Irrigation method for improving phosphate fertilizer utilization efficiency of rice-duckweed symbiotic system

Abstract

The invention discloses an irrigation method for improving the phosphate fertilizer utilization efficiency of a rice-duckweed symbiotic system, and belongs to the technical field of agricultural irrigation. S2, rice transplanting and irrigation; s3, in the period of seedling establishment of the rice, intermittent irrigation and rainfall depth are controlled to be 40 mm; s4, after the rice seedling establishment period, duckweed is applied, and a rice-duckweed symbiotic system is formed; s5, in the tillering stage of rice, tillering fertilizer is applied, and meanwhile intermittent irrigation and rainfall depth are controlled to be 60 mm and 80 mm respectively; s6, in the rice jointing and booting stage, panicle fertilizer is applied, and meanwhile intermittent irrigation and rainfall water depth are controlled to be 60 mm and 80 mm respectively; s7, the water depths of intermittent irrigation and rainfall are controlled to be 60 mm and 80 mm respectively in the heading and flowering stage, the milk-ripe stage and the yellow ripe early stage of the rice; s8, at the yellow ripening later stage of the rice, draining or naturally drying, and harvesting the rice; phosphorus loss is greatly reduced, phosphate fertilizer utilization efficiency is improved, and phosphate fertilizer competition with rice can be avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural irrigation, and particularly relates to an irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system. Background Art

[0002] Rice is one of the important food crops. During its growth and development process, it requires a large amount of the nutrient element phosphorus. However, most of the phosphorus in the soil exists in the form of inorganic insoluble state or organic state, making it difficult for rice to directly absorb it. That is, the available phosphorus naturally supplied in the soil is difficult to meet the phosphorus demand of rice. To solve this problem and promote the growth and development of rice, phosphorus fertilizer is generally applied during the rice planting process. However, under the current rice planting mode, the utilization efficiency of phosphorus fertilizer is low, and a large amount of unabsorbed phosphorus fertilizer is easily lost with the irrigation water, not only causing waste of resources, but also possibly triggering environmental problems such as water eutrophication.

[0003] In view of this, an irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system is designed to solve the above technical problems. Summary of the Invention

[0004] To solve the problems raised in the above background art, the present invention provides an irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system, which has the characteristics of not only greatly reducing phosphorus loss and improving the phosphorus fertilizer utilization efficiency, but also being able to avoid competing with rice for phosphorus fertilizer.

[0005] To achieve the above object, the present invention provides the following technical solution: An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system, comprising the following steps:

[0006] S1: Level the paddy field and apply base fertilizer;

[0007] S2: Transplant rice seedlings and irrigate water;

[0008] S3: During the rice seedling recovery period, irrigate water when the water level is lower than the lower limit of irrigation, and control the water depth during irrigation and rainfall to 40 mm;

[0009] S4: After the rice seedling recovery period, scatter duckweed to form a rice-duckweed symbiotic system;

[0010] S5: During the rice tillering period, apply tillering fertilizer, and at the same time irrigate water when the soil volume saturation moisture content of the paddy field is lower than 90%, and control the water depth during irrigation and rainfall to 60 mm and 80 mm respectively;

[0011] S6: During the rice jointing and booting period, apply panicle fertilizer, and at the same time irrigate water when the water level is lower than the lower limit of irrigation, and control the water depth during irrigation and rainfall to 60 mm and 80 mm respectively;

[0012] S7: During the heading and flowering stage, milk-ripe stage, and early yellow-ripe stage of rice, irrigation is carried out when the soil volume saturation moisture content in the paddy field is lower than 90%. The water depths during irrigation and when rainfall occurs are controlled at 60 mm and 80 mm respectively.

[0013] S8: In the late yellow-ripe stage of rice, drain the water or let it dry naturally, and then harvest the rice.

[0014] Furthermore, in the step S1, the basal fertilizer includes nitrogen fertilizer, phosphate fertilizer, and potassium fertilizer. Among them, the nitrogen fertilizer is urea, the phosphate fertilizer is superphosphate, and the potassium fertilizer is potassium sulfate.

[0015] Furthermore, in the step S1, the application rate of nitrogen fertilizer in terms of pure nitrogen is 193 kg / ha -1 , the application rate of phosphate fertilizer is 65 kg / ha -1 , and the application rate of potassium fertilizer is 65 kg / ha -1 .

