A recommended method for peanut nitrogen fertilizer that coordinates yield and biological nitrogen fixation.

Abstract

This invention belongs to the field of agricultural technology, specifically relating to a method for recommending nitrogen fertilizer for peanuts that coordinates yield and biological nitrogen fixation. The method includes determining the agronomic critical nitrogen application rate based on peanut yield and a model showing the relationship between nitrogen application rate and peanut yield; determining the nitrogen inhibition threshold based on peanut root nodule weight, root nodule nitrogenase capacity, and a model showing the relationship between nitrogen application rate and root nodule weight and root nodule nitrogen fixation capacity; and determining the nitrogen fertilizer application rate that is conducive to yield formation and fully utilizing root nodule nitrogen fixation capacity based on the agronomic critical nitrogen application rate and the nitrogen inhibition threshold. This method coordinates yield and biological nitrogen fixation, minimizing problems caused by excessive nitrogen fertilizer application, such as inhibited root nodule nitrogen fixation, decreased nitrogen use efficiency, increased production costs, and environmental pollution.

Description

Technical Field

[0001] This invention belongs to the field of agricultural technology, specifically relating to a recommended method for peanut nitrogen fertilizer that coordinates yield and biological nitrogen fixation. Background Technology

[0002] Peanuts are one of my country's important oilseed crops, playing a crucial role in national economic development and safeguarding national food and oil security. As a legume, nitrogen is one of the most important nutrients for peanuts, primarily sourced from soil nitrogen, fertilizer nitrogen, and root nodule nitrogen fixation. Compared to chemical nitrogen fertilizers, biological nitrogen fixation is a sustainable, pollution-free, inexpensive, and more efficient nitrogen source. While root nodule nitrogen fixation is an important nitrogen source for peanuts, it cannot meet the demands of high-yield cultivation, necessitating the addition of exogenous nitrogen fertilizers. Although nitrogen fertilizer input plays a significant role in increasing yield, high nitrogen levels do not lead to a linear increase in peanut yield. Furthermore, due to the nitrogen repression effect in legumes, excessive exogenous nitrogen strongly inhibits root nodule nitrogen fixation. This inhibition is a major factor limiting the efficient utilization of nitrogen in peanuts, while also leading to negative impacts such as increased production costs and environmental pollution.

[0003] Nitrogen fixation by rhizobia in legumes is a highly energy-intensive process. When large amounts of exogenous nitrogen enter the soil, nitrogen-fixing plants choose less energy-intensive methods to absorb available nitrogen from the soil, strongly inhibiting the symbiotic nodulation nitrogen fixation process. This results in nitrogen repression phenomena such as a decrease in the number and size of nodules and reduced nitrogen fixation activity, ultimately leading to a decrease in the amount of nitrogen fixed by nodules. Appropriate nitrogen levels promote the nitrogen fixation capacity of legumes, reaching maximum nitrogen fixation efficiency. Exceeding this critical threshold leads to inhibition; this critical value is the nitrogen threshold that triggers the nitrogen repression effect.

[0004] Currently, peanut fertilization methods are similar to those of other crops, primarily based on nitrogen requirements conducive to yield formation, i.e., the agronomic critical nitrogen application rate. This neglects the nitrogen sources within the peanut plant and the nitrogen inhibition effect. Consequently, current peanut nitrogen fertilizer application strategies tend to suppress the nitrogen-fixing capacity of peanut root nodules, leading to fertilizer waste, increased production costs, and environmental pollution. A suitable nitrogen application rate should achieve both high peanut yields and fully utilize the peanut's nitrogen-fixing potential. Therefore, this technology, based on the peanut nitrogen inhibition threshold and the agronomic critical nitrogen application rate, develops a recommended nitrogen fertilizer method that coordinates biological nitrogen fixation and yield, providing a method for achieving nitrogen reduction and efficiency improvement in peanuts and creating green, low-carbon peanut cultivation techniques. Summary of the Invention

[0005] The purpose of this invention is to provide a recommended nitrogen fertilizer method for peanuts that coordinates yield and biological nitrogen fixation. This method fully utilizes the nitrogen-fixing capacity of peanut root nodules while achieving high yields.

[0006] The recommended method for coordinating peanut yield and root nodule nitrogen fixation includes: determining the agronomic critical nitrogen application rate based on peanut yield and the relationship between nitrogen application rate and peanut yield.

[0007] Based on peanut root nodule weight, root nodule nitrogen fixation capacity, and the relationship between nitrogen application rate and root nodule nitrogen fixation capacity, the nitrogen inhibition threshold for peanuts was determined. Based on the agronomic critical nitrogen application rate and the nitrogen inhibition threshold, the range of nitrogen fertilizer application rates was determined. Within this range, an appropriate nitrogen application rate was selected based on the variation in yield and root nodule nitrogen fixation capacity.

