Method for determining nitrogen fertilizer application amount of rice

Abstract

The invention relates to the field of agricultural fertilizers, and discloses a method for determining the nitrogen fertilizer application amount of rice. The method comprises the steps that the soil nitrogen supply amount is determined according to the soil texture, the soil CEC content and the soil organic matter content OM of a target rice field; calculating the nitrogen application amount of the target rice field according to the following formula: nitrogen application amount = total nitrogen demand of rice-nitrogen supply amount of soil; wherein the CEC content of the soil is calculated according to the following formula: the CEC content of the soil is equal to C1 / A1 + C2 / A2 + C3 / A3 + SEA. By means of the method, the application amount of the nitrogen fertilizer can be accurately calculated under different soil conditions, it is guaranteed that the rice can obtain enough nitrogen elements, the optimal growth and yield are achieved, meanwhile, excessive application of the nitrogen fertilizer is avoided, and nitrogen emission is reduced.

Description

Technical Field

[0001] The present invention relates to the field of agricultural fertilizers, and particularly to a method for determining the nitrogen fertilizer application rate for rice. Background Art

[0002] Rice is one of the important food crops. Rice has a relatively high demand for nitrogen, because nitrogen is one of the essential nutrients for constructing proteins and promoting crop growth. Nitrogen fertilizer has become the main factor affecting rice yield in rice production, and its importance is second only to water. Increasing rice yield by applying nitrogen fertilizer is also the only way to achieve the super-high-yield goal of rice. However, excessive, insufficient or unreasonable operation of nitrogen fertilizer will affect the production of rice and ultimately affect the yield. Appropriate nitrogen supply is crucial for the growth and development of rice, and can significantly increase the yield and improve the quality of paddy rice.

[0003] Precision quantitative fertilization will be an effective way to improve the quality of the soil environment, reduce water, air and soil pollution, and improve crop yield and quality. Making good use of and managing fertilizer sources is crucial both from an economic perspective and in terms of food production safety, environmental protection, soil and plant health.

[0005] By determining the nitrogen fertilizer application rate required for the target yield, the nitrogen supply of the soil, and the nitrogen utilization rate in the current season, and applying the difference method to reasonably determine the nitrogen fertilizer application rate, is a fertilization measure that needs to be strongly promoted at present. However, for the current calculation of nitrogen fertilizer based on soil testing and formulated fertilization, one is to deduce the nitrogen fertilizer input according to the effective utilization coefficient of soil nutrients or the 3414 experiment. This method has the disadvantages of a long experimental period and large fluctuations in the algorithm of the effective utilization coefficient of nutrients, and requires frequent calibration; the other is to calculate the nitrogen supply of the soil based on the target yield and the basic yield, and then calculate the nitrogen fertilizer input. This method has the disadvantages of requiring a large number of experiments and differences in variety yields in different regions or soil types.

[0006] Therefore, it is crucial to develop a method for determining the nitrogen fertilizer application rate that can overcome the above disadvantages. Summary of the Invention

[0007] The purpose of the present invention is to overcome the above problems existing in the prior art, and provide a method for determining the nitrogen fertilizer application rate for rice. This method can accurately calculate the nitrogen fertilizer application rate under different soil conditions, helps to ensure that rice can obtain sufficient nitrogen elements, achieve the best growth and yield while avoiding excessive application of nitrogen fertilizer and reducing nitrogen emissions.

[0008] As described above, the present invention provides a method for determining the nitrogen fertilizer application rate for rice, and the method includes: calculating the nitrogen application rate of the target paddy field according to Formula I:

[0009] Nitrogen application rate = total nitrogen requirement of rice - nitrogen supply of soil Formula I;

[0010] Among them, the unit of the nitrogen application rate is kg / mu, the unit of the total nitrogen requirement of the rice is kg / mu, and the unit of the soil nitrogen supply is kg / mu; the soil nitrogen supply is obtained according to the soil texture, the soil CEC content and the soil organic matter content of the target paddy field;

[0011] The soil CEC content is calculated according to Equation II:

[0012] Soil CEC content = C 1 / A 1 +C 2 / A 2 +C 3 / A 3 +SEA Equation II;

[0013] Among them, C 1 is the soil available potassium concentration, with the unit of mg / kg, A 1 is the potassium ion conversion factor, which is 390 meq / 100 g; C 2 is the soil available magnesium concentration, with the unit of mg / kg, A 2 is the magnesium ion conversion factor, which is 120 meq / 100 g; C 3 is the soil available calcium concentration, with the unit of mg / kg, A 3 is the calcium ion conversion factor, which is 200 meq / 100 g; SEA is the exchangeable acidity. Define the soil pH value as C 4 , when C 4 > 7, SEA is 0 meq / 100 g; when C 4 ≤ 7, SEA is 12×(7 - C 4 ) meq / 100 g;

