Simplified rice nitrogen fertilizer dosage recommendation method based on nitrogen balance standard

Abstract

The invention discloses a simplified rice nitrogen fertilizer dosage recommendation method based on a nitrogen balance standard, and relates to the technical field of agricultural resource environment. According to the rice nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard, the nitrogen fertilizer dosage can be recommended only by knowing the rice yield and the soil fertility grade, the surplus of nitrogen in soil can be reduced to the maximum extent on the basis of ensuring the crop yield, the environmental loss of active nitrogen is further reduced, and the economic benefit is improved. Therefore, high-yield, high-efficiency, sustainable and healthy development of agriculture is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural resources and environment, and in particular to a lightly simplified method for recommending nitrogen fertilizer dosage for rice based on a nitrogen balance standard. Background Art

[0002] Rice is an important food crop. However, the excessive application of nitrogen fertilizer in the rice production process is extremely serious. Under the conditions of flooded rice cultivation, 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] At present, the method for recommending the amount of nitrogen fertilizer for crops is mainly developed based on one or more of soil nutrient testing, fertilizer effect function, crop or soil model. However, most small farmers do not have the conditions for soil testing or other scientific fertilization. Especially in rice, there are problems such as the untimely soil testing results due to the tight planting rotation, and the poor correlation between nitrogen testing and crop response under flooding conditions. A large number of small farmers still apply fertilizers according to experience, and unreasonable fertilization is common.

[0004] Therefore, it is an urgent need to develop a recommended fertilization technology that is both scientific and reasonable as well as simple and efficient to promote the efficient application of nitrogen fertilizer in rice and to save fertilizer and reduce emissions. Summary of the invention

[0005] The purpose of the present invention is to provide a lightly simplified method for recommending nitrogen fertilizer dosage for rice based on nitrogen balance standard, so as to solve the problems existing in the above-mentioned prior art.

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

[0007] The present invention provides a method for recommending nitrogen fertilizer dosage for rice based on nitrogen balance standard, comprising the following steps:

[0008] Step 1): Identify the soil fertility level of paddy fields: In nitrogen fertilizer recommendations, soil fertility is mainly reflected in the nitrogen supply capacity of the soil.

[0009] The present invention provides four methods for determining the soil nitrogen supply level:

[0010] Method 1: Determine based on the nitrogen absorption of the aboveground part of rice without nitrogen fertilizer application in the target plot. The present invention collects and summarizes the fertilization field test data conducted in the main rice producing areas in China and establishes a database. The first 25%, middle 25%-75%, and last 25% of the nitrogen absorption data set of the aboveground part of rice without nitrogen fertilizer application in the database (1315 samples) are used as the classification criteria for high, medium, and low levels of nitrogen supply in paddy field soil (Table 1);

[0011] Method 2: Determine based on the rice yield of the target plot without nitrogen fertilizer application. Based on the database of Method 1, the first 25%, middle 25%-75%, and last 25% of the rice yield data set without nitrogen fertilizer application were 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, it is divided according to the soil organic matter content (Table 3); specifically:

[0013] The soil nitrogen supply level is based on the soil organic matter content level, and the soil hydrolyzable nitrogen is used as the adjustment factor: when the soil hydrolyzable nitrogen is ≥180 mg / kg, the low supply capacity of the soil nitrogen supply level is adjusted to the medium supply capacity; when the soil hydrolyzable nitrogen is ≤100 mg / kg, the high supply capacity of the soil nitrogen supply level is adjusted to the medium supply capacity;

[0014] Method 4: Determine based on the apparent properties of the target plot’s soil, such as texture and color (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 establishes the relationship between the nitrogen yield response (i.e., the rice yield increment of the target plot treated with nitrogen fertilizer compared with that treated without nitrogen fertilizer) and the apparent nitrogen balance of the soil (i.e., the difference between the amount of nitrogen applied and the amount absorbed and removed by rice) (4393 samples, covering major rice-growing areas in China). On the basis of ensuring rice yield and minimizing nitrogen surplus in the soil, the maximum economic benefit algorithm is used to propose nitrogen balance standards under high, medium and low soil nitrogen supply levels of paddy fields.

