Why Liming The Soil Is Necessary

2023 Author: Sebastian Paterson | [email protected]. Last modified: 2023-07-30 21:03

Soil reaction and regulation

The productivity of a significant part of the soils in the Nonchernozem zone of Russia is limited by their increased acidity, as well as an increased content of hydrogen ions (H +).

The harm of acidity

The negative effect of increased acidity is most often associated with the following phenomena and processes:

• suppression of soil microflora, primarily bacterial, necessary for nitrogen fixation, mineralization and synthesis of humus and many other processes;
• an increase in the content of aluminum, iron and manganese. Particularly harmful is mobile (dissolved) aluminum, which has a depressing effect on both the soil microflora and the plants themselves (tested on beets, cabbage and other plants). In addition, aluminum binds assimilable phosphorus compounds, converting them into compounds inaccessible to plants.
• in an acidic environment in plants, metabolic processes are disrupted, they lose frost and heat resistance, resistance to drought, diseases and pests.
• at strongly acidic pH values (less than 3.5), the soil structure is destroyed (floats).
• there is a lack of calcium, magnesium and potassium.

Different types of plants have different attitudes towards acidity levels. According to this principle, all cultures are conventionally subdivided into "calcephiles" and "calcephobes".

Calcephiles are called plants that need an almost neutral reaction of the environment (soil solution) - pH 5.5-7, they can grow even on slightly alkaline soil. These include most plants of the legume family, including peas, beans, beans, as well as tomatoes, root crops (beets, carrots).

"Calcephobes" are plants that thrive on slightly acidic soil with a pH of 5-6. "Calcephobes" are potatoes, strawberries and some other crops.

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When, how and what to lime the soil

It is possible to reduce soil acidity with one of the following types of agromeliorants (deoxidizers): limestone flour, agromel, waste chalk, dolomite flour, phosphate rock, wood ash.

Limestone flour is ground limestone and has the same chemical composition as chalk - calcium carbonate (CaCO3). The difference is that chalk is a finer powder and shows the maximum effect in the next year after application. Limestone flour can fully manifest itself for 4-5 years.

Dolomite flour is calcium and magnesium carbonate (CaCO3xMgCO3). Due to its magnesium content in light soils, it is more valuable than limestone flour or chalk.

Phosphoric flour is a weaker deoxidizer, and it is required (according to my calculations) by 1/4 more, but it is also a phosphorus fertilizer.

As for ash, the CaCO3 content in it is about 50%, in addition, due to the wide ratio of potassium and magnesium on light soils, after the application of increased doses of ash, plants sometimes experience a lack of magnesium.

Considering the speed of interaction of the most common deoxidizers, it is better to add chalk under "calciphiles", as the most responsive to liming crops. If liming is planned to be carried out before planting "calcephobes", it is better to add lime (it is assumed that crop rotation is observed).

As for the doses of the agromeliorant, they are calculated for a shift in pH: the required shift in pH is the difference between the optimal pH value for the crop in question and its actual value for a specific area. You can also use the average recommended dosage to bring the pH to 5.5. Gardeners can determine the pH value in water and salt extracts of the soil by dipping indicator paper in them.

In the instructions for indicator papers, it is proposed to make a water extract (determine the actual acidity, the pH of the water extract is taken as the pH of the soil solution). However, rNCL or pHsal is more common in the literature, which implies the extraction of soil in a 7.5% solution of potassium chloride. The pH value of the salt extract means exchangeable acidity - the acidity of the soil after the application of mineral fertilizers.

I offer gardeners a reference table for determining the doses of deoxidizers on soils of different mechanical composition. The pH values are based on the salt extract. I calculated the doses from t / ha to g / m².

Lime rates for sod-podzolic and gray forest soils. (Yulushev I. G., 1989)

Dose of CaCO 3, g / m2	pH <4.5	pH 4.6-5.0	pH 5.1-5.5
Sandy, sandy loam
0.1 pH	42	50	53
Up to pH 5.5	400	250-400	150-200
Light and medium loamy
0.1 pH	56	66	110
Up to pH 5.5	500	350-450	250-300
Heavy loams and clays
0.1 pH	75	89	145
Up to pH 5.5	700	550-600	300-400

In conclusion, I would like to once again advise you to choose a deoxidizer depending on the culture under which you are liming. Fertile soil and high yields!