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Soil liming

Soil liming is a chemical reclamation technique that involves adding calcium and/or magnesium carbonate, oxide, or hydroxide to the soil to neutralize excessive acidity.

Importance of liming

The average annual increase in yields of crops on sandy loam soil in the long-term experiment, depending on the doses of lime (0.5-2.5 on hydrolytic acidity) was 0.31-0.7 tons of grain units from 1 hectare. Net income increased at a decreasing rate with increasing doses of lime and mineral fertilizers, cost recovery was reduced, the maximum cost-effectiveness corresponded to doses of 0.5-1.5 hydrolytic acidity.

In another long-term experiment of the All-Russian Institute of Fertilizers and Agrochemistry (VIUA) on light loamy soils, the maximum average annual productivity increase over 9 years (960 kg of grain units from 1 ha) was achieved at a dose of 1.5 Hg lime, one ruble cost recovery for liming with increasing doses (0.5-1.5 Hg) decreased from 4.0 to 1.8 rubles.

Table. Effect of soil agrochemical properties on barley yield (after 18 years of ammonium nitrate application)[1]Yagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry/ Edited by B.A. Yagodin. - Moscow: Kolos, 2002. - 584 p.: ill.

Crop
Дозы CaCO3, т/га
2,1
4,2
6,3
8,4
Barley
4,9
4,0
3,5
2,6
Clover (1st year of use)
1,4
1,6
1,7
1,5
Clover (2nd year of use)
0,9
0,9
0,7
0,6
Flax
3,5
3,5
3,4
3,1
Oats
4,1
3,3
2,3
1,7
Potato
5,3
5,2
5,2
4,9
Winter rye
2,1
0,5
2,5
1,5

Supportive liming of weakly acidic soils also shows economic efficiency. At increase in doses of lime from 2.1 to 6.3 t/ha recoupment of one ruble of expenses on crop rotation in average for 11 years was 3.6-3.9 rubles.

Economic efficiency in specific production conditions may strongly depend on market conditions, economic opportunities of the enterprise, the payback on liming for individual crops.

According to generalized data of All-Russian Institute of Fertilizers and Agrochemistry 2300 experiments under individual crops and in agrocenoses, the effectiveness of liming increases with increasing soil acidity, as well as on soils with the same acidity with increasing doses of lime.

Table. Average annual increase in yields t/ha of crops different in acidity sod-podzolic soils depending on doses of lime (according to the recommendations of the All-Russian Institute of Fertilizers and Agrochemistry, 1992)

Культура
рНsalt
Doses CaCO3, t/ha
2-4
4-6
6-8
> 8
Winter wheat
< 4,5
0,39
0,46
0,55
0,66
4,6-5,0
0,27
0,40
0,46
0,50
5,1-5,5
0,10
0,15
0,20
0,25
Barley
< 4,5
0,36
0,40
0,45
0,51
4,6-5,0
0,30
0,36
0,41
0,44
5,1-5,5
0,14
0,18
0,20
0,20
Winter wheat
< 4,5
0,20
0,23
0,34
0,38
4,6-5,0
0,17
0,20
0,24
0,28
5,1-5,5
0,05
0,10
0,12
0,12
Oats
< 4,5
0,20
0,23
0,26
0,29
4,6-5,0
0,17
0,20
0,22
0,25
5,1-5,5
0,05
0,10
0,12
0,12
Spring wheat
< 4,5
0,20
0,24
0,26
0,28
4,6-5,0
0,10
0,15
0,20
0,20
5,1-5,5
0,05
0,08
0,08
0,10
Perennial grasses (hay)
< 4,5
1,8
2,5
2,7
3,0
4,6-5,0
1,2
1,5
1,8
2,0
5,1-5,5
0,9
1,2
1,3
1,5
Annual grasses (hay)
< 4,5
1,2
1,4
1,6
1,6
4,6-5,0
0,6
0,8
1,0
1,0
5,1-5,5
0,5
0,8
0,8
0,8
Forage root crops
≤ 4,5
6,0
9,0
12,0
14,0
4,6-5,0
2,0
4,0
5,0
6,0
5,1-5,5
1,0
1,5
1,5
1,5
Potato
≤ 4,5
1,0
1,4
1,8
2,0
4,6-5,0
1,3
1,7
1,7
1,0
5,1-5,5
0,5
0,5
0,5
-
Flax (straw)
≤ 4,5
0,14
0,21
0,26
0,30
4,6-5,0
0,18
0,20
0,22
0,22
Cabbage
4,6-5,0
4,0
4,4
4,1
3,9
Legume-cereal seeded meadows (hay)
≤ 4,5
1,0
1,5
1,8
2,0
4,6-5,0
0,6
0,8
1,3
-
Natural meadows (hay)
≤ 4,5
0,3
0,4
0,4
-
4,6-5,0
0,2
0,2
-
-

Liming helps to improve the quality of products: the content of sugars in root crops, fat and protein in seeds, carotene and ascorbic acid in vegetables and herbs increases, the seeding quality of seeds is improved.

Lime treatment of acidic soils is a way to reduce the intake of radionuclides into plants. According to the data of Belorussian scientists, the introduction of lime in doses equivalent to hydrolytic acidity reduces the content of strontium-90 and cesium-137 in products 1.5-2 times, in some cases – 3 times. Doses of lime fertilizers on such soils depend on the level of contamination with radionuclides.

In the Republic of Belarus at the first contamination level, i.e. 1-5 Ci/km2 of caesium-137 and 0.15-0.3 Ci/km2 of strontium-90 the doses of lime fertilizers are increased only on the peaty soils, loosened loamy-sandy soils with рНKСІ 5,51-5,75; loamy-sandy – with рНKСІ 5,51-6,00 are additionally limeed. At the second level of contamination (5-40 Ci/km2 Caesium-137 and 0,30-3,0 Ci/km2 Strontium-90) doses of lime fertilizers are determined on the basis of normalization of the environment to optimum levels in one step.

