A method for improving the utilization of fertilizers and mineral nutrients under different continuous cropping years

Abstract

This invention belongs to the field of agricultural technology, specifically disclosing a method for improving the utilization rate of fertilizers and mineral nutrients under different continuous cropping years. First, soil samples are taken from experimental sites with different continuous cropping years for testing. Then, the experimental sites are furrowed and ridged, and fertilization is carried out according to the adjusted fertilization plan based on conventional fertilization. After fertilization, tobacco seedlings are transplanted. Conventional field management is then carried out on the transplanted experimental fields. Samples are taken for analysis 70-80 days after transplanting to determine the utilization rate of fertilizers and mineral nutrients. This invention optimizes fertilization by reducing nitrogen and increasing potassium, increasing the application of maifanite, applying high-carbon base fertilizer, and using Trichoderma root irrigation. This can increase the accumulation of dry matter and nutrient absorption in various parts of the tobacco plant, significantly improving fertilizer and mineral nutrient utilization rates. It provides a feasible solution for overcoming the obstacles of continuous cropping in tobacco-growing areas, improving the utilization rate of fertilizers and mineral elements, reducing fertilizer application, promoting sustainable tobacco production, and improving the yield and quality of tobacco leaves.

Description

Technical Field

[0001] This invention relates to the field of agricultural technology, specifically to a method for improving the utilization rate of fertilizers and mineral nutrients under different continuous cropping years. Background Technology

[0002] Tobacco is a cash crop that is susceptible to continuous cropping problems, and this problem has become a significant factor restricting the improvement of tobacco yield and quality. Long-term continuous cropping leads to the deterioration of soil properties, imbalance of microbial communities, and decreased soil enzyme activity. Disturbance of the microbial community and soil degradation are the main factors causing crop yield decline. Long-term continuous cropping in tobacco fields results in a sharp decrease in the number of beneficial soil microorganisms such as nitrogen-fixing bacteria and phosphate-solubilizing bacteria, while harmful microorganisms accumulate in large quantities. These harmful microorganisms infect the roots, hindering nutrient absorption and utilization, and have a significant negative impact on soil enzyme activity. Furthermore, long-term continuous cropping causes a sharp decline in the content of nitrogen, phosphorus, and potassium in the soil, while micronutrients such as calcium and magnesium accumulate relatively. This imbalance in nutrient ratios in tobacco plants leads to a decrease in soil organic matter content, resulting in increased pests and diseases, poor growth and development, and reduced yield and quality. Continuous cropping problems in tobacco also inhibit normal plant growth, gradually reduce the maximum leaf area, and decrease the number of leaves. Furthermore, continuous cropping leads to the accumulation of phenolic acids and terpenes secreted by the roots, and increases the solubility of elements such as iron and aluminum, giving tobacco allelopathic autotoxicity and severely affecting root growth. These problems not only directly affect the growth and development of tobacco plants and nutrient absorption, but also significantly reduce the utilization efficiency of fertilizers and mineral nutrients. In agricultural planting, other crops also face the problem of continuous cropping obstacles leading to decreased fertilizer utilization and crop yield and quality.

[0003] Currently, methods to address continuous cropping obstacles mainly include soil improvement, rational crop rotation and intercropping, application of organic fertilizers instead of chemical fertilizers, microbial biological control, and selection of tobacco varieties with strong stress resistance. However, these existing measures all have limitations. For example, soil improvement is difficult to eliminate autotoxic substances secreted by roots; crop rotation is limited by arable land resources and crop types; selecting tobacco varieties with strong stress resistance may lead to a decline in tobacco leaf quality and a long breeding cycle; application of organic fertilizers instead of chemical fertilizers has limited effectiveness against soil-borne diseases; and biological control agents are easily affected by the field environment and have high transportation and storage requirements.

[0004] Currently, there are also publicly reported patent documents related to improving fertilizer utilization efficiency. For example: 1. CN202510363159.8 discloses a technical measure and method for intelligent fertilization to improve fertilizer utilization efficiency. This invention, through precise fertilization, can accurately control the type, amount, and application time of fertilizer according to the growth needs of different crops and soil conditions, ensuring that the fertilizer is efficiently absorbed by the crops, thereby significantly improving fertilizer utilization efficiency. Compared with traditional fertilization methods, this invention can reduce fertilizer waste and lower agricultural production costs. 2. CN 201710412305.7 discloses a fertilizer with added organic matter monoammonium phosphate to improve fertilizer utilization efficiency. This invention alters the growth state of crops and prolongs the nitrogen release time. The urea-encapsulated fertilizer has a more reasonable element ratio than pure urea, which is more conducive to crop absorption and utilization, reduces fertilizer nutrient loss, and improves fertilizer utilization efficiency. Summary of the Invention

[0005] The technical problem this invention aims to solve is the issue of soil degradation and low fertilizer and mineral nutrient utilization rates caused by long-term continuous cropping due to limited land resources in national agriculture. This invention provides a method to improve fertilizer and mineral nutrient utilization rates under different continuous cropping periods. By optimizing fertilization through nitrogen reduction and potassium increase, increased application of maifanite, application of high-carbon base fertilizer, and Trichoderma root irrigation, this invention can increase the accumulation of dry matter and nutrient absorption in various parts of tobacco plants, significantly improving fertilizer and mineral nutrient utilization rates. This provides a feasible solution for reducing fertilizer use in tobacco-growing areas of my country, promoting sustainable tobacco production, and improving tobacco yield and quality.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a method for improving the utilization rate of fertilizers and mineral nutrients under different continuous cropping years, the method comprising the following steps:

[0008] a. First, soil samples were taken and tested from the experimental sites with different continuous cropping years;

[0009] b. Then, the experimental site was dredged and ridged, and the fertilization plan was adjusted based on the conventional fertilization.

