A simplified method for recommending nitrogen fertilizer application rate in rice based on nitrogen balance criteria

Abstract

The present invention discloses a simplified method for recommending nitrogen fertilizer application rate for rice based on nitrogen balance criteria, which relates to the technical field of agricultural resources and environment. The present invention proposes a method for recommending nitrogen fertilizer application rate for rice based on nitrogen balance criteria. This method only needs to know the rice yield and soil fertility level to recommend the nitrogen fertilizer application rate. It can minimize the surplus of nitrogen in the soil to the greatest extent on the basis of ensuring crop yield, thereby reducing the environmental loss of reactive nitrogen, and thus promoting the high-yield, high-efficiency, sustainable and healthy development of agriculture.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural resources and environment, and particularly relates to a simplified method for recommending nitrogen fertilizer application rate for rice based on nitrogen balance criteria. Background Art

[0002] Rice is an important food crop. However, the situation of excessive application of nitrogen fertilizer during the rice production process is extremely serious. Under the flooded rice cultivation conditions, excessive application of nitrogen fertilizer leads to increased ammonia volatilization and nitrification-denitrification losses, becoming an important source of global nitrogen pollution and greenhouse gas emissions.

[0003] Currently, the methods for recommending nitrogen fertilizer application rate for crops are mainly developed based on one or more of soil nutrient testing, fertilizer effect functions, crop or soil models. However, most of the small-scale farmer management models do not have the conditions for soil testing fertilization or other scientific fertilization methods. Especially in the case of rice, there are problems such as tight planting schedules resulting in untimely soil testing results, and poor correlation between nitrogen testing under flooded conditions and crop responses. A large number of small-scale farmers still apply fertilizers according to experience, and the phenomenon of unreasonable fertilization is relatively common.

[0004] Therefore, the development of a scientific, reasonable, simple and efficient recommended fertilization technology is an urgent need to promote the efficient application of nitrogen fertilizer in rice and reduce fertilizer use and emissions. Summary of the Invention

[0005] The purpose of the present invention is to provide a simplified method for recommending nitrogen fertilizer application rate for rice based on nitrogen balance criteria to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] The present invention provides a method for recommending nitrogen fertilizer application rate for rice based on nitrogen balance criteria, including the following steps:

[0008] Step 1): Identify the soil fertility grade of the paddy field: In nitrogen fertilizer recommendation, soil fertility is mainly manifested as the nitrogen supply capacity of the soil.

[0009] The present invention provides 4 methods to determine the soil nitrogen supply grade:

[0010] Method 1: Determine according to the nitrogen uptake of the above-ground part of rice in the target plot without applying nitrogen fertilizer. The present invention has collected and summarized the fertilization field test data carried out in the main rice production areas of China and established a database. The first 25%, the middle 25%-75%, and the last 25% of the nitrogen uptake dataset of the above-ground part of rice without applying nitrogen fertilizer in the database (with a sample size of 1315) are used as the classification criteria for high, medium, and low grades of soil nitrogen supply in the paddy field (Table 1);

[0011] Method 2: Determine based on the rice yield of the target plot without applying nitrogen fertilizer. Based on the database of Method 1, the first 25%, the middle 25%-75%, and the last 25% of the rice yield dataset without applying nitrogen fertilizer are used as the classification criteria for high, medium, and low levels of nitrogen supply in paddy field soil (Table 2);

[0012] Method 3: If the target plot has soil test results, classify according to the soil organic matter content (Table 3); Specifically:

[0013] The nitrogen supply level of the soil uses the soil organic matter content level as the basis for judging the nitrogen supply level, and the hydrolyzable nitrogen in the soil as an adjustment factor: when the hydrolyzable nitrogen in the soil ≥ 180 mg / kg, adjust the low supply capacity of the soil nitrogen supply level to medium supply capacity; when the hydrolyzable nitrogen in the soil ≤ 100 mg / kg, adjust the high supply capacity of the soil nitrogen supply level to medium supply capacity;

[0014] Method 4: Determine according to the apparent traits such as soil texture and color of the target plot (Table 4).

[0015] Table 1

[0016]

[0017] Table 2

[0018]

[0019] Table 3

[0020]

[0021] Table 4

[0022]

[0023]

[0024] Step 2): Determine the nitrogen balance standard of the target plot: Based on the above database, the present invention established the relationship between the nitrogen application yield response (i.e., the rice yield increment of the target plot with nitrogen fertilizer treatment compared to the treatment without nitrogen fertilizer) and the apparent nitrogen balance in the soil (i.e., the difference between the nitrogen application amount and the amount absorbed and removed by rice) (with a sample size of 4393, covering the main rice planting areas in China). On the basis of ensuring rice yield and minimizing the surplus of nitrogen in the soil to the greatest extent, using the maximum economic benefit algorithm, the nitrogen balance standards for high, medium, and low levels of soil nitrogen supply in paddy fields are proposed.

