The influence of calcium and liming on plant yield

Calcium is the dominant cation both in the sorption complex and in the soil solution of arable soils. The calcium content in the soil is mainly determined by the type of parent rock from which the soil originated and the degree of weathering and leaching processes. Typically, the calcium content in the soil solution is 200-300 mg Ca2+∙dm-3. However, natural and anthropogenic processes cause annual losses of calcium in the soil of at least 140 kg CaO·ha-1, and under intensive cultivation and fertilization, especially nitrogen fertilization, and in heavily polluted areas, even exceeding 250 kg CaO·ha-1. Losses of this element and the use of physiologically acidic fertilizers lead to soil acidification. It is estimated that about 80% of agricultural lands in Poland are acidified to varying degrees (very acidic 29%, acidic 28%, slightly acidic 24%). Research conducted by Regional Chemical-Agricultural Stations has shown that over 50% of Polish soils are highly acidic and acidic. In soils with a pH of 5.0 and lower, aluminum mobility increases, which inhibits root growth and exerts phytotoxic effects on root hairs, causing them to die off. This adversely affects the transport of water and mineral salts from the soil solution to the aboveground parts of plants. High aluminum concentration in the soil solution inhibits the uptake and transport of calcium and magnesium by plants. Plants grown on acidified soils have lower resistance to drought, freezing, and disease and pest damage. In addition to an excess of hydrogen and aluminum cations, the concentration of manganese also increases in acidified soils. The only effective way to regulate soil pH is through liming. Therefore, it is particularly important to persuade agricultural producers to increase lime fertilizer doses and to use it more frequently. Calcium contained in lime fertilizers should be treated as a macronutrient and applied annually, just like nitrogen, potassium, or phosphorus. Agricultural soils should have a pH value ranging from 5.5 to 7.0 (lower value for light soils, higher for heavy soils).

Different crops vary in their soil pH requirements, which should be considered when planning liming practices in crop rotation. 
Crops that respond very favorably to soil pH ranging from 6.0 to 7.5 include wheat, barley, corn, sugar beets, rapeseed, soybeans, and other leguminous plants. Symptoms of calcium deficiency observed on plantations include stem twisting just below the inflorescence, resulting in wilting during flowering. Conversely, crops less sensitive to acidic pH (below pH 5.0) include buckwheat, lupines, seradella, radish, and black turnip. The tolerance range of plants to soil pH is closely related to their yield. Sensitive plants such as corn, rapeseed, wheat, and sugar beet yield the highest possible when soil pH is around 6.8-7.5 (Table 1). These plants absorb significant amounts of calcium, which is accumulated in vegetative and generative organs. It has been shown that winter rapeseed, to produce 3 tons of seeds along with byproduct yield, accumulates about 124 kg Ca·ha-1, which is only slightly less than potassium (153 kg K·ha-1) and several times more than phosphorus, with uptake levels around 30 kg P·ha-1. Adequate calcium supply to leguminous plants is a necessary condition for the formation of root nodules, where nitrogen fixation occurs (Table 2).

Table 1. The influence of soil reaction on the yield of selected crop species

Table 2. Average nutrient uptake from the main yield of selected crop species along with the corresponding amount of byproduct yield (according to Kocoń 2012).

Calcium - Polcalc AgroLuz Calcium Polcalc AgroLuz Calcium should be applied as a pre-crop treatment for highly demanding plants such as rapeseed, corn, and wheat. If, for various reasons, it was not applied during this period, the optimal time for liming the soil is the post-harvest period. This timing allows for thorough mixing of the applied lime with the soil and provides a longer period for soil pH stabilization before sowing or planting crops. Adequate soil moisture during the autumn period contributes to the proper distribution of fertilizer Polcalc AgroLuz Calciumwhich then acts effectively and quickly. If organic fertilization (manure, slurry) is not used, the field can be limed in pre-sowing autumn tillage or pre-winter plowing.