Table. Average doses of lime fertilizers (t/ha CaCO3) for liming of acidic sod-podzolic and peaty soils at the density of radionuclide contamination by 5,0-40,0 Ci/km2 cesium-137 or 0,30-3,0 strontium-90[2]Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. - M.: Publishing house of the All-Russian Scientific and Research Institute named after D.N. Pryanishnikov, 2017. - 854 с.

Soil group
Humus content, %
рНKCl
4,25 and below
4,26-4,50
4,51-4,75
4,76-5,00
5,01-5,25
5,26-5,50
5,51-5,75
5,76-6,00
Mineral
Sandy
less than 1,50
8,0
7,5
6,5
5,5
4,5
3,5
-
-
1,51-3,0
8,5
8,0
7,0
6,0
5,0
4,0
-
-
more than 3,0
9,0
8,5
7,5
6,5
5,5
4,5
-
-
Loose-sandy
less than 1,50
10,0
9,0
8,5
7,0
5,5
5,0
3,0
-
1,51-3,0
10,5
9,5
9,0
8,0
6,5
6,0
3,5
-
more than 3,0
11,0
10,0
9,5
8,5
7,5
7,0
4,5
-
Cohesive-sandy
2,0 or less
12,0
10,5
10,0
9,0
8,0
6,5
5,0
4,0
more than 2,0
13,0
11,5
11,0
10,0
8,5
7,0
5,5
4,5
Light and medium loamy
2.0 or less
15,0
14,0
13,0
12,0
11,0
9,5
7,0
6,0
more than 2,0
16,0
15,0
14,0
13,0
12,0
10,5
8,0
7,0
Peaty
Peaty
-
13,0
10,0
7,5
5,0
-
-
-
-
(19,0)*

* (19,0) – for soils with рНKСІ 4.0 and below.

Processes occurring in the soil during liming

The neutralizing effect of calcium and magnesium carbonates is the interaction of carbon dioxide solution (carbonic acid) of the soil solution with the gradual formation of soluble hydrocarbonates, which are hydrolytic alkaline salts:

CaCO3 + H2O + CO2 = Ca(HCO3)2;

Ca(HCO3)2 + 2H2O = Ca2+ + 2OH + 2H2O + 2CO2.

The appearance of Ca2+ and Mg2+ cations in the soil solution leads to the displacement of hydrogen, aluminum, iron, and manganese cations from the soil absorption complex (SAC):

[SAC](Ca, Al, H3) + 3Ca(OH)2 → [SAC]Ca4 + Al(OH)3↓ + 3H2O.

Calcium and magnesium carbonates interact with humic, fulvic acids, amino acids and other soil organic and mineral acids:

CaCO3 + 2RCOOH → (RCOO)2Ca + H2O + CO2;

CaCO3 + 2HNO3 → Ca(NO3)2 + H2O + CO2.

When making a full dose of lime in acidic soils, actual and exchange acidity is eliminated, hydrolytic acidity is reduced, the content of mobile forms of aluminum, iron, manganese and heavy metals copper, lead, arsenic toxic to plants is reduced.

Balance of calcium and magnesium in the soil

The calcium balance is a theoretical basis for the calcium supply to plants and soils in liming, to assess its effectiveness and to predict changes in the reaction of the soil environment. According to lysimetric experiments, the calcium balance shows that in acid soils there is a constant deficit of calcium, i.e. there is a constant depletion of the arable soil layer with this element.

Calcium balance data are an indicator of stabilization of soil acidity at an optimum level and show the need and timing of supporting liming in a particular agrocenosis, and also serve as a theoretically justified method for determining the rates of lime application for supporting liming for individual crops.

Depending on the ratio of calcium balance inputs and outputs, soil liming can be divided into:

  • basic, or ameliorative, which provides a shift in the reaction of the environment to an optimum pH value;
  • maintenance, which compensates for the loss of calcium and stabilizes the achieved level of reaction.

Even in highly acidic soils, the exchangeable calcium content often exceeds the needs of crops, and growth and development are severely inhibited by an unfavorable reaction. Therefore, only compounds affecting the reaction are accounted for in calcium balance inputs: lime fertilizers, phosphorit flour, manure and high-ash lowland peat, including composts based on them, calcium cyanamide, and calcium nitrate. Calcium falling out with atmospheric precipitation and dust can be included in the income items if there are relevant data. According to the All-Russian Institute of Fertilizers and Agrochemistry, this amount for Moscow and Kaluga regions is 40-70 kg/ha (according to other data 15-25 kg/ha). However, atmospheric precipitation includes a sufficient amount of sulfate forming substances, which causes an acidic reaction of precipitation, which can lead to accelerated acidification of soils. In such cases calcium and acids that come with precipitation are taken into account, otherwise refrain from accounting for these balance items.

Additional sources of calcium can be organic fertilizers, in which calcium content in terms of CaCO3 reaches 0.32-0.40%, phosphate meal with neutralizing ability of about 22% CaCO3. Calcium contained in superphosphate does not significantly affect soil pH.

Leaching (leaching) of calcium by infiltration waters from soil profile and domestic removal with crops prevail among expenditure items. Calcium leaching increases with the application of mineral, primarily physiologically acidic forms. In the absence of data on the effect on calcium losses from the quantity and quality of applied mineral fertilizers, the amount of calcium necessary to eliminate the acidifying (cumulative for the rotation of crop rotation) effect of specific forms of nitrogen and potassium fertilizers is added to the expense items. For example, to neutralize 100 kg of fertilizer requires the amount of CaCO3 (kg): NH4NO3 – 75 kg, liquid ammonia – 50-150 kg, (NH4)2SO4 – 120-170 kg, NH4Cl – 140 kg, CO (NH2)2 – 80-120 kg, KCl – 50 kg, Ca(H2PO4)2 – 10 kg. Application of acidic (upland and transitional) peats as organic fertilizers is also an additional item of consumption in the balance.

