What is compound fertilizer, and how should it be applied rationally?
What is compound fertilizer? How should compound fertilizer be applied rationally? Please give an introduction. The first fertilizer invented and produced by humans in the world was mixed fertilizer (a mixed fertilizer containing nitrogen, phosphorus, potassium and various medium and trace elements produced from guano plus sulfuric acid), but it was low concentration. With the development of the chemical fertilizer industry, humans successively invented...
What is compound fertilizer? How should compound fertilizer be applied rationally? Please give an introduction.
The first fertilizer invented and produced by humans in the world was mixed fertilizer (a mixed fertilizer containing nitrogen, phosphorus, potassium and various medium and trace elements produced from guano plus sulfuric acid), but it was low concentration. With the development of the chemical fertilizer industry, humans successively invented high-concentration single-element chemical fertilizers. Because of people's understanding of balanced fertilization, the continuous improvement of rational fertilization techniques, and especially the development of soil-testing recommended fertilization, people again combined various single-element fertilizers for use, which in turn promoted the development of fertilizer compounding and mixing processes. China developed mixed fertilizer and the mixed fertilizer industry suited to China on the basis of fully drawing on these advanced foreign experiences.
The advantage of mixed fertilizer lies in the fact that it is the product of combining the principles and techniques of balanced fertilization with fertilizer products, or it can be called the product of materializing scientific and technological achievements. At present, it still has strong vitality, will continue to develop and continuously improve, and will still develop with the progress and development of scientific balanced fertilization techniques as well as the progress of process technology. Even in today's era of high-tech development, newer high-tech achievements will continue to be incorporated into mixed fertilizer.
(1) Fertilizer efficiency of mixed fertilizer
From the comparison between the fertilizer efficiency of mixed fertilizer and conventional fertilization, the fertilizer efficiency of mixed fertilizer with a reasonable formula is always higher than that of conventional fertilization: the principle is that the effect of balanced fertilization (soil-testing recommended fertilization, or formula fertilization) is always better than that of conventional (habitual) fertilization. Mixed fertilizer with scientific and technological content, whether it is a general-purpose fertilizer suitable for various crops in certain regions or a special-purpose fertilizer for various crops in certain regions, is produced precisely according to the principles of balanced fertilization, and its field effect is better than local habitual fertilization. At present, developing blended fertilizers with even higher scientific and technological content in China to fully meet the nutrient needs of different soils and different crops is a common task for agricultural research and industrial production departments.
(2) Rational application of mixed fertilizer
The yield-increasing effect of mixed fertilizer is related to soil fertility, crop type, fertilizer nutrient form, amount and ratio, and application techniques.
1. Apply according to soil
At present, the area of potassium-deficient soil in southern China is continuously expanding, while the degree of phosphorus deficiency has eased somewhat, so mixed fertilizer based mainly on nitrogen and potassium (N, K) is suitable for application. In most areas of the north, phosphate fertilizer has a significant effect, while potassium fertilizer temporarily shows no effect, so mixed fertilizer based mainly on nitrogen and phosphorus (N, P) is suitable for application. However, for cash crops and high-yield areas, the application of nitrogen-phosphorus-potassium (N, P, K) three-element mixed fertilizer should be advocated, and the yield-increasing effect is more significant. In 8 rice trials by the Soil and Fertilizer Institute of the Guangdong Academy of Agricultural Sciences, where soil available phosphorus (P) and available potassium (K) averaged 10.9 mg/kg and 30 mg/kg respectively, that is, under conditions of rich phosphorus and deficient potassium, 20.8 kg of nitrogen-phosphorus-potassium (NPK) mixed fertilizer was applied per mu. The ratio of nitrogen (N), phosphorus (P), and potassium (K) was 1 to 0.6 to 0.48, and the average yield per mu was 374.5 kg; when 16 kg of nitrogen-phosphorus (N, P) mixed fertilizer was applied per mu, the ratio of nitrogen (N) to phosphorus (P2O5) was 1 to 0.6, and the average yield per mu was 330.1 kg; when 14.8 kg of nitrogen-potassium (N, K) mixed fertilizer was applied per mu, the ratio of nitrogen (N) to potassium (K2O) was 1 to 0.48, and the average yield per mu was 358 kg. From this it can be seen that on this type of soil there is little difference in yield between applying nitrogen-potassium and nitrogen-phosphorus-potassium mixed fertilizers, and the yield-increasing effect of phosphate fertilizer is very small.
Many years of trials by the Tea Research Institute of the Chinese Academy of Agricultural Sciences show that for tea gardens where soil hydrolytic nitrogen is 100-150 mg/kg, available phosphorus is 15-20 mg/kg, and available potassium is 50-80 mg/kg, a 2 to 1 to 1 type mixed fertilizer generally has a better yield-increasing effect. If soil available phosphorus is below 10 mg/kg and available potassium is less than 50 mg/kg, the yield-increasing effect of applying high-phosphorus and high-potassium mixed fertilizer is even better.
