A method for preventing and controlling greenhouse gas emissions from rice fields

Abstract

The present invention discloses a method for controlling greenhouse gas emissions from rice fields, comprising the following steps: applying basal fertilizer 4 to 6 days before transplanting, applying tillering fertilizer after the seedlings turn green, applying ear fertilizer 1 during the panicle differentiation period when the seedlings grow branches and ears, and applying ear fertilizer 2 2 to 3 days before the seedlings head; adding potassium humate bio-organic fertilizer at a rate of 30% pure nitrogen of chemical fertilizer as basal fertilizer, and applying tillering fertilizer 1, ear fertilizer 2, and ear fertilizer 2 to prevent and control greenhouse gas emissions from rice fields. The method comprises applying functional organic fertilizer and nitrification inhibitor to rice soil, thereby reducing chemical fertilizer input, lowering fertilizer costs, improving nitrogen fertilizer utilization, ensuring rice yield, regulating the population structure of soil nitrifying and denitrifying functional microorganisms, and significantly reducing greenhouse gas emissions from farmland soil.

Description

Technical Field

[0001] The present invention relates to the technical field of rice field fertilization, and in particular to a method for preventing and controlling greenhouse gas emissions from rice fields. Background Art

[0002] Rice fields are the most important farmland ecosystems in my country. While ensuring my country's food security, they are also an important source of emissions of greenhouse gases such as N2O.

[0003] For a long time, rice fertilization has primarily relied on nitrogen fertilizer, with smaller amounts of phosphorus and potassium fertilizers, and even smaller amounts of organic fertilizers. The prolonged application of a single fertilizer not only leads to an imbalance in nutrient supply, failing to meet the diverse nutrient needs of rice growth and development, but also results in increasing fertilizer application rates while utilization rates gradually decrease. This leads to soil compaction caused by a severe lack of soil organic matter, reduced rice yields, and deteriorating rice quality. Furthermore, paddy field soils suffer from severe nitrogen losses, low nitrogen utilization rates, and a lack of effective means to control nitrogen losses. The excessive application of nitrogen fertilizers increases production costs, greenhouse gas emissions, and groundwater nitrogen levels, severely restricting the sustainable development of circular agriculture. The resulting negative effects cannot be ignored.

[0004] Therefore, it is of great practical significance to study the comprehensive technology of high rice yield and greenhouse gas emission reduction and develop a new rice farming model. The Chinese invention patent with application number 202211470139.3 discloses a method for reducing greenhouse gas emissions in rice fields. The ridge-forming, planting and fertilizing methods facilitate the air to enter the deep soil layer along the channel, which can inhibit the growth of methanogens, thereby significantly reducing the generation and emission of greenhouse gas CH4 in rice fields. This method requires ridge-forming to form ridge stalks and furrows, and to form a number of vertical channels on the ridge stalks, and to reduce the generation and emission of greenhouse gases in rice fields through water management at different times. However, this method is complicated to operate and is not conducive to large-scale promotion and utilization. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a method for preventing and controlling greenhouse gas emissions from rice fields, which is simple and easy to implement and can significantly reduce greenhouse gas emissions from farmland soil.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0007] A method for controlling greenhouse gas emissions from rice fields is provided, the method comprising the following steps:

[0008] Apply base fertilizer once 4 to 6 days before transplanting, apply tillering fertilizer after the seedlings turn green, apply spike fertilizer 1 during the spike differentiation period when the seedlings grow branches and spikes, and apply spike fertilizer 2 2 to 3 days before the seedlings head.

[0009] Potassium humate bio-organic fertilizer is added as base fertilizer according to 30% pure nitrogen dosage of chemical fertilizer, and the tillering fertilizer, ear fertilizer 1 and ear fertilizer 2 include 50% NPK compound fertilizer and nitrification inhibitor, wherein the nitrogen dosage of the NPK compound fertilizer in the base fertilizer, tillering fertilizer, ear fertilizer 1 and ear fertilizer 2 is 0:4:4:2 according to the mass ratio.