Table. Calcium and magnesium removal from crops (kg per 1 ton of production) in terms of CaCO3[3]Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. - M.: Publishing house of the All-Russian Scientific and Research Institute named after D.N. Pryanishnikov, 2017. - 854 с.

Crop
CaCO3
MgCO3
Amount** of carbonates
Winter rye*
8,8
6,0
14,8
Winter wheat*
6,3
6,5
12,8
Spring wheat*
5,6
7,8
13,4
Spring barley*
7,7
6,3
14,0
Oats*
9,7
7,2
16,9
Buckwheat*
18,0
8,5
26,5
Peas*
31,5
10,0
41,5
Fiber flax*
17,1
16,4
33,5
Sugar beet (roots)
2,9
1,3
4,2
Potato (tubers)
0,5
1,5
2,0
Forage root crops
0,5
1,0
1,5
Fodder lupine (green mass)
2,9
1,5
4,4
Red clover (hay)
42,2
19,0
61,2
Lucerne
45,5
7,8
53,3
Perennial grasses (hay)
27,0
12,5
39,5
Annual grasses (hay)
30,0
10,6
40,6
Cabbage
1,3
0,8
2,1
Meadow legume-cereal grasses (hay)
17,1
10,2
27,3
Meadow cereals grasses (hay)
7,2
5,0
12,2

* Grain + straw

** Calcium and magnesium removal from limed soils is 10-20% higher

Changes caused by lime in the soil

Correlation analysis according to more than 500 field experiments summarized by the All-Russian Institute of Fertilizers and Agrochemistry established a direct relationship between the effect and aftereffect of lime doses (in t CaCO3/ha) and pH value shifts (ΔрН): increasing doses of CaCO3 leads to an increase in pH shift. The effect of lime on the pH shift reaches its maximum in the first two years after application. Over the next five years there is a gradual acidification and loss of 29% of the achieved shift to a neutral area. After 7-8 years, the loss reaches 50% of the pH level obtained in the first two years.

At equal values of pH in calcareous soils (at applied doses of full hydrolytic acidity) for a long time (before reaching the initial pH value) exchange acidity and the content of mobile forms of aluminum at a high degree of saturation with bases are at a low level. On sour loamy and heavy loamy soils application of full hydrolytic acidity doses of lime may be insufficient to achieve optimum pH values.

Doses and forms of lime fertilizers affect the dynamics of the magnitude and structure of acidity, the degree of saturation of the bases, the content and form of calcium, magnesium and other elements. For example, in long-term studies of the All-Russian Institute of Fertilizers and Agrochemistry, on sod-podzolic light loamy soils, the maximum effect of limestone flour on agrochemical parameters manifested in 2-3 years, dolomite flour – in 5-6 years after application.

The dynamics of soil reaction after liming depends on the created level of environmental reaction. The larger the dose, the higher the pH value is achieved. However, the higher the pH at liming, especially at pH>6, the faster subsequent acidification occurs, which is caused by growth of losses of calcium and magnesium. Therefore, liming by high doses “in reserve” economically, agronomically unreasonable and will create a negative impact on the environment.

Application of high doses of lime does not have a significant impact on the content of humus in the soil, but its quality is improved. In the organic matter at the same time improves the ratio of carbon and nitrogen, increasing the content of more valuable humic acids. Mineralization of organic fertilizers is faster and more stable humic substances are formed.

Liming improves the provision of plants with nitrogen, ash elements, promotes the transition of iron and aluminum phosphates available for plants phosphorus calcium salts.

After liming boron passes to less accessible to plants compounds, forming insoluble compounds with calcium. Increased microbiological activity also increases boron uptake by bacteria. The resulting lack of boron is eliminated by applying boron fertilizer.

Changes caused by lime in the soil

The need for liming of soils arises when there is a mismatch between the reaction of the soil and the requirements of cultivated crops. The need for liming is established by the following signs.

  1. Poor growth and development of cultivated crops with good agrotechnics and fertilization. In this case, crops that require a neutral or weakly acidic reaction (barley, corn, sugar beet, wheat, legumes) grow poorly, and weed plants (sorrel (Rumex), horsetail (Equisetum), Sitnik (Juncus), pike (Deschampsia), etc.) are common. In meadow lands with acidic reaction are common: whitegrass (Nardus), pikegrass (Deschampsia), creeping buttercup (Ranunculus repens), bentgrass (Agrostis), heather (Calluna), rosemary (Ledum), frogweed (Juncus bufonius), field broom (Spergula arvensis), pickleweed (Galeopsis), while clover (Trifolium), foxtail (Alopecurus), hedgehog (Dactylis glomerata) and other sweet grasses are absent.
  2. Low pH. To determine the need for liming, determine the reaction of the soil environment (pH of the salt extract) and the degree of saturation with bases (V). The following limits are adopted: pH less than 4.5 – the need for liming is high; pH 4.6-5.0 – medium need; pH 5.1-5.5 – weak; more than 5.5 – none. According to the degree of saturation of the bases (V) clarify the need for liming soils: V < 50% – strong, V = 51-70% – average, V = 71-80% – weak, V > 80% – is not present.
  3. Indicators of hydrolytic acidity, the amount of absorbed bases, granulometric composition, the content of mobile aluminum and manganese, the specialization of crop rotation. On soils with heavy granulometric composition the need for liming is higher than on light soils. The presence of mobile aluminum also increases the need for liming.
  4. Acidic sod-podzolic soils with well developed white podzolic horizon at least 8-10 cm deep, strongly swamped surface of the arable layer; often manifested surface crust, lack of structure. If the subsoil horizon is not clearly expressed and has small podzolic layers, such soils are characterized by low acidity and do not need liming or weakly need liming. This pattern appears on loamy and clayey soils. Sandy and sandy loam soils even in the absence of whitish podzolic horizon are limed with small doses. Soils underlain by calcareous rocks at a depth of 40-50 cm usually do not need liming.

