When considering the mineral nutrition of sunflower, nitrogen, phosphorus and potassium are, of course, the mainstays. But is it possible to achieve record harvests only by adding macronutrients? The answer is NO.
It has been proven that 20 elements are essential because plants cannot live without them and they cannot be replaced by other elements.
These are oxygen, carbon, hydrogen, nitrogen, phosphorus, potassium, calcium, magnesium, sodium, sulfur, iron, chlorine, manganese, boron, zinc, copper, molybdenum, cobalt, vanadium, and iodine.
Compared to N, P, K, such mesoelements as calcium, (Ca) magnesium (Mg) and sulfur (S) are also absorbed by the plant in significant quantities. Let's talk about them.
The recommended rate of mesoelements for sunflower per 1 ton of the planned yield is 30 kg/ha of sulfur, 20 kg/ha of magnesium, and 50 kg/ha of calcium.
Sulfur (S)
Sulfur is responsible for the metabolism and transfer of substances, in the general processes of ionic balance in plant cells, and is a component of proteins - one of the starting products for the biosynthesis of amino acids. Sulfur activates growth processes, promotes nitrogen uptake by plants, improves resistance to drought, low temperatures, diseases, etc. With a lack of sulfur, not only sunflower yields are reduced, but also the oil content in the seeds.
How to determine sulfur deficiency in sunflower?
Sulfur deficiency is often confused with nitrogen deficiency in visual analysis. In both cases, there is a stunted growth of the plants, accompanied by a general yellowing of the leaves. Sulfur in a plant is immobile and does not move from old leaves to young ones. In case of sulfur deficiency, young leaves often turn yellow first, while in case of nitrogen deficiency, old leaves turn yellow first.
On soils poor in sulfur, you need to plan the introduction of this element. After all, sunflower needs three times more sulfur than cereals.
The source of sulfur for sunflower.
The source of sulfur can be well-water-soluble fertilizers: magnesium sulfate, superphosphate, ammonium sulfate.
Sulphur is a spring fertilizer, so its application in the fall is not recommended due to possible leaching.
The lack of sulfur in crop nutrition is manifested on soils of light particle size distribution, with an acidic soil reaction, poorly aerated, and low in organic matter.
Calcium (Ca)
Calcium is responsible for the regulation of water, carbohydrate and nitrogen metabolism in plants and is a component of cell membranes. Thus, calcium increases the heat resistance of plants, promotes the synthesis of chlorophyll, ensures good development of the root system, contributing to the formation of more root hairs, which help to transfer the bulk of water and nutrients dissolved in it from the soil to the plants.
Symptoms of calcium deficiency in sunflower.
Calcium deficiency inhibits the growth of leaves, their veins turn brown, light yellow spots appear on them first (chlorotic), and then they die. At the same time, the leaves that were formed earlier do not experience a lack of calcium and remain normal: they contain more calcium than young leaves, since plants cannot redistribute it.
The source of calcium.
Calcium is contained in granular superphosphate, calcium nitrate.
Calcium is necessary for the normal growth of above-ground organs and the root system of plants. It is supplied to plants throughout the entire period of active growth.
Magnesium (Mg)
Magnesium affects all processes in plant cells, where chemical energy is transferred and accumulated (photosynthesis, respiration, glycolysis). Unlike calcium, magnesium is more mobile and can be redistributed by the plant: it moves from old leaves to young ones, and after flowering, from leaves to seeds. Magnesium deficiency has a greater impact on seed development.
Symptoms of magnesium deficiency in sunflower.
With a deficiency of magnesium in plants, the leaves become pale, and spots often appear on old leaves. Later, brown spots appear between the veins on the leaves, while the veins remain green. Since magnesium and potassium are antagonists, excessive application of potassium fertilizers can cause magnesium deficiency. Unlike potassium, it is easily washed out of the soil,
Magnesium affects plant growth, so it is most needed in the initial stages, and should therefore be included in the main fertilizer. This element is also well absorbed through the leaves, 10-15 times faster than potassium or phosphorus.
A source of magnesium.
Contained in magnesium sulfate, potassium magnesium.
Please note.
It should be noted that about 6% of calcium is taken out with the seeds, the rest is returned with plant residues, 20% of magnesium is taken out with the seeds, and 17% of sulfur. Another interesting phenomenon is the synergism of elements, which means that some elements increase the absorption and positive effect of other elements (nitrogen - magnesium, magnesium - phosphorus, potassium - manganese and iron, molybdenum - nitrogen, sulfur - nitrogen, potassium, copper, magnesium and manganese).
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