[0010] Furthermore, the N, P, and K dosage of the 50% NPK compound fertilizer is 50% of that of the SSNM fertilizer treatment, and the N, P, and K come from urea, superphosphate, and potassium chloride, respectively.

[0011] Furthermore, the potassium fulvic acid biological organic fertilizer has N+P2O5+K2O≥5%, humic acid≥15%, and a moisture content of 40-50%.

[0012] Furthermore, the nitrification inhibitor is 2-chloro-6-trichloromethylpyridine, and the dosage of pure nitrogen is 0.0025g of 2-chloro-6-trichloromethylpyridine per gram of pure nitrogen. The nitrogen fertilizer is added after the nitrification inhibitor. The nitrogen fertilizer is applied by using a water-based nitrogen method, that is, after the water layer of the rice field dries up, the fertilizer is evenly spread on the field, and then water is slowly irrigated with small streams so that the fertilizer dissolves with water and gradually penetrates into the soil, thereby achieving the purpose of deep fertilizer application.

[0013] Furthermore, the planting density of rice is 7 inches x 4 inches.

[0014] Furthermore, potassium humate bio-organic fertilizer is added as base fertilizer according to 30% of the pure nitrogen dosage of chemical fertilizer, and the dosage of potassium humate bio-organic fertilizer calculated by using 30% of the pure nitrogen dosage of SSNM chemical fertilizer replaces 50% of the pure nitrogen dosage of SSNM chemical fertilizer.

[0015] The beneficial effects of the present invention are:

[0016] The method of the present invention combines inorganic and organic biofertilizers, reducing the input of chemical nitrogen fertilizers, reducing soil and environmental pollution caused by excessive fertilizer application, reducing nitrogen fertilizer losses, controlling nitrogen fertilizer pollution, and improving the nitrogen fertilizer utilization rate of rice. It plays an important role in stabilizing rice yield, increasing soil organic matter content, improving soil physical properties, fertilizing the soil, and increasing soil microbial activity. It can also improve crop quality, increase crop yield potential, ensure the safe supply of agricultural products, improve the agricultural ecological environment, and reduce the overall greenhouse effect of rice fields. It is of great significance for developing low-carbon agriculture, mitigating climate change, reducing the impact of greenhouse gases produced by human activities on global warming and the series of environmental problems it brings, and achieving sustainable agricultural development and ecological harmony. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the global warming potential values ​​of different fertilization treatments provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0019] Example

[0020] In this embodiment, the test site is located in Laosha Village, Xihu District, Hangzhou City, Zhejiang Province (120.16°E, 30.13°N), which has a subtropical humid monsoon climate. The average annual temperature in the past ten years is 17-19°C, the average annual rainfall is 1000-1200 mm, and the annual sunshine hours are 1700-1800 h.

[0021] The test soil is a paddy soil developed from alluvial parent material (Yangtze River alluvial deposits), with an organic matter content of 22.2 g·kg -1 , total nitrogen 1.53g·kg -1 , alkaline nitrogen 179 mg kg -1 , fast-acting phosphorus 16 mg kg -1 , fast-acting potassium 246 mg·kg -1 , pH 5.57 (water-soil ratio 2.5:1). The test crop was rice, cultivar 'Jia 58'. The fertilizers tested included urea (46.4% N), superphosphate (12% P₂O₅), potassium chloride (60% K₂O), and organic biofertilizer (potassium fulvic acid biofertilizer, N+P₂O₅+K₂O ≥ 5%, humic acid ≥ 15%, organic matter ≥ 45%, Henan Lianxingyuan Fertilizer Co., Ltd.).

[0022] A randomized block design was used. The ridges between the plots were isolated and prevented from seepage with waterproof plastic film. Protective rows were set up around the plots. The plot area was 18m 2 (5m x 3.6m), with ridges 30cm wide at the bottom and approximately 15cm high, forming independent ridges after irrigation. Each plot has its own inlet and outlet. The rice planting density is 7 inches x 4 inches (13.33cm x 23.33cm), with two plants per clump. Each plot has 16 rows, 38 clumps per row, for a total of 608 clumps per plot. Seedlings are selected similarly across all plots, and routine field management is employed. Fertilization is based on local practices and the results of long-term field placement experiments.

