Nitrogen fertilizer application method for coordinating high-yield rice planting and healthy procypris merus breeding in rice-fish symbiotic system

Abstract

The invention discloses a nitrogen fertilizer application method for coordinating high-yield rice planting and healthy procypris merus breeding in a rice-fish symbiotic system, and the method is characterized in that the nitrogen fertilizer required by the whole growth cycle of rice is divided into a base fertilizer and a panicle fertilizer which are applied twice in two specific periods, and the mass ratio of the application amount of the base fertilizer to the application amount of the panicle fertilizer is 7: 3. Through reasonable fertilization control, the nitrogen fertilizer absorption and utilization rate is effectively improved, and the yield of rice in the rice-fish symbiotic system is stabilized. In addition, the nitrogen fertilizer application method can reduce the toxic effect of ammonia nitrogen in the rice field water body on procypris merus, the high and stable yield of rice is guaranteed, meanwhile, the stocking density of the procypris merus in the rice field can be increased, and the yield and economic benefits of the procypris merus are increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of nitrogen fertilizer application in the rice-fish symbiotic system. More specifically, it relates to a method for applying nitrogen fertilizer to coordinate high-yield rice cultivation and healthy farming of rice-field eels in the rice-fish symbiotic system. Background Art

[0002] Rice-field fish farming has a long history in China and is an ecological agriculture model that realizes the symbiosis of "multiple uses of one water", namely "rice cultivation" and "fish farming", which is conducive to improving the economic benefits of rice cultivation and stabilizing the rice planting area in China. Common varieties of fish for rice-field fish farming include carp, grass carp, tilapia, crucian carp, silver carp, etc. Among them, compared with other varieties of fish, the rice-field eel in carp, also known as rice-field fish, has delicate meat, few spines, more meat, soft bones without fishy smell, delicious taste, high protein content, fresh and sweet fish meat, and has the fragrance of rice flowers. Whether steamed, fried, braised or stewed, the rice-field eel is delicious. It was once famous as a "tribute to the imperial court" during the Qing Dynasty and is well-known at home and abroad. However, compared with other fish species, the rice-field eel is more sensitive to the paddy field water environment, and the yield of the rice-field eel in rice-field fish farming is relatively low. There are many and complex factors affecting the survival and growth of the rice-field eel.

[0003] At present, the main way to solve the yield of the rice-field eel is to apply feed to improve the survival rate and yield of the rice-field eel. However, this method will instead have an adverse impact on rice. The feed will cause eutrophication of the water body, affect the absorption and utilization of fertilizer nutrients by rice, and lead to a reduction in rice yield. Therefore, it is of great significance to seek a technology that takes into account the double yields of rice and the rice-field eel.

[0004] Chinese Patent (Patent No. CN108718639A) discloses "A method for applying fertilizer and its application in the rice-shrimp symbiotic system in paddy fields". This method is to centrally apply all the nutrients required during the whole growth period of rice in the root zone of rice in the rice-shrimp symbiotic system to reduce the impact of fertilization on the growth of shrimps in paddy fields. However, this method does not consider that the demand for fertilizer in the later growth stage of rice is also very large, and the shrimps cultured in this method in paddy fields are crayfish. Chinese Patent (Patent No. CN113455157A) discloses a "fertilizer application device and method for comprehensive cultivation of rice and crayfish". This method is to invent a fertilizer application device in the rice-crayfish comprehensive cultivation system so that the fertilizer will not be scattered into the cultivation pond and is relatively fertilizer-saving, but it does not specifically describe the fertilizer application rate and application method.

