A simplified method for recommending nitrogen fertilizer dosage for corn based on nitrogen balance standard

Abstract

The present invention discloses a simplified method for recommending nitrogen fertilizer dosages for corn based on a nitrogen balance standard, relating to the field of agricultural resources and environmental technology. This method, based on a nitrogen balance standard, can recommend nitrogen fertilizer dosages for corn using only corn yield and soil fertility level. This method minimizes nitrogen surplus in the soil while ensuring crop yield, thereby reducing the environmental loss of active nitrogen and promoting high-yield, efficient, and sustainable agricultural development.

Description

Technical Field

[0001] The present 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 corn based on a nitrogen balance standard. Background Art

[0002] Corn has a very high planting area and total yield among food crops. A large amount of nitrogen fertilizer is consumed during corn cultivation. However, in general, nitrogen fertilizer is applied excessively during corn cultivation. Excessive application of nitrogen fertilizer leads to increased ammonia volatilization, leaching and runoff losses, exacerbating problems such as air and water pollution.

[0003] Currently, methods for recommending nitrogen fertilizer dosages for crops are primarily based on one or more of soil nutrient testing, fertilizer response functions, and crop or soil models. However, smallholder farmers often lack the resources for soil testing and fertilization, or other scientific fertilization methods. Especially for summer corn, the short interval between harvesting the previous crop and sowing summer corn results in delayed soil testing and analysis results, making it impossible to implement soil testing and fertilization formulas. Consequently, many farmers rely primarily on experience-based fertilization, and irrational fertilization is common. Developing scientifically sound, simple, and rapid fertilization recommendation techniques is urgently needed to promote scientific fertilization in corn. Summary of the Invention

[0004] The purpose of the present invention is to provide a simplified method for recommending nitrogen fertilizer dosage for corn based on nitrogen balance standards, so as to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a method for recommending nitrogen fertilizer dosage for corn based on a nitrogen balance standard, comprising the following steps:

[0007] Step 1): Identify the fertility level of cultivated land soil: In nitrogen fertilizer recommendations, soil fertility is mainly reflected in the soil's nitrogen supply capacity.

[0008] The present invention provides four methods for determining the soil nitrogen supply level:

[0009] Method 1: Determine nitrogen uptake by aboveground maize in the target plot without nitrogen fertilizer application. This method compiles and compiles data from fertilization field trials conducted in major maize-producing regions in China and establishes a database. The top 25%, middle 25%-75%, and bottom 25% of the aboveground maize nitrogen uptake data set (1,315 samples) without nitrogen fertilizer application were used as the criteria for classifying arable land soil nitrogen supply as high, medium, or low (Table 1).

[0010] Method 2: Determine the corn yield of the target plot without nitrogen fertilizer application. Based on the database of Method 1, the top 25%, middle 25%-75%, and bottom 25% of the corn yield dataset without nitrogen fertilizer application are used as the classification criteria for high, medium, and low levels of soil nitrogen supply in cultivated land (Table 2).

[0011] Method 3: If the target plot has soil test results, divide it according to the soil organic matter content (Table 3); specifically:

[0012] The soil nitrogen supply level is based on the soil organic matter content, 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;

[0013] Method 4: Determine based on the apparent properties of the target plot’s soil, such as texture and color (Table 4).

[0014] Table 1

[0015]

[0016] Table 2

[0017]

[0018] Table 3

[0019]

[0020] Table 4

[0021]

[0022] 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 corn yield increment of the target plot treated with nitrogen fertilizer compared to the treatment without nitrogen fertilizer) and the soil apparent nitrogen balance (i.e., the difference between the amount of nitrogen applied and the amount absorbed and removed by corn). On the basis of ensuring corn 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. 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, deep mechanical nitrogen fertilizer application, organic fertilizer application, straw return to the field and other fertilization modes, and then proposes a reference standard for nitrogen balance of different fertilization modes (Table 5). According to the soil nitrogen supply level and nitrogen fertilizer application mode identified in step 1, refer to Table 5 to determine the nitrogen balance standard of the target plot.

[0023] Based on 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.

[0024] Table 5

[0025]

[0026] Step 3) Determine the nitrogen uptake by corn plants in the target plot:

[0027] The nitrogen absorption of corn aboveground plants takes into account the nitrogen absorption of grains and the nitrogen absorption of straw, which can be calculated using formula (1):

[0028] N uptake = N grain + N straw = Y grain * X grain + Y straw * X straw (1)

[0029] Among them, N uptake 、N grain 、N straw represents the nitrogen absorption of aboveground part, nitrogen absorption of corn kernels and nitrogen absorption of corn straw in the target plot (kg N / ha); Y grain and Y straw represent corn grain yield and corn stover biomass (kg / ha), respectively; X grain and X straw They represent the nitrogen content of corn kernels and corn stover (mg / kg), respectively.