[0023] Fertilization plan

[0024] The experiment has 6 treatments:

[0025] 1) CK: no fertilizer;

[0026] 2) CF: According to the fertilizer application rate of local farmers, fertilizer N, P, K (N is 240kg·hm -2 , P2O5 is 90kg·hm -2 , K2O is 120 kg·hm -2 );

[0027] 3) SSNM: Calculate the amount of fertilizer to be applied based on SSNM. The amount of fertilizer N, P, and K (N is 167 kg·hm -2 , P2O5 is 115kg·hm -2 , K2O is 109 kg·hm -2 );

[0028] 4) The nitrogen content of organic biofertilizer is 30% of that of SSNM treatment (i.e. 50.1 kg·hm -2 , 2000kg·hm -2 )+50%NPK 50%NPK compound fertilizer (N, P and K dosage is 50% of SSNM treatment, i.e. N is 83.5kg·hm -2 , P2O5 is 57.5 kg·hm -2 , K2O is 54.5 kg·hm -2 );

[0029] 5) The nitrogen content of organic biofertilizer is 30% of that of SSNM treatment (i.e. 50.1 kg·hm -2 , 2000kg·hm -2 )+50%NPK 50%NPK compound fertilizer+nitrification inhibitor (N, P and K dosage is 50% of SSNM treatment, i.e. N is 83.5kg·hm -2 , P2O5 is 57.5 kg·hm -2 , K2O is 54.5 kg·hm -2 ), nitrogen fertilizer is urea containing nitrification inhibition.

[0030] 6) The nitrogen content of organic biofertilizer is 45% of that of SSNM treatment (i.e. 75.15 kg·hm -2 , 3000kg·hm -2 )+50%NPK 50%NPK compound fertilizer+nitrification inhibitor (N, P and K dosage is 50% of SSNM treatment, i.e. N is 83.5kg·hm -2 , P2O5 is 57.5 kg·hm -2 , K2O is 54.5 kg·hm -2 ), nitrogen fertilizer is urea containing nitrification inhibition.

[0031] The nitrogen content of the treated organic biofertilizer was 15% of that of the SSNM treatment (i.e. 25.05 kg·hm -2 , 1000kg·hm-2 ) + 50% NPK has been shown to have too low a yield in previous experiments and is not considered here.

[0032] Basal fertilizer should be applied once 4 to 6 days before transplanting. It should be evenly spread before plowing the field, and then deep plowed to a depth of 15 to 30 cm to bury the fertilizer deep into the ground. Tillering fertilizer should be applied after the seedlings turn green, approximately 3 to 7 days after transplanting. Ear fertilizer 1 should be applied during the spike differentiation stage when the branches and ears grow, generally 20 to 40 days after the first application of tillering fertilizer. Ear fertilizer 2 should be applied 2 to 3 days before heading.

[0033] The nitrogen application rate of N2 treatment was 4:4 (mass ratio) for tillering fertilizer and ear fertilizer 1; the nitrogen application rate of N3, N4 and N5 treatments was 0:4:4:2 (mass ratio) for base fertilizer, tillering fertilizer, ear fertilizer 1 and ear fertilizer 2.

[0034] Table 1 Schematic diagram of rice field plot

[0035]

[0036] Table 2 Specific arrangements for field fertilization (urea)

[0037] <![CDATA[Unit: g / 18m 2 > N1 N2 N3 N4 N5 N6 base fertilizer 0 0 0 0 0 0 Tillering fertilizer 0 465.28 259.01 129.50 129.50 129.50 Booting fertilizer 0 465.28 258.01 129.50 129.50 129.50 Heading fertilizer 0 0 129.50 64.75 64.75 64.75

[0038] Table 3 Specific arrangements for field fertilization of base fertilizer P, K fertilizer and organic fertilizer

[0039] <![CDATA[Unit: g / 18m 2 > N1 N2 N3 N4 N5 N6 P 0 1349.3 1724.14 862.07 862.07 862.07 K 0 359.8 326.84 163.42 163.42 163.42 organic fertilizer 0 3598.20 35998.20 5397.30

[0040] In the table, N1-N6 represent the 6 treatment groups in the experiment.