[0005] The above - disclosed methods are all for cultivating crayfish in paddy fields. However, the tolerance of crayfish to water conditions is very different from that of rice - flower carp, and the above - mentioned methods cannot fully meet the requirements of high - yield rice and the healthy growth of rice - flower carp. Therefore, exploring the technology for coordinating high - yield rice cultivation and healthy breeding of rice - flower carp in the rice - fish symbiotic system, reducing the amount of fertilizer while ensuring high - yield rice and high nitrogen - use efficiency, and guaranteeing the healthy growth of rice - flower carp is of great significance for stabilizing and increasing the comprehensive benefits of paddy fields. Summary of the Invention

[0006] The present invention aims to overcome the defects and deficiencies of the prior art and provides a nitrogen - fertilizer application method for coordinating high - yield rice cultivation and healthy breeding of rice - flower carp in the rice - fish symbiotic system, that is, applying nitrogen fertilizer in two specific periods according to a specific ratio of 7:3 at the basal - fertilizer stage and the panicle - fertilizer stage, achieving no reduction in rice yield and normal survival and growth of rice - flower carp, and stabilizing food safety production and paddy - field economic benefits.

[0007] The first object of the present invention is to provide a nitrogen - fertilizer application method for coordinating high - yield rice cultivation and healthy breeding of rice - flower carp in the rice - fish symbiotic system.

[0008] The second object of the present invention is to provide the application of the above - mentioned method.

[0009] The above objects of the present invention are achieved by the following technical solutions:

[0010] The present invention has conducted a large number of research and explorations on cultivating rice - flower carp in paddy fields, and proposed a scheme of dividing the total amount of nitrogen fertilizer required for the entire growth period of rice into two applications of basal fertilizer and panicle fertilizer according to a specific ratio of 7:3. On the one hand, considering that the demand for nitrogen is large in the middle and late stages of rice growth (panicle - differentiation stage - maturity stage), and the reasonable post - ponement of nitrogen fertilizer can increase the demand for nitrogen in the middle and late stages of rice growth, promoting high - yield rice and improving nitrogen - use efficiency. On the other hand, considering that rice - flower carp is extremely sensitive to ammonia nitrogen in water, and the ammonia nitrogen in water will rapidly increase after applying nitrogen (urea) in paddy fields, which will directly affect the growth of fish. Therefore, a nitrogen - fertilizer application method for coordinating high - yield rice cultivation and healthy breeding of rice - flower carp in the rice - fish symbiotic system provided by the present invention can not only meet the growth requirements of rice but also reduce the impact of water - body ammonia nitrogen on rice - flower carp.

[0011] The present invention provides a nitrogen - fertilizer application method for coordinating high - yield rice cultivation and healthy breeding of rice - flower carp in the rice - fish symbiotic system. The method is to divide the total amount of nitrogen fertilizer required for the entire growth period of rice into two applications of basal fertilizer and panicle fertilizer, and the mass ratio of the application amounts of the basal fertilizer and the panicle fertilizer is 7:3.

[0012] As an alternative implementation, the nitrogen fertilizer is urea or controlled - release urea, and the nitrogen content is 35 - 55%.

[0013] As an alternative embodiment, the nitrogen fertilizer includes urea or controlled-release urea, with a nitrogen content of 46%.

[0014] Specifically, the total amount of the nitrogen fertilizer is determined according to the local standard of Guangdong Province, "Technical Regulations for the Three-Control Fertilization Technology of Rice" (DB44 / T 969-2011).

[0015] As an alternative embodiment, the applicable area is Guangdong Province, and the total amount of the nitrogen fertilizer: the total amounts of nitrogen fertilizer for early rice and late rice are 150 kg / ha and 180 kg / ha respectively.

[0016] As an alternative embodiment, the application method of the base fertilizer is: when preparing the land before transplanting rice seedlings, apply 70% of the total amount of nitrogen fertilizer, and make the fertilizer fully mixed with the soil evenly.

[0017] As an alternative embodiment, the application method of the panicle fertilizer is: at the initial stage of rice panicle differentiation, that is, at the stage of the first branch primordium differentiation of the rice young panicle, evenly spread 30% of the total amount of nitrogen fertilizer in the paddy field.

[0018] Specifically, the stage of the first branch primordium differentiation of the rice young panicle is: for early-season rice, it is 35 days after transplanting; for late-season rice, it is 30 days after transplanting.