[0008] The beneficial effects of this invention are as follows:

[0009] This method effectively avoids excessive nitrogen fertilizer application in peanut cultivation. The recommended nitrogen application method balances yield and root nodule nitrogen fixation capacity, minimizing nitrogen inhibition caused by excessive application compared to previous nitrogen fertilizer recommendations that only considered yield. Reducing fertilization can fully utilize peanut's nitrogen fixation capacity, lower production costs, and mitigate environmental pollution, aligning perfectly with my country's goals of prioritizing ecological security and ensuring sustainable agricultural development. Attached Figure Description

[0010] Figure 1 Peanut yield under different nitrogen application rates and the relationship between nitrogen application rate and yield

[0011] Figure 2 Peanut root nodule weight under different nitrogen application rates and the relationship between nitrogen application rate and root nodule weight per plant

[0012] Figure 3 Relationship between nitrogenase activity under different nitrogen application rates and nitrogen application rate and nitrogen fixation capacity of single plant root nodules Detailed Implementation

[0013] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are implemented based on the technical solutions of the present invention, and it should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0014] The experiment was conducted in 2023 at the Jiangsu Academy of Agricultural Sciences experimental field. Five nitrogen application treatments were set up: 0, 45, 90, 135, and 180 kg / hm². -2 Pure nitrogen was labeled N0, N45, N90, N135, and N180, respectively. Each treatment was treated with the same amount of phosphate and potassium fertilizer, 120 kg / hm². -2 Ca(H2PO4)2 and 100 kg hm -2 KCl; each treatment had the same density, 120,000 holes / hm². -2Peanut nodule weight and nitrogenase activity per plant were measured during the pegging and pod-setting stages, and peanut yield was measured after harvest. Nitrogen fixation capacity per plant nodule = nitrogenase activity per nodule * nodule weight per plant. Each treatment was replicated three times in a randomized block design with a plot size of 15 m². 2 .

[0015] (1) Relationship between nitrogen application rate and peanut yield and determination of agronomic critical nitrogen application rate

[0016] Nitrogen application rate affects peanut yield. Under five nitrogen application rate conditions, the nitrogen application rate was 90 kg / hm². -2 Peanut yield was highest at that time. Figure 1 A) The relationship between nitrogen application rate and peanut yield conforms to a quadratic curve model, Y=aX 2 +bX+c; where X is the nitrogen application rate; Y is the peanut yield; and a, b, and c are constants. The relationship between nitrogen application rate X and peanut yield Y established in this experiment is: Y = -0.1161X 2 +23.672X+4106.4 ( Figure 1 B). Under the conditions of this experiment, the maximum theoretical yield of peanuts was 5313.04 kg / hm². -2 The agronomic critical nitrogen application rate is 101.95 kg N hm. -2 (Table 1).

[0017] Table 1. Functional model parameters of nitrogen application rate, single-plant root nodule weight, single-plant root nodule nitrogen fixation capacity, and yield.

[0018]

[0019] (2) Relationship between nitrogen application rate and nitrogen fixation in peanut root nodules and determination of nitrogen inhibition threshold

[0020] The pegging stage is a critical period for both vegetative and reproductive growth, while the pod-setting stage is a critical period for reproductive growth. Therefore, this example mainly analyzes the effects of nitrogen application rate on peanut root nodule formation and nitrogen fixation potential during the pegging and pod-setting stages. The relationships between nitrogen application rate during the pegging and pod-setting stages and the weight of root nodules per plant and the nitrogen fixation capacity per plant both conform to a quadratic curve model, Y=aX. 2 +bX+c; where X is the nitrogen application rate; Y represents the peanut root nodule weight and nitrogen fixation capacity, respectively; a, b, and c are constants. This experiment established a model relating the nitrogen application rate X to the root nodule weight of a single peanut plant, which at the pegging stage is: Y = -0.00006X 2 +0.0076X+0.9939, during the pod-setting stage: Y=-0.00009X 2 +0.011X+1.3659 ( Figure 2The nitrogen fixation capacity of a single peanut plant = nitrogenase activity * root nodule weight per plant. This experiment established a model relating nitrogen application rate (X) to the nitrogen fixation capacity (Y) of peanut root nodules. At the pegging stage, the model was: Y = -0.0122X 2 +1.2035X+224.44, at the pod-setting stage: Y=-0.0141X 2 +1.3515X+273.38 ( Figure 3 ).

[0021] Table 1 shows that the nitrogen application rate suitable for peanut root nodule growth and to fully utilize the nitrogen-fixing capacity of root nodules is significantly lower than the nitrogen application rate suitable for peanut yield formation. Under the conditions of this experiment, the theoretical maximum weight of root nodules per peanut plant during the pegging and pod-setting stages were 1.23 g and 1.70 g, respectively, corresponding to nitrogen application rates of 63.33 kg N hm² and 61.11 kg N hm², respectively. -2 This indicates that the nitrogen application rate exceeded 61.11 kg N / hm. -2 It affects root nodule formation. The theoretical maximum nitrogen fixation capacity of a single peanut plant's root nodules during the pegging and pod-setting stages are 254.12 and 306.17 nmol h, respectively. -1 The corresponding nitrogen application rates were 49.32 and 47.93 kg N hm², respectively. -2 This indicates that the nitrogen application rate exceeded 47.93 kg N hm. -2 The nitrogen inhibition capacity of root nodules was suppressed. Therefore, under the conditions of this experiment, the nitrogen inhibition threshold of peanut was 47.93 kg Nhm. -2 .