[0041] Gas samples were collected using a static closed chamber method. The chamber, a rectangular 0.5m × 0.5m × 0.9m cube, was constructed from PVC panels and covered with aluminum foil to minimize temperature fluctuations caused by solar radiation during the collection process. Each chamber was equipped with a base to maintain a water seal during gas collection. Gas sampling was conducted weekly between 7:00 AM and 10:00 AM. After closing the chamber, 60 mL of gas was collected using a 60 mL syringe at 0, 10, 20, and 30 minutes after closing the chamber. The collected gas was then transferred to a 100 mL vacuum aluminum bag for testing.

[0042] HZS-β gene sequencing revealed high Anammox bacterial biodiversity in rice-season soil samples, with Ca. Brocadia (13.51% of total sequences), Ca. Scalindua (8.11% of total sequences), and Ca. Jettenia (78.38% of total sequences) being the dominant genera. High alpha diversity indices were observed in treatments N4, N5, and N6 (Simpson and Shannon indices of 0.81 and 2.65, respectively), indicating that these treatments enhanced the diversity of Anammox community structure. Anammox activity was detected in all treatments using stable isotope tracing.

[0043] The cumulative N2O emissions from different treatments during the entire rice growth period were N2 > N3 > N4 > N6 > N5 > N1, with corresponding emissions of 48633.68, 34459.92, 20310.08, 13901.98, 10864.66, and 5027.28 μg·m -2 The N5 treatment reduced N2O emissions by 77.66% compared to farmers' usual N2 fertilization, the N6 treatment reduced N2O emissions by 71.41%, the N4 treatment reduced N2O emissions by 58.24%, and the N3 treatment reduced N2O emissions by 29.14%. The N3, N4, N5, and N6 treatments were all effective in reducing N2O emissions.

[0044] The CH4 emissions during the entire rice growth period were accumulated. From rice transplanting to rice harvest, the cumulative emissions of different treatments were N2>N6>N4>N3>N5>N1, and the corresponding emissions were 21860.29, 18746.72, 17490.85, 16596.01, 16205.98, and 15530.43 μg·m -2 The N5 treatment reduced CH4 emissions by 25.87% compared to farmers' usual N2 fertilization, the N3 treatment reduced CH4 emissions by 24.08%, the N4 treatment reduced CH4 emissions by 19.99%, and the N6 treatment reduced CH4 emissions by 14.24%. The N5, N3, N4, and N6 treatments were all effective in reducing CH4 emissions.

[0045] Reference Figure 1 The global warming potential values ​​of different fertilization treatments are N2>N6>N4>N3>N5>N1 from large to small, and the corresponding GWP values ​​are 4743.80, 3981.90, 3737.91, 3593.78, 3438.65, and 3278.61 kg·m -2N5 reduced the warming effect by 27.51% compared to N2, N3 by 24.24%, N4 by 21.20%, and N6 by 16.06%. N5 significantly reduced emissions without significantly changing yields, reducing warming potential by 27.51% compared to traditional fertilization, demonstrating significant ecological benefits.

[0046] Table 4 Rice yield under different fertilization treatments

[0047]

[0048]

[0049] The analysis of variance for yield showed that there was no significant difference among treatments N2-N6.

[0050] Table 5 Rice-grain-to-grass ratio under different fertilization treatments

[0051]

[0052] The higher straw ratios of N3, N4, and N5 indicate that organic fertilizer application improves nitrogen conversion efficiency. The global warming potential values ​​of the different fertilization treatments, from highest to lowest, are N2, N6, N4, N3, N5, and N1. N5 has a 27.51% lower global warming effect than N2. While maintaining no yield reduction, N5 significantly reduces emissions, reducing global warming potential by 27.51% compared to conventional fertilization, demonstrating significant ecological benefits.

