A method for applying chemical fertilizer and recycled organic fertilizer based on soil comprehensive fertility feedback

Abstract

The application provides a chemical fertilizer and recycled organic fertilizer combined application method based on soil comprehensive fertility feedback, and relates to the technical field of soil quality maintenance.The application combines nitrogen, phosphorus and potassium fertilizer nutrient supplement, crop straw bedding utilization, livestock and poultry manure and used straw bedding mixed composting, recycled organic fertilizer field application and soil comprehensive fertility index feedback regulation, realizes the sustainable maintenance of farmland plough layer soil quality, the dynamic optimization of nutrient supply structure and the recycling utilization of straw and livestock and poultry manure resources, and has the application prospect in the fields of crop rotation farmland, grain production farmland, dry farming farmland and soil degradation prevention and control.

Description

Technical Field

[0001] This invention relates to the field of soil quality maintenance technology, and in particular to a method for the combined application of chemical fertilizers and cyclic organic fertilizers based on comprehensive soil fertility feedback. Background Technology

[0002] The topsoil of farmland is the main carrier for crop root growth, nutrient absorption, and water regulation. Its fertility level not only affects crop yield and quality but also relates to the stability of the farmland ecosystem and the sustainability of agricultural production. Under long-term continuous planting, crop rotation, or high-intensity cultivation conditions, it is easy to cause insufficient replenishment of soil organic matter, depletion of nutrient reserves, degradation of topsoil structure, and decline in overall soil fertility.

[0003] Among existing farmland fertilization methods, chemical fertilizers are widely used due to their clearly defined nutrient content, ease of application, and rapid effect. Chemical fertilizers can provide nitrogen, phosphorus, and potassium nutrients relatively promptly during the critical growth stages of crops. However, long-term application of nitrogen fertilizer alone or improper fertilizer ratios can lead to problems such as soil acidification, phosphorus and potassium nutrient imbalance, insufficient organic carbon accumulation, and reduced soil buffering capacity.

[0004] On the other hand, agricultural organic wastes such as straw and livestock manure contain organic matter and various nutrients. Returning them to the field after treatment helps replenish soil organic carbon and mineral nutrients. However, direct return of straw to the field or direct application of livestock manure is easily affected by factors such as the degree of material decomposition, carbon-nitrogen ratio, moisture content, application time, and soil environmental conditions. This may lead to problems such as asynchronous nutrient release with crop nutrient requirements, insufficient decomposition, difficulty in determining the application rate, and unstable resource utilization efficiency. Currently, straw utilization, livestock manure treatment, and farmland fertilization management are often independent, lacking a continuous management approach that utilizes straw as bedding material, co-decomposes it with livestock manure, prepares recycled organic fertilizer, and returns it to the field.

[0005] Furthermore, existing soil quality assessments typically rely on indicators such as organic carbon, nitrogen, phosphorus, potassium, and pH to detect or evaluate soil fertility. However, most of these assessment results are not directly applied to fertilization adjustments for the next crop cycle. Different fields exhibit variations in basic fertility, crop type, crop rotation system, and nutrient consumption. If fertilization plans remain unchanged over a long period, it can easily lead to localized nutrient excess, nutrient deficiency, or the accumulation of soil acidification risks, making it difficult to adapt to dynamic changes in topsoil quality.

[0006] Therefore, it is necessary to provide a comprehensive method for maintaining the fertility of farmland topsoil that combines precise application of chemical fertilizers, recycling of agricultural organic waste, return of recycled organic fertilizer to the field, and feedback regulation of soil quality, so as to achieve synergy between crop nutrient supply, resource utilization of agricultural waste, and maintenance of topsoil quality. Summary of the Invention