[0025] Meanwhile, the present invention compared the differences in soil apparent nitrogen balance among conventional nitrogen fertilizer application, slow / controlled-release nitrogen fertilizer, deep mechanical application of nitrogen fertilizer, combined application of organic fertilizer, straw return to field and other fertilization patterns (with a sample size of 1,807, covering the application effects of major rice planting regions in China and typical fertilization patterns), and then proposed a reference standard for nitrogen balance in paddy fields under different fertilization patterns (Table 5).

[0026] According to the soil nitrogen supply level and nitrogen fertilizer application pattern identified in step 1), refer to Table 5 to determine the nitrogen balance standard for the target plot.

[0027] Table 5

[0028]

[0029]

[0030] Step 3) Determine the nitrogen uptake of rice plants in the target plot:

[0031] The nitrogen uptake of above-ground rice plants takes into account two parts: nitrogen uptake in grains and nitrogen uptake in straws, and can be calculated by formula (1):

[0032] N uptake = N grain + N straw = Y grain * X grain + Y straw * X straw (1)

[0033] Wherein, N uptake , N grain , N straw respectively represent the above-ground nitrogen uptake, nitrogen uptake in grains and nitrogen uptake in straws of rice in the target plot (kg N / ha); Y grain and Y straw respectively represent the rice grain yield and rice straw biomass (kg / ha); X grain and X straw respectively represent the nitrogen content in rice grains and the nitrogen content in rice straws (mg / kg).

[0034] Specifically, Y grain is determined according to the average rice yield without biological stress in the past 3 - 5 years in the target plot.

[0035] Y straw If there is no measured data, it can be obtained by formula (2):

[0036] Y straw = Y grain * a (2)

[0037] Among them, a represents the conversion coefficient of rice grain yield to rice straw biomass, and the reference value is shown in Table 6.

[0038] X grain If there are no measured data, then N grain is obtained through formula (3):

[0039] N grain = Y grain * b * 0.001 (3)

[0040] Among them, b represents the conversion coefficient of rice grain yield to rice grain nitrogen uptake, and the reference value is shown in Table 6.

[0041] X straw If there are no measured data, then N straw is obtained through formula (4):

[0042] N straw = Y straw * c * 0.001 (4)

[0043] Among them, c represents the conversion coefficient of rice straw biomass to rice straw nitrogen uptake, and the reference value is shown in Table 6.

[0044] Table 6

[0045] Conversion factor Single-season rice Middle-season rice Early-season rice Late-season rice a 0.90(964) 1.00(3307) 0.88(1137) 0.94(1126) b 9.0(1572) 11.8(2631) 11.9(1351) 11.5(1270) c 5.5(1412) 6.5(2135) 7.8(1222) 7.5(1168)

[0046] Note: The numbers in parentheses are the sample sizes.

[0047] Step 4) Calculate the nitrogen fertilizer application rate for rice in the target plot: Predict the recommended nitrogen fertilizer application rate based on the aboveground nitrogen uptake of rice in the target plot and the nitrogen balance standard of the paddy field, and specifically obtain it through formula (5):

[0048] N = N uptake + N balance (5)

[0049] Among them, N represents the recommended nitrogen fertilizer application rate for the target plot (kg N / ha); N uptake represents the aboveground nitrogen uptake of rice in the target plot (kg N / ha), which is obtained from step 3); N balance represents the nitrogen balance standard of the target plot (kg N / ha), which is obtained from steps 1) and 2).

[0050] The nitrogen fertilizer application rate recommendation method based on the nitrogen balance standard of the present invention is a simplified recommendation method, which can be used with or without soil test results. Ordinary farmers with a certain scientific knowledge reserve only need to know the rice yield level of the target plot, identify the soil fertility level, and then through a simple calculation process, they can achieve scientific and reasonable nitrogen fertilizer recommendation. Compared with the existing technology, it is more suitable for small farmers who do not have the conditions of soil testing and formulated fertilization or other fertilization technologies that require professional testing equipment and personnel.

[0051] The present invention not only provides nitrogen balance standard parameters for conventional nitrogen fertilizer products and application methods, but also corrects the parameters for high-efficiency fertilization scenarios such as slow / controlled-release fertilizers, deep mechanical application of nitrogen fertilizers, combined application of organic fertilizers, and straw returning to the field. Therefore, compared with the existing technology, the present invention is more applicable to the current diverse rice nitrogen fertilizer application scenarios.