When setting the sequence of liming in the rotation take into account agrochemical parameters and biological characteristics of crops. Different plants have different attitudes to lime: most respond positively to the introduction of lime, but crops such as potatoes, flax, lupine, can reduce yield and product quality. In this case, apply small doses of lime or combine with manure. For crops most sensitive to acidity, lime is applied in the first place.

Table. Priority of liming of soils depending on the type of crop rotation[4]Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al; ed. by V.G. Mineev. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, … Continue reading

Structure of sown areas and crop rotation
The sequence of liming at
high need
medium need
low need
out of necessity
Field intensive crop rotations with 20% corn, 5% - sugar beets, 20% - leguminous crops, from sowing cereals
need first
need first
need first
liming is carried out with small doses of lime
Vegetable crop rotations
need first
need first
need first
liming is carried out with small doses of lime
Field crop rotations with a large share of flax and potatoes
need first
need in the second turn
no liming
no liming
In the radical improvement of meadows
need in the second turn
need in the third turn
supported by small doses
no liming

Soils of the third stage are limed in cases of economic feasibility of this method. In crop rotations with intensive crops and vegetable rotations soils are limed regardless of the need. Crop rotations of potato or lye specialization are limed only in case of high soil needs. In meadows liming is carried out in the second and third turn.

In the first turn, lime is applied to strongly and moderately acidic soils for crops which are more sensitive to acidity, i.e. in vegetable, feed and field crop rotations (with perennial grasses), as well as acidic soils when establishing cultivated meadows and pastures before sowing grass mixtures. Surface liming is less effective and is carried out on natural forage lands.

Research results show that the danger of negative effects of full doses of lime on flax, potatoes and lupine is exaggerated. Systematic application of organic and mineral fertilizers, high soil fertility, the combination of liming with the application of magnesium, boron and increased doses of potassium fertilizers can recommend on sandy and sandy loam soils 1/2-2/3 of the norm of lime, on loamy – 3/4-1 of the full dose.

The effectiveness of potassium, magnesium and boron fertilizers increases with high doses of lime. In flax crop rotations, lime is introduced under the cover crop for perennial grasses, if the grasses are after flax. In other cases, lime is brought closer to the sowing of flax.

In specialized potato crop rotations with 30-40% in the structure of sowing areas, lime doses are reduced. Liming is brought closer to the planting of potatoes to reduce the common scab.

When determining the place of lime application in the rotation, the following shall be taken into account:

  • sensitivity of cultivated crops to acid reaction and the content of aluminum and manganese;
  • period from applying till manifestation of maximum neutralizing ability of a particular type of lime fertilizers;
  • organizational and technical possibilities of carrying out lime treatment works.

The need for liming increases with the systematic application of high doses of physiologically acidic mineral fertilizers, as well as with the development of new lands that require cultivation of the arable layer.

Table. Classification of arable soils according to the degree of need for lime treatment (according to the recommendations of the All-Russian Institute of Fertilizers and Agrochemistry, 1992)

Soils
Organic matter content, %
Levels рНsalt*
do not need
need
highly in need
1
1а*
2
3
4
5
Sandy
< 4
6,2-5,5
6,3
5,4-5,2
5,1-4,8
4,7-4,3
4,2
4-8
5,8-5,1
5,9
5,0-4,8
4,7-4,5
4,4-4,1
4,0
8,1-15
5,5-4,8
5,6
4,7-4,5
4,4-4,2
4,1-3,9
3,8
Sandy loam and light loam
< 4
6,5-5,8
6,6
5,7-5,4
5,3-4,9
4,8-4,4
4,3
4-8
6,1-5,4
6,2
5,3-5,0
4,9-4,6
4,5-4,2
4,1
8,1-15
5,7-5,0
5,8
4,9-4,6
4,5-4,2
4,1-3,8
3,7
Medium and heavy loam
< 4
6,8-6,1
6,9
6,0-5,6
5,5-5,1
5,0-4,6
4,5
4-8
6,3-5,6
6,4
5,5-5,2
5,1-4,8
4,7-4,4
4,3
8,1-15
6,0-5,2
6,1
5,1-4,8
4,7-4,4
4,3-4,0
3,9
Heavy clays
< 4
7,2-6,4
7,3
6,3-5,9
5,8-5,4
5,3-4,8
4,7
4-8
6,9-5,9
7,0
5,8-5,5
5,4-5,1
5,0-4,7
4,6
8,1-15
6,5-5,5
6,6
5,4-5,1
5,0-4,7
4,6-4,3
4,2
Peaty
> 15
4,3
-
4,2-3,9
3,8-3,5
3,4-3,1
3,0

* Level of possible harmful effects of soil reaction

When soil pH exceeds 6.0, calcium losses from leaching increase, so the All-Russian Institute of Fertilizers and Agrochemistry has proposed levels of possible harmful effects of soil reaction.

First of all, highly needy soils of the fifth group, which, as a rule, are the least fertile, are subject to liming. However, if for financial and economic reasons there is no possibility to perform liming of all the available areas of acidic soils, it is advisable to liming first medium- and weakly acidic soils, which are more fertile. This approach allows for lower costs (with lower doses of lime and fertilizers) to obtain higher yields of the most valuable crops.