[0007] In view of this, the present invention provides a method for the combined application of chemical fertilizers and cyclical organic fertilizers based on comprehensive soil fertility feedback, comprising the following steps: S1. Detect the organic carbon, total nitrogen, available nitrogen, total phosphorus, total potassium, available phosphorus, available potassium, and pH value of the topsoil layer (0-20 cm) of the target farmland to obtain basic soil quality data; S2. Establish a crop planting management unit in the target farmland. The crop planting management unit is a grain-legume rotation, grain crop rotation, or grain crop continuous planting management unit. S3. Apply chemical fertilizers before, during, or during the crop growth period; The fertilizer is at least one of nitrogen, phosphorus, or potassium fertilizer; for gramineous grain crops, the nitrogen fertilizer application rate is 120-180 kg / hm² based on the mass of nitrogen, phosphorus, and potassium elements. 2 The application rate of phosphate fertilizer is 20-35 kg / hm. 2 Potassium fertilizer application rate is 45-90 kg / hm. 2 For legume crops, the nitrogen fertilizer application rate, calculated by mass of nitrogen, phosphorus, and potassium, is 0-45 kg / hm². 2 The application rate of phosphate fertilizer is 15-35 kg / hm. 2 Potassium fertilizer application rate is 30-75 kg / hm. 2 ; S4. After the crop is harvested, 30%-100% of the crop straw is crushed and used as bedding material for livestock and poultry pens. Livestock and poultry manure and used straw bedding material are collected and aerobically decomposed to obtain recycled organic fertilizer. The initial moisture content of the material during the aerobic composting process is 50%-65%, the composting time is 40-90 days, and the material is turned over 1-5 times during the composting process. The recycled organic fertilizer has a C / N ratio of 15-25, a seed germination index of not less than 70%, and no obvious fresh manure odor; S5. Apply the recycled organic fertilizer obtained in step S4 to the target farmland before the next crop season sowing, or during land preparation in the following spring or autumn. The amount of recycled organic fertilizer returned to the field is 3.0-10.0 t / hm² (dry matter weight). 2 And mix it into the 0-25 cm topsoil layer by plowing or rotary tillage; S6. Retest the soil indicators described in step S1 every 1-3 years, calculate the membership degree Ui and weight Wi of each indicator, and calculate the comprehensive fertility index IFI according to the formula IFI=Σ(Wi×Ui), where ΣWi=1. S7. Based on the test results of IFI, pH value, available phosphorus and available potassium, feedback regulation is carried out on the amount of recycled organic fertilizer returned to the field and the ratio of chemical fertilizer in the next crop cycle. When IFI < 0.60, or the current monitored pH value decreases by more than 0.30 compared to the pH value in the baseline soil quality data, the amount of recycled organic fertilizer returned to the field in the next cropping cycle should be increased by 10%-25%, based on the amount returned in the previous cropping cycle, and the adjusted amount of recycled organic fertilizer returned to the field should not exceed 10.0 t / hm. 2 ; When the available phosphorus is below 15 mg / kg, the application rate of phosphate fertilizer should be increased by 10%-20% based on the application rate of the phosphate fertilizer in the immediate preceding crop cycle. When the available potassium is below 100 mg / kg, the potassium fertilizer application rate should be increased by 10%-20% based on the potassium fertilizer application rate of the crop cycle immediately preceding the previous one. When the pH is below 5.8, or the current pH is more than 0.30 lower than the baseline pH and urea is used as nitrogen fertilizer, the proportion of urea top dressing should be reduced by 10 percentage points compared with the previous crop cycle, while keeping the total amount of urea applied unchanged. When multiple control conditions are met simultaneously, the increase in the amount of recycled organic fertilizer returned to the field is taken as the larger value among the increase values ​​corresponding to each triggering condition, without repeated accumulation.

[0008] Preferably, the target farmland is dryland farmland, grain production farmland, crop rotation farmland, or grain-legume rotation farmland; the 0-20 cm topsoil layer of the target farmland meets at least four of the following conditions: organic carbon 6-25 g / kg, total nitrogen 0.5-2.0 g / kg, total phosphorus 0.20-1.00 g / kg, total potassium 8-30 g / kg, available phosphorus 3-40 mg / kg, available potassium 40-180 mg / kg, and pH value 5.2-8.0.

[0009] Preferably, the crop planting management unit is continuous corn planting, wheat-corn rotation, soybean-corn rotation, soybean-corn-corn rotation, peanut-corn rotation, or rotation of legumes with gramineous food crops.

[0010] Preferably, the nitrogen fertilizer is at least one of urea, ammonium sulfate, and calcium ammonium nitrate; the phosphate fertilizer is at least one of superphosphate, triple superphosphate, diammonium phosphate, and monoammonium phosphate; and the potassium fertilizer is at least one of potassium sulfate and potassium chloride.

[0011] Preferably, for gramineous grain crops, 50%-70% of the nitrogen fertilizer is applied as basal fertilizer, and the remaining nitrogen fertilizer is applied as top dressing during the jointing stage, booting stage, or rapid growth stage; all phosphorus fertilizer is applied as basal fertilizer; all potassium fertilizer is applied as basal fertilizer; or, Apply 20%-40% of the total potassium fertilizer application during the rapid growth period of the crop.