[0010] c. Select tobacco seedlings for transplanting;

[0011] d. After transplanting the tobacco seedlings, the experimental field was managed using routine field practices;

[0012] e. Samples were taken and analyzed 70–80 days after the tobacco seedlings were transplanted to determine the utilization rate of fertilizers and mineral nutrients.

[0013] According to the above method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years, the different continuous cropping years mentioned in step a are 1-2 years, 5-6 years, or 10 years of continuous cropping.

[0014] According to the above methods for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years, the sampling in step a is to use the five-point sampling method for random sampling, dig up the topsoil, take soil samples with a soil depth of 5-20cm, remove impurities, air dry naturally, and pass through a 60-mesh sieve.

[0015] The test involves determining the content of available nitrogen (using the alkaline diffusion method), available potassium (using the flame photometry method), and available phosphorus (using the double acid extraction-molybdenum antimony colorimetric method) in the soil after sampling and treatment.

[0016] According to the above method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years, when ridging in step b, the ridge height is controlled to be 15-20cm, the ridge top width to be 40-48cm, the ridge bottom width to be 50-60cm, and the row spacing to be 1.1-1.2m.

[0017] Based on the above methods for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years, the fertilization plan adjusted in step b is as follows: reduce nitrogen by (5-10)% and increase potassium by (5-10)% according to conventional fertilization + (5-20) kg of maifanite per mu (hole application) + high carbon base fertilizer (50-100) kg / mu + Trichoderma root irrigation (1-2) kg / mu.

[0018] According to the above methods for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years, the adjusted fertilization plan is as follows: reduce nitrogen by 10% + increase potassium by 10% + 5 kg of maifanite per mu (applied in holes) + 60 kg of high-carbon base fertilizer per mu + 1 kg of Trichoderma root irrigation per mu; the Trichoderma root irrigation is to dissolve Trichoderma in water and apply it when transplanting tobacco seedlings.

[0019] According to the above methods for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years, the transplanting mentioned in step c is carried out 10 to 15 days after fertilization; the plant spacing is controlled at 0.5 to 0.6 m and the row spacing at 1.1 to 1.2 m during transplanting.

[0020] Based on the above methods for improving fertilizer and mineral nutrient utilization under different continuous cropping years, the sampling and analysis in step e involves: selecting tobacco plants with uniform growth and measuring their plant height, stem circumference, leaf length, and leaf width; taking roots, stems, leaves, and flowers of the tobacco plants and blanching them at 105–110℃ for 15–30 minutes, then balancing the moisture at 55–60℃, and weighing the dry weight of the roots, stems, leaves, and flowers respectively to obtain the dry weight of each organ of the tobacco plant; pulverizing the dry weight of each organ of the tobacco plant, and then determining its total nitrogen content, total potassium content, total phosphorus content, magnesium content, calcium content, and sodium content to obtain the content of each element in each organ of the tobacco plant.

[0021] According to the above method for improving the utilization rate of fertilizers and mineral nutrients under different continuous cropping years, the determination of the utilization rate of each fertilizer and mineral nutrient in step e includes the utilization rate of nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, magnesium, calcium and sodium.

[0022] According to the above methods for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years, the process for determining the nitrogen utilization rate is as follows: first, the nitrogen accumulation is calculated, and then the apparent nitrogen utilization rate and the economic nitrogen utilization rate are calculated.

[0023] The nitrogen accumulation rate (kg / hm) 2 =Total dry weight of all parts of tobacco plant × Total nitrogen content of all parts of tobacco plant;

[0024] The apparent nitrogen utilization rate = (nitrogen accumulation in the whole plant under fertilized treatment - nitrogen accumulation in the whole plant under no-fertilized treatment) / nitrogen application rate × 100%;

[0025] Nitrogen economic utilization rate = (Nitrogen accumulation in fertilized tobacco leaves - Nitrogen accumulation in unfertilized tobacco leaves) / Nitrogen application rate × 100%;

[0026] The nitrogen application rate refers to the nitrogen content in the fertilizer.

[0027] The utilization rates of phosphate fertilizer, potassium fertilizer, magnesium, calcium, and sodium are all measured using the same procedure as those for nitrogen utilization.

[0028] The positive and beneficial effects of this invention are as follows:

[0029] 1. The technical solution of this invention, based on conventional fertilization, involves reducing nitrogen and increasing potassium, applying maifanite, replacing chemical fertilizers with high-carbon base fertilizer, and applying microbial agents (Trichoderma) for root irrigation. Maifanite is a natural composite mineral rich in various trace elements. Due to its good solubility, it can provide tobacco with a variety of beneficial mineral elements, promoting the absorption and utilization of mineral nutrients by tobacco plants. The application of high-carbon base fertilizer promotes the absorption and utilization of nitrogen, phosphorus, and potassium nutrients by tobacco plants, improves the soil's nutrient supply capacity, increases the relative abundance of beneficial bacteria while inhibiting pathogens, and promotes the transformation of nutrients by microorganisms, thereby increasing the forms of nutrients available to plants and thus increasing crop yield. In addition, high-carbon base fertilizer has the ability to adsorb autotoxic substances secreted by roots, reducing the toxicity of phenolic acids to crops. High-carbon base fertilizer also alleviates the obstacles of continuous cropping of tobacco plants by improving the soil environment, promoting tobacco growth, and controlling soil-borne diseases. Trichoderma improves the nutrient utilization rate of tobacco plants by promoting root growth, improving soil microbial communities, and enhancing the root system's ability to absorb nutrients. However, it is easily inactivated in high temperature and high humidity environments and is susceptible to environmental influences. The organic matter in high-carbon fertilizers can provide nutrients for the reproduction of microorganisms, and the network structure of its biochar can prevent soil moisture loss.