[0025] At the same time, the present invention compares the differences in soil apparent nitrogen balance between conventional nitrogen fertilizer application and slow-release nitrogen fertilizer, mechanical deep nitrogen fertilizer application, organic fertilizer application, and straw return to the field (1,807 samples, covering China's major rice-growing areas and the application effects of typical fertilization modes), and then proposes reference standards for nitrogen balance in paddy fields under different fertilization modes (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 of 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 absorption of the aboveground rice plant is calculated by considering the nitrogen absorption of the grain and the nitrogen absorption of the straw, which can be obtained by formula (1):

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

[0033] Among them, N uptake 、N grain 、N straw represents the nitrogen absorption of the aboveground part, the nitrogen absorption of rice grains and the nitrogen absorption of rice straw in the target plot (kg N / ha); Y grain and Y straw represent rice grain yield and rice straw biomass (kg / ha), respectively; X grain and X straw They represent the nitrogen content of rice grains and rice straw (mg / kg), respectively.

[0034] Specifically, Y grain Determined based on the average rice yield of the target plot in the past 3-5 years without biological stress.

[0035] Y straw If there is no measured data, the following formula (2) can be used to obtain:

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

[0037] Where a represents the conversion coefficient between rice grain yield and rice straw biomass, and the reference value is shown in Table 6.

[0038] X grain If there is no measured data, then N grain By formula (3), we can obtain:

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

[0040] Wherein, b represents the conversion coefficient between rice grain yield and rice grain nitrogen absorption. The reference value is shown in Table 6.

[0041] X straw If there is no measured data, then N straw By formula (4), we can obtain:

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

[0043] Wherein, c represents the conversion coefficient between rice straw biomass and rice straw nitrogen absorption, and the reference value is shown in Table 6.

[0044] Table 6

[0045] Conversion Factor One-season rice Medium Rice Early Rice Late 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 brackets are sample sizes.

[0047] Step 4) Calculate the amount of nitrogen fertilizer for rice in the target plot: The recommended amount of nitrogen fertilizer is predicted based on the nitrogen absorption of the aboveground part of rice in the target plot and the nitrogen balance standard of the paddy field, which is specifically obtained by formula (5):

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

[0049] Wherein, N represents the recommended amount of nitrogen fertilizer for the target plot (kg N / ha); uptake represents the aboveground nitrogen absorption of rice in the target plot (kg N / ha), obtained in step 3); N balance represents the nitrogen balance standard (kg N / ha) of the target plot, obtained by steps 1) and 2).

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

[0051] The present invention not only provides standard parameters for nitrogen balance for conventional nitrogen fertilizer products and application methods, but also performs parameter correction for efficient fertilization scenarios such as slow-release fertilizers, mechanical deep application of nitrogen fertilizers, organic fertilizer application, and straw return to the field. Therefore, compared with the prior art, the present invention is more suitable for the current diversified rice nitrogen fertilizer application scenarios.

[0052] The present invention generates relevant nitrogen fertilizer recommendation parameters based on field test big data, rather than on individual or a few test results, and is widely representative. At the same time, the present invention uses rice yield response as a response indicator of nitrogen balance changes, rather than directly using rice yield, because the yield response is the increment of the yield of nitrogen treatment relative to the yield of no nitrogen treatment, and the yield of no nitrogen treatment represents the soil fertility level of the plot, thus eliminating the deviation of recommended fertilization parameters caused by differences in soil fertility levels at different test points to the greatest extent. Therefore, the nitrogen balance standard provided by the present invention is suitable for different rice types, varieties and soil climate and environmental conditions.