[0012] Preferably, 50%-100% of the legume crop straw is crushed and used as bedding material for livestock and poultry pens, and 30%-70% of the gramineous grain crop straw is crushed and used as bedding material for livestock and poultry pens; the livestock and poultry manure is at least one of pig manure, cow manure, sheep manure, and chicken manure.

[0013] Preferably, a positive membership function is used for organic carbon, total nitrogen, alkaline-available nitrogen, total phosphorus, total potassium, available phosphorus, and readily available potassium: When Xi ≤ Ai, Ui = 0; When Ai<Xi<Bi, Ui=(Xi-Ai) / (Bi-Ai); When Xi ≥ Bi, Ui = 1; Where Xi is the measured value of the i-th soil index, and Ai and Bi are the lower limit evaluation boundary value and upper limit evaluation boundary value of the i-th soil index, respectively.

[0014] Preferably, the Ai of organic carbon is 6 g / kg and the Bi is 18 g / kg; the Ai of total nitrogen is 0.5 g / kg and the Bi is 1.5 g / kg; the Ai of alkaline-available nitrogen is 40 mg / kg and the Bi is 120 mg / kg; the Ai of total phosphorus is 0.20 g / kg and the Bi is 0.80 g / kg; the Ai of total potassium is 8 g / kg and the Bi is 25 g / kg; the Ai of available phosphorus is 5 mg / kg and the Bi is 35 mg / kg; and the Ai of available potassium is 40 mg / kg and the Bi is 150 mg / kg.

[0015] Preferably, a membership function is used for the pH value: UpH = 0 when pH ≤ 5.0 or pH ≥ 8.5; When 5.0 < pH < 6.5, UpH = (pH - 5.0) / (6.5 - 5.0); When 6.5 ≤ pH ≤ 7.2, UpH = 1; When 7.2 < pH < 8.5, UpH = (8.5 - pH) / (8.5 - 7.2).

[0016] Preferably, the weights of each indicator are as follows: organic carbon weight 0.20, total nitrogen weight 0.15, alkaline nitrogen weight 0.15, total phosphorus weight 0.10, total potassium weight 0.10, available phosphorus weight 0.15, available potassium weight 0.10, and pH value weight 0.05.

[0017] This invention provides the application of the method in maintaining farmland soil quality, improving topsoil fertility, mitigating soil acidification, utilizing straw and livestock manure resources, managing crop rotation nutrient management, or providing early warning of farmland soil degradation.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are as follows: Based on crop planting management units and the quality of topsoil, this invention coordinates the supplementation of chemical fertilizer nutrients, utilization of crop straw, decomposition of livestock and poultry manure, return of recycled organic fertilizer to the field, and feedback regulation of soil indicators. It can not only meet the needs of crops for nutrients such as nitrogen, phosphorus, and potassium at different growth stages, but also continuously supplement the topsoil with organic carbon and organic nutrients, thereby helping to maintain the nutrient supply capacity and overall fertility level of farmland soil.

[0019] This invention uses crushed crop straw as bedding material for livestock and poultry pens, and then aerobically decomposes the used straw bedding material with livestock and poultry manure to prepare recycled organic fertilizer. This realizes the recycling of nutrients among crop straw, livestock and poultry manure and farmland soil, which helps to improve the problems of unstable material composition, insufficient decomposition and low resource utilization efficiency when using straw alone or treating livestock and poultry manure alone.

[0020] This invention combines the application of recycled organic fertilizer with nitrogen, phosphorus, and potassium fertilizers, integrating the rapid nutrient supply of chemical fertilizers with the slow-release nutrient supply and organic matter replenishment of recycled organic fertilizers. On the one hand, chemical fertilizers can provide timely nutrient support for crops during critical growth stages; on the other hand, recycled organic fertilizers can replenish soil organic carbon, nitrogen, phosphorus, potassium, and other components, which is beneficial for improving soil nutrient structure, enhancing the fertilizer retention and buffering capacity of the topsoil, and reducing the risk of soil quality decline caused by long-term excessive application of chemical fertilizers.

[0021] This invention incorporates periodic monitoring of indicators such as organic carbon, total nitrogen, available nitrogen, total phosphorus, total potassium, available phosphorus, readily available potassium, and pH value. It quantifies the quality of topsoil using membership functions and comprehensive fertility indicators, providing a measurable, calculable, and comparable basis for assessing soil fertility changes. When comprehensive fertility indicators decline, pH decreases, or available phosphorus or readily available potassium is insufficient, targeted adjustments are made to the amount of recycled organic fertilizer returned to the field, the amount of phosphate fertilizer applied, the amount of potassium fertilizer applied, and the proportion of nitrogen fertilizer topdressing in the next cropping cycle.