The application of mixed fertilizer should also be flexibly controlled according to local soil nutrients as well as actual conditions such as climate change. Some crops and plots also require the addition of certain trace elements to the mixed fertilizer.
2. Apply according to crop
Select suitable mixed fertilizer varieties according to crop type and different nutritional characteristics. For example, applying chlorine-free three-element mixed fertilizer to tobacco can increase tobacco leaf thickness and improve the combustibility and aroma of tobacco leaves; applying three-element mixed fertilizer to crops such as fruit trees and watermelon can reduce fruit acidity and increase sweetness; applying three-element mixed fertilizer to sugarcane, sugar beet, and others can increase their sugar content; cereal crops are mainly determined according to the abundance or deficiency of soil nutrients. Special-purpose mixed fertilizer, because it requires additional processing costs, is mostly used on cash crops, where the benefit will be higher. According to trial results from various places, the suitable nutrient ratios for applying mixed fertilizer to several cash crops are approximately as follows. For cotton, choose about a 1:0.5:1 or 1:0.5:0.5 type mixed fertilizer; for hemp, 1:0.35:0.8; for sugarcane, 1:0.23:1.1; for sugar beet, 1:0.7:0.8; for peanut and soybean, 1:2:1; for watermelon, 1:0.4:0.8; for apple, 1:1:0.5 during the seedling stage and young tree stage, and 1:0.4:0.8 for a single annual application on fruiting trees; in tea gardens, generally 1:0.5-1:0.5-1; as far as tea types are concerned, black tea-producing areas should apply more phosphate fertilizer, and green tea-producing areas should apply more nitrogen fertilizer.
3. Apply according to nutrient form
The properties of mixed fertilizer are mainly determined by its nutrient form. Fertilizer containing nitrate nitrogen should be used little or not at all on paddy fields; fertilizer containing citrate-soluble phosphorus is more suitable for application on acidic soil, and fertilizer containing high chloride ions is not suitable for application on chlorine-sensitive crops such as tobacco and potato. The water-soluble phosphorus compound fertilizers in Table 2-7 refer to the average yields of varieties such as the urea-ammonium phosphate series, urea-heavy calcium series, and urea-single superphosphate series. The fertilizer efficiency of these mixed fertilizer varieties is relatively stable, and they are suitable for various crops in both southern and northern China, in both paddy and dry fields. Compared with nitric phosphate series mixed fertilizer, there is a certain difference in the current-season fertilizer efficiency on soils with different available phosphorus contents; the lower the available phosphorus content of the tested soil, the better the fertilizer efficiency of water-soluble phosphate fertilizer. Some trials reached the "significant" or "extremely significant" level after significance testing. Therefore, soils severely deficient in phosphorus should be treated with water-soluble phosphorus mixed fertilizer.
Half of the nitrogen contained in nitric phosphate series and nitro-phosphorus-potassium fertilizer series is nitrate nitrogen, which is easily leached away on rainy southern slopes and paddy fields, causing fertilizer efficiency to decline. Therefore, this type of mixed fertilizer is suitable for application on dryland soil, and is especially suitable for northern dryland crops.
4. Mainly apply as base fertilizer
Mixed fertilizer contains phosphorus or phosphorus and potassium nutrients, and at the same time the fertilizer is mostly granular and decomposes more slowly than single-element chemical fertilizers. Therefore, it is better used as base fertilizer or seed fertilizer. The Soil and Fertilizer Institute of the Chinese Academy of Agricultural Sciences conducted trials in North China. Under the condition of adding single-element nitrogen fertilizer as topdressing at the early or middle stage of crop growth, both binary and three-element mixed fertilizers were better applied as base fertilizer, and using half as base fertilizer and half as topdressing significantly reduced yield. The yield reduction range was above 6%. According to wheat trials by the Soil and Fertilizer Institute of the Shaanxi Academy of Agricultural Sciences, even if no single-element nitrogen fertilizer was added as topdressing during crop growth, the effect of a single basal application of mixed fertilizer was better than the practice of half base fertilizer and half topdressing.
Is it better to apply mixed fertilizer deeply throughout the entire plow layer, or as a seed fertilizer in bands? Most trial results suggest that on high-fertility soil, there is little difference between the two, while on medium- and low-yield fields, band application as seed fertilizer is better, increasing wheat yield by 6.3% and corn yield by 6.5% compared with deep application throughout the entire plow layer. When applying as seed fertilizer in bands, the seeds and fertilizer must be separated, otherwise the emergence rate will be seriously affected and yield will decrease. When the amount of mixed fertilizer used is relatively large, base application should be dominant; when the amount used is relatively small, it can be concentrated as seed fertilizer, and an appropriate amount of single-element nitrogen fertilizer can be applied as topdressing according to seedling conditions during the growth stage. In the case of base fertilizer or insufficient base fertilizer, early topdressing with an appropriate amount of mixed fertilizer also has a very good yield-increasing effect. For perennial crops, applying mixed fertilizer with a suitable nutrient ratio throughout the entire growth period also has a very good yield-increasing effect.
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