When growing plants in a greenhouse in a low-volume technology, the nutrient solution for them should contain all the necessary elements of nutrition in the correct proportion. The preparation of a nutrient solution is a job for agronomist, agrochemist, which requires special knowledge and has its own intricacies. The disadvantage or excess of these or other elements of nutrition affects the yield and can cause the development of various diseases of plants.
Water treatment is the first one, from which the preparation of a nutrient solution begins. That is, it is necessary to prepare the water before it comes to the watering plant. To properly prepare a nutrient solution, you need to bring the normal amount of bicarbonates in the water. For example, if we have 7 millimeters of bicarbonate in water. We "quench", for example, 5 of 7 mmole and we have 2 mmole in water. If we add nitric acid to this nutrient solution, then hydrogen will join bicarbonate and H2O + CO2 + NO3 will be obtained from it. CO2 is volatile and the amount of bicarbonates in water decreases. Thus, before reaching the tank with fertilizers, we get in the water nutrients of nitrogen in a rather large quantity. When preparing water, it is possible to take nitrogen very strongly. And if you think that in a solution of nitrogen is normal in comparison with potassium, then in reality there may be more nitrogen or, in some cases, less - it depends on how many bicarbonates you have in water.
Nutrient solutions are always made by the agronomist, usually agrochemical, for this there are several programs. All of them are paid, the Dutch do not give their programs for calculating nutrient solutions. They say they will appeal to them, and they will calculate themselves. This is done to tie its consumers to their firm, as a result of which two programs were issued in Russia: one is called the Agronomist of the firm "Fito", the second is called "Agrochemic", this is the program of the company "Korolyov Agro". These are two programs that are used in Russia to calculate nutrient solutions.
Several types of fertilizers are used to make a nutrient solution, as a rule, at least two varieties of the origin of one element. For example, if it is Magnesium, magnesium sulfate and magnesium nitrate may be used. If potassium, then nitrate, potassium sulfate or may be potassium monophosphate. There are 2 sources of phosphorus: orthophosphoric acid and potassium monophosphate. The calcium source is calcium nitrate, but very often, especially in the cultivation of tomatoes, calcium chloride is used, in small quantities (in the amount of 1 mmole).
When you have made water, it flows through the base pump to the injector. Injectors are diluted 1: 100 per 100 parts of water taken 1 part of the concentrated fertilizer from each tank, the acid tank is not involved, because it works according to its program and operates on pH and is not tied to concentration, and EU work precisely from tanks A and B. Why do tanks 2 not one? Because there are fertilizers that are not compatible with each other and a few fertilizers. The first one is calcium nitrate, as a rule, it always poured into the tank A, and it cannot be combined with sulfates. If you ever add magnesium sulfate, potassium sulfate to this tank, you will receive a very bad reaction, called the formation of gypsum. Flakes are formed, if this powder falls into the pipes, then you will glue the entire system. And if your operator messed up the bag and filled the sulfate into a calcium tank, then it was necessary to drain all this fertilizer, to wash the pipes, to punish the operator, to deprive the prize and everything else. Under the threat of firing, under any circumstances, sulfate should not mix with calcium - it can disable drip systems. Several times in my life it turned out that after 1-2 months it was necessary to wash all this with the help of orthophosphoric acid and other solutions. In a tank you can add potassium nitrate, magnesium nitrate, ferrum chelate. It is also possible to add fertilizers that cannot be mixed with calcium (potassium sulfate, magnesium sulfate), which can be added to bucket B, orthophosphoric acid (H2PO4) in an amount of 1 to 3 liters can be added to lower the pH. Typically, one cubic meter of nutrient solution, depending on the water, experimentally determine how much of the acid can be poured into tanks A and B. In a tank A, usually, pours nitrogen, and in the tank B, orthophosphoric acid.
The ratio of all elements must correspond to a definite formula, this formula is standard for most plant species. The standard element ratio is made on five elements. This is a formula that helps to calculate any nutrient solution per minute in a piece of paper.
If nitrogen is 1 (mole or mg), then phosphorus should be 0.25-0.45 (depending on the crop), Potassium should be 0.3-1.7, relative to nitrogen; Calcium should be 0.8 g of calcium, and magnesium - 0.3 c Calcium.
If these ratios are sustained, then you can make any nutrient solution for any culture, but this will only produce standard yields. In order to get the maximum yield, you will need to play these thin faces, for example: slightly increase nitrogen, reduce potassium a little, reduce calcium slightly in favor of magnesium, etc.
Ferrum chelate is always poured into the tank at a specific amount. It falls asleep last, after acid and checking the pH with a litmus paper. Because if you fill up iron with acid, then the ferrum chelate will fall into the precipitate. Ferrum is a constant element and is added to all nutrient solutions. Ferrum, which is present in water, sometimes even in quantities exceeding the norm, is in a trivalent oxidized state that is not available to plants. Without the chelates of the ferrum, the plant will have a deficiency of this element.
Nourishing solution is done every day. The preparation of the nutrient solution is not even an agronomist, but an operator. When the tank finishes, the irrigation computer stops and pours it again, it's a cyclical process. The contents of the tanks should end in parallel, because if this does not happen simultaneously, then, the injectors will not work correctly, which means the ratio of the elements will not be correct.
Each salt gives not the same concentration. If you take 1 g / l of potassium sulfate, then it will give you 1,3 in distilled water, and if you take potassium nitrate 1 g / l, it will give you a concentration of 0.6. Each salt gives a different concentration at equal weight composition, therefore everything is determined by the ratio of the elements of the food in tanks. If the agronomist correctly calculated the nutrient solution, then it may not be necessary to think that it is not even necessary to have an agrochemical laboratory at a greenhouse that calculates all the elements of the food, it is enough to have a device for determining the EU, a pH meter, a conductivity meter. And the agronomist can calmly monitor for several weeks until the next analysis. But at the same time, he should not dramatically change the volumes of irrigation and drainage. He can track the feed solution and the solution leaving the drainage. The difference between these solutions should not exceed 2 units. If you go beyond 2 units, you increase the volume of irrigation, if less than two units, then you can reduce this irrigation a little and adjust the needs of the plant accordingly in this way.
If it is necessary to increase the concentration of nutrient solution, then everything is not so unambiguous. You reduce the acid consumption, and consequently you change the value of nitrogen, because when you increase the concentration of fertilizers, you have bicarbonates that need to be removed from the water, require less nitric acid, and accordingly nitrogen, which comes from nitric acid, will be lower. When increasing the concentration, as a rule, there is a decrease in the nitrogen component of the total volume of the solution. The difference is some interest, but this must be taken into account. Also, the percentage of nitrogen is sharply reduced if there is very sunny weather on the street. When an agronomist knows from a meteorological forecast that he will have sunny weather, then, purely from practice, he gives the operator the task to add 3 kg of ammonium nitrate per 1 m3 of solution to the A tank. Ammonium nitrate, firstly, acidifies the solution very well, and thus provides readily available nitrogen in the form of NH4, which is rapidly processed in the sunny weather, which makes it impossible to prevent the generative development of the plant towards the thinning of the "head" - just such a little trick. But this is to be done only in the sunny weather, because if you throw 3 kg of ammonium nitrate in a cloudy weather, the steppes will climb on all sides. Again, the amount of solution is not taken into account in the calculation, but only from the practice: someone sighs 2 kg, someone 4 kg. On tomato you can also pour 4 kg, if the plant is weak, and if strong, then you cannot add at all, so the solution turns out to be relative.
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