Crop Nutrition

Plant uptake of nutrients

Plants cannot distinguish between natural fertilizers and chemical fertilizers. They can take in some ions and small molecules from the soil. In traditional vegetable garden planting, these nutrients are derived from bio-organic fertilizer after decomposing. Plants mainly absorb nitrogen in the form of ammonium or nitrate. Nitrogen in organic fertilizers exists in various forms, including organic nitrogen, ammonia, ammonium, hydrazine, hydroxylamine, nitrogen, nitrous oxide, nitric oxide, nitrous acid, nitrite, nitrogen dioxide, nitric acid, and Nitrate. The process of breaking down primitive nutrient sources like manure into small molecules and ions that plants can use is affected by various factors, including bacterial colonies, soil temperature, and moisture content. In the current general soilless fertilizer, nitrogen is in the form (ammonium salt and nitrate) that can be directly absorbed by plants, and does not need to be decomposed by bacteria.

The root system helps plants absorb water from the soil. The nutrients dissolved in the soil moisture are also called soil solution, which can be well utilized by the root system. The availability of nutrients in the soil depends not only on the content of nutrients, but also on soil moisture, pH, nutrient distribution, and cation exchange capacity.

The plants growing in the hydroponic system can continuously obtain nutrients from the nutrient solution. Nutrients are evenly dissolved in water to form a nutrient solution similar to soil solution. Plants can use them at any time when they need nutrients, so that they can reach their maximum growth potential without being affected by nutritional deficiencies.

Definition of nutrient solution

Nutrient solution: Dissolve the fertilizer containing the nutrient elements necessary for plant growth in water, which is the nutrient solution.
Mother liquor: The concentration of mother liquor is very high, usually 50 to 200 times the concentration of nutrient solution.
The reason for preparing mother liquor is that adding undissolved fertilizer directly is not as effective as applying liquid fertilizer.

Fertilizer

Decades ago, most growers needed to mix more than ten nutrient elements to formulate a nutrient solution that meets the nutritional needs of crops. The operation is very cumbersome! Today, many growers still mix various chemical reagents to prepare nutrient solutions, but the use rate of premixed fertilizers is increasing. Growers only need to purchase 2 to 3 different pre-mixed fertilizers to prepare a nutrient solution that meets the nutritional needs of crops. There are also some hydroponic fertilizer manufacturers invented a “single bottle fertilizer” to further simplify the preparation process of the nutrient solution. Its use is as simple as making a glass of juice with fruit juice powder. The grower only needs to add a certain amount of water to the fertilizer powder or liquid according to the proportion on the package.

Organic hydroponic fertilizer

Organic hydroponics is feasible, but it is not recommended for novices to try. This requires the grower to have a certain amount of hydroponic planting experience. Before using organic hydroponics, you should master how to grow plants under normal conditions. If novice growers in hydroponic vegetable gardens want to use organic hydroponics, aquaponics is a good choice. Fish-vegetable symbiosis combines hydroponic gardening and aquaculture well. In this system, the waste produced by fish undergoes a series of biological decomposition processes into nutrients that can be used by plants.
Growers may try to use organic fertilizers used in traditional planting, but this often produces foul smells. Many organic fertilizers are made from animal stools or by-products of the meat industry. These fertilizers will quickly decay when applied in the hydroponic system, causing the nutrient solution to emit a foul smell. The hydroponic system is easily covered by impurities, and growers need to clean and cut frequently. Cultivating system. The most successful use in hydroponic systems is organic fertilizer made from plants such as sugar cane. Some growers have successfully used a kind of Ganyuan fertilizer called Pre-Emt to grow organic hydroponic vegetable gardens.

Conventional fertilizer types

Liquid or solid fertilizer

There are several types of conventional fertilizers. Most hydroponic growers usually use liquid fertilizer or solid fertilizer. Liquid fertilizers are easier to use because they are easy to measure and do not require mixing, but liquid fertilizers are more expensive. Most liquid fertilizers are bottled and are made by dissolving solid fertilizers in a certain amount of water by the manufacturer. The concentration of liquid fertilizer is usually higher than that of solid fertilizer, and it is more expensive due to increased transportation costs.

Single bottle of fertilizer, double bottle of fertilizer, multiple bottle of fertilizer

Many water-soluble fertilizer manufacturers try to add many additives to develop new products, but for healthy plants, these additives are unnecessary. Many new hydroponic growers do not understand these new products. After using them, they will cause more harm than good, and may “spoil” the plants. They want to give plants more nutrients, but too much can be fatal.
A single bottle of fertilizer can grow healthy plants without adding other non-essential components, with a success rate of 99%. Most single-bottle fertilizers can be used for both vegetative growth (lettuce or plant seedlings, etc.), but also for reproductive growth (tomato maturity or other flowering crops).