[0022] (3) Determine the nitrogen application rate by coordinating peanut yield and root nodule nitrogen fixation capacity.

[0023] Based on the agronomic critical nitrogen application rate and the nitrogen inhibition threshold of peanuts under the conditions of this experiment, it was found that the optimal nitrogen application rate for peanuts that is both beneficial to yield formation and can effectively utilize the nitrogen fixation capacity of root nodules is 47.93 kg N hm². -2 and 101.95 kg N hm -2 between.

[0024] Apply nitrogen at a rate of 40-110 kg / hm². -2 The values ​​were substituted into the above model for single peanut root nodule weight, single root nodule nitrogen fixation capacity, and yield to obtain the corresponding single root nodule weight, single root nodule nitrogen fixation capacity, and yield (Table 2), and the obtained values ​​were compared with the theoretical maximum values ​​(Table 3).

[0025] Table 2. Variation of peanut plant root nodule weight, nitrogen fixation capacity of root nodules, and yield with nitrogen application rate.

[0026]

[0027] Table 3. Weight of root nodules per plant, nitrogen fixation capacity of root nodules per plant, and percentage of yield relative to the theoretical maximum under different nitrogen application rates.

[0028]

[0029] Yield is a crucial indicator in production; therefore, this experiment selected a nitrogen application range where the yield exceeded 98% of the theoretical maximum. To fully utilize the nitrogen-fixing capacity of root nodules, a nitrogen application range was selected where the root nodule weight and nitrogen-fixing capacity per plant both exceeded 90% of the theoretical maximum. Table 3 shows that the optimal nitrogen application rate for peanuts meeting these two conditions is 70–90 kg / hm². -2 The optimal nitrogen application rate for peanuts that achieves high yield while maintaining good nitrogen fixation capacity in root nodules is 90 kg / hm². -2 .

[0030] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A recommended method for peanut nitrogen fertilizer that coordinates yield and biological nitrogen fixation, characterized in that, include: Step 1: Determine the agronomical critical nitrogen application rate based on peanut yield and the functional relationship between nitrogen application rate and peanut yield; the relationship model between nitrogen application rate and peanut yield is: Y=aX 2 +bX+c, where X is the nitrogen application rate; Y is the peanut yield; a, b, and c are constants obtained through field trials; based on the obtained model formula parameters, the theoretical maximum peanut yield and the corresponding nitrogen application rate are calculated, and the nitrogen application rate that forms the maximum yield, i.e., the agronomic critical nitrogen application rate, is obtained. Step 2: Based on the weight of peanut nodules per plant, the activity of nitrogenase in nodules, and the functional relationship between nitrogen application rate and nitrogen fixation capacity of peanut nodules per plant, the nitrogen inhibition threshold is obtained; the nitrogen fixation capacity of peanut nodules per plant = weight of peanut nodules per plant * nitrogenase activity in nodules; the relationship model between nitrogen application rate and the weight of peanut nodules per plant and the nitrogen fixation capacity of peanut nodules per plant is: Y = aX 2 +bX+c, where X is the amount of nitrogen applied; Y is the weight of a single peanut root nodule or the nitrogen fixation capacity of a single peanut root nodule; a, b, and c are constants obtained through field trials; based on the obtained model formula parameters, the theoretical maximum value of the weight of a single peanut root nodule, the nitrogen fixation capacity of a single peanut root nodule, and the corresponding amount of nitrogen applied are calculated, and the amount of nitrogen applied to fully utilize the nitrogen fixation capacity of root nodules, i.e., the nitrogen inhibition threshold, is obtained. Step 3: Based on the relationship model between nitrogen application rate and peanut yield, and the relationship model between nitrogen application rate and peanut nodule weight and peanut nodule nitrogen fixation capacity, calculate the changes in peanut yield, peanut nodule weight, and peanut nodule nitrogen fixation capacity under various nitrogen application rates between the nitrogen inhibition threshold and the agronomic critical nitrogen application rate. Analyze the percentage of the calculated values ​​relative to the theoretical maximum values, and select the appropriate nitrogen application rate that is both conducive to yield formation and fully utilizes the nodule nitrogen fixation capacity based on the range of changes.

2. The recommended method for peanut nitrogen fertilizer that coordinates yield and biological nitrogen fixation according to claim 1, characterized in that, When applying nitrogen fertilizer, a gradient of nitrogen fertilizer application rate should be set.

3. The recommended method for peanut nitrogen fertilizer that coordinates yield and biological nitrogen fixation according to claim 2, characterized in that, When applying nitrogen fertilizer, the same amount of phosphate fertilizer and potassium fertilizer are also applied.

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