Effectiveness of liming

The effectiveness of liming is affected by:

  • soil acidity;
  • relation of crops in the crop rotation to liming;
  • norms, scales, methods of applying lime fertilizers;
  • combination of liming with the introduction of organic and mineral fertilizers;
  • evenness of application; 
  • types and quality of lime fertilizers;
  • properties and granulometric composition of soils.

Table. Effect of the combination of lime, mineral fertilizers and manure on crop yields (average for 6 years) in fodder units of 100 kg/ha[5]Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al; ed. by V.G. Mineev. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, … Continue reading

Options
Soil is highly acidic
Soil is moderately acidic
harvest
increase
harvest
increase
Mineral fertilizers - background
21,9
-
54,7
-
Background + lime
52,2
30,3
59,9
5,2
Background + manure 80 t/ha
50,8
28,9
62,3
14,2
Background + lime + manure
69,7
47,8
68,9
14,2

Liming is most effective in combination with the application of mineral fertilizers and manure. Yields in this case on strongly acidic and moderately acidic soils are equalized. Liming should be preceded or combined with the introduction of organic and mineral fertilizers. Under the influence of lime accelerates the mineralization of organic fertilizers. A combination of lime with organic fertilizers can halve the norms of making without reducing efficiency under the first culture and at the expense of this doubling the fertilized area.

The effectiveness of mineral fertilizers, especially physiologically acidic forms, increases by 2-3 times on the background of lime. Moreover, the increase in yields at simultaneous application of lime and mineral fertilizers is greater than the sum of additions at their separate use, especially this is noted on crops responsive to liming.

Application of physiologically acidic forms of mineral fertilizers leads to depletion of the arable horizon calcium and magnesium. Therefore, prolonged use of mineral fertilizers on acidic soils leads to their irrational use and has a negative impact on soil fertility, which is restored by subsequent liming very slowly and incompletely.

After liming on the hydrolytic acidity neutral reaction of the soil is usually established in 2-3 years.

Lime can be applied simultaneously with organic fertilizers in different ways. It is not recommended to apply manure together with burnt or slaked lime, as it leads to increased loss of ammonia. Also lime application is not compatible with the application of phosphate and bone meal (except composts) because of the transition of P2O5 in a form difficult for plants.

On sandy loam and sandy soils it is more appropriate to apply dolomite flour because of the deficit of magnesium on these soils. Sandy and sandy loamy soils are 5-6 times poorer in calcium and 15-20 times poorer in magnesium than loamy and clay soils. Dolomite flour is applied at 1/2 of the hydrolytic acidity.

When making lime or dolomite meal one of the agrotechnical requirements is the uniformity of distribution over the surface of the field. Uneven application leads to a local overabundance of lime, which can cause plants to die from an alkaline reaction. Dry lime fertilizers can be applied with a variety of fertilizer spreaders. The most favorable days for the application of lime fertilizer are windless days and days with thaws.

When liming the soils of fields with hilly terrain take into account:

  1. Lime spreading by pneumatic spreaders of РУП-8, АРУП-8 type on the fields with 7-10° slope is not recommended.
  2. On fields with steep slopes, it is recommended to use the РУМ-3 spreader which ensures normal spreading on slopes up to 15°.
  3. On slopes with a slope of 5-7°, spreaders can be oriented, depending on the wind, in any direction, including across the slope.
  4. In fields with a 10-15° slope, spreaders should drive uphill; if the slope is steeper than 15°, only drive downhill.
  5. The coefficient of non-uniformity of lime application on the field with hilly terrain may be by 5-10% higher than on level terrain.

Full doses of lime (by hydrolytic acidity, balance or pH shift), depending on economic opportunities, are made under a particular crop rotation or separately in several receptions. With a single application of a full dose is achieved rapid and complete neutralization of acidity of the arable layer for a long period (4-5 years or more) and provides the maximum increase in yield of crops. Full doses of lime is especially important to apply under the cultures sensitive to acidity on the strong, medium and weakly acidic soils, as well as during deepening of the arable layer of poorly cultivated acidic soils.

For economic reasons full doses can be reduced by 25-50%, a half dose allows doubling the treatment area; yield increases are 20-50% lower, but the total economic effect can be greater. In the first years the difference in efficiency of full and half doses is small, but after 3-5 years at half doses it decreases by 2 or more times.

With very limited financial and economic resources, liming is carried out by 20-25% of the full dose of lime (0.5-1.0 t/ha), applying it when sowing or planting acidity-sensitive crops. Such small doses reduce acidity in the root zone and provide an increase in yield only for crops under which lime is introduced, so they are carried out 4-5 times per rotation. At the same time the reduction of acidity of the arable layer in general is postponed for a long period, which leads to increased labor intensity and economic costs in the long term.

The results of numerous field experiments show the high economic return of lime treatment: all costs, depending on the composition of crops, doses of lime and fertilizers pay for themselves by an increase in the first yields of one, two, maximum three crops.

Fertilization system on acidic soils is effective if properly combined with liming. The combined application of lime and organic fertilizers changes the conditions of mineralization of organic matter.

Lime application rates (doses)

Lime application rates depend on the sensitivity of crops in the rotation to acidity, granulometric composition, environmental reaction, humus content, depth of the arable layer and the quality of lime fertilizers. Half doses of lime give an increase in yield, but do not provide a radical change in soil reaction.

Rates of lime fertilizers are calculated in most cases by the value of hydrolytic acidity of the soil, determined by the method of Kappen. To neutralize 1 mg-eq of acidity in 100 g of soil (Hg), 1 mg-eq (or 50 mg) of CaCO3 is needed. If this value is multiplied by the mass of arable layer of 1 ha, which on average for medium-loamy soils is 3⋅106 kg, and to convert milligrams to tons divide by 109, the total dose of СаСО3 (RCaCO3) will be equal:

RCaCO3 = Hg⋅50⋅10⋅3⋅106/109 = 1,5Нg t/ha.