[0014] Define the soil organic matter content as OM. The soil nitrogen supply, the soil texture, the soil CEC content and the soil organic matter content satisfy at least one of the following relationships:

[0015] (1) The soil texture is sandy soil, loamy sandy soil and / or sandy loam, and the soil CEC content < 10 meq / 100 g. When OM < 0.5 wt%, the soil nitrogen supply is 1.5 kg / mu; when OM is 0.5 wt% - 1.5 wt%, the soil nitrogen supply is 300×OM kg / mu; when OM > 1.5 wt%, the soil nitrogen supply is 4.5 kg / mu;

[0016] (2) The soil texture is at least one of loam, silt loam, sandy clay loam, and the soil CEC content is 10 - 18 meq / 100g. When OM < 2wt%, the nitrogen supply of the soil is 3 kg / mu; when OM is 2wt% - 4wt%, the nitrogen supply of the soil is 150×OM kg / mu; when OM > 4wt%, the nitrogen supply of the soil is 6 kg / mu;

[0017] (3) The soil texture is at least one of clay loam, silt clay loam, sandy clay, loamy clay, silt clay, clay, heavy clay, and the soil CEC content > 18 meq / 100g. When OM < 2wt%, the nitrogen supply of the soil is 1.5 kg / mu; when OM is 2wt% - 5wt%, the nitrogen supply of the soil is 75×OM kg / mu; when OM > 5wt%, the nitrogen supply of the soil is 3.75 kg / mu.

[0018] In the research process, the inventors of the present invention found that the existing methods for determining nitrogen fertilizer application rates did not fully consider the effects of soil texture, organic matter, and CEC content on nitrogen. Among them, soil texture affects the retention and release ability of nitrogen fertilizer, while CEC content affects the migration and leaching of nitrogen.

[0019] The method provided by the present invention determines the nitrogen fertilizer requirement in crop soil based on different soil textures and soil fertility levels. By using the soil texture, organic matter content, and CEC content obtained in a specific manner of the target paddy field, the soil nitrogen supply is calculated. Then, based on the target yield and the nitrogen requirement per unit of rice (straw and grains), the total nitrogen requirement of rice is calculated. The total nitrogen requirement of rice minus the soil nitrogen supply is the nitrogen application rate required for rice to reach the target yield.

[0020] Through the above technical solutions, the method provided by the present invention has the following advantages:

[0021] 1. The method provided by the present invention comprehensively calculates the nitrogen fertilizer application rate according to the soil texture, soil CEC content, soil organic matter content, and total nitrogen requirement of rice in the target paddy field, avoiding the factors of only focusing on yield or soil in the existing nitrogen fertilizer calculation technology. It helps to ensure that crops can obtain sufficient nitrogen elements to achieve optimal growth and yield, avoid excessive application of nitrogen fertilizer, reduce nitrogen emissions, and avoid waste of energy and resources. By understanding the nitrogen content in the soil, it is possible to plan and manage the use of nitrogen fertilizer more precisely to improve the fertilization efficiency, save costs, and increase income.

[0022] 2. Different soil types have different nitrogen fertilizer requirements. The method provided by the present invention can adapt to different soil types to ensure accurate calculation of nitrogen fertilizer application rates under different soil conditions, which helps to protect the health of soil, water resources, and ecosystems and improve agricultural sustainability.

[0023] In summary, the method provided by the present invention can estimate nitrogen fertilizer input based on different soil textures and soil fertility levels to support crop growth, while reducing over-fertilization and minimizing adverse environmental impacts, contributing to more sustainable agricultural production. Description of the Drawings

[0024] Figure 1 It is a flowchart of a method for determining the nitrogen fertilizer application rate of rice in a specific embodiment of the present invention. Detailed Embodiments

[0025] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0026] In the present invention, the term "CEC" refers to the cation exchange capacity of the soil, which refers to the total amount of various cations adsorbed by the soil that can be exchanged, mainly including H + , K + , Na + , Ca 2+ , Mg 2+ , etc. Its value represents the fertilizer retention capacity of the soil. The larger the cation exchange capacity, the stronger the fertilizer retention capacity of the soil.