[0030] 2. The fertilization scheme of this invention optimizes fertilization by reducing nitrogen and increasing potassium, increasing the application of maifanite, applying high-carbon base fertilizer, and using Trichoderma root irrigation, thereby increasing the accumulation of dry matter and nutrient absorption in all parts of the tobacco plant, significantly improving fertilizer utilization and mineral nutrient utilization, and achieving the best results when continuously cropped for 1-2 years; it provides a feasible solution for reducing the application of chemical fertilizers in tobacco-growing areas of my country, promoting sustainable production in tobacco fields, and improving the yield and quality of tobacco leaves.

[0031] In summary, the technical solution of this invention solves the problems of soil degradation and low utilization rates of fertilizers and mineral nutrients caused by long-term continuous cropping due to limited land resources in my country's agriculture. This technical solution is not only applicable to tobacco but can also be applied to other crops, and it has reference value for my country's large-scale agriculture. Detailed Implementation

[0032] The present invention will be further illustrated below with reference to the embodiments, but this does not limit the scope of protection of the technical solution of the present invention.

[0033] The following embodiments of the present invention were conducted in Yongfeng Town, Luonan County, Shangluo City, Shaanxi Province from April to October 2024. The experimental sites were selected as flat, neat, uniformly fertile plots with medium soil fertility levels. For sloping areas, plots with gentle slopes and small differences in fertility were selected. The experimental sites should avoid special plots such as roads and composting sites. A total of 3 experimental sites were selected (representing 1-2 years of continuous cropping, 5-6 years of continuous cropping, and 10 years of continuous cropping), with an area of ​​about 1.2 mu per plot. The experimental variety was Qinyan 99.

[0034] Two fertilization treatments were set up during the experiment: CK: no fertilization; T1: conventional fertilization; T2: the optimized fertilization scheme of this invention. T1: 50 kg / mu of tobacco-specific fertilizer + 100 kg / mu of organic fertilizer; T2: conventional fertilization with 10% reduction in nitrogen + 10% increase in potassium + 5 kg / mu of maifanite (applied in holes) + 60 kg / mu of high-carbon base fertilizer + 1 kg / mu of Trichoderma root irrigation. Both the tobacco-specific fertilizer and the organic fertilizer were commercially available products. The tobacco-specific fertilizer contained 12% total nitrogen (N), 11% phosphorus (P2O5), and 22% potassium (K2O); the organic fertilizer contained 3% total nitrogen (N), 2.8% phosphorus (P2O5), and 2.3% potassium (K2O); and the high-carbon base fertilizer contained 1.74% total nitrogen (N), 1.28% phosphorus (P2O5), and 0.86% potassium (K2O). The calcium and magnesium contents of tobacco-specific fertilizer are 5% and 3%, respectively; the calcium and magnesium contents of organic fertilizer are 3% and 0.5%, respectively; the calcium and magnesium contents of high-carbon base fertilizer are 5% and 3%, respectively; the main mineral elements contained in maifanite are magnesium, potassium, calcium, and sodium, with contents of 1.05%, 1.65%, 2.50%, and 2.59%, respectively.

[0035] Example 1:

[0036] The method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years according to the present invention comprises the following detailed steps:

[0037] a. Select local plots that have been continuously cropped for 1-2 years as test sites. Randomly sample the selected test sites using the five-point sampling method. Remove the topsoil and take soil samples from a depth of 5-20 cm. Remove impurities, air dry naturally, and pass through a 60-mesh sieve. Then test the treated soil. Use the alkaline diffusion method to determine the alkaline nitrogen content, the flame photometry method to determine the available potassium content, and the double acid extraction-molybdenum antimony colorimetric method to determine the available phosphorus content.

[0038] b. Then, the selected experimental plots were dredged and ridged, and fertilization was adjusted based on conventional fertilization. When ridging, the ridge height was controlled to be 15-20cm, the ridge top width to be 40-48cm, the ridge bottom width to be 55-60cm, and the row spacing to be 1.1-1.2m. The fertilization plan (T2) was: conventional fertilization with 10% reduction in nitrogen + 10% increase in potassium + 5kg of maifanite per mu (applied in holes) + 60kg of high-carbon base fertilizer per mu + 1kg of Trichoderma root irrigation per mu. The Trichoderma root irrigation was done by dissolving Trichoderma in water and applying it when transplanting tobacco seedlings (conventional fertilization T1 and no fertilization CK were used as control groups).

[0039] c. Transplant the tobacco seedlings 10-12 days after fertilization (the tobacco variety is Qinyan 99); when transplanting, control the plant spacing to be 0.5-0.6m and the row spacing to be 1.1-1.2m.

[0040] d. After transplanting the tobacco seedlings, the experimental field was managed using routine field practices;

[0041] e. Seventy-five days after transplanting, select representative tobacco plants with uniform growth at the experimental site. Measure the plant height, stem circumference, leaf length, and leaf width of the selected plants according to the standard YC / T 142-2010 "Methods for Surveying and Measuring Agronomic Traits of Tobacco". In addition, the roots, stems, leaves, and flowers of the tobacco plants are blanched at 105℃ for 30 minutes, then balanced at 60℃. The dry weight of the roots, stems, leaves, and flowers is measured separately to obtain the dry weight of each organ of the tobacco plant. The dry weight of each organ is then pulverized, and the total nitrogen, total potassium, total phosphorus, magnesium, calcium, and sodium contents are determined to obtain the content of each element in each organ of the tobacco plant. Simultaneously, the same tests are performed on tobacco plants in both conventionally fertilized and unfertilized areas.