If the content of the active substance in the lime fertilizer is not specified in the form of CaCO3, and in the form of MgCO3, CaO or Ca(OH)2, then the obtained value is recalculated by taking into account the equivalent mass of these compounds, ie multiplying by a factor of 0.84; 0.56; 0.74, respectively. Correction for the content of the active substance Df (t/ha) in a particular fertilizer, taking into account the ballast impurities is equal:

Df = Da.s.⋅100/%a.s. of fertilizer

Particles of lime material larger than 1 mm interact slowly with the soil. The dose of a particular lime fertilizer, taking into account all corrections, is calculated according to the formula:

where D – dose of lime fertilizer, t/ha; W – moisture content, %; N – number of particles larger than 1 mm, %; H – neutralizing capacity, % СаСО3; T – total dose of СаСО3, t/ha.

Doses of lime can be determined by the pH of the salt extract and the granulometric composition.

Table. CaCO3 doses for soils in the Central region of the Non-Black Earth zone, t/ha (All-Russian Institute of Fertilizers and Agrochemistry, 2003)

Soils
рНKCl
3,8-3,9
4,0-4,1
4,2-4,3
4,4-4,5
4,6-4,7
4,8-4,9
5,0-5,1
5,2-5,3
5,4-5,5
5,6-5,8
Sandy
4,5
4,0
3,5
3,0
2,5
2,0
1,5
1,2
1,0
-
Sandy loamy
7,0
5,5
4,5
3,5
3,0
2,5
2,0
1,5
1,2
-
Light loamy
8,0
6,5
5,5
4,5
4,0
3,5
3,0
2,5
2,5
1,5
Medium loamy
9,0
8,0
6,5
5,5
5,0
4,5
4,0
3,5
3,0
2,5
Heavy loamy
10,5
9,5
7,5
6,5
6,0
5,5
5,0
4,5
4,0
3,0
Clayey
12,5
10,5
9,0
7,0
6,5
6,0
5,5
5,0
4,5
3,5

For sod-podzolic and gray forest soils of Russia on the basis of numerous studies established the dependence between the values of pH and hydrolytic acidity (Hg), which allowed to determine for each region of the country full doses of lime fertilizers, taking into account the granulometric composition.

Table. Lime doses (t CaCO3/ha) for soils in the Moscow region with humus content less than 3% (according to the recommendation of All-Russian Institute of Fertilizers and Agrochemistry, 1992)

Soils
Basic liming
Supportive liming
first
second
third*
рНKCl
< 4,1
4,1-4,2
4,5-4,6
4,9-5,0
5,3-5,4
5,7-5,8
5,9-6,0
Sandy
5,5
5,0
4,0
3,5
2,5
2,0
-
Sandy loamy
6,5
6,0
5,0
4,0
3,0
2,5
-
Light loamy
8,0
7,5
6,5
6,0
5,0
3,5
2,5
Medium loamy
8,5
8,0
7,0
6,5
5,5
4,5
4,0
Heavy loamy
13,0
11,0
9,0
7,5
6,5
5,0
4,5
Clayey
14,0
13,0
10,0
8,0
7,0
6,0
5,5

Peat-bog soils with an acidic reaction have a high potential acidity due to the high concentration of hydrogen ions. At the same time, these soils are characterized by a high buffering capacity due to the high content of organic matter, so at pH above 5.0 do not need liming.

Table. Doses of lime (t/ha) depending on the acidity of peat-bog soils (as recommended by the All-Russian Institute of Fertilizers and Agrochemistry, 1992)

рНsalt
Нg, mg⋅eq/100 g
V, %
Doses of CaCO3 at a mass of 20 cm of arable layer
< 500 т/га
> 500 т/га
< 3,9
> 100
< 25
10-12
12-16
3,9-4,3
100-60
25-50
4,0-6,0
6,0-8,0
4,3-4,7
60-40
55-65
2,5-4,0
3,5-5,0
4,7-5,0
40-30
65-75
1,0-2,0
2,0-3,0
> 5,0
< 30
> 75
Do not need

Table. CaCO3 doses for peat-bog soils, t/ha (All-Russian Institute of Fertilizers and Agrochemistry, 2003)

рНKCl
Hydrolytic acidity, mmol/100g soil
Degree of base saturation, %
Soil mass in the 0-20 cm layer
< 500 t/ha
> 500 t/ha
< 3,9
> 100
< 25
10-12
12-16
3,9-4,3
100-60
25-50
4-6
6-8
4,3-4,7
60-40
50-65
3-4
4-5
4,7-5,2
40-30
65-75
2-3
3-4
> 5,2
< 30
> 75
not applied

Lime application rates can be determined by taking into account the exchange (pHsalt), hydrolytic (Hg) acidity and the degree of saturation of the bases (V), taking into account the mass of the arable layer.

Black soils in rotations with sugar beet liming for hydrolytic acidity is more than 1.8 mmol and the degree of saturation of the bases below 93%. Doses of lime determined by the value of the hydrolytic acidity. The above rates of lime are suitable for plowing to a depth of 20 cm. At a different depth of plowing the dose is adjusted.

Table. Average doses of lime fertilizers (t/ha CaCO3) for liming acidic soils of hayfields and pastures[6]Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. - M.: Publishing house of the All-Russian Scientific and Research Institute named after D.N. Pryanishnikov, 2017. - 854 с.