[0019] As an alternative embodiment, keep the water layer in the paddy field at 10-20 cm before applying the panicle fertilizer, and do not drain or irrigate the paddy field after applying the panicle fertilizer.

[0020] The present invention provides the application of the above method in the symbiotic system of rice planting and rice flower carp.

[0021] The present invention also provides the application of the above method in improving the rice yield and the rice flower carp yield in the symbiotic system of rice planting and rice flower carp.

[0022] The present invention has the following beneficial effects:

[0023] The present invention provides a nitrogen fertilizer application method for coordinating high-yield rice planting and healthy breeding of rice flower carp in the rice-fish symbiotic system. Through reasonable fertilization and water management, the nitrogen fertilizer absorption and utilization rate is effectively improved, and the rice yield in the rice-fish symbiotic system is stabilized, providing scientific and technological support for the stable food production in the rice-fish symbiotic system. In addition, the nitrogen fertilizer application method of the present invention can reduce the toxic effect of ammonia nitrogen in the paddy field water on the rice flower carp. While ensuring high and stable rice yield, it can increase the stocking density of rice flower carp in the paddy field, improve the rice flower carp yield and economic benefits, and provide guarantee for the healthy growth and yield increase of the rice flower carp. Description of the Drawings

[0024] Figure 1Effects of different nitrogen application methods on the paddy field water environment in the early season (A / B / C / D) and late season (E / F / G / H) of 2021; the data are from Dafeng Experimental Base, Guangdong Academy of Agricultural Sciences, Guangzhou in 2021.

[0025] Figure 2 Effects of different nitrogen application methods on the paddy field water environment in the early season (A / B / C / D) and late season (E / F / G / H) of 2022; the data are from Dafeng Experimental Base, Guangdong Academy of Agricultural Sciences, Guangzhou in 2022.

[0026] Figure 3 Effects of different nitrogen application methods on the yields of rice and rice field eels; the data are from Dafeng Experimental Base, Guangdong Academy of Agricultural Sciences, Guangzhou in 2021 and 2022. Specific implementation manners

[0027] The present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field.

[0028] Unless otherwise specified, the reagents and materials used in the following embodiments are all commercially available.

[0029] The following embodiments adopt the method of field experiments, which were carried out at Dafeng Experimental Base, Guangdong Academy of Agricultural Sciences, Tianhe District, Guangzhou, Guangdong Province in 2021 and 2022. The experimental sites in Guangzhou (113°E, 23°N) belong to the marine subtropical monsoon climate, with annual rainfall of 1503 mm and 2071 mm respectively, and the average annual temperature of 16.3 - 33.8 °C and 15.7 - 32.3 °C throughout the year. The physical and chemical properties of the soil before the field experiment were as follows: pH value 5.68, total organic matter 24.71 g / kg, total nitrogen 1.42 g / kg, total phosphorus 0.10 g / kg, total potassium 12.09 g / kg, available nitrogen 80.27 mg / kg, available phosphorus 17.65 mg / kg, and available potassium 78.01 mg / kg.

[0030] The rice variety used in the field experiment was Huanghuazhan, and the breeding unit was the Rice Research Institute of Guangdong Academy of Agricultural Sciences. This variety has a moderate plant type, good stem toughness, strong lodging resistance, narrow leaves, straight leaf posture, strong tillering ability, many effective panicles, high seed setting rate, and a wide application area. The tested variety of rice field carp was Ruyuan Shili No. 1, and the breeding unit was the Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences. This variety has a short and round body shape, a short caudal peduncle, weak jumping and escaping ability, fast growth, high survival rate, soft fish bones, and smooth meat, and is suitable for breeding in paddy fields. It is the first new variety approved for paddy field breeding in China at present. In the early season of 2021, sowing was carried out on March 5, transplanting on April 2, and harvesting on July 8; in the late season, sowing was carried out on July 19, transplanting on August 9, and harvesting on November 20. In the early season of 2022, sowing was carried out on March 6, transplanting on April 5, and harvesting on July 11; in the late season, sowing was carried out on July 21, transplanting on August 8, and harvesting on November 13. In the two-year field experiment, fry were released 10 - 15 days after transplanting of early and late season rice. The stocking density of fry was 18,000 tails / ha, and the size of the released fry was about 10 g. The row spacing of rice planting was 20 cm × 20 cm.