[0052] The relevant nitrogen fertilizer recommendation parameters of the present invention are generated based on big data of field experiments, rather than based on individual or a few experimental results, and have broad representativeness. At the same time, the present invention uses the rice yield response as the response index for nitrogen balance change, rather than directly using the rice yield. This is because the yield response is the increment of the yield of the nitrogen application treatment relative to the non-nitrogen application treatment, and the yield of the non-nitrogen application treatment represents the soil fertility level of the plot. Therefore, the deviation of the recommended fertilization parameters caused by the difference in soil fertility levels at different experimental sites is eliminated to the greatest extent. Therefore, the nitrogen balance standard provided by the present invention is suitable for different rice types, varieties and soil and climate environmental conditions.

[0053] The method of the present invention only needs to know the rice yield and soil fertility grade to recommend the nitrogen fertilizer application rate according to the relevant parameters, and is applicable to different nitrogen fertilizer application scenarios such as conventional nitrogen fertilizers, slow / controlled-release fertilizers, deep mechanical application of nitrogen fertilizers, combined application of organic fertilizers, and straw returning to the field. Based on the recommended fertilization practice results of a large amount of field experiment data in different rice planting areas, the nitrogen fertilizer application rate recommended by the method of the present invention is basically equivalent to the recommended result of soil testing and formulated fertilization, and is significantly lower than that of farmers' conventional fertilization, achieving the goal of light, efficient and scientific fertilization, and is particularly suitable for small farmers who do not have the conditions of soil testing and formulated fertilization and other scientific fertilization technologies.

[0054] The present invention discloses the following technical effects:

[0055] The present invention proposes a method for recommending the nitrogen fertilizer application rate of rice based on the nitrogen balance standard. This method only needs to know the rice yield and soil fertility grade to recommend the nitrogen fertilizer application rate, and can minimize the surplus of nitrogen in the soil to the greatest extent on the basis of ensuring the crop yield, thereby reducing the environmental loss of reactive nitrogen and promoting the high-yield, efficient, sustainable and healthy development of agriculture. Detailed implementation manners

[0056] A detailed description of various exemplary embodiments of the present invention will now be given. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0057] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0058] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0059] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0060] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0061] Example 1

[0062] In order to verify the feasibility of applying the nitrogen fertilizer rate recommendation method based on the nitrogen balance criterion to rice, the present invention conducts recommended fertilization practices using a large amount of field trial data of different rice regional types, and compares the recommended results with those of local farmers' customary fertilization and other widely recognized scientific fertilization methods to verify whether the recommended results are reasonable.

[0063] Field experiments were carried out in the single - cropping rice regions of Heilongjiang and Jilin provinces, the middle - season rice regions of Hubei and Anhui provinces, and the early / late double - cropping rice regions of Hunan and Jiangxi provinces from 2017 to 2020. The recommended method for nitrogen fertilizer application based on the nitrogen balance standard was verified. There were a total of 136 experimental plots. The number of experiments and regions for different fertilization methods are shown in Table 7. According to the above - ground nitrogen uptake of rice in the no - nitrogen - fertilizer treatment of each experimental plot, the soil nitrogen supply level of the plot was judged using the standard provided in Table 1 (Table 7). According to the fertilization method and soil nitrogen supply level of each experimental plot, the nitrogen balance standard of the plot was judged using the standard provided in Table 5 (Table 8). Taking the measured value of the highest above - ground nitrogen uptake of rice in all treatments as the target nitrogen uptake, the recommended nitrogen fertilizer application rate (abbreviated as OPT) for the plot was predicted by formula (5), and compared with the local farmers' conventional nitrogen fertilizer application rate (abbreviated as FP), the recommended nitrogen fertilizer application rate of local soil testing and formulated fertilization (abbreviated as ST), and the recommended nitrogen fertilizer application rate of the nutrient expert method (abbreviated as NE) for the same plot (Table 8).

[0064] Table 7

[0065]

[0066]

[0067] Table 8

[0068]

[0069] Table 8 classified and summarized the average nitrogen fertilizer application rate results of 4 fertilization methods on related plots of the same rice region type and soil fertility level. The results showed that in single - cropping rice, the average OPT nitrogen fertilizer application rate under high, medium, and low soil fertilities was 171 kg N / ha, which was 6.7% lower than the average FP nitrogen fertilizer application rate, and was basically equivalent to the ST recommended result; in middle - season rice, the average OPT application rate under 3 soil fertilities was 185 kg N / ha, which was 2.8% lower than the average OPT nitrogen fertilizer application rate, but was higher than the ST and NE application rates. This was mainly because the recommended result of the method of the present invention was higher on low - fertility soils to ensure the target yield level; in early - rice and late - rice, the average OPT application rates were 184 and 194 kg N / ha respectively. The OPT application rate on late - rice was lower than the FP application rate, but the OPT application rate on early - rice was higher than the FP application rate. Similarly, the recommended result on low - fertility soils was higher.