Soil groups
рНKCl
4.25 or less
4,26-4,50
4,51-4,75
4,76-5,00
5,01-5,25
5,26-5,50
5,51-5,75
5,76-6,00
Soils not contaminated with radionuclides
Sandy
6,0
5,5
5,0
4,5
4,0
3,5
-
-
Loose-sandy loamy
6,5
6,0
5,5
5,0
4,5
4,0
-
-
Cohesive-sandy loamy
7,5
7,0
6,5
6,0
5,5
4,5
-
-
Light and medium loamy
9,0
8,5
8,0
7,5
7,0
6,0
5,0
4,0
Heavy loamy
10,0
9,5
9,0
8,5
8,0
7,0
6,0
5,0
Peaty
8,0
(12,0)*
6,5
5,0
3,0
-
-
-
-
Cesium-137 contamination density - 1.0-4.9, strontium-90 - 0.15-0.29 Ci/km2
Sandy
6,0
5,0
5,0
4,5
4,0
3,5
-
-
Loose-sandy loamy
6,5
6,0
5,5
5,0
4,5
4,0
3,5
-
Cohesive-sandy loamy
7,5
7,0
6,5
6,0
5,5
4,5
4,0
3,5
Loamy and clayey
9,0
8,5
8,0
7,5
7,0
6,0
5,0
4,0
Peaty
13,0
(19,0)*
10,0
7,5
5,0
-
-
-
-
Cesium-137 contamination density - 5.0-40.0, strontium-90 - 0.30-3.0 Ci/km2
Sandy
9,0
8,5
7,5
6,5
5,5
4,5
-
-
Loose-sandy loamy
11,0
10,0
9,5
8,5
7,5
7,0
4,5
-
Cohesive-sandy loamy
13,0
11,5
11,0
10,0
8,5
7,0
5,5
4,5
Loamy and clayey
16,0
15,0
14,0
13,0
12,0
10,5
8,0
7,0
Peaty
13,0
(19,0)*
10,0
7,5
5,0
-
-
-
-

*- for soils with рНKСІ 4.0 and below

In crop rotations with a predominance of low-sensitivity to acidity crops such as potatoes, flax, rye, oats, goatgrass, lupine, seradella, complete elimination of acidity is not required, and it is only necessary to maintain an optimal low acidic reaction (pHKCl) of the soil. For these purposes, the method of calculating doses of lime is used according to the standard costs of shifting the pHKCl value. This method is also used to determine the need for lime fertilizers for the regions of Russia as a whole. The method is based on the dependence of pH-sol change on the doses of lime fertilizers in specific soil and climatic conditions. Thus, in the All-Russian Institute of Fertilizers and Agrochemistry, when summarizing the data from 575 field experiments, the dependences for sod-podzolic and gray forest soils with humus content less than 3 % were obtained.

Table. Effect of increasing doses of lime and its costs (t/ha) on the shift of reaction (pHsalt) of sod-podzolic and gray forest soils (Shilnikov generalization)

Dose CaCO3t/ha
Soils with humus content less than 3%
sandy loam
loamy
heavy loamy
overall change рН
CaCO3 consumption for a 0.1 pH change
overall change рН
CaCO3 consumption for a 0.1 pH change
overall change рН
CaCO3 consumption for a 0.1 pH change
3
0,75
0,40
0,57
0,53
0,32
0,94
4
0,97
0,41
0,72
0,55
0,44
0,91
5
1,16
0,43
0,85
0,59
0,55
0,91
6
1,34
0,45
0,96
0,62
0,64
0,94
7
1,50
0,47
1,07
0,65
0,73
0,96
8
1,64
0,49
1,17
0,68
0,81
0,99
9
1,76
0,51
1,26
0,71
0,89
1,01
10
1,86
0,54
1,35
0,74
0,97
1,03
11
1,95
0,56
1,43
0,77
1,03
1,07
12
2,02
0,59
1,51
0,79
1,10
1,09

In practice, the rate of lime CaCO3 (t/ha) is calculated by the formula:

DCaCO3 = ΔрН⋅C⋅10,

where ΔpH is the planned pH change; C is the cost of CaCO3 to shift by 0.1 pH, t/ha; 10 is the coefficient for conversion to t/ha.

Approximate doses of lime can be determined by the value of pHsalt, taking into account the granulometric composition.

Table. CaCO3 doses (t/ha) depending on pH and granulometric composition of soil with organic matter content less than 3% (according to the recommendations of the All-Russian Institute of Fertilizers and Agrochemistry)

Soils
рНsalt
≤ 4,5
4,6
4,8
5,0
5,2
5,2-5,4
Sandy loamy and light loamy
4,0
3,5
3,0
2,5
2,0
2,0
Medium- and heavy loamy
6,0
5,5
5,0
4,5
4,0
3,5

For cabbage, beet dose of lime is calculated by full hydrolytic acidity. When saturation of crop rotation with potatoes, flax, or low-buffered light soils, the dose of lime is reduced to 1/2 hydrolytic acidity. In meadows, lime is made in doses of 1/2 and 3/4 of hydrolytic acidity in autumn or spring with harrowing. With radical improvement of meadows, make a full dose of lime under the plowing. All fruit crops respond well to liming, so when laying nurseries and orchards carry out liming with full doses of lime.

In crop rotations with potato specialization (more than 40% of the sown areas) reduction of full doses by 20-25% is advisable on sandy and sandy loam soils. Magnesium-containing lime fertilizers (dolomite flour, dolomitized and magnesian limestone) are more preferable. To prevent scab infestation of tubers, lime is applied under potatoes before planting.

In crop rotations with flax specialization increase of pH over 6,0 is not recommended, the optimum values of pH in loamy varieties are 5,0-5,5, light and medium loamy – 5,3-5,8, heavy loam and clay – 5,5-6,0. With full doses of lime increase the norms of potash fertilizers, apply boric and, if necessary, manganese fertilizers.

Forage crop rotations, which are often cultivated sensitive to acidity crops, such as fodder root crops, clover, alfalfa, make full or half the hydrolytic acidity of lime doses, followed by periodic maintenance liming.