[0031] In the following examples, except for the different methods of nitrogen fertilizer application, the field management measures (irrigation and drainage, pesticide spraying, weeding, etc.) of all experimental plots were the same, that is, all experimental fields uniformly used 375 kg / ha of superphosphate (containing 12% P2O5) and 225 kg / ha of potassium chloride (containing 60% K2O) as the base fertilizer and applied them into the soil at one time before rice transplanting and thoroughly mixed them. Before releasing fry, a shallow water layer was maintained in the field, and the water layer in the field was maintained at 10 cm - 20 cm from the time of releasing fry until the harvest of rice field carp. In each quarter of the experiment, in addition to the examples and the control group, a nitrogen-free experiment was set up to calculate the nitrogen fertilizer absorption utilization rate. On the day before and for seven days after topdressing, the water pH was measured continuously using the PHC10103 electrode of the American Hach HQ4300 multi-parameter water quality analyzer (Hach Company, CO, USA), and the dissolved oxygen concentration in the water was measured using the LDO10103 electrode. At the same time, water samples were taken using a syringe by the 5-point sampling method and brought back to the laboratory, and then the ammonium nitrogen (NH4 + -N) concentration and nitrate nitrogen (NO3 - -N) concentration were measured by a flow analyzer (AA3, Bran + Luebbe, Germany); the nitrogen uptake of rice plants was measured at the mature stage of rice to calculate the nitrogen fertilizer absorption utilization rate; the rice yield and the rice field carp yield were measured at the rice harvest stage.

[0032] Example 1

[0033] A method for applying nitrogen fertilizer to coordinate high-yield rice cultivation and healthy breeding of rice field carp, comprising the following steps:

[0034] a. According to the local standard of Guangdong Province, "Technical Regulations for the Three-Control Fertilization of Rice" (DB44 / T 969-2011), taking the amount of pure nitrogen as the basis, the total nitrogen fertilizer application rates for early rice and late rice are determined to be 150 kg / ha and 180 kg / ha respectively;

[0035] b. The nitrogen fertilizer in step a is specifically divided into two applications: basal fertilizer and panicle fertilizer, and the application rate ratio is 70%:30%. That is, the application rate of nitrogen fertilizer as basal fertilizer is 105 kg / ha (early rice) or 126 kg / ha (late rice), and the application rate of nitrogen fertilizer as panicle fertilizer is 45 kg / ha (early rice) or 54 kg / ha (late rice).

[0036] The basal fertilizer is applied during land preparation before transplanting rice seedlings, so that the fertilizer is fully mixed with the soil evenly, and shallow water is maintained for transplanting rice seedlings. The panicle fertilizer is evenly broadcast into the paddy field at the initial stage of rice panicle differentiation, that is, at the stage of the first branch primordium differentiation of the rice young panicle. In the early season, it is about 35 days after transplanting, and in the late season, it is about 30 days after transplanting.

[0037] The nitrogen fertilizer used in this example is urea, and the nitrogen content is 46%.

[0038] On the day before and for 7 consecutive days after topdressing the panicle fertilizer for early rice and late rice respectively, the pH value and dissolved oxygen concentration of the paddy field surface water are monitored on-site, and 5-point mixed sampling is taken to measure the concentrations of NH4 + -N and NO3 - -N concentrations.

[0039] At the maturity stage of early rice and late rice respectively, 5 m of actual cutting is carried out in the middle of each plot 2 to measure the rice yield. And according to the formula: nitrogen fertilizer absorption utilization rate (%) = (nitrogen accumulation in plants in the nitrogen application area - nitrogen accumulation in the above-ground part of plants in the blank control area) / total nitrogen application amount × 100%.

[0040] At the harvest stage of early rice and late rice respectively, all the rice field carp in each plot are fished and counted for production.

