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Different growth and development stages of wheat have different requirements on the types, quantity and proportion of nutrients. The law is: the amount and intensity of absorption in the early stage of growth are low, and then gradually increase, and then tend to weaken at the mature stage. According to the research of Shandong Agricultural University, before the greening period, the absorption of nitrogen, phosphorus and potassium accounted for 17.04%, 11.11% and 9.75% of the total absorption during the growth period, respectively; from the jointing to the flowering stage, it was nitrogen, phosphorus and potassium. The periods of maximum absorption reached 71.97%, 92.57% and 100%, respectively.
Wheat has a long growth period, high yield, and large amount of fertilizer. It is often difficult to meet the needs of growth and development of nutrients in one application; the fertilizer efficiency can not be played well and the utilization rate is low. It is generally necessary to apply fertilizer several times before and during the sowing period. According to the time sequence of implementation, it is divided into base fertilizer, seed fertilizer and top dressing.
Fertilization of irrigated wheat
Formulation of base fertilizer for watering conditions, to achieve high yield and stable yield of wheat, base fertilizer dosage: generally about 3000 kg per mu of organic fertilizer; pure nitrogen (N) 5 to 7 kg, phosphorus pentoxide (P2O5) 6 to 8 kg Potassium oxide (K2O) 4 to 6 kg. According to the above-mentioned amount of fertilization, the fertilizer used as the base fertilizer for autumn can be selected from the following several fertilization schemes: Option 1: 11-15 kg of urea and 40-50 kg of superphosphate (including P2O516%). Potassium chloride 7-10 kg. Option 2: 30-40 kg of ammonium bicarbonate, 40-50 kg of superphosphate (including P2O516%) and 7-10 kg of potassium chloride. Option 3: 40-50 kg of ternary compound fertilizer (15% for each of N, P2O5 and K2O). Option 4: 13-17 kg of diammonium phosphate (or monoammonium phosphate), 10 kg of urea (or 30 kg of ammonium bicarbonate), and 7-10 kg of potassium chloride.
The principle of the selection scheme is: the lower limit of fertilization in the past, the fertilization amount is higher than the recommended fertilization amount, such as: the use of phosphorus fertilizer in a large amount in many years, the soil available phosphorus (P) is greater than 20 PPM, and the rich in the yellow pan area. Potassium soil, the lower limit of the amount of phosphorus and potassium can be taken, and vice versa; the upper limit of the amount of nitrogen fertilizer that can be taken from all the corn stalks is returned to the field.
For wheat fields lacking trace elements such as zinc and boron or not used for a long time, it can be used as a base fertilizer for 1 - 1.5 kg of zinc sulfate and 0.5 kg of borax. For wheat fields that are deficient in calcium, magnesium, and sulfur, or that do not use calcium phosphate for a long time, a fertilization scheme with superphosphate may be used.
The general application of fertilizers can quickly meet the nutrient requirements of seedlings and is very beneficial for the formation of strong seedlings. When used, the fertilizer and the fertilizer should be applied separately to avoid burning. The main varieties suitable for seed fertilizer are: urea, diammonium phosphate. It is best to mix the two by 1:1 when using. The dosage is generally about 30% of the weight of the seed.
Skillful application of topdressing to the beginning of the period: the growing field, the group is reasonable and prosperous, the group is too large in the wheat field, the returning period to the rising period is generally not topdressing without watering, the topdressing can be delayed until the wheat is up to the jointing stage. When the wheat seedlings are weak and the group is too small, they can be properly topdressed in advance. For the first time in the greening period, the urea is applied for 5-7 kilograms. After the second jointing, depending on the seedlings, the urea is applied for 5-10 kilograms. The wheat fields with medium fertility and small population are generally combined with watering before the jointing stage or at the beginning of the jointing stage (1.5 to 2 cm from the first section of the base). The seedlings will grow 15-20 kg of urea depending on the growth of the seedlings. Wheat fields with high level of soil fertility, excessive growth, and suitable or large populations can be appropriately pushed back to the middle and late stages of jointing (the first section of the base is close to the fixed length) for topdressing and watering. Generally, 10-15 kg of urea should be applied.
Fertilization of dryland wheat is based on the application of more than 2000 kg of organic fertilizer per mu, and nitrogen, phosphorus and potassium fertilizers are used together to obtain high yield. The target yield is in the plot of more than 300 kg per mu. The total amount of chemical fertilizer applied is 10-12 kg of pure nitrogen, 8-10 kg of phosphorus (P2O5) and 5 kg of potassium (K2O). Among the above total fertilization amounts, all organic fertilizers, phosphate fertilizers, potassium fertilizers, and 70%-80% of nitrogen fertilizers are applied as base fertilizers. In the spring of the second year, the soil will be ditched and the remaining 20%-30% of the nitrogen fertilizer will be applied (or the wheat will be reclaimed after raining).
According to the above-mentioned fertilization dosage, the fertilizer used for the autumn fertilizer can be selected from any of the following three fertilization schemes: Option 1: Fertilization of 16-20 kg of urea (or 40-50 kg of ammonium bicarbonate), superphosphate 50-60 kg, 8 kg of potassium chloride. Option 2: 50-70 kg of ternary compound fertilizer (15% for each of N, P2O5 and K2O). Option 3: 18 to 22 kg of diammonium phosphate (or monoammonium phosphate), 8 to 13 kg of urea (or 22-35 kg of ammonium bicarbonate), and 8 kg of potassium chloride.
The principle of the selection scheme is: the dry land with a yield of less than 300 kg per mu. On the basis of more than 2000 kg of high-quality organic fertilizer per mu, the total amount of chemical fertilizer applied should be lower than the above-mentioned fertilization amount, and no potassium fertilizer can be applied. In the past, the amount of fertilization was higher than the recommended limit of fertilization, and the lower limit of fertilization of soil fertilization. On the contrary, the upper limit was selected.
For dryland wheat, the spring should be combined with rainfall and timely topdressing. If there is no rain, the urea can be dissolved in water and then drained. The average use of urea is 5 - 7.5 kg.
The nutrients necessary for the growth and development of wheat include: 16 kinds of elements such as carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, potassium, magnesium, calcium, iron, manganese, zinc, copper, chlorine, boron and molybdenum. Among them, carbon, hydrogen and oxygen are mainly supplied by air and water, and the other 13 nutrients are mainly supplied by soil. According to the content of the crop body, the essential nutrients are generally divided into a large number of nutrients and micronutrients: a large number of nutrients are carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur 9 (also have calcium , magnesium, sulfur is called a medium amount of elements), and their content accounts for tens to thousands of parts of the dry weight of the crop. There are 7 kinds of micronutrients such as iron, boron, manganese, copper, zinc, molybdenum and chlorine, and their content accounts for a few parts per thousand to 100,000 parts of the dry weight of the crop. These elements are equally important in crops regardless of the quantity, and the supply of any nutrient elements is insufficient, and the growth and development of crops will be affected. Usually, the nitrogen, phosphorus and potassium three-element crops require more quantities, while the amount of soil available in the soil is relatively small. It is often necessary to fertilize to meet the requirements of high crop yield. Therefore, it is called “three elements of crop nutrition†or “fertilizer threeâ€. In addition, some of the soil-supplied zinc, boron and individual soil available sulfur, iron and molybdenum in some soils in our province are low. The use of these nutrients on these soils also has a good yield-increasing effect.
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