[0070] In summary, the application of the recommended nitrogen fertilizer rate method based on the nitrogen balance standard in the present invention can significantly reduce the nitrogen fertilizer rate used by current farmers. In the case of high fertility, the recommended results are basically equivalent to those of soil testing and formulated fertilization. In the case of medium and low fertility, the recommended results are improved compared with the other two scientific fertilization methods. This is mainly considered to ensure the yield level of the plot by increasing the input of fertilizer nitrogen while avoiding excessive consumption of soil organic matter. Therefore, the results of field verification tests show that the recommended nitrogen fertilizer rate method based on the nitrogen balance standard proposed in the present invention can be used for nitrogen fertilizer rate decision-making in rice cultivation.

[0071] The embodiments described above are only used to describe the preferred mode of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A simplified method for recommending nitrogen fertilizer application rate in rice based on nitrogen balance criteria, characterized in that, It includes the following steps: (1) Determine the soil nitrogen supply level of the target plot by using any one of Method 1 - Method 4: Method 1: According to different rice varieties, determine the soil nitrogen supply level of the target plot based on the nitrogen uptake of the above-ground parts of rice without applying nitrogen fertilizer: Method 2: According to different rice varieties, determine the soil nitrogen supply level of the target plot based on the yield of rice without applying nitrogen fertilizer: Method 3: Divide the soil nitrogen supply level of the target plot according to the soil organic matter content: The soil nitrogen supply level takes the soil organic matter content level as the basis for judging the nitrogen supply level and the soil hydrolyzable nitrogen as the adjustment factor: When the soil hydrolyzable nitrogen ≥ 180 mg / kg, adjust the low supply capacity of the soil nitrogen supply level to medium supply capacity; when the soil hydrolyzable nitrogen ≤ 100 mg / kg, adjust the high supply capacity of the soil nitrogen supply level to medium supply capacity; Method 4: Determine the soil nitrogen supply level of the target plot according to the soil texture and apparent properties: (2) According to the soil nitrogen supply level of the target plot determined in step (1), combined with the fertilization method, determine the nitrogen balance standard of the target plot according to the following table: (3) Obtain Y based on the target yield grain For the rice grain yield, determine the above-ground nitrogen uptake of rice in the target plot according to formula (a-1) or (a-2): N uptake = N grain + N straw (a - 1) Where: N uptake is the nitrogen uptake in the aboveground part of rice, kg N / ha; N grain is the nitrogen uptake by rice grains, kg N / ha; N straw Nitrogen uptake of rice straw, kg N / ha; N uptake = Y grain * X grain + Y straw * X straw (a - 2) Where: N uptake Nitrogen uptake in the above-ground parts of rice, kg N / ha; Y grain is the rice grain yield, kg / ha; Y straw is the rice straw biomass, kg / ha; X grain is the nitrogen content in rice grains, mg / kg; X straw is the nitrogen content of rice straw, mg / kg; (4) Calculate the recommended nitrogen fertilizer application rate for rice in the target plot according to formula (b): N = N uptake +N balance (b); Among them, N represents the recommended nitrogen application rate for rice, kg N / ha; N uptake represents the nitrogen uptake in the above-ground part of rice, kg N / ha; N balance represents the nitrogen balance standard, kg N / ha.

2. According to the method described in claim 1, if there is no measured value of the rice straw biomass, it is calculated according to formula (c): Y straw = Y grain * a(c) Y straw is the rice straw biomass, kg / ha; Y grain is the rice grain yield, kg / ha; a represents the conversion coefficient of rice grain yield to rice straw biomass, where The conversion coefficients of different rice varieties are shown in the following table; If there is no measured value of the nitrogen uptake of rice grains, it is calculated according to formula (d): N grain = Y grain * b * 0.001 (d) N grain is the nitrogen uptake of rice grains, kg N / ha; Y grain is the rice grain yield, kg / ha; b represents the conversion coefficient between the rice grain yield and the nitrogen uptake of rice grains. For the conversion coefficients of different rice varieties, see the following table; If there is no measured value of the nitrogen uptake of rice straw, it is calculated according to formula (e): N straw = Y straw * c * 0.001 (e) N straw is the nitrogen uptake of rice straw, kg N / ha; Y straw is the biomass of rice straw, kg / ha; c represents the conversion coefficient between the biomass of rice straw and the nitrogen uptake of rice straw. For different rice varieties, the conversion coefficients are shown in the following table: 。

Images