Nutrient absorption
The growth and development of rice requires 17 nutrient elements such as carbon, hydrogen, oxygen, silicon, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, zinc, boron, copper, molybdenum, and chlorine. There are great differences in supply and demand. The nutrient elements are nitrogen, phosphorus, and potassium.
The amount of nutrients absorbed by rice during its lifetime is mainly calculated based on the content of the harvested material. Generally, for every 500kg of rice and rice straw produced, nitrogen (N) 7~16kg, phosphorus pentoxide (P2O5) 4~8kg, potassium oxide (K2O) 10~25kg, N: P2O5: K2O=1:0.5:0.5 should be absorbed. . It should be noted that these figures do not include the amount of extravasation in the roots and the leaching of nutrients in the mature body. Therefore, the total absorption of rice should be higher than this value. The nitrogen, phosphorus and potassium nutrients absorbed at the same yield level differ greatly, which is related to factors such as region, yield, rice varieties, and cultivation level.
2. Absorption of nutrients at different growth stages in rice
The absorption of nutrients at different growth stages of rice is quite different due to different types. The double-season rice has a short growing period, especially the shortening of the vegetative growth period in the field. The vegetative and reproductive growth overlaps shortly after transplanting. In other words, ear differentiation begins at the time of childbirth in Daejeon, and it enters into a flooding stage during the process of ear differentiation. Therefore, a prominent uptake peak is formed 2 to 3 weeks after transplantation; single-season rice is transplanted 2 to 3 weeks and 7 days after transplanting. Two uptake peaks are formed in ~9 weeks.
The rate of absorption of various nutrients by rice reached its maximum value before heading and then decreased afterwards. In all kinds of nutrients, the absorption rates of nitrogen, phosphorus and potassium were the fastest, reaching a maximum about 20 days before heading; the absorption of silicon reached a maximum value later.
The absorption of nitrogen, phosphorus and potassium was earlier by nitrogen and reached 80% of the total absorption before ear differentiation. Potassium fertilizers were the most absorbed from ear to ear to flowering stage, accounting for about 60% of the total amount, and they stopped absorbing after flowering. Phosphorus absorption is slightly later than nitrogen and potassium.
In short, various types of rice have absorbed most of the total amount of nutrients before heading, so early supply of various fertilizers should be emphasized.
3. Fertilization of rice
Fertilization laws of rice are compatible with its three growth centers throughout the growing season. In the tillering stage, the center of growth of plants is a large amount of roots, leaves, and tillers, which require more nitrogen to form nitrides. The physiological characteristics of nutrition during this period were mainly nitrogen metabolism, less accumulation of carbohydrates, and the demand for nitrogen was greater than the absorption of phosphorus and potassium.
From the ear to the heading stage, stem elongation and ear formation are the center of growth and development. The nutrient characteristics of this stage are the strong metabolism of carbon and nitrogen in the early stage, and the carbon metabolism in the later stage is gradually dominant, then the more nitrogen fertilizer is absorbed. Long leaf, long stem and young panicle differentiation, but also to accumulate a lot of carbohydrates for the panicle after the ear, so the absorption of nitrogen, phosphorus and potassium are more.
After heading, the growth of stems and leaves and roots basically stopped, and the plant growth center turned to the formation of grains. Its nutrient characteristics are mainly carbon metabolism, and it accumulates a large amount of carbohydrates, which are transported and stored in the grains. Therefore, the absorption of phosphorus and potassium is reduced. More.
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