[0053] Taking into account the three factors of rice yield, grain-to-straw ratio and global warming potential reduction, it was found that the fertilization treatment N5 was the most suitable. The N5 fertilization scheme corresponds to the integrated exogenous regulation technology of controlling rice field ecosystem emissions, which includes 50% SSNM, organic biofertilizer, and nitrification inhibitor. The organic biofertilizer, 50% NPK, 50% NPK compound fertilizer, and nitrification inhibitor were added at a rate of 30% pure nitrogen of chemical fertilizer (the N, P, and K rates were 50% of those of the SSNM treatment, i.e., N was 83.5 kg·hm-3). -2 , P2O5 is 57.5 kg·hm -2 , K2O is 54.5 kg·hm -2 ) fertilization mode, nitrogen application is based on the ratio of 0:4:4:2 (mass ratio) for base fertilizer, tillering fertilizer, panicle fertilizer 1 and panicle fertilizer 2. It is a source control method. When there is no significant difference in rice yield, compared with traditional farmers' fertilization habits, it can reduce N2O emissions by 77.66%, CH4 emissions by 25.87%, and global warming potential by 27.51%. It is beneficial to energy conservation and emission reduction in rice fields, not only maintaining a high rice yield, but also reducing greenhouse gas emissions, reducing global warming potential, and having obvious ecological benefits.

[0054] In the technical solution of the present invention, SSNM treatment is a prior art and is not protected by the present invention, so it will not be described in detail here. The present invention applies functional organic fertilizer and nitrification inhibitors to rice soil to regulate the population structure of soil nitrification and denitrification functional microorganisms. Organic fertilizer is used instead of chemical fertilizer as base fertilizer, which reduces the addition of nitrogen fertilizer and greenhouse gas emissions throughout the rice growth period, especially in the early growth period, and improves nitrogen utilization efficiency. With no significant difference in yield, the emission reduction effect is significant, effectively reducing N2O and CH4 emissions, and reducing the global warming potential by 27.51% compared to traditional fertilization, with significant ecological benefits.

[0055] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0056] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preventing and controlling greenhouse gas emissions from rice fields, characterized in that: The following steps are involved: Apply base fertilizer 4 to 6 days before transplanting, apply tillering fertilizer after the seedlings turn green, apply spike fertilizer 1 during the spike differentiation period when the seedlings grow branches and spikes, and apply spike fertilizer 2 2 to 3 days before the seedlings head. Potassium humate bio-organic fertilizer is added as base fertilizer according to the amount of 30% pure nitrogen of chemical fertilizer. The tillering fertilizer, ear fertilizer 1 and ear fertilizer 2 include 50% NPK compound fertilizer and nitrification inhibitor, wherein the amount of N, P and K of the 50% NPK compound fertilizer is 50% of the reduced fertilization mode of SSNM fertilizer treatment, that is, N is 83.5 kg·hm -2 , P2O5 is 57.5 kg·hm -2 , K2O is 54.5 kg·hm -2 The nitrogen dosage of the 50% NPK compound fertilizer is in the base fertilizer, tillering fertilizer, ear fertilizer 1, and ear fertilizer 2 in a mass ratio of 0:4:4:2; The potassium humate bio-organic fertilizer is added as base fertilizer according to 30% of the pure nitrogen dosage of chemical fertilizer, and the dosage of potassium humate bio-organic fertilizer calculated by using 30% of the pure nitrogen dosage of SSNM chemical fertilizer replaces 50% of the pure nitrogen dosage of SSNM chemical fertilizer.

2. The method for preventing and controlling greenhouse gas emissions from rice fields according to claim 1, characterized in that: The N, P and K of the 50% NPK compound fertilizer come from urea, superphosphate and potassium chloride respectively.

3. The method for controlling greenhouse gas emissions from rice fields according to claim 1, characterized in that: The potassium fulvic acid biological organic fertilizer contains N+P2O5+K2O≥5%, humic acid≥15%, and a moisture content of 40-50%.

4. The method for preventing and controlling greenhouse gas emissions from rice fields according to claim 1, characterized in that: The nitrification inhibitor is 2-chloro-6-trichloromethylpyridine, and 0.0025 g of 2-chloro-6-trichloromethylpyridine is added per gram of pure nitrogen.

5. The method for preventing and controlling greenhouse gas emissions from rice fields according to claim 1, characterized in that: The planting density of rice is 7 inches x 4 inches.

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