[0022] This invention achieves synergistic effects in ensuring stable crop yields and nutrient supply, maintaining comprehensive soil fertility in the topsoil, and utilizing agricultural waste resources through the coordinated application of chemical fertilizers and recycled organic fertilizers, the recycling of agricultural organic waste, and dynamic feedback regulation of soil fertility. This is conducive to improving the pertinence, stability, and operability of farmland nutrient management and has the potential for widespread application in fields such as continuous cropping of grain crops, crop rotation, grain-legume rotation, dryland farming, and the prevention and control of farmland soil degradation. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise stated, in the following examples and comparative examples, the fertilizer application rate is per hectare, and the nitrogen, phosphorus, and potassium application rates are all calculated as elements; the soil layer tested is the 0-20 cm topsoil layer, and the depth of the recycled organic fertilizer return to the field and mixing is 0-25 cm.

[0025] Each treatment employed a randomized block design with three duplicate cells, each cell having an area of ​​30 m². 2 A 0.5 m buffer zone was set up between plots. All treatments used the same crop variety, sowing density, irrigation management, and pest and disease control measures. Soil samples were obtained using a multi-point pooled sampling method, and the results are expressed as mean ± standard deviation.

[0026] Detection and Evaluation Methods Soil organic carbon and total nitrogen were determined using an elemental analyzer; alkaline available nitrogen was determined using the alkaline diffusion method; total phosphorus was determined using the Na2CO3 fusion-molybdenum-antimony colorimetric method; available phosphorus was determined using the NaHCO3 extraction-molybdenum-antimony colorimetric method; total potassium was determined using the NaOH alkaline fusion-flame photometric method; available potassium was determined using the NH4OAc extraction-flame photometric method; and pH was determined using the potentiometric method with a water-to-soil mass ratio of 2.5:1.

[0027] The Integrated Fertility Index (IFI) is calculated using the following formula: IFI = Σ(Wi × Ui) Where Wi is the weight of the i-th indicator, Ui is the membership degree of the i-th indicator, and ΣWi=1.

[0028] Positive membership functions were applied to organic carbon, total nitrogen, alkaline-available nitrogen, total phosphorus, total potassium, available phosphorus, and readily available potassium: When Xi ≤ Ai, Ui = 0; When Ai<Xi<Bi, Ui=(Xi-Ai) / (Bi-Ai); When Xi≥Bi, Ui=1.

[0029] The evaluation boundary values ​​for each indicator are as follows:

[0030] A suitable membership function is used for pH value: UpH = 0 when pH ≤ 5.0 or pH ≥ 8.5; When 5.0 < pH < 6.5, UpH = (pH - 5.0) / (6.5 - 5.0); When 6.5 ≤ pH ≤ 7.2, UpH = 1; When 7.2 < pH < 8.5, UpH = (8.5 - pH) / (8.5 - 7.2).

[0031] When a region-specific weight model is not established, the following default weights are used:

[0032] The following are examples of methods for preparing recycled organic fertilizer: After the crops are harvested, all the soybean stalks are crushed and 50% of the corn stalks are crushed into stalk fragments 3-5 cm in length, which are then used as bedding material for pigsties. Collect pig manure and used straw bedding, mix them at a dry weight ratio of 3.2:1, the initial C / N ratio of the mixture is 28.4, and the initial moisture content is 60%. The mixture was piled into windrows 2.0 m wide, 1.5 m high, and 12 m long, and aerobic composting was carried out using a combination of natural ventilation and mechanical turning. The pile was turned three times during composting, on days 10, 25, and 45. The highest temperature in the pile was 63.2℃, and the temperature remained above 55℃ for 12 days. The total composting time was 60 days.

[0033] After decomposition, the moisture content of the recycled organic fertilizer was 28.6%, the organic matter content was 43.8%, the organic carbon content was 25.0%, the total nitrogen content was 1.29%, the total phosphorus content was 0.52%, the total potassium content was 0.86%, the pH value was 7.48, the C / N ratio was 19.4, the seed germination index was 91.3%, and there was no obvious fresh manure odor.

[0034] Feedback control rules: When IFI < 0.60, the amount of organic fertilizer returned to the field in the next crop cycle should be increased by 10%-25% compared to the previous cycle.