[0027] In the present invention, the term "soil texture" includes sandy soil, loam, clay loam, and clay, which refers to the proportion of particles with different particle sizes in the soil. The particles include three categories: clay particles, silt particles, and sand particles, and are usually represented by the proportion of the three.

[0028] In the present invention, the unit "meq / 100g" means milliequivalents of cations adsorbed per 100 g of soil.

[0029] As described above, the present invention provides a method for determining the nitrogen fertilizer application rate of rice, and the method includes: calculating the nitrogen application rate of the target paddy field according to Formula I:

[0030] Nitrogen application rate = total nitrogen requirement of rice - soil nitrogen supply, Formula I;

[0031] Among them, the unit of the nitrogen application rate is kg / mu, the unit of the total nitrogen requirement of rice is kg / mu, and the unit of the soil nitrogen supply is kg / mu; the soil nitrogen supply is obtained according to the soil texture, soil CEC content, and soil organic matter content of the target paddy field;

[0032] The soil CEC content is calculated according to Formula II:

[0033] Soil CEC content = C 1 / A 1 +C 2 / A 2 +C 3 / A 3 + SEA formula II;

[0034] Wherein, C 1 is the available potassium concentration in the soil, with the unit of mg / kg, and A 1 is the potassium ion conversion factor, which is 390 meq / 100g; C 2 is the available magnesium concentration in the soil, with the unit of mg / kg, and A 2 is the magnesium ion conversion factor, which is 120 meq / 100g; C 3 is the available calcium concentration in the soil, with the unit of mg / kg, and A 3 is the calcium ion conversion factor, which is 200 meq / 100g; SEA is the exchangeable acidity, and the soil pH value is defined as C 4 , when C 4 > 7, SEA is 0 meq / 100g; when C 4 ≤ 7, SEA is 12×(7 - C 4 ) meq / 100g;

[0035] Define the soil organic matter content as OM, and at least one of the following relationships is satisfied among the soil nitrogen supply, the soil texture, the soil CEC content, and the soil organic matter content:

[0036] (1) The soil texture is sandy soil, loamy sandy soil and / or sandy loam, and the soil CEC content < 10 meq / 100g. When OM < 0.5 wt%, the soil nitrogen supply is 1.5 kg / mu; when OM is 0.5 wt% - 1.5 wt%, the soil nitrogen supply is 300×OM kg / mu; when OM > 1.5 wt%, the soil nitrogen supply is 4.5 kg / mu;

[0037] (2) The soil texture is at least one of loam, silty loam, sandy clay loam, and the soil CEC content is 10 - 18 meq / 100g. When OM < 2 wt%, the soil nitrogen supply is 3 kg / mu; when OM is 2 wt% - 4 wt%, the soil nitrogen supply is 150×OM kg / mu; when OM > 4 wt%, the soil nitrogen supply is 6 kg / mu;

[0038] (3) The soil texture is at least one of clay loam, silt clay loam, sandy clay, loamy clay, silt clay, clay, and heavy clay, and the soil CEC content > 18 meq / 100g. When OM < 2 wt%, the nitrogen supply of the soil is 1.5 kg / mu; when OM is 2 wt% - 5 wt%, the nitrogen supply of the soil is 75 × OM kg / mu; when OM > 5 wt%, the nitrogen supply of the soil is 3.75 kg / mu.

[0039] According to some embodiments of the present invention, in Formula II, when the soil pH value C 4 ≥ 7, there is no exchangeable acidity, and the soil CEC content is only the sum of the potassium ion exchange capacity, magnesium ion exchange capacity, and calcium ion exchange capacity. Among them, C 1 / A 1 is the potassium ion exchange capacity, C 2 / A 2 is the magnesium ion exchange capacity, C 3 / A 3 is the calcium ion exchange capacity.

[0040] According to some embodiments of the present invention, preferably, based on the total amount of the soil CEC content, the proportion of the calcium ion exchange capacity is 65 - 80%, the proportion of the magnesium ion exchange capacity is 10 - 15%, and the proportion of the potassium ion exchange capacity is 1 - 5%.

[0041] According to some embodiments of the present invention, it is defined that the soil organic matter content is OM, with the unit of wt%, that is, 10 g / kg. It should be noted that in relationship (1), when OM is 0.5 wt% - 1.5 wt%, the nitrogen supply of the soil is 300 × OM kg / mu. For example, when OM is 1 wt%, the corresponding nitrogen supply of the soil is 300 × 0.01 (i.e., 1 wt%) = 3 kg / mu. The calculation relationships in relationships (1), (2), and (3) are defined similarly and will not be elaborated here.