[0042] Then, based on the dry weight of each organ of the tobacco plant and the content of each element in each organ of the tobacco plant, the utilization rates of nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, magnesium, calcium and sodium are calculated.

[0043] The process for determining nitrogen utilization rate is as follows: first, the nitrogen accumulation is calculated, and then the apparent nitrogen utilization rate and the economic nitrogen utilization rate are calculated.

[0044] The nitrogen accumulation (kg / hm) 2 = Total dry weight of all parts of the tobacco plant × Total nitrogen content of all parts of the tobacco plant;

[0045] The apparent nitrogen utilization rate = (nitrogen accumulation in the whole plant under fertilized treatment - nitrogen accumulation in the whole plant under no-fertilized treatment) / nitrogen application rate × 100%;

[0046] Nitrogen economic utilization rate = (Nitrogen accumulation in fertilized tobacco leaves - Nitrogen accumulation in unfertilized tobacco leaves) / Nitrogen application rate × 100%;

[0047] The nitrogen application rate refers to the nitrogen content in the fertilizer.

[0048] The utilization rates of phosphate fertilizer, potassium fertilizer, magnesium, calcium, and sodium are all measured using the same procedure as those for nitrogen utilization.

[0049] Example 2:

[0050] The method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years of the present invention is basically the same as that in Example 1, except that:

[0051] In step a: Select a plot of land in the local area that has been continuously cropped for 5-6 years as the test site.

[0052] Example 3:

[0053] The method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years of the present invention is basically the same as that in Example 1, except that:

[0054] In step a: Select a plot of land in the local area that has been continuously cropped for 10 years as the test site.

[0055] The data obtained from the detection in Examples 1-3 of this invention and the data analysis process are as follows:

[0056] 1. The contents of basic available nitrogen, available phosphorus and available potassium in the soil under different continuous cropping years are shown in Table 1.

[0057] Table 1. Detection data of basic soil nutrient content under different continuous cropping years in Examples 1-3 of the present invention.

[0058] .

[0059] As shown in Table 1, with the increase of continuous cropping years, the content of available nitrogen in the soil gradually decreased, while the content of available phosphorus first increased and then decreased, with significant variations. The content of available phosphorus was highest after 5-6 years of continuous cropping (40.68 mg / kg). Under different continuous cropping years, the content of available potassium did not change significantly.

[0060] 2. Effects of different fertilization treatments on the agronomic traits of Qinyan 99 under different continuous cropping years:

[0061] The effects of different fertilization treatments on the agronomic traits of Qinyan 99 under different continuous cropping years are detailed in Table 2.

[0062] Table 2. Effects of different treatments on the agronomic traits of Qinyan 99 under different continuous cropping years.

[0063] .

[0064] As shown in Table 2, under the same continuous cropping years, the maximum leaf length, leaf width, plant height, and stem circumference of tobacco plants treated with T2 (the fertilization scheme of this invention) were superior to those treated with T1 (conventional fertilization). Under 1-2 years of continuous cropping, the maximum leaf length of the T2 treatment increased by 11.1%, leaf width by 20.06%, plant height by 4.5%, and stem circumference by 4.5% compared to the T1 treatment, and these increases were significantly higher than the control (CK). However, under 5-6 years of continuous cropping, there were no significant differences in leaf length, leaf width, and stem circumference between the different fertilization treatments and the CK. Under 10 years of continuous cropping, leaf width, plant height, and stem circumference were significantly higher than the CK, while the maximum leaf length was not significantly different from the CK. The experimental results indicate that the optimized fertilization of this invention (T2 treatment) can increase the maximum leaf length, leaf width, plant height, and stem circumference of tobacco plants compared to conventional fertilization (T1 treatment), with significant effects under 1-2 years of continuous cropping; while under 5-6 years and 10 years of continuous cropping, there were no significant differences in maximum leaf length, leaf width, plant height, and stem circumference among the different treatments.

[0065] 3. Effects of different continuous cropping years and different fertilization treatments on the dry weight of Qinyan 99:

[0066] Table 3 shows the dry weight data of tobacco plants under different fertilization treatments 75 days after transplanting.

[0067] Table 3. Dry weight of tobacco plants under different continuous cropping years and different fertilization treatments

[0068] .

[0069] The data in Table 3 show that, under the same number of consecutive cropping years, the dry weights of roots, stems, leaves, and flowers under the optimized fertilization treatment T2 of this invention were all greater than those under the T1 treatment, and showed significant differences from the control (CK). Under the same fertilization treatment, the tobacco leaf dry weight was highest under the T2 treatment after 1-2 years of continuous cropping, followed by 5-6 years. Under different number of consecutive cropping years, the T2 treatment had the most significant effect on root dry weight, followed by stem dry weight. These results indicate that the optimized fertilization treatment T2 of this invention significantly increased the dry weight of tobacco plants, significantly increased the dry weight of tobacco roots, and allowed tobacco plants to accumulate more nutrients, with the best effect observed during 1-2 years of continuous cropping.

[0070] 4. Fertilizer utilization rate

[0071] 4.1 Nitrogen utilization rate:

[0072] The calculation data related to nitrogen utilization under different treatments are shown in Table 4.

[0073] Table 4. Nitrogen utilization rate under different treatments (75 days after transplanting)

[0074] .