[0035] When the current pH value drops by more than 0.30 from the baseline pH value, the amount of organic fertilizer returned to the field in the next crop cycle should be increased by 10%-25% compared to the previous cycle.

[0036] When urea is used as nitrogen fertilizer, and the pH is below 5.8 or the current pH is more than 0.30 lower than the baseline pH, the proportion of urea applied as top dressing should be reduced by 10 percentage points, while keeping the total amount of urea applied unchanged.

[0037] When the available phosphorus is below 15 mg / kg, the amount of phosphate fertilizer applied in the next crop cycle should be increased by 10%-20% based on the previous cycle; when no phosphate fertilizer was applied in the previous crop cycle, phosphate fertilizer should be applied at the lower limit of the corresponding crop season's phosphate fertilizer application rate.

[0038] When the available potassium is below 100 mg / kg, the amount of potassium fertilizer applied in the next crop cycle should be increased by 10%-20% based on the previous cycle; when no potassium fertilizer was applied in the previous crop cycle, potassium fertilizer should be applied at the lower limit of the corresponding crop season potassium fertilizer application amount.

[0039] When IFI ≥ 0.60, the current pH value decreases by less than 0.30 from the baseline pH value, the available phosphorus is not less than 15 mg / kg, the available potassium is not less than 100 mg / kg, and the pH value is not less than 5.8, maintain the amount of recycled organic fertilizer returned to the field and the fertilizer ratio of the previous cropping cycle.

[0040] When multiple control rules are triggered simultaneously, the increase in the amount of recycled organic fertilizer returned to the field is taken as the larger value among the increase values ​​corresponding to each triggering condition, and they are not repeatedly accumulated.

[0041] Example 1 This embodiment was implemented in a typical dryland farmland in the Liaohe Plain, and the tested soil was plain alluvial brown soil.

[0042] The basic physicochemical properties of the 0-20 cm topsoil layer in the test field were as follows: organic carbon 12.12 g / kg, total nitrogen 1.13 g / kg, available nitrogen 86.0 mg / kg, total phosphorus 0.44 g / kg, total potassium 16.4 g / kg, available phosphorus 10.6 mg / kg, available potassium 88.0 mg / kg, and pH 6.50.

[0043] Establish soybean-corn-corn rotation management units in the target fields.

[0044] During the corn season, apply urea, superphosphate, and potassium sulfate at a rate equivalent to 150 kg / hm² of pure nitrogen (N element). 2 Pure phosphorus (i.e., calculated as elemental phosphorus) 25 kg / hm 2 Pure potassium (i.e., calculated as K element) 60 kg / hm 2 Of the total amount of nitrogen fertilizer, 60% is applied as base fertilizer and 40% is applied as top dressing during the corn jointing stage. All of the phosphorus and potassium fertilizers are applied as base fertilizer.

[0045] During the soybean season, apply urea, superphosphate, and potassium sulfate at a rate equivalent to 15 kg / hm² of pure nitrogen. 2 20 kg / hm of pure phosphorus 2 45 kg / hm of pure potassium 2 Nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer are all applied as base fertilizer.

[0046] The following spring, the resulting recycled organic fertilizer was returned to the field, with a dry return rate of 6.0 t / hm². 2 It is then incorporated into the 0-25cm topsoil layer through rotary tillage.

[0047] Based on the nutrient test results of the recycled organic fertilizer, an application rate of 6.0 t / hm² is calculated. 2 Recycled organic fertilizer can input 77.4 kg / hm of nitrogen into the soil. 2 Phosphorus 31.2 kg / hm 2 Potassium 51.6 kg / hm 2 .

[0048] In Example 1, the following treatments were set up. The treatments in Table 1 are used to compare the effects of chemical fertilizers, recycled organic fertilizers and their combined application on soil fertility and crop yield.

[0049] Table 1 Processing Settings

[0050] Note: N, P and K in the table are all expressed as elemental mass.

[0051] Table 2 Soil quality and yield test results

[0052] To ensure the IFI results are recalculated, the detection results for total nitrogen, alkaline nitrogen, total phosphorus, and total potassium for each treatment are as follows: Table 3 Complete Soil Index Data Required for IFI Calculation

[0053] Taking the T1 treatment as an example, the membership degree of organic carbon is 0.817, the membership degree of total nitrogen is 0.750, the membership degree of alkaline nitrogen is 0.569, the membership degree of total phosphorus is 0.567, the membership degree of total potassium is 0.506, the membership degree of available phosphorus is 0.887, the membership degree of available potassium is 0.645, and the membership degree of pH is 0.680.