[0042] According to some embodiments of the present invention, preferably, the soil available potassium concentration, the soil available magnesium concentration, and the soil available calcium concentration are measured by the Mehlich3 method, and the Mehlich3 method includes the following steps:

[0043] (a) Contact the soil of the target paddy field with an extractant for mixing, and then filter the mixed product to obtain a filtrate; wherein, the extractant is Mehlich3 reagent;

[0044] (b) Test the element content of the filtrate by an inductively coupled plasma optical emission spectrometer.

[0045] Adopting the above preferred implementation mode, there are many detection indexes and high detection efficiency, which can shorten the detection cycle.

[0046] According to some embodiments of the present invention, preferably, in step (a), the Mehlich3 reagent contains ammonium fluoride, ethylenediaminetetraacetic acid, ammonium nitrate, acetic acid and nitric acid;

[0047] In the Mehlich3 reagent, the concentration of ammonium fluoride is 3.5 - 4 mol / L, the concentration of ethylenediaminetetraacetic acid is 0.2 - 0.3 mol / L, the concentration of ammonium nitrate is 0.2 - 0.3 mol / L, the concentration of acetic acid is 0.15 - 0.25 mol / L, and the concentration of nitric acid is 0.01 - 0.03 mol / L.

[0048] According to some embodiments of the present invention, preferably, in step (a), the dosage ratio of the soil to the extractant is 2 g : 15 - 25 mL.

[0049] According to some embodiments of the present invention, preferably, in step (a), the pH value of the Mehlich3 reagent is 2.4 - 2.6.

[0050] According to some embodiments of the present invention, preferably, in step (b), the concentration w of the available elements in the soil is calculated according to formula III, and the unit is mg / kg:

[0051]

[0052] Wherein, c1 is the mass concentration of the target test element in the sample, and the unit is mg / L; c0 is the mass concentration of the target test element in the blank sample, and the unit is mg / L; V is the volume of the extractant, and the unit is mL; f is the dilution factor of the sample; m is the mass of the soil, and the unit is g; W dm is the dry matter content of the soil, and the unit is wt%.

[0053] According to some embodiments of the present invention, preferably, the total nitrogen requirement of the rice is calculated according to formula IV:

[0054] Total nitrogen requirement of rice = Vm × Nv + Yg × Ng Formula IV;

[0055] Wherein, Vm is the weight of the straw, and the unit is kg / mu; Nv is the nitrogen content of the straw, and the unit is wt% / mu; Yg is the target yield, and the unit is kg / mu; Ng is the nitrogen content of the grain, and the unit is wt% / mu.

[0056] According to some embodiments of the present invention, preferably, the soil texture is obtained according to the international soil texture classification standard.

[0057] According to some embodiments of the present invention, preferably, the variety of the rice is japonica rice and / or indica rice.

[0058] According to some embodiments of the present invention, preferably, the method further includes: obtaining the nitrogen fertilizer application rate of the target paddy field according to the nitrogen application rate and fertilization data; the fertilization data includes fertilizer nutrient content and nitrogen fertilizer utilization rate.

[0059] Figure 1 It is a flowchart of a method for determining the nitrogen fertilizer application rate of rice in a specific embodiment of the present invention.

[0060] The present invention will be described in detail below through examples.

[0061] In the following examples, unless otherwise specified, the raw materials used are commercially available products.

[0062] In the following examples, the relevant parameters were measured by the following methods:

[0063] (1) Soil pH value: Measured by the method of GB / T 27501-2011;

[0064] (2) Soil organic matter content: Measured by the method of GB / T 19656-2006;

[0065] (3) Soil available potassium concentration, soil available magnesium concentration and soil available calcium concentration: Detected by the Mehlich3 (M3) method, specifically as follows:

[0066] S1. Preparation of reagent A: Weigh 138.9 g of ammonium fluoride and add it to 600 mL of deionized water, stir until dissolved, then add 73.5 g of EDTA, stir until dissolved (while stirring, heat in a 95 °C water bath for 15 min to promote dissolution), and then make up to 1000 mL with deionized water to obtain reagent A;

[0067] S2. Preparation of extractant: Add 200.0 g of ammonium nitrate to 6000 mL of deionized water, stir until dissolved, then add 40.0 mL of reagent A, stir, then add 115 mL of acetic acid and 8.25 mL of nitric acid, and make up to 10 L with deionized water to obtain the extractant, whose pH value is 2.50 ± 0.05, and the validity period of this extractant is 6 months;

[0068] S3. Soil sample preservation: Collect and preserve soil samples according to the relevant regulations of HJ / T 166, air-dry naturally, and grind through a 10-mesh sieve;

[0069] S4. Determination of soil dry matter content: Performed according to HJ 613.

