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Video: Calcium And Magnesium In Plant Nutrition. Lime Fertilizers
2023 Author: Sebastian Paterson | [email protected]. Last modified: 2023-11-26 20:34
Why lime soils (part 2)
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Calcium in plant nutrition
The effect of increased soil acidity depends not only on the characteristics of plants, but also on the composition and concentration of other cations in the soil solution, on the total content of nutrients and other properties of the soil. With a lack of calcium, as a nutrient for plants, leaf growth is inhibited. Light yellow spots appear on them (chloroticity), then the leaves die off, and the leaves formed earlier (with the previous optimal calcium nutrition) remain normal.
Unlike magnesium, old leaves contain more calcium than young ones, since it cannot be reused in plants. As the leaves age, the amount of calcium in them increases. Therefore, all the calcium that enters the soil returns with fallen leaves, tops or manure. Calcium enhances the metabolism in plants, plays an important role in the movement of carbohydrates, affects the conversion of nitrogenous substances, accelerates the breakdown of storage proteins in the seed during germination. In addition, it is essential for the construction of normal cell walls and for the establishment of a favorable acid-base balance in plants.
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Calcium in plants is in the form of salts of pectic acid, sulfate, carbonate, phosphate and calcium oxalate. A significant part of it in plants (from 20 to 65%) is soluble in water, and the rest can be extracted from the leaves by treatment with weak acids. It enters plants during the entire period of active growth. In the presence of nitrate nitrogen in the solution, its penetration into plants increases, and in the presence of ammonia nitrogen, due to antagonism between Ca2 + and NH4 + cations, it decreases.
Hydrogen ions and other cations interfere with the intake of calcium at their high concentration in the soil solution. Different plants differ dramatically in the amount of this element consumed. With high yields, agricultural crops carry it in the following quantities (in grams of CaO per 1 m²): cereals - 2-4, legumes - 4-6; potatoes, lupines, corn, beets - 6-12; perennial legumes - 12-25; cabbage - 30-50. Most of all calcium is consumed by cabbage, alfalfa and clover. These crops are also characterized by a very high sensitivity to increased soil acidity.
However, the need of plants for calcium and their ratio to soil acidity do not always coincide. So, all grain breads absorb little calcium, but they differ sharply in sensitivity to an acid reaction - rye and oats tolerate it well, while barley and wheat do not. Potatoes and lupines are not sensitive to high acidity, but they consume relatively high amounts of calcium. Unlike magnesium, calcium is found less in seeds and much more in leaves and stems. Therefore, most of the calcium taken by plants from the soil is not alienated, but through feed and litter it enters the manure and returns with it to summer cottages.
The loss of calcium from the soil occurs not so much as a result of its removal with crops, but as a result of leaching. The loss of this element from the soil greatly increases with its acidification. 10-50 g of CaO from 1 m² is washed out annually. Five years later, by the time of re-liming, taking into account the annual removal of calcium by plants (20-50 g / m²), there is practically no lime added in a dose of 400-600 g / m² in the soil. On calcium-poor acidic sandy and sandy loam soils when cultivating cabbage, alfalfa, clover, fruit and berry crops, there may be a need for its introduction not only to neutralize acidity, but also to improve their nutrition with this element.
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Magnesium in plant nutrition
It plays an important role in plant life. It is part of the chlorophyll molecule and is directly involved in photosynthesis. However, chlorophyll contains a smaller part of this element, about 10% of the total content in plants.
Magnesium is also found in pectin and phytin, which accumulates mainly in seeds. With a lack of magnesium, the chlorophyll content in the green parts of the plant decreases. The leaves, first of all the lower ones, become spotty, "marbled", turn pale between the veins, and along the veins the green color is still preserved (partial chlorosis). Then the leaves gradually turn yellow, curl off the edges and fall off prematurely. As a result, the development of plants slows down and their growth deteriorates.
Magnesium, together with phosphorus, is found mainly in the growing parts and seeds of plants. Unlike calcium, it is more mobile and can be reused in plants. From old leaves, magnesium moves to young ones, and after flowering, it flows out of the leaves into the seeds, where it is concentrated in the embryo. Seeds contain more magnesium, and leaves less than calcium. The lack of magnesium affects the yield of seeds, roots and tubers more sharply than that of straw or tops. This element plays an important role in various life processes, it participates in the movement of phosphorus in plants, activates some enzymes (for example, phosphatase), accelerates the formation of carbohydrates, and affects the redox processes in plant tissues.
A good supply of plants with magnesium helps to enhance the reduction processes in them and leads to a greater accumulation of reduced organic compounds - essential oils, fats, etc. With a lack of magnesium, on the contrary, oxidative processes intensify, the activity of the peroxidase enzyme increases, and the content of sugar and ascorbic acid decreases.