[0030] Specifically, Y grain Determined based on the average corn yield of the target plot in the past 3-5 years without biological stress.

[0031] Y straw If there is no measured data, the following formula (2) can be used to obtain:

[0032] Y straw =Y grain * a (2)

[0033] Where a represents the conversion coefficient between corn grain yield and corn straw biomass. The reference value is shown in Table 6.

[0034] X grain If there is no measured data, then N grain Obtained by formula (3):

[0035] N grain = Y grain* b * 0.001 (3)

[0036] Where b represents the conversion coefficient between corn grain yield and corn grain nitrogen absorption. The reference value is shown in Table 6.

[0037] X straw If there is no measured data, then N straw Obtained by formula (4):

[0038] N straw = Y straw * c * 0.001 (4)

[0039] Where c represents the conversion coefficient between corn straw biomass and corn straw nitrogen absorption. The reference value is shown in Table 6.

[0040] Table 6

[0041]

[0042] Step 4) Calculate the nitrogen fertilizer dosage for corn in the target plot: The recommended nitrogen fertilizer dosage is predicted based on the nitrogen absorption of the aboveground part of corn in the target plot and the nitrogen balance standard of cultivated land. The specific amount is obtained by formula (5):

[0043] N=N uptake +N balance (5)

[0044] Wherein, N represents the recommended nitrogen fertilizer dosage for the target plot (kg N / ha); uptake represents the aboveground nitrogen uptake of corn in the target plot (kg N / ha), obtained in step 3); N balance represents the nitrogen balance standard of the target plot (kg N / ha), obtained from steps 1) and 2).

[0045] The present invention's nitrogen fertilizer dosage recommendation method, based on the nitrogen balance standard, is a simplified recommendation method that can be used with or without soil test results. Grassroots agricultural technicians or farmers with a certain level of scientific knowledge only need to understand the corn yield level of the target plot, identify the soil fertility level, and then use a simple calculation process to make scientific and reasonable nitrogen fertilizer recommendations. Compared with existing technologies, this method is more suitable for corn-growing areas where soil testing is not timely, soil testing and fertilization formula are not available, or other fertilization techniques that require professional testing equipment and personnel are not available.

[0046] Compared with the existing technology that only formulates application methods for conventional nitrogen fertilizer products, the present invention not only proposes standard nitrogen balance parameters based on conventional nitrogen fertilizer products and fertilization techniques, but also calibrates parameters for high-efficiency fertilization scenarios such as slow-release fertilizers, deep mechanical nitrogen fertilizer application, organic fertilizer application, and straw return to the field. It is more suitable for the current diverse corn nitrogen fertilizer application scenarios.

[0047] Compared with traditional technologies that mostly directly use corn yield and nitrogen fertilizer application amount to establish a fertilizer effect function and then propose relevant fertilization parameters, the present invention uses yield response and nitrogen balance as indicators to establish a function model. This is because these two indicators are indirect indicators. The yield response is the increase in yield of nitrogen treatment relative to that of no nitrogen treatment, and the yield of no nitrogen treatment represents the soil fertility level of the plot. Therefore, the deviation of recommended fertilization parameters caused by differences in soil fertility levels at different test points is eliminated to the greatest extent. Compared with traditional technologies, the nitrogen fertilizer application amount determined based on the fertilizer effect function is only applicable to the field scale, and the nitrogen balance is the difference between the nitrogen application amount and the nitrogen absorption amount of the crop. Therefore, the nitrogen balance standard proposed in the present invention can realize dynamic decision-making on nitrogen fertilizer application amount based on the difference in crop nitrogen absorption amount, and is more suitable for the regional scale.

[0048] 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.

[0049] The present invention discloses the following technical effects:

[0050] The present invention proposes a method for recommending nitrogen fertilizer dosage for corn based on the nitrogen balance standard. This method only requires understanding the corn yield and soil fertility level to make nitrogen fertilizer dosage recommendations. On the basis of ensuring crop yield, it can minimize the surplus of nitrogen in the soil to the greatest extent, thereby reducing the environmental loss of active nitrogen, thereby promoting high-yield, efficient, sustainable and healthy development of agriculture. DETAILED DESCRIPTION

[0051] 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 rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0052] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0053] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice 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 any conflict with any incorporated document, the contents of this specification shall prevail.

[0054] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0055] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0056] Example 1

[0057] In order to verify the feasibility of applying the nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard to corn, the present invention uses a large amount of field test data from different corn planting season 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.