[0070] S5. Preparation of soil test samples: Weigh 2.00 g of the sieved soil sample in step S3 into a plastic cup, add 20 mL of extractant, cover it, shake it at a frequency of 180 r / min at room temperature for 5 min ± 30 s, let it stand, filter it with medium-speed quantitative filter paper, and use ICP for determination within 48 h;

[0071] Among them, the instrument parameters and the concentration range of the standard solution are shown in Table 1 (in order to reduce the dilution process, this table formulates the corresponding calibration curve concentration according to the available content of each element in the soil, and the calibration curve concentration can be adjusted accordingly according to the instrument status during the actual detection process):

[0072] Table 1

[0073]

[0074] Calculate the concentration w of the available elements in the soil according to Equation III, with the unit of mg / kg:

[0075]

[0076] Among them, c1 is the mass concentration of the target test element in the sample, with the unit of mg / L; c0 is the mass concentration of the target test element in the blank sample, with the unit of mg / L; V is the volume of the extractant, with the unit of mL; f is the dilution factor of the sample; m is the mass of the soil, with the unit of g; W dm is the dry matter content of the soil, with the unit of wt%.

[0077] Quality control requirements:

[0078] a. Two laboratory blank samples need to be made for each batch of samples, and their determination results should be lower than the determination limit (detection limit * 4);

[0079] b. A standard curve should be established for each analysis, and its correlation coefficient should not be less than 0.999. For every 10 samples or each batch (less than 10 samples / batch) of samples, one calibration point should be analyzed, and the relative deviation between its determination result and the actual concentration value should not be greater than 10%. Otherwise, the reason should be found or the standard curve should be re-established;

[0080] c. At least 10% of each batch of samples should be determined in parallel duplicates. When the number of samples is less than 10, at least one parallel duplicate should be determined, and the relative deviation of the parallel duplicate determination results should not be greater than 20%.

[0081] The following examples are used to illustrate the method provided by the present invention:

[0082] Example 1

[0083] The rice variety is Nanjing 46; the target paddy field is the Wuhu E'qiao Base, with the sampling number WHEQ-T-221231-WMW-005, the plot is H13-1, and the treatment number is H13-AM. The soil data is shown in Table 2:

[0084] Table 2

[0085]

[0086] Table 2 (continued)

[0087] Parameter Available iron Available zinc Available boron Available calcium Available magnesium Available potassium Test method M3 M3 M3 M3 M3 M3 Unit mg / kg mg / kg mg / kg mg / kg mg / kg mg / kg Data 942 2.47 6.96 2120 348 130

[0088] The target yield of the rice is 600 kg / mu, and the grain-straw ratio is 1:1, that is, the straw weight is 600 kg / mu. The nitrogen content of the straw is 0.6 wt%, and the nitrogen content of the grains is 1.3 wt%. Then the total nitrogen requirement of the rice = 600×0.6 wt% + 600×1.3 wt% = 11.4 kg / mu;

[0089] According to the international soil texture classification standard, the soil texture of the target paddy field is silt loam; the soil CEC content calculated according to formula II is 15.14 meq / 100 g;

[0090] The soil nitrogen supply obtained based on the above soil texture, soil CEC content, and soil organic matter content of the target paddy field is 3.27 kg / mu;

[0091] The nitrogen application rate of the target paddy field = total nitrogen requirement of the rice - soil nitrogen supply = 11.4 kg / mu - 3.27 kg / mu = 8.13 kg / mu;

[0092] Calculated at a nitrogen fertilizer utilization rate of 40%, the nitrogen fertilizer application rate of the target paddy field = nitrogen application rate / nitrogen fertilizer utilization rate = 20.325 kg / mu.