[0075] Table 4 shows the effects of different fertilization treatments on nitrogen use efficiency in tobacco plants. Under the same continuous cropping duration, nitrogen accumulation in treatment T2 was higher than in treatments T1 and the control (CK). With increasing continuous cropping duration, nitrogen accumulation in treatment T1 decreased, while nitrogen accumulation in treatment T2 remained relatively stable. Under the same continuous cropping duration, the apparent nitrogen use efficiency and economic utilization rate of tobacco plants under treatment T2 were higher than those under treatment T1. Specifically, under 1-2 years of continuous cropping, the apparent nitrogen use efficiency of treatment T2 was 3.28% higher than that of treatment T1; under 5-6 years of continuous cropping, the apparent nitrogen use efficiency of treatment T2 was 6.79% higher than that of treatment T1; and under 10 years of continuous cropping, the apparent nitrogen use efficiency of treatment T2 was 2.44% higher than that of treatment T1. Under the same fertilization conditions, under 1-2 years of continuous cropping, the apparent nitrogen use efficiency of treatment T2 was 0.36% higher than that under 5-6 years of continuous cropping and 6.90% higher than that under 10 years of continuous cropping. Furthermore, under continuous cropping conditions of 1-2 years, the nitrogen economic utilization rate of the T2 treatment was 3.83% higher than that of the T1 treatment; under continuous cropping conditions of 5-6 years, the nitrogen economic utilization rate of the T2 treatment was 3.88% higher than that of the T1 treatment; and under continuous cropping conditions of 10 years, the nitrogen economic utilization rate of the T2 treatment was 0.31% higher than that of the T1 treatment. These results indicate that the optimized fertilization method of this invention (T2 treatment) can increase nitrogen accumulation in tobacco plants and improve both apparent and economic nitrogen utilization rates compared to conventional fertilization (T1 treatment). While both apparent and economic nitrogen utilization rates decreased with increasing continuous cropping years, the optimized fertilization scheme of this invention (T2 treatment) showed higher apparent and economic nitrogen utilization rates than conventional fertilization (T1 treatment). Among these, the optimized fertilization scheme of this invention (T2 treatment) exhibited the highest apparent and economic nitrogen utilization rates under continuous cropping conditions of 1-2 years.

[0076] 4.2 Phosphorus utilization rate:

[0077] Table 5 shows the relevant calculation data of phosphorus utilization rate under different treatments.

[0078] Table 5. Phosphorus utilization rate under different treatments (75 days after transplanting)

[0079] .

[0080] Table 5 shows the effects of different fertilization treatments on phosphorus utilization in tobacco plants. Under the same continuous cropping duration, the phosphorus accumulation in treatment T2 was higher than that in treatments T1 and the control (CK). With increasing continuous cropping duration, phosphorus accumulation in treatment T1 first decreased and then increased, while phosphorus accumulation in treatment T2 remained relatively stable. Under the same continuous cropping duration, the apparent and economic phosphorus utilization rates in treatment T2 were higher than those in treatment T1. Specifically, under 1-2 years of continuous cropping, the apparent phosphorus utilization rate in treatment T2 was 4.18% higher than that in treatment T1; under 5-6 years of continuous cropping, the apparent phosphorus utilization rate in treatment T2 was 7.11% higher than that in treatment T1; and under 10 years of continuous cropping, the apparent phosphorus utilization rate in treatment T2 was 1.49% higher than that in treatment T1. Under the same fertilization conditions, under 1-2 years of continuous cropping, the apparent phosphorus utilization rate in treatment T2 increased by 4.83% compared to 5-6 years and by 4.75% compared to 10 years. Furthermore, under continuous cropping conditions of 1-2 years, the T2 treatment showed a 5.31% increase in phosphorus economic utilization rate compared to the T1 treatment; under continuous cropping conditions of 5-6 years, the T2 treatment showed a 6.46% increase; and under continuous cropping conditions of 10 years, the T2 treatment showed a 1.34% increase. These results indicate that the optimized fertilization scheme of this invention (T2 treatment) can increase phosphorus accumulation in tobacco plants and improve both apparent and economic phosphorus utilization rates compared to conventional fertilization (T1 treatment). While the apparent and economic phosphorus utilization rates initially decreased and then increased with increasing continuous cropping years, the optimized fertilization scheme of this invention (T2 treatment) consistently showed higher levels of both apparent and economic phosphorus utilization rates than conventional fertilization (T1 treatment).

[0081] 4.3 Potassium utilization rate:

[0082] Table 6 shows the relevant calculation data of potassium utilization rate under different treatments.

[0083] Table 6 Potassium utilization rate under different treatments (75 days after transplanting)

[0084] .