[0053] The method of the present invention only needs to understand the rice yield and soil fertility level, and can recommend the amount of nitrogen fertilizer based on the relevant parameters. It is applicable to different nitrogen fertilizer application scenarios such as conventional nitrogen fertilizer, slow-release fertilizer, mechanical deep application of nitrogen fertilizer, organic fertilizer application, and straw return to the field. Based on the recommended fertilization practice results of a large number of field test data in different rice-growing areas, the amount of nitrogen fertilizer recommended by the method of the present invention is basically equivalent to the recommended results of soil testing and formula fertilization, which is significantly lower than the farmers' usual fertilization, achieving the goal of simple, efficient, and scientific fertilization, and is particularly suitable for small farmers who do not have the conditions for soil testing and formula fertilization and other scientific fertilization technologies.

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

[0055] The present invention proposes a method for recommending nitrogen fertilizer dosage for rice based on the nitrogen balance standard. This method only requires understanding of rice yield and soil fertility level to recommend nitrogen fertilizer dosage. It can minimize nitrogen surplus in the soil on the basis of ensuring crop yield, thereby reducing the environmental loss of active nitrogen, thereby promoting high-yield, efficient, sustainable and healthy development of agriculture. DETAILED DESCRIPTION

[0056] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0057] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0058] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only 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 associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0059] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0060] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0061] Example 1

[0062] In order to verify the feasibility of applying the nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard to rice, the present invention uses a large amount of field test data from different rice regional types to carry out recommended fertilization practices, and compares the recommended results with the local farmers' habitual fertilization and other widely recognized scientific fertilization methods to verify whether the recommended results are reasonable.

[0063] The field test was conducted in the single-season rice producing areas of Heilongjiang and Jilin provinces, the mid-season rice producing areas of Hubei and Anhui provinces, and the early / late double-season rice producing areas of Hunan and Jiangxi from 2017 to 2020. The recommended method of nitrogen fertilizer application based on the nitrogen balance standard was verified for a total of 136 test plots. The number and regions of the tests for verifying different fertilization methods are shown in Table 7. According to the nitrogen absorption of the aboveground part of rice in each test plot without nitrogen fertilizer treatment, the soil nitrogen supply level of the plot was judged using the standards provided in Table 1 (Table 7). According to the fertilization method and soil nitrogen supply level of each test plot, the nitrogen balance standard of the plot was judged using the standards provided in Table 5 (Table 8). The highest measured value of nitrogen uptake by aboveground rice in all treatments was used as the target nitrogen uptake. The recommended nitrogen fertilizer dosage (OPT) for the plot was predicted using formula (5) and compared with the local farmers’ habitual nitrogen fertilizer dosage (FP), the nitrogen fertilizer dosage recommended by local soil testing formula fertilization (ST), and the nitrogen fertilizer dosage recommended by the nutrient expert method (NE) (Table 8).

[0064] Table 7

[0065]

[0066]

[0067] Table 8

[0068]

[0069] Table 8 classifies and summarizes the average nitrogen fertilizer application results of the four fertilization methods on the relevant plots of the same rice regional type and soil fertility level. The results show that for single-season rice, the average application of OPT nitrogen fertilizer under high, medium and low soil fertility is 171 kg N / ha, which is 6.7% lower than the average application of FP nitrogen fertilizer, but basically equivalent to the ST recommended result; for medium-season rice, the average application of OPT under the three soil fertilities is 185 kg N / ha, which is 2.8% lower than the average application of OPT nitrogen fertilizer, but higher than ST and NE, which is mainly due to the fact that the method of the present invention has a higher recommended result on low-fertility soil to ensure the target yield level; for early rice and late rice, the average OPT application is 184 and 194 kg N / ha, respectively. The OPT application for late rice is lower than that for FP, but the OPT application for early rice is higher than that for FP, which is also reflected in the higher recommended result on low-fertility soil.