[0093] Example 2

[0094] The rice variety is Quanyou 607; the target paddy field is the Wuhu E'qiao Base; its soil data is shown in Table 3:

[0095] Table 3

[0096]

[0097] Table 3 (continued)

[0098] Parameter Available iron Available zinc Available boron Available calcium Available magnesium Available potassium Test method M3 M3 M3 M3 M3 M3 Unit mg / kg mg / kg mg / kg mg / kg mg / kg mg / kg Data 554 2.23 8.29 2030 323 151

[0099] The target yield of rice is 550 kg / mu, and the grain-straw ratio is 1:1, that is, the straw weight is 550 kg / mu. The nitrogen content of the straw is 0.7 wt%, and the nitrogen content of the grain is 1.2 wt%. Then the total nitrogen requirement of this rice = 550×0.7 wt% + 550×1.2 wt% = 10.45 kg / mu;

[0100] According to the international system soil texture classification standard, the soil texture of the target paddy field is silt loam; the soil CEC content calculated according to formula II is 13.59 meq / 100 g;

[0101] The soil nitrogen supply obtained based on the above soil texture, soil CEC content and soil organic matter content of the target paddy field is 3 kg / mu;

[0102] The nitrogen application rate of the target paddy field = total nitrogen requirement of rice - soil nitrogen supply = 10.45 kg / mu - 3 kg / mu = 7.45 kg / mu.

[0103] Calculated at a nitrogen fertilizer utilization rate of 40%, the nitrogen fertilizer application amount of the target paddy field = nitrogen application rate / nitrogen fertilizer utilization rate = 18.63 kg / mu.

[0104] Control Example 1 (soil testing and formulated fertilization calculation method)

[0105] The rice variety is Nanjing 46, and the target paddy field is the Wuhu E'qiao base. The target yield of this variety of rice is 600 kg / mu. The basic yield calculation method is as follows:

[0106] (1) The five conventional soil data (soil pH value, organic matter, hydrolyzable nitrogen, available phosphorus, available potassium) are shown in Table 2.

[0107] (2) Calculate the fertility index of each soil index according to Table 4:

[0108] Table 4

[0109]

[0110] The fertility indexes of each soil index obtained are shown in Table 5:

[0111] Table 5

[0112]

[0113] Note: The fertility index of the soil pH value is the fertility index 1 ; the fertility index of the organic matter is the fertility index 2 ; the fertility index of the hydrolyzable nitrogen is the fertility index 3 ; the fertility index of the available phosphorus is the fertility index 4 ;

[0114] The fertility index of available potassium is the fertility index 5 .

[0115] (3) Calculate the comprehensive fertility index

[0116] Based on multiple soil data of the target paddy field in Table 6, calculate the correlation of each index:

[0117] Table 6

[0118]

[0119] The weights of each soil index obtained are shown in Table 7:

[0120] Table 7

[0121]

[0122]

[0123] Note: The weight of soil pH value is the weight 1 ; the weight of organic matter is the weight 2 ;

[0124] The weight of hydrolyzable nitrogen is the weight 3 ; the weight of available phosphorus is the weight 4 ;

[0125] The weight of available potassium is the weight 5 .

[0126] (4) Obtain the comprehensive fertility index IFI:

[0127] IFI = fertility index 1 * weight 1 + fertility index 2 * weight 2 + fertility index 3 * weight 3 + fertility index 4 * weight 4 + fertility index 5 * weight 5 = 0.77 * 36.8% + 1.0 * 14.1% + 0.11 * 11.3% + 1 * 10.4% + 0.1 * 27.3% = 0.568

[0128] (5) Calculate the basic yield:

[0129] Basic yield = target yield * IFI = 600 * 0.568 = 340.8 kg / mu

[0130] (6) Grain nitrogen content:[[ID=8I]]

[0131] Nitrogen requirement per 100 kg of target grain yield = 2.1 kg / mu

[0132] Nitrogen requirement per 100 kg of basic grain yield = 1.75 kg / mu

[0133] (7) Nitrogen fertilizer utilization rate: Calculated at 40%.

[0134] (8) Calculation of nitrogen application rate:

[0135] Nitrogen application rate = (target yield * nitrogen requirement per 100 kg of target grain yield / 100 - basic yield * nitrogen requirement per 100 kg of basic grain yield) / 0.4 = 16.59 kg / mu.

[0136] Comparative Example 2 (conventional fertilization scheme)

[0137] The rice variety is Nanjing 46, and the target paddy field is Wuhu E'qiao Base; the calculation of nitrogen application rate is as follows:

[0138] Base fertilizer: 15-15-15 compound fertilizer, application rate per mu: 35 kg / mu, the nitrogen content of 15-15-15 compound fertilizer is 15%, so the nitrogen application amount of the base fertilizer is 5.25 kg / mu;

[0139] Tillering fertilizer: Urea, application rate per mu 20 kg / mu, the nitrogen content of urea is 46%, so the nitrogen application amount of the tillering fertilizer is 9.2 kg / mu;

[0140] Panicle fertilizer: Urea, application rate per mu 15 kg / mu, potassium chloride application rate 5 kg / mu, the nitrogen content of urea is 46%, so the nitrogen application amount of the panicle fertilizer is 6.9 kg / mu;

[0141] Thus, the cumulative nitrogen application amount of conventional fertilization is: 5.25 + 9.2 + 6.9 = 21.25 kg / mu.