Vegetable crop rotations make full or on heavy soils half-and-half on hydrolytic acidity doses of lime with subsequent systematic supporting liming. In these crop rotations the most effective are lime-silicate (shale ash, cement dust) and magnesium-lime (dolomite flour) fertilizers.

According to the sensitivity to acidity, meadow grasses are divided into:

  • the most sensitive – alfalfa, melilot, sainfoin;
  • sensitive – meadow clover, hybrid and creeping clover;
  • moderately sensitive – fescue, foxtail, awnless brome, timothy.

Rates of lime application to meadows and pastures during sowing or reseeding grasses do not differ from doses for arable soils of field crop rotations, but they are applied in layers: one half for the main tillage (plowing), the other half for pre-sowing (discing). On lands with low thickness turf lime is applied on the surface with subsequent embedding by discing or milling.

In spite of reduction of calcium leaching on meadows and pastures by 25-40% (120-140 kg СаСO3/ha) in comparison with arable lands, herbage as a result of annual economic calcium removal (100-120 kg СаСO3/ha) needs supporting liming.

Another reason for rapid restoration of acidity after liming in long-standing cultivated meadows and pastures is the application of large (up to 240-360 kg/ha) doses of nitrogen fertilizers to cereal grasses which require 500-700 kg CaCO3/ha annually for neutralization.

With short-term (5-6 years) use of meadows and pastures supporting liming, as well as phosphoritization and the introduction of organic fertilizers, is carried out in the period of repairs (reclamation). With prolonged (more than 10 years) intensive use of lime every 5-6 years after mowing and leaching during the growing season with embedding lime disc or milling.

Lime treatment of acidic soils is carried out during establishment of orchards and berries by full doses of lime, taking into account deepening of tillage horizon up to 35-40 cm in orchards and peculiarities of planted crops. Thus, for apple, pear, plum, cherry, and currant in loamy soils with strong and medium acidic pH, at least 6-8 tons of СаСО3/ha is applied; for light and weakly acidic – 4-6 tons of СаСО3/ha, for raspberry and gooseberry – 3-4 t СаСО3/ha and 2-3 t СаСО3/ha respectively.

When establishing orchards and berries, lime may be applied by mixing with soil to planting holes: plum and cherry – 3-5 kg СаСO3, apple and pear – 2-3 kg СаСO3, gooseberry – 0.1-0.2 kg СаСO3. Under mature fruit crops, if liming was not carried out before planting, lime is applied under the recultivation of bedding circles in the doses recommended during planting.

Timing and methods of liming

The following optimal periods of liming (for Russian conditions) are recommended. 

APRIL-MAY
JUNE-JULY-AUGUST
SEPTEMBER-OCTOBER
Under spring crops, seeded fallow, perennial grass cover, perennial grasses, hayfields and pastures
After harvesting winter crops, annual grasses for green fodder and perennial grasses. On newly developed lands. Under winter crops
After harvesting winter and spring crops on ploughed ground and before the plowing of ground on newly developed lands

Full and half hydrolytic acidity doses of lime are applied under the fall main tillage, under the plowing of the spring furrow or in the fallow field for winter crops. When deepening the topsoil of sod-podzolic soils lime is carried out to neutralize increased acidity of podzolic horizon, which is included in the topsoil.

If liming and phosphoritization are combined under the same crop, phosphoritic meal is put in autumn under the main treatment, and lime – in spring under the plowing or cultivation of the arable land.

In field crop rotations with cereals and perennial grasses it is optimal to apply lime under the cover crop.

When making 1/4-1/2 of the full dose of lime is carried out by cultivators or harrows. At lower doses, local application to wells during cabbage planting at the rate of 5-15 cwt/ha or banding together with seeds is used.

Plant response to lime fertilizers

Rye, spring wheat, and oats tolerate soil acidity relatively easily and respond weakly to liming, they are not depressed by increased doses of lime. Flax, potatoes, lupine, seradella give a yield increase only at moderate doses of lime with appropriate doses of mineral fertilizers, especially potassium.

Quality control of lime treatment works

When carrying out lime treatment systematically carry out agrochemical control over the fulfillment of agrotechnical requirements for the quality of work. The most important indicators include:

  • non-uniformity of spreading over the working width;
  • deviation from the calculated dose;
  • spillage on the field and headlands;
  • compliance with technological requirements at the headlands.

Table. Indicators for assessing the quality of work (uniformity) when applying lime fertilizers[7]Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al; ed. by V.G. Mineev. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, … Continue reading

Technological indicators
Quality assessment
excellent
good
satisfactory
poorly
Uneven spreading over the working width of the machine:
a) with a centrifugal spreader
up to ±15%
±16-20%
±21-25%
over ±25%
b) with a pneumatic spreader
up to ±20%
±21-25%
±26-30%
over ±30%
Deviation from dose
up to ±3%
±4-5%
±6-10%
over ±10%
Working width
observed
observed
observed with slight deviations
mistakes at the joints of passages

During the machine operation the spreading width, uniformity of lime fertilizer distribution and compliance with the application rates are monitored. The value of deviation of the working width should not be more than ± 10% of the recommended one. Unevenness of spreading – ± 25-30%.

Rate of lime application is determined by the actual weight of the fertilizer applied and the treated area. The frequency of determination depends on the application rate and the quality of the lime fertilizer. If the dose differs from the set dose by more than 10%, adjust the metering device of the spreader.

Sources

Yagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry / Edited by B.A. Yagodin. – Moscow: Kolos, 2002. – 584 p.: ill.

Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. – M.: Publishing house of the All-Russian Scientific and Research Institute named after D.N. Pryanishnikov, 2017. – 854 с.

Fundamentals of agricultural production technology. Farming and crop production. Ed. by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.