The magnesium requirements of individual plants differ. With high yields, they consume from 1 to 7 g of MgO per 1 m². The greatest amount of magnesium is absorbed by potatoes, beets, legumes and legumes. Therefore, they are most sensitive to the lack of this element. Many crops on acidic soils (legumes, cabbage, onions, garlic) lack magnesium and calcium as nutrients, most of all due to antagonism with hydrogen, aluminum, manganese and iron, which are very abundant in acidic soils. There is less magnesium in soils than calcium. Strongly podzolized acidic soils of light texture are especially poor in them. In such soils, the application of lime fertilizers containing magnesium significantly increases the yield.
Regular liming of the soils of the summer cottage, on average once every five years, with one of the following fertilizers provides a radical improvement in acidic soils, increases their fertility and improves plant nutrition.
Limestone and dolomite flour
Obtained by grinding and crushing limestone and dolomite. The speed of interaction with the soil and the effectiveness of ground limestone and dolomite are highly dependent on the degree of grinding. Particles larger than 1 mm dissolve poorly and very weakly reduce soil acidity. The finer the grinding, the better they mix with the soil, dissolve faster and more completely, act faster and the higher their efficiency.
Burnt and slaked lime
When firing hard limestones, calcium and magnesium carbonates lose carbon dioxide and turn into calcium oxide or magnesium oxide CaO and MgO. When they interact with water, calcium or magnesium hydroxide is formed, that is, the so-called slaked lime - "fluff". It is a fine crumbling powder of Ca (OH) 2 and Mg (OH) 2. You can extinguish burnt lime directly in the field, sprinkling it with damp earth.
The fastest-acting lime fertilizer, especially valuable for clay soils. It dissolves much better in water (about 100 times) than carbon dioxide, but magnesium hydroxide Mg (OH) 2 is almost insoluble in water. In the first year after application, the efficiency of slaked lime is higher than that of carbonic lime. In the second year, the difference in their effect is largely smoothed out, and in subsequent years, their effect is leveled. According to the ability to neutralize soil acidity, 1 ton of Ca (OH) 2 is equal to 1.35 ton of CaCO3.
Calcareous tuffs (key lime)
Usually contain 90-98% CaCO3, and a small amount of mineral and organic impurities. Their deposits are most often found in near-terrace floodplains, in the places where the keys exit. In appearance, calcareous tuffs are a loose, porous, easily crumbling gray mass, in some cases colored with an admixture of iron hydroxide and organic matter in dark, brown and rusty colors of varying intensity.
Drywall (lake lime)
Contains 80-95% CaCO3, its deposits are confined to the places of dried up enclosed reservoirs, which in the past received water rich in calcium. Lacustrine lime has a fine-grained constitution, easily crumbles and crushes, mainly into particles less than 0.25 mm. Its moisture capacity is small, it does not smudge and retains good flowability.
Contains from 25 to 50% CaCO3, some MgCO3 and other impurities. It is a rock in which calcium carbonate is mixed with clay, and often with clay and sand.
It is low-lying peat rich in lime. Contains CaCO3 from 10-15 to 50-70%. Valuable peat-lime fertilizer, most suitable for liming acidic soils, poor in organic matter and located near the places of occurrence of peat tufts.
Natural dolomite flour
Contains 95% CaCO3 and MgCO3. This is a free-flowing mass of fine texture, 98-99% consists of particles less than 0.25 mm, sometimes pieces of hard rock come across in it, which must be sifted out before introduction. This is a very valuable lime fertilizer, as it also contains magnesium in addition to calcium.
It is obtained by burning oil shale at industrial enterprises and power plants, contains 30-48% CaO and 1.5-3.8 MgO and has a significant neutralizing ability. In addition, it includes potassium, sodium, sulfur, phosphorus, and some trace elements. This is the reason for the high efficiency of oil shale ash. Most of the calcium and magnesium in it is in the form of silicates, which are less soluble than carbonates, therefore, in comparison with calcium carbonate, it reduces the acidity of the soil somewhat weaker and slower. However, this does not reduce its value, and for some crops (flax, potatoes, etc.) it is a favorable property.
Organics used as mulch cannot be called plant nutrition. Plants do not "eat" grass, straw, compost, etc. Microbes, fungi, insects, worms decompose organic matter to a state that can be assimilated by plants
Magnesium is a key element for the heart. Calcium deficiency can trigger atherosclerosis. Silicon makes vessels elastic. Chromium - a regulator of cholesterol synthesis
With liming of acidic soils, plant nutrition with nitrogen and ash elements - phosphorus, calcium, magnesium and molybdenum - improves. Improved nutrition on limed soils is also explained by the fact that plants develop a more powerful root system and therefore are more able to absorb nutrients from soil and fertilizers. However, this cannot happen automatically. A number of conditions must be met
Mineral fertilizers and plant growth regulators Zeba®, Kornevin®, Emistim® from the Oktyabrina Aprelevna trademark
In the process of using the soil, a certain amount of "garbage" always appears. Such wastes can be residues from the use of fertilizers, various excretions from plant roots, etc. How to get rid of them?