[0142] Test example

[0143] Based on the nitrogen fertilizer application rates calculated from the examples and comparative examples respectively, and according to the fertilizer formula in Table 8, nitrogen fertilizers were applied in the target paddy fields of the examples and comparative examples respectively. The specific application steps are as follows:

[0144] Base fertilizer: Definition of base fertilizer: It is the fertilizer applied before rice planting, mainly to provide the basic nutrients required for rice growth. Fertilization period: During the land preparation stage before rice planting. In this experiment, the base fertilizer was applied 3 days before rice transplanting; Fertilization method: Spread the fertilizer evenly on the soil surface, and then plow and harrow to make the fertilizer fully mixed with the soil.

[0145] Tillering fertilizer: Definition of tillering fertilizer: It is the fertilizer applied during the rice tillering stage after greening, mainly to promote rice tillering. Fertilization time: Applied 10 days after rice transplanting. Fertilization method: Drone spreading.

[0146] Panicle fertilizer: Definition of panicle fertilizer: Fertilizer applied during the booting stage of rice, mainly to promote the development and formation of rice panicles, increase the grain weight and seed setting rate of rice. Fertilization period: Applied 67 days after rice transplanting. Fertilization method: Broadcasting by drone.

[0147] Table 8 (The nitrogen distribution ratio is the effective nitrogen ratio in the basal fertilizer, tillering fertilizer, and panicle fertilizer, and the sum is the nitrogen fertilizer application rate calculated above)

[0148]

[0149]

[0150] At the maturity stage of rice, the experimental plots are harvested separately, weighed separately, and the moisture content is measured separately. The wet rice yield is obtained on-site and converted into the dry rice yield. The rice yield data of each target paddy field are shown in Table 9:

[0151] Table 9

[0152]

[0153] From the above results, it can be seen that in Example 1 and Comparative Examples 1-2, the yield per mu from high to low is Example 1 > Comparative Example 1 > Comparative Example 2. Compared with the soil testing and formulated fertilization calculation method of Comparative Example 1, the method of Example 1 of the present invention can increase the yield by 5.5% per mu. Compared with the conventional fertilization scheme of Comparative Example 2, the method of Example 1 of the present invention can increase the yield by 9.3% per mu.

[0154] In terms of nitrogen fertilizer input, in Example 1 and Comparative Examples 1-2, the nitrogen fertilizer application rates from high to low are Comparative Example 2 > Example 1 > Comparative Example 1. Compared with the conventional fertilization scheme of Comparative Example 2, the method of Example 1 of the present invention can reduce the nitrogen fertilizer application rate by 0.925 kg / mu, and save 4.35% of nitrogen per mu.

[0155] Thus, it can be seen that the method provided by the present invention can accurately calculate the nitrogen fertilizer application rate under different soil conditions, which helps to ensure that rice can obtain sufficient nitrogen elements to achieve the best growth and yield, while avoiding excessive application of nitrogen fertilizer and reducing nitrogen emissions.