[0058] Field trials were conducted from 2017 to 2020 across 124 plots in major spring corn-producing regions such as Heilongjiang, Jilin, and Inner Mongolia, and major summer corn-producing provinces such as Hebei and Shanxi. The field trials validated the recommended nitrogen fertilizer rate based on the nitrogen balance standard. The number of trials and regions tested for different fertilization methods are shown in Table 7. Based on the nitrogen uptake of aboveground corn in the no-nitrogen fertilizer treatment (Table 7), the soil nitrogen supply level for each plot was determined using the criteria provided in Table 1 (Table 7). Based on the fertilization method and soil nitrogen supply level for each plot, the nitrogen balance standard for each plot was determined using the criteria provided in Table 5 (Table 8). The measured value of the highest nitrogen uptake by the upper part of the jade in all treatments was used as the target nitrogen uptake. The recommended nitrogen fertilizer rate (OPT) for the plot was predicted using formula (5) and compared with the local farmers' customary nitrogen fertilizer rate (FP), the nitrogen fertilizer rate recommended by local soil testing and formula fertilization (ST), and the nitrogen fertilizer rate recommended by the nutrient expert method (NE) based on the same plot (Table 8).

[0059] Table 7

[0060]

[0061] Table 8

[0062]

[0063] Table 8 summarizes the nitrogen requirements of maize and the recommended rates for the four fertilization methods for different maize planting seasons and soil fertility levels. The results show that across all spring maize plots, the average OPT nitrogen fertilizer rate was 220 kg N / ha, a 6.4% decrease compared to the average FP nitrogen fertilizer rate, but an 8.6%–13.1% increase compared to the ST and NE recommendations. This is due to the lower native nitrogen supply capacity in low-fertility soils, necessitating a higher rate of exogenous nitrogen fertilizer to maintain yield. Across all summer maize plots, the average OPT nitrogen fertilizer rate was 185 kg N / ha, essentially the median of the ST and NE recommendations, and a 20.8% decrease compared to the FP average nitrogen fertilizer rate.

[0064] Overall, the nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard proposed in this invention can significantly reduce the current nitrogen fertilizer usage of farmers, achieving the goal of reducing nitrogen fertilizer usage and increasing efficiency. The recommended results deviate from the two scientific fertilization methods, ST and NE, primarily due to differences in the recommendation principles, but are generally within the upper and lower ranges of the recommended values ​​of the two methods, indicating that the recommended amounts are generally reasonable. Therefore, the field validation test results show that the nitrogen fertilizer dosage recommendation method based on the nitrogen balance standard proposed in this invention can be used for nitrogen fertilizer dosage decisions for corn.

[0065] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A simplified method for recommending nitrogen fertilizer dosage for corn 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: Determine the soil nitrogen supply level of the target plot based on different corn varieties and the nitrogen absorption of the aboveground parts of the corn without nitrogen fertilizer: Method 2: Determine the soil nitrogen supply level of the target plot based on different corn varieties and the corn 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, 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 corn grain yield, determine the nitrogen absorption of the aboveground part of corn 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 uptake by aboveground parts of maize, kg N / ha; N grain is the nitrogen uptake by maize kernels, kg N / ha; N straw is the nitrogen absorption of corn straw, kg N / ha; N uptake =And grain *X grain +Y straw *X straw (a-2) in: N uptake is the nitrogen uptake by aboveground parts of maize, kg N / ha; Y grain is maize grain yield, kg / ha; Y straw is the corn stover biomass, kg / ha; X grain is the nitrogen content of corn kernels, mg / kg; X straw is the nitrogen content of corn straw, mg / kg; (4) Calculate the recommended nitrogen fertilizer dosage for corn in the target plot according to formula (b): N=N uptake +N balance (b); Where N represents the recommended amount of nitrogen fertilizer for corn, kg N / ha; N uptake Indicates the nitrogen absorption of corn aboveground parts, kg N / ha; N balance It represents the nitrogen balance standard, kg N / ha; The corn straw biomass is calculated according to formula (c): AND straw =And grain *a (c) Y straw is the biomass of corn straw, kg / ha; Y grain is the corn grain yield, kg / ha; a is the conversion coefficient between corn grain yield and corn straw biomass. The conversion coefficients of different corn varieties are shown in the following table: The nitrogen absorption of corn kernels was calculated according to formula (d): N grain =Y grain *b*0.001 (d) N grain is the nitrogen absorption of corn kernels, kg N / ha; Y grain is the corn grain yield, kg / ha; b is the conversion coefficient between corn grain yield and corn grain nitrogen absorption. The conversion coefficients of different corn varieties are shown in the following table: The nitrogen absorption of corn straw is calculated according to formula (e): N straw =Y straw *c*0.001 (e) N straw is the nitrogen absorption of corn straw, kg N / ha; Y straw is the corn straw biomass, kg / ha; c is the conversion coefficient between corn straw biomass and corn straw nitrogen absorption. The conversion coefficients of different corn varieties are shown in the following table:

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