[0085] Table 6 shows the effects of different fertilization treatments on potassium utilization in tobacco plants. Under the same continuous cropping duration, the potassium accumulation in treatment T2 was higher than that in treatments T1 and CK. However, with increasing continuous cropping duration, the potassium accumulation in both treatments T1 and T2 decreased. Under the same continuous cropping duration, the apparent and economic potassium utilization rates of tobacco plants under treatment T2 were higher than those under treatment T1. Specifically, under 1-2 years of continuous cropping, the apparent potassium utilization rate of treatment T2 was 17.59% higher than that of treatment T1; under 5-6 years of continuous cropping, the apparent potassium utilization rate of treatment T2 was 14.24% higher than that of treatment T1; and under 10 years of continuous cropping, the apparent potassium utilization rate of treatment T2 was 16.5% higher than that of treatment T1. Under the same fertilization conditions, under 1-2 years of continuous cropping, the apparent potassium utilization rate of treatment T2 increased by 6.73% compared to 5-6 years of continuous cropping and by 5.29% compared to 10 years of continuous cropping. Furthermore, under continuous cropping conditions of 1-2 years, the T2 treatment showed a 9.01% increase in potassium economic utilization rate compared to the T1 treatment; under continuous cropping conditions of 5-6 years, the T2 treatment showed a 7.45% increase; and under continuous cropping conditions of 10 years, the T2 treatment showed a 7.00% increase. These results indicate that the optimized fertilization scheme of this invention (T2 treatment) can increase potassium accumulation in tobacco plants and improve both apparent and economic potassium utilization rates compared to conventional fertilization (T1 treatment). The optimized fertilization scheme (T2 treatment) showed the highest apparent and economic potassium utilization rates under continuous cropping conditions of 1-2 years. With increasing continuous cropping years, both apparent and economic potassium utilization rates under conventional fertilization (T1 treatment) showed a decreasing trend. The apparent utilization rate of the optimized fertilization scheme (T2 treatment) of this invention initially decreased and then increased. However, the apparent and economic phosphorus utilization rates of the optimized fertilization scheme (T2 treatment) of this invention were higher than those under conventional fertilization (T1 treatment).

[0086] 4.4 Utilization rate of magnesium element in mineral nutrients:

[0087] Table 7 shows the relevant calculation data of magnesium utilization rate under different treatments.

[0088] Table 7 Magnesium utilization rate under different treatments (75 days after transplanting)

[0089] .

[0090] Table 7 shows the effects of different fertilization treatments on magnesium utilization in tobacco plants. Under the same continuous cropping duration, the magnesium accumulation in treatment T2 was higher than that in treatments T1 and the control (CK). With increasing continuous cropping duration, the magnesium accumulation in treatment T1 decreased, while that in treatment T2 first decreased and then increased. Under the same continuous cropping duration, the apparent and economic utilization rates of magnesium in tobacco plants under treatment T2 were higher than those under treatment T1. Specifically, under 1-2 years of continuous cropping, the apparent magnesium utilization rate of treatment T2 was 8.03% higher than that of treatment T1; under 5-6 years of continuous cropping, the apparent magnesium utilization rate of treatment T2 was 8.09% higher than that of treatment T1; and under 10 years of continuous cropping, the apparent magnesium utilization rate of treatment T2 was 6.62% higher than that of treatment T1. Under the same fertilization conditions, under 1-2 years of continuous cropping, the apparent magnesium utilization rate of treatment T2 increased by 5.82% compared to 5-6 years of continuous cropping and by 4.60% compared to 10 years of continuous cropping. Furthermore, under continuous cropping conditions of 1-2 years, the T2 treatment showed a 4.99% higher economic utilization rate of magnesium compared to the T1 treatment; under continuous cropping conditions of 5-6 years, the T2 treatment showed a 5.93% higher economic utilization rate of magnesium compared to the T1 treatment; and under continuous cropping conditions of 10 years, the T2 treatment showed a 4.31% higher economic utilization rate of magnesium compared to the T1 treatment. These results indicate that the optimized fertilization scheme of this invention (T2 treatment) can increase the accumulation of magnesium in tobacco plants compared to conventional fertilization (T1 treatment), thereby improving the apparent and economic utilization rates of magnesium. Among these, the optimized fertilization scheme (T2 treatment) showed the highest apparent and economic utilization rates of magnesium under the 1-2 year continuous cropping conditions. With increasing continuous cropping years, the apparent utilization rates of magnesium under both conventional fertilization (T1 treatment) and the optimized fertilization scheme of this invention (T2 treatment) showed a trend of first decreasing and then increasing; however, the apparent and economic utilization rates of magnesium under the optimized fertilization scheme of this invention (T2 treatment) were both higher than those under conventional fertilization (T1 treatment).

[0091] 4.5 Calcium utilization rate of mineral nutrients:

[0092] Table 8 shows the relevant calculation data of calcium utilization rate under different treatments.

[0093] Table 8. Calcium utilization rate under different treatments (75 days after transplanting)

[0094] .

[0095] As shown in Table 8, under the same continuous cropping years, the calcium accumulation in treatment T2 was higher than that in treatments T1 and CK. With increasing continuous cropping years, the calcium accumulation in treatment T1 increased, while that in treatment T2 first decreased and then increased. Under the same continuous cropping years, the apparent and economic utilization rates of calcium in tobacco plants under treatment T2 were higher than those under treatment T1. Specifically, under 1-2 years of continuous cropping, the apparent calcium utilization rate in treatment T2 was 13.35% higher than that in treatment T1; under 5-6 years of continuous cropping, the apparent calcium utilization rate in treatment T2 was 9.95% higher than that in treatment T1; and under 10 years of continuous cropping, the apparent calcium utilization rate in treatment T2 was 10.09% higher than that in treatment T1. Under the same fertilization conditions, under 1-2 years of continuous cropping, the apparent calcium utilization rate in treatment T2 increased by 6.29% compared to 5-6 years and by 1.33% compared to 10 years of continuous cropping. Furthermore, under continuous cropping conditions of 1-2 years, the T2 treatment showed an 8.89% higher economic utilization rate of calcium compared to the T1 treatment; under continuous cropping conditions of 5-6 years, the T2 treatment showed a 7.44% higher economic utilization rate of calcium compared to the T1 treatment; and under continuous cropping conditions of 10 years, the T2 treatment showed a 5.23% higher economic utilization rate of calcium compared to the T1 treatment. These results indicate that the optimized fertilization scheme of this invention (T2 treatment) can increase the accumulation of calcium in tobacco plants compared to conventional fertilization (T1 treatment), thereby improving the apparent and economic utilization rates of calcium. Among these, the optimized fertilization scheme (T2 treatment) showed the highest apparent and economic utilization rates of calcium under continuous cropping conditions of 1-2 years. With increasing continuous cropping years, the apparent utilization rates of calcium under both conventional fertilization (T1 treatment) and the optimized fertilization scheme of this invention (T2 treatment) showed a trend of first decreasing and then increasing; however, the apparent and economic utilization rates of calcium under the optimized fertilization scheme of this invention (T2 treatment) were both higher than those under conventional fertilization (T1 treatment).

