Development and Application of Controlled Release Fertilizers Covered in Japan

When the supply of nutrients in the soil does not meet the objectives of crop production, it is necessary to artificially apply fertilizers to the soil or to supplement the nutrients missing from the growth of the crop. The main method for supplementing crop nutrients is to apply base fertilizers to soils. This method of fertilization shows that there are many shortcomings: First, the utilization of nutrients is not high. Studies have shown that in China's seasonal fertilizer utilization of nitrogen fertilizer is 30% -35%, phosphorus fertilizer is 10% -25%, potassium fertilizer is 35% -50%, most of the nutrients in the applied soil are leached, volatilized and fixed . The second is that this fertilization method is easy to pollute the environment. Taking nitrogen fertilizer as an example, long-term high-dose application of nitrogen fertilizer to the soil will increase nitrogen content in soil and groundwater, leading to soil acidification and salinization, and nutrient accumulation in rivers and lakes. In addition, a large amount of nitrogen applied under denitrification conditions generates N2O, which volatilizes into the human atmosphere, destroys the ozone layer, and exacerbates the greenhouse effect. Third, crops are vulnerable to pests and diseases. After a large number of available fertilizers are used, the crops grow lushly in a short period of time, the leaves are juicy, the resistance is weakened, the pests and diseases are severe, and the application of pesticides for pest control increases the production costs and pollutes the environment. Fourth, one-time application of quick-acting fertilizers can not meet the needs of growing crops during the whole growth period, and the growth is fast in the early growth period, and the phenomenon of defertilization appears in the later period. The top-dressing increases the labor intensity and cost. For this reason, scientists from various countries are actively developing various kinds of slow-release or controlled-release fertilizers. On the one hand, they can provide stable nutrition to crops. On the other hand, they can reduce the loss of fertilizers and reduce pollution to the environment.
First, the development of coated controlled-release fertilizers Japan developed controlled-release fertilizers successfully in the 1980s. After continuous improvement, the products have now become commercial fertilizers for sale in the international market. The international trade names are Meister and Nutricote. Japan's controlled-release fertilizer is made of polyene resin as the main body, and is coated with different proportions of surfactants and additives on the surface of the fertilizer. This coated fertilizer has a certain permeability to moisture, resists certain pressure, and is beneficial to machine application. The coated controlled-release fertilizers are divided into many types (days when controlled-release fertilizers release water containing 80% of nutrients in 25°C water). There are mainly 30, 40, 50, 70, 100, 140, 180, 360, containing nutrients N, NP, NPK, NCa, NPK trace elements and so on. Different types of fertilizers can be used alone or in combination to meet the needs of different crops.
There are two main types of coated controlled-release fertilizers: one is the Ordinary release group and the other is the Delnyed release group. The regular releasing nutrient release follows the quadratic equation, while the delayed-release nutrient release follows the S-curve controlled-release fertilizer. The nutrient release is mainly controlled by soil temperature, high soil temperature, rapid nutrient release, low temperature, nutrients. Released slowly. The release of nutrients is not affected by soil moisture (in the normal physiological metabolism of crops), soil pH, Eh, and anions and cations. This characteristic of the film-coated controlled-release fertilizer ensures that the release of nutrients can be matched with the growth and development period of crops and can be used as a base fertilizer for one-time investment. This saves labor, improves fertilizer utilization, and can meet the requirements of crops. The need for growth during the growing period.
The successful development of coated controlled-release fertilizers brought about an innovation in fertilization technology. It is well known that soil fertigation can be divided into two parts: seed fertilizer and base fertilizer. Fertilizer dosage is very small, the main reason is that if the amount of seed fertilizer is large, there is a phenomenon of burning seeds and burning seedlings, and the application of coated fertilizer controlled release fertilizer can be a good solution to this issue. The one-time technique used by Japan to fertilize the fertilizer needed for crops throughout their growing period is called contact fertilization (Co-situs application and Contact placement). The contact fertilization technology can avoid seed germination obstacles, increase the utilization of fertilizers, and promote the growth and development of the plant above and below the ground. The 15N labeling study showed that rice sulfate was applied on the surface with a utilization rate of only 9% and the side application rate was 33%, while the surface application rate of the coated controlled release fertilizer LP-100 was 61%, and the lateral utilization rate was 78%. Fertilization at contact was 83%.
Second, the application of film-coated controlled-release fertilizers in agricultural production 1. The technology of full-scale application of rice seedbed fertilizers is to apply all the nutrients required for the whole growth period of rice to the seedbeds, transplant them with seedlings, and apply the seedlings to the roots. The controlled-release fertilizers were packaged and transplanted into the field; studies have shown that when rice seedbeds were applied with delayed-release urea LP-S100 (40% nitrogen), at the ground temperature of 25°C, the initial 30d release was small, only 3%; and the subsequent 70d 80% of the nitrogen released. In this way, the rice seeds will not produce fertilizer damage in the seedbed, nor will they lead to leggy seedlings. After transplanting to Honda, with the increase of cumulative ground temperature, nitrogen release coincides with the growth process of rice, and no fertilization is required during growing period. The amount of nitrogen fertilizer applied by this fertilization method is only 60% of the conventional amount, and the yield is more than 10% higher than the conventional method. The full-amount fertilization technology of rice acres bed has a broad application prospect in rice no-tillage cultivation.
2, the same field fertilization technology of field crop seeds and fertilizers When the crops are sown, the seeds and coated controlled release fertilizers can be applied in the same layer. In the amount of fertilizer and fertilizer, according to the law of fertilizer demand of different crops, combined with the local For meteorological data, the use of different types of fertilizers to meet the needs of both the seedling stage and the later stage crop growth can be met. This technology has good results in the application of corn and sugar beet seedling transplanting and no-tillage cultivation.
3. Application in Topless Cultivation Soilless cultivation has many advantages, but due to the need to regularly adjust the acidity and ion concentration of the cultivation nutrient solution, the operation is complicated and limits its rapid development. The application of film-coated controlled-release fertilizers requires only the mixing of fertilizers containing various nutrients with the cultivation substrate, and regularly supplies the water needed for plant growth. The various nutrients contained in the fertilizers will follow the process of the fertility of the plants. Released to meet the needs of plant growth and development, reduced labor intensity, making soilless cultivation techniques a simple, popular production technology.