[0041] Comparative Example 1

[0042] A method of applying nitrogen fertilizer according to farmers' habits in the rice-fish symbiotic system, the steps are as follows:

[0043] a. According to the method of applying nitrogen fertilizer according to farmers' habits in the rice-fish symbiotic system, mainly all (100%) of it is applied as a one-time basal application, and no nitrogen fertilizer is topdressed in the middle and late stages of rice growth.

[0044] b. The nitrogen application rate in step a is determined according to the local standard of Guangdong Province, "Technical Regulations for the Three-Control Fertilization Technology of Rice" (DB44 / T 969-2011) for comparison with Example 1. The application rate for early rice is 150 kg / ha, and the application rate for late rice is 180 kg / ha. Both are evenly broadcast at 100% once before rice transplanting after plowing the paddy field, so that the fertilizer is fully mixed with the soil, and shallow water is maintained for transplanting.

[0045] The nitrogen fertilizer used in this comparative example is urea, with a nitrogen content of 46%.

[0046] On the day before and for 7 consecutive days after topdressing the panicle fertilizer for early and late rice respectively, the pH value and dissolved oxygen concentration of the paddy field surface water are monitored on-site, and 5-point mixed sampling is used to measure the water body NH4 + -N and NO3 - -N concentration.

[0047] At the maturity stage of early and late rice respectively, 5 m is actually cut in the middle of each plot 2 to measure the rice yield. And according to the formula: Nitrogen fertilizer utilization efficiency (%) = (Nitrogen accumulation in plants in the nitrogen application area - Nitrogen accumulation in the above-ground parts of plants in the blank control area) / Total nitrogen application amount × 100%.

[0048] At the harvest stage of early and late rice respectively, all the rice flower carps in each plot are fished and the yield is counted.

[0049] Comparative Example 2

[0050] A method for simply applying nitrogen fertilizer to rice is as follows:

[0051] a. The total nitrogen application amount of a method for simply applying nitrogen fertilizer to rice is determined according to the local standard of Guangdong Province, "Technical Regulations for the Three-Control Fertilization Technology of Rice" (DB44 / T 969-2011) for comparison with Example 1. The application rate for early rice is 150 kg / ha, and the application rate for late rice is 180 kg / ha.

[0052] b. The nitrogen fertilizer in step a is specifically divided into two applications as basal fertilizer and panicle fertilizer, and the proportion of the application amount is 40%:60%, that is, the application amount of nitrogen fertilizer as basal fertilizer is 60 kg / ha (early rice) or 72 kg / ha (late rice), and the application amount of nitrogen fertilizer as panicle fertilizer is 90 kg / ha (early rice) or 108 kg / ha (late rice).

[0053] The basal fertilizer is applied during land preparation before transplanting, so that the fertilizer is fully mixed with the soil, and shallow water is maintained for transplanting. The panicle fertilizer is evenly broadcast into the paddy field at the initial stage of rice panicle differentiation, that is, at the first branch primordium differentiation stage of the rice young panicle, about 35 days after transplanting in the early season and about 30 days after transplanting in the late season.

[0054] The nitrogen fertilizer used in this comparative example is urea, with a nitrogen content of 46%.

[0055] On the day before and for 7 consecutive days after topdressing panicle fertilizer for early and late rice respectively, the pH value and dissolved oxygen concentration of the paddy field surface water were monitored in the field, and water samples were mixed and taken at 5 points to measure the NH4 + -N and NO3 - -N concentrations.

[0056] At the maturity stage of early and late rice respectively, 5 m was actually cut in the middle of each plot 2 to measure the rice yield. And according to the formula: nitrogen fertilizer absorption utilization rate (%) = (nitrogen accumulation in plants in the nitrogen application area - nitrogen accumulation in the above-ground parts of plants in the blank control area) / total nitrogen application amount × 100%.

[0057] At the harvest stage of early and late rice respectively, all the rice flower carps in each plot were fished and counted.