[0016] Furthermore, in the step S2, the row spacing and plant spacing for transplanting rice seedlings are 15 cm × 20 cm, and 3 seedlings are planted in each hole.

[0017] Furthermore, in the step S4, the duckweed needs to be processed as follows before being applied:

[0018] Repeatedly wash the duckweed collected from the test area and surrounding ditches with tap water;

[0019] Rinse the washed duckweed with distilled water;

[0020] Place the rinsed duckweed in a special duckweed nutrient solution for acclimation cultivation until it is amplified to the required amount.

[0021] Furthermore, in the step S4, the application rate of duckweed is 200 g / m² -2 .

[0022] Furthermore, in the step S5, before applying the tillering fertilizer for rice, the duckweed needs to cover ≥ 80% of the paddy field area.

[0023] Furthermore, in the step S5, the tillering fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea.

[0024] Furthermore, in the step S6, the panicle fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea.

[0025] Furthermore, in the steps S1, S5, and S6, the application ratio of the basal fertilizer, tillering fertilizer, and panicle fertilizer is 5:3:2.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] The present invention adopts the method of rice-duckweed symbiosis and intermittent irrigation to grow rice. When the rice field is flooded during irrigation, duckweed can absorb phosphorus in the paddy field and reproduce rapidly. When the rice is short of water and suffers from drought, duckweed continuously withers and decomposes, releasing phosphorus into the soil to provide phosphorus for the rice. This cycle repeats, and intermittent irrigation is used to regulate the growth and decomposition process of duckweed, enabling duckweed to play the roles of "phosphate fertilizer reservoir" and "slow-release and controlled-release fertilizer". After absorbing the applied phosphate fertilizer, it continuously transports it to the paddy field, not only greatly reducing phosphorus loss and improving the utilization efficiency of phosphate fertilizer, but also avoiding competing with rice for phosphate fertilizer. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flowchart of the method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] Embodiment 1

[0031] Intermittent irrigation light drought mode:

[0032] An irrigation method for improving the utilization efficiency of phosphate fertilizer in a rice-duckweed symbiotic system, comprising the following steps:

[0033] S1: Prepare the paddy field and apply basal fertilizers, including nitrogen fertilizer, phosphate fertilizer and potassium fertilizer. Among them, the nitrogen fertilizer is urea, and the application rate is 193 kg / ha in terms of pure nitrogen -1 , the phosphate fertilizer is superphosphate, and the application rate is 65 kg / ha -1 , the potassium fertilizer is potassium sulfate, and the application rate is 65 kg / ha -1 ;

[0034] S2: Transplant rice seedlings, with 3 seedlings per hole. The row spacing of rice transplantation in the season is 15 cm × 20 cm. After transplantation, irrigate with water.

[0035] S3: During the rice green-recovery period, when the water depth on the field surface is lower than the lower limit of irrigation (10 mm), irrigate with water until the water depth is 40 mm above the field surface. At the same time, when there is rainfall and the water depth on the field surface exceeds the rainfall limit (40 mm), drain the water until the water depth on the field surface remains at 40 mm.

[0036] S4: Harvest duckweed from the test area and surrounding ditches, wash it repeatedly with tap water, then rinse it with distilled water after cleaning. Then place the washed duckweed in a special duckweed nutrient solution for acclimation cultivation until it expands to the required amount. After the rice returns to the green stage, apply duckweed, and the application rate is 200 g m -2 , to form a rice-duckweed symbiotic system;

[0037] S5: During the tillering stage of rice, when the duckweed covers ≥80% of the paddy field area, apply tillering fertilizer with a ratio of 5:3 to the base fertilizer application. The tillering fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea. At the same time, when the soil moisture content in the paddy field is lower than the lower irrigation limit (90% θs), irrigate the water to the upper irrigation limit (60 mm). At the same time, when there is rainfall and the water depth on the paddy field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the paddy field surface remains at 80 mm;

[0038] S6: During the jointing and booting stage of rice, apply panicle fertilizer with a ratio of 5:2 to the base fertilizer application. The panicle fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea. At the same time, when the water depth on the paddy field surface is lower than the lower irrigation limit (10 mm), irrigate the water to the upper irrigation limit (60 mm). At the same time, when there is rainfall and the water depth on the paddy field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the paddy field surface remains at 80 mm;

[0039] S7: During the heading, flowering, milk ripening, and early yellow ripening stages of rice, when the soil moisture content in the paddy field is lower than the lower irrigation limit (90% θs), irrigate the water to the upper irrigation limit (60 mm). At the same time, when there is rainfall and the water depth on the paddy field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the paddy field surface remains at 80 mm;

[0040] S8: In the late yellow ripening stage of rice, drain the water or let it dry naturally, and harvest the rice to facilitate the rice harvest, as shown in Table 1 specifically.

