g., 2-3 tablespoons) into a glass of cold water. If you almost immediately get a "milky" suspension, then you have an original product. However, if after a while small pebbles remain at the bottom of the glass, there is undoubtedly an attempt at deception.

Lime itself, if storage conditions allow, can be purchased throughout the year. It's essential to ensure that during unfavorable weather conditions, it doesn't get damaged by freezing (for granulated moist lime) or moisture. For high-quality granulated lime, purchases can be made after the season, i.e., in January-February and June-July. Many producers offer seasonal discounts during these periods.

In some provinces of our country, it is possible to apply for such funding. It's worth noting that subsidies within provinces may change from year to year, and the application system almost annually undergoes changes. Therefore, it's best to contact the nearest District Chemical-Agricultural Station or the Agricultural Chamber operating in the respective district to obtain complete information.

The price of lime is influenced by many factors. The most crucial factor is the quality of the raw material from which the granules are obtained. Another cost-determining factor is the long and technologically advanced process of granule production. It starts with obtaining the "raw" rock in open-pit mines. Its subsequent stages involve crushing rocks, purifying the raw material from troublesome impurities, grinding in ball mills, drying, and granulating. Additionally, there are costs of transportation, storage, market servicing, and scientific research ensuring the maintenance of high product quality.

Granulated lime, like other granulated fertilizers, should be stored in a dry place, preventing it from getting damp or freezing. Granulated carbonate lime, when exposed to water, will not change its chemical composition, but it may weaken the structure of the granules.