[0058] Experimental Example 1 Effects of different nitrogen application methods on the paddy field water environment

[0059] According to the methods of Example 1, Comparative Example 1, and Comparative Example 2 above, experiments were carried out in the same period and the same area in 2021 and 2022 respectively.

[0060] The effects of different nitrogen application methods on the paddy field water environment in the early and late seasons of 2021 are as Figure 1 shown, and the effects of different nitrogen application methods on the paddy field water environment in the early and late seasons of 2022 are as Figure 2 shown.

[0061] The results showed that according to the nitrogen fertilizer application method in Example 1 (Example 1 is the nitrogen fertilizer application method for coordinating high-yield rice cultivation and healthy breeding of rice flower carps, that is, the proportions of basal fertilizer and panicle fertilizer are 70% and 30% respectively; Comparative Example 1 is the nitrogen application method of farmers' habits, that is, the proportions of basal fertilizer and panicle fertilizer are 100% and 0% respectively; Comparative Example 2 is the simple nitrogen application method for rice, that is, the proportions of basal fertilizer and panicle fertilizer are 40% and 60% respectively; another nitrogen fertilizer-free experiment is set, that is, the nitrogen fertilizer application amount is 0 kg / ha, and the obtained rice yield and nitrogen accumulation data are used to calculate the nitrogen fertilizer utilization efficiency), after topdressing nitrogen fertilizer, the pH value of the paddy field water will first rise and then fall, and the change range is mainly between 6 and 8. Only in the late season of 2022 in Comparative Example 2, the pH value of the water body after topdressing nitrogen fertilizer increased to 8.87, but soon dropped to between 6 and 7. The dissolved oxygen concentration of the paddy field water will rapidly decrease after topdressing nitrogen fertilizer, and after 24 h, the dissolved oxygen concentration of the water body will stabilize between 3.5 and 8.2 mg / L. The NH4 + -N concentration in the paddy field water will rise rapidly after topdressing nitrogen fertilizer, but will rapidly decrease after 72 h, and will return to the level before fertilization after about 7 d. The NO3 --N concentration will first increase and then decrease after topdressing nitrogen fertilizer, and will drop to the level before fertilization after 48h - 96h. Generally speaking, after topdressing nitrogen fertilizer, the pH value, dissolved oxygen, NH4 + -N, NO3 - -N concentration will change with the dissolution of urea, but will return to the level before fertilization within 24h - 96h. The changes in this process may have a greater impact on rice field fish, but none of them caused the death of rice field fish. This also indicates that using this nitrogen application method may cause the ammonia nitrogen concentration in the paddy field water body to rise rapidly, but the change in ammonia nitrogen concentration is still within the tolerable range of rice flower carp, indicating that the fertilization rate of 45kg / ha - 90kg / ha or 54kg / ha - 108kg / ha is the safe dosage of nitrogen fertilizer in the rice-fish symbiotic system.

[0062] Experimental Example 2 Effects of Different Nitrogen Application Methods on Rice Yield, Rice Flower Carp Yield and Nitrogen Fertilizer Absorption and Utilization Rate in Rice-Fish Symbiotic System

[0063] The effects of different nitrogen application methods on rice and rice flower carp yields in the rice-fish symbiotic system are as Figure 3 shown, and the specific data are shown in Table 1 and Table 2.

[0064] The results show that the paddy yields of Example 1 and Comparative Example 2 are both higher than that of Comparative Example 1, but there is no significant difference; the trend of the annual paddy yield shown in Table 2 is similar to the result of Table 1. The results in Table 1 also show that the rice flower carp yields in the late seasons of 2021 and 2022 in Example 1 are both higher than those in Comparative Example 1 and Comparative Example 2, and the one in the late season of 2022 reaches a significant level, indicating that basal application of 70% and topdressing of 30% of nitrogen fertilizer are more conducive to the stable yield of rice and the improvement of rice flower carp yield under the same nitrogen fertilizer application rate. In addition, the results in Table 1 show that the nitrogen fertilizer utilization efficiency of Example 1 is higher than that of Comparative Example 1 and reaches a significant level in the early and late seasons of 2021 and the late season of 2022, but is lower than that of Comparative Example 2 in the early and late seasons of the two years.