[0156] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for determining the nitrogen fertilizer application rate of rice, characterized in that, The method includes: calculating the nitrogen application rate of the target paddy field according to Formula I: Nitrogen application rate = Total nitrogen requirement of rice - Soil nitrogen supply, Formula I; wherein, the unit of the nitrogen application rate is kg / mu, the unit of the total nitrogen requirement of rice is kg / mu, and the unit of the soil nitrogen supply is kg / mu; the soil nitrogen supply is obtained based on the soil texture, soil CEC content, and soil organic matter content of the target paddy field; The soil CEC content is calculated according to Formula II: Soil CEC content = C 1 / A 1 +C 2 / A 2 +C 3 / A 3 + SEA formula II; Among them, C 1 is the available potassium concentration in soil, with the unit of mg / kg, and A 1 is the potassium ion conversion factor, which is 390 meq / 100 g; C 2 is the available magnesium concentration in soil, with the unit of mg / kg, and A 2 is the magnesium ion conversion factor, which is 120 meq / 100 g; C 3 is the available calcium concentration in soil, with the unit of mg / kg, and A 3 is the calcium ion conversion factor, which is 200 meq / 100 g; SEA is the exchangeable acidity, and the soil pH value is defined as C 4 , when C 4 > 7, SEA is 0 meq / 100 g; when C 4 ≤ 7, SEA is 12×(7 - C 4 ) meq / 100 g; Defining the soil organic matter content as OM, the soil nitrogen supply, the soil texture, the soil CEC content, and the soil organic matter content satisfy at least one of the following relationships: (1) The soil texture is sandy soil, sandy loam, and / or sandy loam, and the soil CEC content < 10 meq / 100g. When OM < 0.5 wt%, the soil nitrogen supply is 1.5 kg / mu; when OM is 0.5 wt% - 1.5 wt%, the soil nitrogen supply is 300×OM kg / mu; when OM > 1.5 wt%, the soil nitrogen supply is 4.5 kg / mu; (2) The soil texture is at least one of loam, silt loam, sandy clay loam, and the soil CEC content is 10 - 18 meq / 100g. When OM < 2 wt%, the soil nitrogen supply is 3 kg / mu; when OM is 2 wt% - 4 wt%, the soil nitrogen supply is 150×OM kg / mu; when OM > 4 wt%, the soil nitrogen supply is 6 kg / mu; (3) The soil texture is at least one of clay loam, silt clay loam, sandy clay, silty clay, silt clay, clay, heavy clay, and the soil CEC content > 18 meq / 100g. When OM < 2 wt%, the soil nitrogen supply is 1.5 kg / mu; when OM is 2 wt% - 5 wt%, the soil nitrogen supply is 75×OM kg / mu; when OM > 5 wt%, the soil nitrogen supply is 3.75 kg / mu.

2. The method according to claim 1, wherein, The soil available potassium concentration, the soil available magnesium concentration, and the soil available calcium concentration are measured by the Mehlich3 method, and the Mehlich3 method includes the following steps: (a) Contact the soil of the target paddy field with an extractant for mixing, and then filter the mixed product to obtain a filtrate; wherein, the extractant is Mehlich3 reagent; (b) Test the element content of the filtrate by an inductively coupled plasma emission spectrometer.

3. The method according to claim 2, wherein In step (a), the Mehlich3 reagent contains ammonium fluoride, ethylenediaminetetraacetic acid, ammonium nitrate, acetic acid, and nitric acid; In the Mehlich3 reagent, the concentration of ammonium fluoride is 3.5 - 4 mol / L, the concentration of ethylenediaminetetraacetic acid is 0.2 - 0.3 mol / L, the concentration of ammonium nitrate is 0.2 - 0.3 mol / L, the concentration of acetic acid is 0.15 - 0.25 mol / L, and the concentration of nitric acid is 0.01 - 0.03 mol / L.

4. The method according to claim 2, wherein, In step (a), the dosage ratio of the soil to the extractant is 2 g : 15 - 25 mL.

5. The method according to claim 2, wherein In step (a), the pH value of the Mehlich3 reagent is 2.4 - 2.

6.

6. The method according to claim 2, wherein, In step (b), calculate the concentration w of the available elements in the soil according to Formula III, with the unit of mg / kg: Among them, c1 is the mass concentration of the target test element in the sample, with the unit of mg / L; c0 is the mass concentration of the target test element in the blank sample, with the unit of mg / L; V is the volume of the leaching agent, with the unit of mL; f is the dilution factor of the sample; m is the mass of the soil, with the unit of g; W dm is the dry matter content of the soil, with the unit of wt%.

7. The method according to any one of claims 1-6, wherein Based on the total amount of the soil CEC content, the proportion of the calcium ion exchange capacity is 65 - 80%, the proportion of the magnesium ion exchange capacity is 10 - 15%, and the proportion of the potassium ion exchange capacity is 1 - 5%.

8. The method according to any one of claims 1-6, wherein, The total nitrogen requirement of the rice is calculated according to Formula IV: Total nitrogen requirement of rice = Vm × Nv + Yg × Ng Formula IV; wherein, Vm is the weight of the straw, with the unit of kg / mu; Nv is the nitrogen content of the straw, with the unit of wt% / mu; Yg is the target yield, with the unit of kg / mu; Ng is the nitrogen content of the grain, with the unit of wt% / mu.

9. The method according to any one of claims 1-6, wherein The soil texture is obtained according to the international soil texture classification standard.

10. The method according to any one of claims 1-6, wherein, The variety of the rice is japonica rice and / or indica rice; Preferably, the method further includes: obtaining the nitrogen fertilizer application rate of the target paddy field according to the nitrogen application rate and the fertilization data; the fertilization data includes the fertilizer nutrient content and the nitrogen fertilizer utilization rate.

Images