If the period between harvesting the pre-crop and sowing the next crop in the rotation is relatively short, it is recommended to apply granulated carbonate lime Polcalc III Generation pre-sowing or directly under the tillage-seeding implement because it can be shallowly mixed with the top 5-10 cm layer of soil. Polcalc III Generation is best applied in autumn, especially between rows of growing plants, as it does not cause their burn as a carbonate lime. This lime can also be applied in spring. The recommended top-dressing dose of granulated carbonate lime varies depending on the species of cultivated plants and ranges from 300 to 1000 kg∙ha-1 (Table 4). It is assumed that on soils with adjusted pH to maintain a stable soil pH level, annually from 200 kg to 400 kg CaO∙ha-1 should be applied. It should be remembered that liming should not be combined with the application of organic and mineral-nitrogen and phosphorus fertilizers, regardless of the timing of this operation. The break between the application of these fertilizers and liming should be 4-6 weeks.

Calcium is not just about soil pH. This element has significant nutritional importance for plants and influences the formation or maintenance of a crumbly soil structure. This structure is particularly important for light soils because it allows for the retention of more water needed for proper plant growth. It is worth mentioning that light soils constitute as much as 60.8% of arable soils in Poland. These soils are mostly acidified and deficient in readily available magnesium for plants. It is assumed that 60% of arable soils in Poland have a very low and low content of this macronutrient. In the case of acidic soils with a pH of 5.0 and lower, magnesium losses due to leaching increase drastically, and the increased availability of aluminum ions worsens its uptake. Therefore, intensive magnesium fertilization without changing the soil pH is not fully effective. In this case, the best solution is to use granulated magnesium lime SuperMag.

The decision to choose a lime fertilizer should be based on current soil sample test results conducted, among others, by Regional Chemical-Agricultural Stations. It should be noted that on acidic soils with low magnesium content, granulated magnesium carbonate lime SuperMagshould always be applied. It contains 55% CaCO3 and 42% MgCO3. These elements, due to the processing of raw materials, are easily assimilated by plants. SuperMag applied at a rate of 500-1000 kg/ha raises soil pH and increases the content of absorbable magnesium, which performs several important physiological functions in plants. This element regulates the intensity of photosynthesis by determining the chlorophyll content in leaves. Magnesium also affects energy metabolism in plants, carbohydrate, fat, and protein synthesis, as well as the transport of assimilates, and limits nitrate content. It has been shown that magnesium stimulates the development of the root system and the uptake of nutrients by plants from the soil. SuperMag like Polcalc III Generation should be applied pre-sowing directly under the tillage-seeding implement because it can be shallowly mixed with the top 5-10 cm layer of soil. SuperMag should not be applied under the plow because deeper soil cover significantly reduces its acidifying and fertilizing function. SuperMag is best applied in autumn, especially between rows of growing plants, as it does not cause their burn as a magnesium carbonate lime. This lime can also be applied in spring.

In the case of acidic soils with a high magnesium content, it is advisable to use granulated carbonate lime Polcalc III Generationwhich contains up to 98% CaCO3.

SuperMag and Polcalc III Generation re 100% reactive granulated fertilizers that can be applied as a top dressing on growing plants. The selection of fertilizer doses should be made based on current soil sample test results and fertilizer dosage tables in the SuperMag and Polcalc system SuperMag and Polcalc (Tables 3 and 4).

Tab. 3. Tabela wapnowania upraw w systemie POLCALC

Tab. 4. Tabela wapnowania upraw w systemie SUPERMAG

Więcej informacji o:

• SuperMag – https://polcalc.pl/wapno-magnezowe-supermag-big-bag/
• Polcalc III generacji – https://polcalc.pl/wapno-nawozowe-polcalc-iii-generacji-big-bag/
• AgroLuz – https://polcalc.pl/agroluz-calcium-wapno-weglanowe/
• Zakup wapna – https://polcalc.pl/opiekunowie-regionalni/