There are also many liquid fertilizers divided into two or three bottles. These multi-bottle fertilizers are different from those with additional chemicals. The reason why they are divided into multiple bottles is because they are easy to combine with each other and cause precipitation when mixed at high concentrations. Calcium and phosphate or calcium and sulfate often precipitate. When these substances are combined, they will produce sediments like sand, which will be deposited at the bottom of the pond and cannot provide nutrients for the plants. Many companies divide fertilizers into two
Bottles are sold: one part is calcium salt; the other part contains phosphorus or sulfur, each of which contains other substances that will not combine with it as a precipitate. The shelf life of a single bottle of fertilizer is usually very short, because the longer the time, the easier it is to produce sediment, which collects at the bottom of the bottle. Therefore, we must shake the bottom of the fertilizer bottle before buying to check if there is fertilizer precipitation.
Another advantage of dividing the fertilizer into two or three bottles is that it can adjust the ratio of nutrients. Fertilizers with different proportions can be used for different growth periods of plants.
Many large commercial hydroponic vegetable garden growers and schools produce fertilizers. If you are very interested in chemistry and want to learn about advanced hydroponic fertilizers, you can start with the research of Hoagland nutrient solution. Hoagland nutrient solution and its derivative formula are made on the basis of the original hydroponic nutrient solution formula of the University of California in the 1930s.

A single bottle of fertilizer is convenient to use, but the price is usually more expensive.
Two bottles and three bottles of fertilizer are also very convenient to use, not only have a long shelf life, but also can adjust the optimal ratio of nutrients.

Fertilizer nutrient determination

There are several methods for determining the concentration of fertilizers in hydroponics. The unit of measurement varies with countries and purposes.

Conductivity

Electrical conductivity (EC) is a measure of the ability of a substance to transmit current. Water conducts electricity, so it is extremely dangerous for us to use electronic equipment when swimming or bathing in a thunderstorm. Surprisingly, pure distilled water without minerals is a very poor body. Pure distilled water is not common, and almost all water sources have some conductivity due to some minerals. In hydroponics, growers increase the mineral content in the water by adding fertilizers, which can increase the conductivity of the nutrient solution. Therefore, we can use EC to reflect the fertilizer concentration of the hydroponic nutrient solution. The commonly used EC unit is mS/cm. Some countries, such as Australia and New Zealand, sometimes use conductivity factor (CF) instead of EC.
(Single bottle of fertilizer is to mix the fertilizer containing the nutrients necessary for plant growth and then put it in a bottle; the double bottle of fertilizer is to mix the nutrient elements necessary for plant growth according to the characteristics of avoiding their mutual combination and reaction. Into two bottles; multiple bottles of fertilizer are more subdivided containing nutrients necessary for plant growth, mixed and placed in multiple bottles. One by one translator’s note)

Parts per million concentration

The concentration in parts per million (ppm) is the concentration expressed in parts per million of the mass of the solute in the mass of the total solution, usually in mg/L. For example, if 1 mg of mass is added to L water, the concentration of the solution is called 1 ppm at this time. ppm is usually related to total dissolved solids (TDS). Because ppm meter/probe manufacturers are different, ppm can be expressed in different ways, so there are several different ppm columns in the conversion table below. For novices who are trying to use the recommended ppm value for hydroponic cultivation, this may be a problem for them because they may not be sure whether their measured ppm is the same as the recommended ppm. To avoid this confusion, the author recommends the use of EC tables. As mentioned earlier, EC can reflect the conductivity of the nutrient solution. When fertilizer is added to the solution, the EC value will increase, but the nutrients in the fertilizer have different effects on the EC value. Some nutrients have little effect on the EC. Some are very large. For example, an EC reading of 1mS/cm may indicate a calcium content of 400ppm, or a phosphorus content of 620ppm. The chemical components in the nutrient solution exist in the nutrient solution in the form of ions, and some ions are good conductors. Almost all ppm testers actually measure the EC value, and then multiply the EC value by the conversion factor recommended by the manufacturer, and the value obtained is the ppm value. This means that the manufacturer must determine the conversion factor in advance based on the nutrient elements contained in the nutrient solution. Therefore, in order to avoid this confusion, the author recommends that EC should be measured first.

Fertilizer storage

Fertilizers should be stored in airtight containers. In dried fertilizer granules, certain components (such as calcium nitrate) can absorb moisture in the air. Once dried fertilizer particles absorb moisture from the air, they will agglomerate. This kind of fertilizer block may be usable, but because the weight and volume are affected by moisture, it will be difficult to weigh accurately.