[0041] Example 2

[0042] Intermittent irrigation with mid-drought mode:

[0043] An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system, comprising the following steps:

[0044] S1: Level the paddy field and apply base fertilizer. The base fertilizer includes nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer. Among them, the nitrogen fertilizer is urea, and the application rate is 193 kg ha in terms of pure nitrogen -1 , the phosphorus fertilizer is superphosphate, and the application rate is 65 kg ha -1 , the potassium fertilizer is potassium sulfate, and the application rate is 65 kg ha -1 ;

[0045] S2: Transplant rice seedlings, with 3 seedlings per hill. The row and hill spacing for rice transplanting is 15 cm × 20 cm. After transplanting, irrigate the water;

[0046] S3: During the rice green-recovery period, when the water depth on the field surface is lower than the lower irrigation limit (10 mm), irrigate until the water depth is 40 mm above the field surface. At the same time, when rainfall occurs and the water depth on the field surface exceeds the rainfall limit (40 mm), drain the water until the water depth on the field surface remains at 40 mm.

[0047] S4: Harvest duckweed from the experimental area and surrounding ditches. First, wash it repeatedly with tap water, then rinse it with distilled water after it is clean. Then place the rinsed duckweed in a special duckweed nutrient solution for acclimation culture until it expands to the required amount. After the rice green-recovery period, apply duckweed at a rate of 200 g m -2 , forming a rice-duckweed symbiotic system.

[0048] S5: During the rice tillering period, when the duckweed covers ≥80% of the paddy field area, apply tillering fertilizer with a ratio of 5:3 to the base fertilizer application. The tillering fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea. At the same time, when the soil moisture content in the paddy field is lower than the lower irrigation limit (80% θs), irrigate until the upper irrigation limit (60 mm). At the same time, when rainfall occurs and the water depth on the field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the field surface remains at 80 mm.

[0049] S6: During the rice jointing and booting period, apply ear fertilizer with a ratio of 5:2 to the base fertilizer application. The ear fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea. At the same time, when the water depth on the field surface is lower than the lower irrigation limit (10 mm), irrigate until the upper irrigation limit (60 mm). At the same time, when rainfall occurs and the water depth on the field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the field surface remains at 80 mm.

[0050] S7: During the rice heading, flowering, milk-ripening, and early yellow-ripening periods, when the soil moisture content in the paddy field is lower than the lower irrigation limit (80% θs), irrigate until the upper irrigation limit (60 mm). At the same time, when rainfall occurs and the water depth on the field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the field surface remains at 80 mm.

[0051] S8: In the late yellow-ripening period of rice, drain the water or let it dry naturally, and harvest the rice for easy harvesting, as shown in Table 1 specifically.

[0052] Example 3

[0053] Intermittent irrigation with mid-drought mode:

[0054] An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system, comprising the following steps:

[0055] S1: Level the paddy field and apply base fertilizer. The base fertilizer includes nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer. Among them, the nitrogen fertilizer is urea, and the application amount is 193 kg ha in terms of pure nitrogen -1 , the phosphorus fertilizer is superphosphate, and the application amount is 65 kg ha -1, the potassium fertilizer is potassium sulfate, and the application rate is 65 kg / ha -1 ;

[0056] S2: Transplant rice seedlings, with 3 seedlings per hill. The row and hill spacing for rice transplanting is 15 cm × 20 cm. After transplanting, irrigate the field;

[0057] S3: During the rice green-recovery period, when the water depth on the field surface is lower than the lower limit of irrigation (10 mm), irrigate the field until the water depth is 40 mm above the field surface. At the same time, when there is rainfall and the water depth on the field surface exceeds the rainfall limit (40 mm), drain the water until the water depth on the field surface remains at 40 mm;