[0096] 4.6 Sodium utilization rate of mineral nutrients:

[0097] The relevant calculation data of sodium element utilization under different treatments are shown in Table 9.

[0098] Table 9. Sodium utilization rate under different treatments (75 days after transplanting)

[0099] .

[0100] As shown in Table 9, under the same continuous cropping years, the sodium accumulation in treatment T2 was higher than that in treatments T1 and CK. With increasing continuous cropping years, the sodium accumulation in both treatments T1 and T2 decreased. Under the same continuous cropping years, the apparent sodium utilization rate and economic utilization rate of tobacco plants under treatment T2 were higher than those under treatment T1. Specifically, under 1-2 years of continuous cropping, the apparent sodium utilization rate of treatment T2 was 7.59 percentage points higher than that of treatment T1 (an increase of 41.29%); under 5-6 years of continuous cropping, the apparent sodium utilization rate of treatment T2 was 10.02% higher than that of treatment T1; and under 10 years of continuous cropping, the apparent sodium utilization rate of treatment T2 was 10.91% higher than that of treatment T1. Under the same fertilization conditions, under 1-2 years of continuous cropping, the apparent sodium utilization rate of treatment T2 increased by 1.28% compared to 5-6 years and by 1.48% compared to 10 years. Furthermore, under continuous cropping conditions of 1-2 years, the T2 treatment showed a 2.00% increase in sodium economic utilization rate compared to the T1 treatment; under continuous cropping conditions of 5-6 years, the T2 treatment showed a 2.35% increase; and under continuous cropping conditions of 10 years, the T2 treatment showed a 2.05% increase. These results indicate that the optimized fertilization scheme of this invention (T2 treatment) can increase sodium accumulation in tobacco plants compared to conventional fertilization (T1 treatment), thereby improving the apparent and economic utilization rates of sodium. Among these, the optimized fertilization scheme of this invention (T2 treatment) showed the highest apparent and economic utilization rates of sodium under continuous cropping conditions of 1-2 years. While both apparent and economic utilization rates of sodium decreased with increasing continuous cropping years, the optimized fertilization scheme of this invention (T2 treatment) still showed higher apparent and economic utilization rates of sodium than conventional fertilization (T1 treatment). Among these, the optimized fertilization scheme (T2 treatment) showed the highest apparent and economic utilization rates of sodium under continuous cropping conditions of 1-2 years.

[0101] In summary, this invention, using Qinyan 99 as the test variety, analyzed the effects of different continuous cropping years and different fertilization treatments on the agronomic traits, fertilizer utilization rate, and mineral nutrient utilization rate of flue-cured tobacco in Luonan area. It revealed the influence of continuous cropping obstacles and optimized fertilization on nutrient utilization rate and nutrient absorption by tobacco plants. The results showed that the optimized fertilization scheme of this invention can significantly improve fertilizer utilization rate and mineral nutrient utilization rate by increasing the dry weight of tobacco plants and nutrient accumulation, and this effect is most significant when continuous cropping lasts for 1-2 years.

[0102] The impact of the optimized fertilization scheme of this invention on fertilizer utilization: Compared with conventional fertilization, the optimized fertilization scheme of this invention improved the apparent and economic utilization rates of nitrogen, phosphorus, and potassium. Among these, potassium utilization was significantly improved. After 1-2 years of continuous cropping, the apparent potassium utilization rate of treatment T2 was 17.59% higher than that of treatment T1, due to the increased potassium content in tobacco leaves from the increased potassium fertilizer application. Furthermore, the optimized fertilization scheme of this invention promoted soil nitrogen transformation and utilization by rationally reducing nitrogen fertilizer, thereby enhancing the root vitality of flue-cured tobacco and reducing nitrogen loss. High-carbon base fertilizer and Trichoderma are another important reason for the improved fertilizer utilization rate in the optimized fertilization scheme of this invention. After the application of high-carbon base fertilizer, the absorption and utilization of nitrogen, phosphorus, and potassium nutrients by tobacco plants were promoted by improving the agronomic traits and dry weight of various parts of the plant. It also had a synergistic effect with Trichoderma, improving the soil microbial community and enhancing the root system's ability to absorb nutrients, thus improving the absorption of fertilizer by tobacco plants.

[0103] The impact of the optimized fertilization scheme of this invention on the utilization rate of mineral nutrients: Experiments of this invention showed that the utilization rates of calcium, magnesium, and sodium elements in the optimized fertilization scheme were all higher than those of conventional fertilization treatments, with the best results observed after 1-2 years of continuous cropping. The maifanite added to the optimized fertilization scheme of this invention not only improves the root growth environment but also contains abundant mineral elements that can directly participate in plant metabolism, enhance root vitality, and thus improve the absorption efficiency of mineral nutrients. In the experiments of this invention, the apparent utilization rates of calcium and magnesium elements were lowest after 5-6 years of continuous cropping. This may be because the soil nutrient utilization coefficient is low after 5-6 years of continuous cropping. In the early stages of continuous cropping, the tobacco plants have a strong ability to absorb nutrients, leading to a gradual decrease in soil nutrient content. As the continuous cropping time increases, the ability of tobacco roots to absorb nutrients is limited, and the ability of microorganisms to decompose organic matter is hindered, resulting in a decrease in the soil nutrient utilization coefficient. After 10 years of continuous cropping, the root system's adaptability gradually recovers, the microbial community gradually optimizes, and the activity of certain enzymes rebounds, leading to an increase in the soil nutrient utilization coefficient.