[0065] Table 1 Effects of Different Nitrogen Application Methods on Rice Yield, Rice Flower Carp Yield and Nitrogen Fertilizer Absorption and Utilization Rate

[0066]

[0067]

[0068] Note: Different letters in the same column indicate no significant difference at the 0.05 level; the data are from Dafeng Experimental Base of Guangdong Academy of Agricultural Sciences in Guangzhou in 2021 and 2022.

[0069] Table 2 Effects of Different Nitrogen Application Methods on Annual Yields of Rice and Rice Flower Carp

[0070]

[0071]

[0072] Note: Different letters in the same column indicate no significant difference at the 0.05 level; the data are from the Dafeng Experimental Base of Guangdong Academy of Agricultural Sciences in Guangzhou in 2021 and 2022.

[0073] In summary, the nitrogen application level and method in Example 1 are sufficient to meet the high and stable yield of rice, and the nitrogen application method has little impact on the paddy field water environment and low harm to the healthy growth of rice field carp, that is, it will not cause a decrease in the yield of rice field carp and may even increase the yield; while Comparative Example 1 has no impact on the healthy growth and yield of rice field carp, but this nitrogen application method will affect the decrease in rice yield; in addition, Comparative Example 2 can meet the high and stable yield of rice, but has a greater impact on rice field carp and may even cause a decrease in the yield of rice field carp. Therefore, the nitrogen application method in Example 1 is more suitable for coordinating the high and stable yield of rice and the healthy growth of rice field carp in the rice-fish symbiotic system, providing scientific and technological support for improving the economic benefits in the rice-fish symbiotic system.

[0074] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for applying nitrogen fertilizer to coordinate high-yield rice cultivation and healthy farming of rice field eels in a rice-fish symbiotic system, characterized in that, The total amount of nitrogen fertilizer required for the entire growth cycle of rice is divided into two applications: basal fertilizer and panicle fertilizer, and the mass ratio of the application rates of the basal fertilizer and the panicle fertilizer is 7:

3.

2. The nitrogen fertilizer application method according to claim 1, characterized in that, The nitrogen fertilizer is urea or controlled-release urea, with a nitrogen content of 35-55%.

3. The nitrogen fertilizer application method according to claim 1, characterized in that, The total amount of nitrogen fertilizer is determined according to the local standard of Guangdong Province, "Technical Regulations for the Three-Control Fertilization of Rice" (DB44 / T 969-2011).

4. The nitrogen fertilizer application method according to claim 1, characterized in that, The applicable area is Guangdong Province. The total amount of nitrogen fertilizer: the total amount of nitrogen fertilizer for early rice and late rice is 150 kg / ha and 180 kg / ha respectively.

5. The nitrogen fertilizer application method according to claim 1, wherein The application method of the basal fertilizer is: apply 70% of the total amount of nitrogen fertilizer during land preparation before transplanting, so that the fertilizer is fully mixed with the soil.

6. The nitrogen fertilizer application method according to claim 1, characterized in that, The application method of the panicle fertilizer is: at the initial stage of rice panicle differentiation, that is, at the first branch primordium differentiation stage of the rice young panicle, evenly spread 30% of the total amount of nitrogen fertilizer in the paddy field.

7. The nitrogen fertilizer application method according to claim 6, characterized in that, The first branch primordium differentiation stage of the rice young panicle is: 35 days after transplanting for early-season rice and 30 days after transplanting for late-season rice.

8. The nitrogen fertilizer application method according to claim 1, wherein Keep the water layer in the paddy field at 10-20 cm before applying the panicle fertilizer, and do not drain or irrigate the paddy field after applying the panicle fertilizer.

9. Application of the method according to any one of claims 1 to 7 in the symbiotic system of rice and rice flower carp.

10. Application of the method according to any one of claims 1 to 7 in the symbiotic system of rice and rice flower carp to increase the yield of rice and increase the yield of rice flower carp.

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