[0070] In summary, the application of the nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard of the present invention can significantly reduce the current nitrogen fertilizer dosage that farmers are accustomed to. Under high fertility conditions, the recommendation results are basically equivalent to the results of soil testing and formula fertilization, and under medium and low fertility conditions, the recommendation results are improved compared with the other two scientific fertilization methods. The main consideration is to ensure the yield level of the plot by increasing the input of fertilizer nitrogen and avoid excessive consumption of soil organic matter. Therefore, the field verification test results show that the nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard proposed by the present invention can be used for nitrogen fertilizer dosage decision-making for rice.

[0071] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A simplified method for recommending nitrogen fertilizer dosage for rice based on nitrogen balance standard, characterized in that: The following steps are involved: (1) Use any of the methods 1 to 4 to determine the soil nitrogen supply level of the target plot: Method 1: According to different rice varieties, the nitrogen supply level of the target plot is determined based on the nitrogen absorption of the aboveground part of the rice without nitrogen fertilizer: Method 2: According to different rice varieties, the soil nitrogen supply level of the target plot is determined based on the rice yield without nitrogen fertilizer application: Method 3: Classify the soil nitrogen supply level of the target plot according to the soil organic matter content: The soil nitrogen supply level is based on the soil organic matter content level, and the soil hydrolyzable nitrogen is used as the adjustment factor: when the soil hydrolyzable nitrogen is ≥180 mg / kg, the low supply capacity of the soil nitrogen supply level is adjusted to the medium supply capacity; when the soil hydrolyzable nitrogen is ≤100 mg / kg, the high supply capacity of the soil nitrogen supply level is adjusted to the medium supply capacity; Method 4: Determine the soil nitrogen supply level of the target plot based on soil texture and surface properties: (2) Based on the soil nitrogen supply level of the target plot determined in step (1), combined with the fertilization method, the nitrogen balance standard of the target plot is determined according to the following table: (3) Obtain Y based on target output grain For rice grain yield, determine the nitrogen absorption of the aboveground part of rice in the target plot according to formula (a-1) or (a-2): N uptake =N grain +N straw (a-1) in: N uptake is the nitrogen absorption of aboveground rice, kg N / ha; N grain is the nitrogen uptake by rice grains, kg N / ha; N straw is the nitrogen absorption of rice straw, kg N / ha; N uptake =And grain *X grain +Y straw *X straw (a-2) in: N uptake is the nitrogen uptake by the aboveground part of wheat, 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 of rice grains, mg / kg; X straw is the nitrogen content of rice straw, mg / kg; (4) Calculate the recommended amount of nitrogen fertilizer for rice in the target plot according to formula (b): N=N uptake +N balance (b); Where N represents the recommended amount of nitrogen fertilizer for rice, kg N / ha; N uptake Indicates the nitrogen absorption of rice aboveground parts, kg N / ha; N balance Expresses nitrogen balance standard, kg N / ha.

2. The method according to claim 1, if there is no measured value of the rice straw biomass, it is calculated according to formula (c): AND straw = And grain * a (c) Y straw is the biomass of rice straw, kg / ha; Y grain is the rice grain yield, kg / ha; a is the conversion coefficient between rice grain yield and rice straw biomass, where The conversion factors for different rice varieties are shown in the table below; If there is no measured value for nitrogen absorption by rice grains, it can be calculated according to formula (d): N grain =Y grain * b * 0.001 (d) N grain is the nitrogen absorption of rice grains, kg N / ha; Y grain is the rice grain yield, kg / ha; b is the conversion coefficient between rice grain yield and rice grain nitrogen absorption, where the conversion coefficients of different rice varieties are shown in the table below; If there is no measured value for the nitrogen absorption of rice straw, it can be calculated according to formula (e): N straw = Y straw * c * 0.001 (e) N straw is the nitrogen absorption of rice straw, kg N / ha; Y straw is the biomass of rice straw, kg / ha; c is the conversion coefficient of rice straw biomass and nitrogen absorption of rice straw. The conversion coefficients of different rice varieties are shown in the table below.

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