[0104] Therefore, the fertilization scheme of this invention optimizes fertilization by reducing nitrogen and increasing potassium, increasing the application of maifanite, applying high-carbon base fertilizer, and using Trichoderma root irrigation. This can increase the accumulation of dry matter and nutrient absorption in all parts of the tobacco plant, significantly improving fertilizer and mineral nutrient utilization rates, with the best results observed during 1-2 years of continuous cropping. This provides a feasible solution to overcome the obstacles of continuous cropping in tobacco-growing areas, improve fertilizer and mineral element utilization, reduce chemical fertilizer application, promote sustainable tobacco production, and enhance the yield and quality of tobacco leaves.

Claims

1. A method for improving the utilization of fertilizers and mineral nutrients in different continuous cropping years, characterized by, The method includes the following steps: a. First, soil samples were taken and tested from the experimental sites with different continuous cropping years; b. Then, the experimental site was dredged and ridged, and the fertilization plan was adjusted based on the conventional fertilization. c. Select tobacco seedlings for transplanting; d. After transplanting the tobacco seedlings, the experimental field was managed using routine field practices; e. Samples were taken and analyzed 70–80 days after the tobacco seedlings were transplanted to determine the utilization rate of fertilizers and mineral nutrients.

2. The method of improving the use efficiency of fertilizers and mineral nutrients in different continuous cropping years according to claim 1, characterized in that: The different consecutive cropping periods mentioned in step a are 1-2 years, 5-6 years, or 10 years of continuous cropping.

3. The method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years according to claim 1, characterized in that: The sampling described in step a involves random sampling using a five-point sampling method. The topsoil is removed, and soil samples are taken from a depth of 5 to 20 cm. Impurities are removed, the soil is air-dried naturally, and then passed through a 60-mesh sieve. The test measures the content of available nitrogen, available potassium, and available phosphorus in the soil after sampling and treatment.

4. The method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years according to claim 1, characterized in that: When ridging in step b, the ridge height should be controlled to be 15-20cm, the ridge top width to be 40-48cm, the ridge bottom width to be 50-60cm, and the row spacing to be 1.1-1.2m.

5. The method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years according to claim 1, characterized in that, The fertilization plan adjusted in step b is as follows: reduce nitrogen by (5-10)% and increase potassium by (5-10)% according to conventional fertilization + increase by (5-20) kg of maifanite per mu + increase high carbon base fertilizer by (50-100) kg per mu + irrigate the roots with Trichoderma by (1-2) kg per mu.

6. The method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years according to claim 5, characterized in that, The adjusted fertilization plan is as follows: reduce nitrogen by 10% and increase potassium by 10% according to conventional fertilization, add 5 kg of maifanite per mu, add 60 kg of high-carbon base fertilizer per mu, and add 1 kg of Trichoderma root irrigation per mu; the Trichoderma root irrigation is to dissolve Trichoderma in water and apply it when transplanting tobacco seedlings.

7. The method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years according to claim 1, characterized in that: The transplanting described in step c is carried out 10 to 15 days after fertilization; the plant spacing is controlled at 0.5 to 0.6 m and the row spacing at 1.1 to 1.2 m.

8. The method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years according to claim 1, characterized in that, The sampling and analysis described in step e are as follows: Select tobacco plants with uniform growth and measure their plant height, stem circumference, leaf length, and leaf width; take roots, stems, leaves, and flowers of the tobacco plants and blanch them at 105-110℃ for 15-30 minutes, then balance the moisture at 55-60℃, and weigh the dry weight of the roots, stems, leaves, and flowers respectively to obtain the dry weight of each organ of the tobacco plant; pulverize the dry weight of each organ of the tobacco plant, and then determine its total nitrogen content, total potassium content, total phosphorus content, magnesium content, calcium content, and sodium content to obtain the content of each element in each organ of the tobacco plant.

9. The method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years according to claim 8, characterized in that: The determination of the utilization rate of each fertilizer and mineral nutrient in step e includes the utilization rate of nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, magnesium, calcium and sodium.

10. The method for improving the utilization rate of fertilizer and mineral nutrients under different continuous cropping years according to claim 9, characterized in that, The process for determining nitrogen utilization rate is as follows: first, the nitrogen accumulation is calculated, and then the apparent nitrogen utilization rate and the economic nitrogen utilization rate are calculated. said amount of nitrogen accumulation kg / hm 2 = total dry weight of each organ of tobacco plant x total nitrogen content of each organ of tobacco plant; The apparent nitrogen utilization rate = (nitrogen accumulation in the whole plant under fertilized treatment - nitrogen accumulation in the whole plant under no-fertilized treatment) / nitrogen application rate × 100%; Nitrogen economic utilization rate = (Nitrogen accumulation in fertilized tobacco leaves - Nitrogen accumulation in unfertilized tobacco leaves) / Nitrogen application rate × 100%; The nitrogen application rate refers to the nitrogen content in the fertilizer. The utilization rates of phosphate fertilizer, potassium fertilizer, magnesium, calcium, and sodium are all measured using the same procedure as those for nitrogen utilization.