[0058] S4: Harvest duckweed from the experimental area and surrounding ditches. First, wash it repeatedly with tap water, then rinse it with distilled water after washing clean. Then place the rinsed duckweed in a special duckweed nutrient solution for acclimation culture until it expands to the required amount. After the rice green-recovery period, spread the duckweed, and the spreading amount is 200 g / m -2 , to form a rice-duckweed symbiotic system;

[0059] S5: During the rice tillering period, when the duckweed covers ≥80% of the paddy field area, apply tillering fertilizer with a ratio of 5:3 to the base fertilizer application. The tillering fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea. At the same time, when the soil moisture content in the paddy field is lower than the lower limit of irrigation (70% θs), irrigate the field until the upper limit of irrigation (60 mm). At the same time, when there is rainfall and the water depth on the field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the field surface remains at 80 mm;

[0060] S6: During the rice jointing and booting period, apply panicle fertilizer with a ratio of 5:2 to the base fertilizer application. The panicle fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea. At the same time, when the water depth on the field surface is lower than the lower limit of irrigation (10 mm), irrigate the field until the upper limit of irrigation (60 mm). At the same time, when there is rainfall and the water depth on the field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the field surface remains at 80 mm;

[0061] S7: During the rice heading, flowering, milk-ripening, and early yellow-ripening periods, when the soil moisture content in the paddy field is lower than the lower limit of irrigation (70% θs), irrigate the field until the upper limit of irrigation (60 mm). At the same time, when there is rainfall and the water depth on the field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the field surface remains at 80 mm;

[0062] S8: In the late yellow-ripening period of rice, drain the water or let it dry naturally, and harvest the rice for easy rice harvesting, as shown in Table 1 specifically.

[0063] Control Example 1

[0064] Flood irrigation mode:

[0065] An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system, comprising the following steps:

[0066] S1: Level the paddy field and apply basal fertilizer. The basal fertilizer includes nitrogen fertilizer, phosphate fertilizer and potassium fertilizer. Among them, the nitrogen fertilizer is urea, and the application rate is 193 kg ha in terms of pure nitrogen. -1 The phosphate fertilizer is superphosphate, and the application rate is 65 kg ha. -1 The potassium fertilizer is potassium sulfate, and the application rate is 65 kg ha. -1 ;

[0067] S2: Transplant rice seedlings. Plant 3 seedlings per hill. The row spacing and plant spacing for rice transplanting are 15 cm × 20 cm. After transplanting, irrigate the field.

[0068] S3: During the rice seedling recovery period, when the water depth on the field surface is lower than the lower limit of irrigation (10 mm), irrigate the field until the water depth is 40 mm above the field surface. At the same time, when there is rainfall and the water depth on the field surface exceeds the rainfall limit (40 mm), drain the water until the water depth on the field surface is maintained at 40 mm.

[0069] S4: Harvest duckweed from the test area and surrounding ditches. First, wash it repeatedly with tap water, then rinse it with distilled water after washing clean. Then place the rinsed duckweed in a special duckweed nutrient solution for acclimation culture until it is amplified to the required amount. After the rice seedling recovery period, apply duckweed, and the application rate is 200 g m. -2 to form a rice-duckweed symbiotic system;

[0070] S5: During the rice tillering period, when the duckweed covers ≥80% of the paddy field area, apply tillering fertilizer with a ratio of 5:3 to the basal fertilizer application ratio. The tillering fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea. At the same time, when the water depth on the field surface is lower than the lower limit of irrigation (10 mm), irrigate the field until the upper limit of irrigation (60 mm). At the same time, when there is rainfall and the water depth on the field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the field surface is maintained at 80 mm.

[0071] S6: During the rice jointing and booting period, apply panicle fertilizer with a ratio of 5:2 to the basal fertilizer application ratio. The panicle fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea. At the same time, when the water depth on the field surface is lower than the lower limit of irrigation (10 mm), irrigate the field until the upper limit of irrigation (60 mm). At the same time, when there is rainfall and the water depth on the field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the field surface is maintained at 80 mm.

[0072] S7: During the rice heading, flowering, milk ripening and early yellow ripening periods, when the water depth on the field surface is lower than the lower limit of irrigation (10 mm), irrigate the field until the upper limit of irrigation (60 mm). At the same time, when there is rainfall and the water depth on the field surface exceeds the rainfall limit (80 mm), drain the water until the water depth on the field surface is maintained at 80 mm.

