What are the main characteristics of iron fertilizer and boron fertilizer? What issues should be noted during use?
With the rise and development of the modern chemical industry, various chemical fertilizers have appeared one after another. Fertilizers are crucial for increasing crop yields, and a deficiency will affect the normal growth and development of crops.So what are the main characteristics of iron fertilizer and boron fertilizer? What issues should be noted during use?
I. Iron fertilizer:
Iron is a trace element required in relatively large amounts during crop growth. The iron content in plants is generally 0.3% of dry weight. It is an essential element for plant photosynthesis. When plants lack iron, chlorophyll cannot be synthesized, and chlorosis occurs. In plant aerobic respiration, the indispensable cytochrome oxidase, catalase, and peroxidase are all iron-containing acids, so iron also participates in crop respiration. In recent years, research has found that both components making up nitrogenase contain iron, which indicates that iron also plays an important role in biological nitrogen fixation.
Iron is one of the least mobile elements in crops. If crops lack iron, the young leaves first lose their green color. At the beginning of chlorosis, the mesophyll turns yellow while the veins remain green; afterward the leaves turn white, the veins turn yellow, and necrotic tissues such as scorched brown spots appear on both sides of the middle of the leaf or at the leaf tip, until finally the leaves fall off, while the old leaves remain normal. Iron fertilizer is suitable for various crops. For example, soybeans, spinach, tomatoes, apples, camellias, and peach trees all require relatively more iron fertilizer, and they are crops that are relatively sensitive to iron fertilizer.
The main materials used as iron fertilizer include: ferrous sulfate (FeSO4·7H2O), which is a green crystalline substance, commonly known as green vitriol, containing about 19% iron; and ferrous ammonium sulfate [(NH4)2SO4·FeSO4·6H2O], with an iron content of about 14%.
The use methods of iron fertilizer are mainly as a base fertilizer or as a foliar topdressing. When iron fertilizer is used as a base fertilizer, ferrous sulfate solution can be sprayed onto organic fertilizer, mixed evenly, and then applied to the soil. For fruit trees, a ditch can be dug around them for ring application or strip application. When iron fertilizer is used for foliar topdressing of crops, a 0.75%-1% ferrous sulfate solution can be sprayed on the crops; root injection can also be used for fruit trees, preferably when fruit trees sprout in spring.
Because ferrous sulfate is rapidly converted into insoluble compounds and fixed in calcareous soil, it usually needs to be mixed with organic fertilizer before application.
II. Boron fertilizer:
Boron is not a structural component within crops, but it has a special influence on certain important physiological processes of crops. It plays an important role in the transport of carbohydrates within crops, and it is also an indispensable component in the formation of crop reproductive organs. In addition, it has an important influence on crop photosynthesis and on improving crop resistance.
The common characteristics of boron deficiency in crops are: an underdeveloped root system, death of the growing point, and incomplete flower development. Rapeseed shows “flowers but no seeds”, and some also show “buds but no flowers”. Boron fertilizer is suitable for various crops and all types of soil, especially on soils with relatively low boron content, where the effect of applying boron fertilizer is even better.
At present, the main varieties used as boron fertilizer are: boric acid (H2BO3), containing 17% boron; borax (Na2B2O7·10H2O), containing 11% boron; in addition, there are boron-containing compound fertilizers and boron-containing industrial waste residues. However, the more widely used are borax and boric acid. Both are white crystals or powders, soluble in water, and are water-soluble boron fertilizers.
Boron fertilizer can be used as a base fertilizer, seed fertilizer, and topdressing. When used as a base fertilizer, it can be mixed evenly with nitrogen fertilizer and phosphate fertilizer and applied together, or applied separately, but care must be taken to apply it evenly to avoid toxicity caused by excessively high local concentration. On boron-deficient soil, 0.5-1 kg of boron fertilizer can be applied per mu, and the fertilizer effect usually lasts 3-5 years. When used as a seed fertilizer, a 0.01%-0.1% concentration aqueous solution of borax or boric acid can be used to soak seeds for 6-12 hours. For grains and vegetables, a 0.01%-0.03% solution can be used, and for rice, a 0.1% solution can be used. When treating seeds, use 0.4-1 gram of borax or boric acid per kilogram of seeds. When used as a foliar topdressing, a 0.1%-0.2% concentration borax or boric acid solution can be sprayed, generally when crops shift from the vegetative growth stage to the reproductive growth stage, that is, preferably around flowering.
When applying boron fertilizer, note that the application amount must not be excessive, and the application must be uniform. The type of crop must also be considered, and application should be classified according to differences in crop boron preference.