[0073] S8: In the late yellow ripening period of rice, drain the water or let it dry naturally, and harvest the rice for easy rice harvesting, as shown in Table 1 specifically.

[0074] Table 1 Control Standards for Field Water Layers under Different Irrigation Modes (mm)

[0075]

[0076] Note: θ s is the soil volume saturation moisture content.

[0077] The test results of each example and comparative example are as follows:

[0078] Processing Phosphorus fertilizer utilization rate (%) <![CDATA[Phosphorus emissions (kg / hm 2 )]]> Example 1 21.3％ 1.07 Example 2 18.1％ 1.35 Example 3 12.9％ 1.57 Comparative Example 1 9.7％ 2.05

[0079] It can be seen from the above test results that: for the irrigation method of Example 1, the phosphorus fertilizer utilization rate is the highest, which is 21.3%, and at the same time, the carbon emission is the lowest, which is 1.07 kg / hm 2 .

[0080] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system, characterized in that, It includes the following steps: S1: Level the paddy field and apply basal fertilizer; S2: Transplant rice seedlings and irrigate the field; S3: During the rice seedling recovery period, irrigate when the water level is lower than the lower limit of irrigation. The water depth during irrigation and rainfall is controlled at 40 mm; S4: After the rice seedling recovery period, scatter duckweed to form a rice-duckweed symbiotic system; S5: During the rice tillering period, apply tillering fertilizer. At the same time, irrigate when the soil volume saturation moisture content of the paddy field is lower than 90%. The water depth during irrigation and rainfall is controlled at 60 mm and 80 mm respectively; S6: During the rice jointing and booting period, apply ear fertilizer. At the same time, irrigate when the water level is lower than the lower limit of irrigation. The water depth during irrigation and rainfall is controlled at 60 mm and 80 mm respectively; S7: During the rice heading and flowering period, milk ripening period and early yellow ripening period, irrigate when the soil volume saturation moisture content of the paddy field is lower than 90%. The water depth during irrigation and rainfall is controlled at 60 mm and 80 mm respectively; S8: During the late yellow ripening period of rice, drain the water or let it dry naturally, and harvest the rice.

2. An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system according to claim 1, characterized in that: In the step S1, the basal fertilizer includes nitrogen fertilizer, phosphate fertilizer and potassium fertilizer. Among them, the nitrogen fertilizer is urea, the phosphate fertilizer is superphosphate, and the potassium fertilizer is potassium sulfate.

3. An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system according to claim 2, characterized in that: In the step S1, the application rate of nitrogen fertilizer is 193 kg / ha in terms of pure nitrogen -1 , the application rate of phosphate fertilizer is 65 kg / ha -1 , the application rate of potassium fertilizer is 65 kg / ha -1 .

4. An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system according to claim 1, characterized in that: In the step S2, the row spacing of rice seedlings during transplantation is 15 cm×20 cm, and 3 seedlings are planted in each hole.

5. An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system according to claim 1, characterized in that: In the step S4, the duckweed needs to be processed as follows before scattering: Repeatedly wash the duckweed collected from the test area and surrounding ditches with tap water; Rinse the washed duckweed with distilled water; Place the rinsed duckweed in a special duckweed nutrient solution for acclimation culture until it is amplified to the required amount.

6. The irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system according to claim 1, wherein: In the step S4, the application amount of duckweed is 200 g / m -2 .

7. An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system according to claim 1, characterized in that: In the step S5, before applying the rice tillering fertilizer, the duckweed needs to cover ≥80% of the paddy field area.

8. An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system according to claim 1, characterized in that: In the step S5, the tillering fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea.

9. An irrigation method for improving the phosphorus fertilizer utilization efficiency of a rice-duckweed symbiotic system according to claim 1, characterized in that: In the step S6, the ear fertilizer is nitrogen fertilizer, and the nitrogen fertilizer is urea.

10. The irrigation method for improving the phosphorus fertilizer utilization efficiency of the rice-duckweed symbiotic system according to claim 1, characterized in that: In the steps S1, S5 and S6, the application ratio of the basal fertilizer, tillering fertilizer and ear fertilizer is 5:3:2.

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