[0054] After substituting the weights: IFI=0.20×0.817+0.15×0.750+0.15×0.569+0.10×0.567+0.10×0.506+0.15×0.887+0.10×0.645+0.05×0.680=0.700.

[0055] Under the conditions of this embodiment, the application of cyclic organic fertilizer is beneficial to improving the overall fertility of the topsoil; when cyclic organic fertilizer is applied on the basis of chemical fertilizer application, soil organic carbon, available phosphorus, available potassium and crop yield are all maintained at a high level.

[0056] Example 2 Same as Example 1, except that: the fertilizer application rate for maize season is equivalent to 120 kg / hm² of pure nitrogen. 2 20 kg / hm of pure phosphorus 2 45 kg / hm of pure potassium 2 The amount of recycled organic fertilizer returned to the field after drying is 6.0 t / hm². 2 The remaining steps for straw bedding utilization, composting, returning to the field, and IFI feedback control are the same as in Example 1.

[0057] Example 3 Same as Example 1, except that: the fertilizer application rate for maize season is equivalent to 180 kg / hm² of pure nitrogen. 2 30 kg / hm of pure phosphorus 2 75 kg / hm of pure potassium 2 The proportion of corn stalks crushed and used as bedding in livestock pens is 60%; the dry conversion rate of recycled organic fertilizer returned to the field is 8.5 t / hm². 2 The remaining steps are the same as in Example 1.

[0058] Example 4 Feedback regulation was validated in another group of soybean-corn-corn rotation fields.

[0059] After the first monitoring cycle, the soil test results were as follows: organic carbon 13.2±0.6 g / kg, total nitrogen 1.30±0.06 g / kg, available nitrogen 95.0±4.2 mg / kg, total phosphorus 0.61±0.03 g / kg, total potassium 18.0±0.7 g / kg, available phosphorus 9.4±0.9 mg / kg, available potassium 76.8±4.1 mg / kg, pH 6.06±0.09, and IFI 0.56±0.04.

[0060] The feedback regulation rule was triggered because the IFI was below 0.60, the pH value decreased by 0.44 from the baseline value, the available phosphorus was below 15 mg / kg, and the available potassium was below 100 mg / kg.

[0061] In the next crop cycle, the amount of recycled organic fertilizer returned to the field after drying will be increased from 6.0 t / hm². 2 Increased to 7.2 t / hm 2 The application rate of phosphate fertilizer was increased from 25 kg / hm². 2 Increased to 28.75 kg / hm 2 The application rate of potassium fertilizer was increased from 60 kg / hm². 2 Increased to 69 kg / hm 2 The proportion of urea applied as top dressing will be reduced from 40% to 30%, the proportion of basal fertilizer will be increased from 60% to 70%, and the total nitrogen fertilizer application rate will be maintained at 150 kg / hm². 2 .

[0062] After one crop rotation cycle, the soil test results are as follows: Table 4. Changes in soil parameters and yield before and after feedback regulation in Example 4

[0063] If, after feedback regulation, the amount of available phosphorus and readily available potassium increases compared to before regulation, but is still below the trigger threshold, the application of phosphate fertilizer and / or potassium fertilizer will continue to be increased in the next crop cycle according to the feedback regulation rules until the corresponding threshold or the upper limit of the application amount for the corresponding crop season is reached.

[0064] Comparative Example 1 No chemical fertilizers were used, nor was the straw bedding-livestock manure recycling system implemented. The remaining crop rotation system and field management were the same as in Example 1.

[0065] Comparative Example 2 Same as Example 1, except that only urea is applied, equivalent to 150 kg / hm² of pure nitrogen. 2 No phosphate fertilizer, potassium fertilizer, or recycled organic fertilizer should be applied.

[0066] Comparative Example 3 Same as Example 1, except that: urea, superphosphate, and potassium sulfate were applied, each equivalent to 150 kg / hm² of pure nitrogen. 2 25 kg / hm of pure phosphorus 2 60 kg / hm of pure potassium 2 However, the recycling of straw bedding and livestock manure into the field is not implemented.

[0067] Comparative Example 4 Same as Example 1, except that: urea and superphosphate were applied, each equivalent to 150 kg / hm² of pure nitrogen. 2 25 kg / hm of pure phosphorus 2 No potassium fertilizer or recycled organic fertilizer is applied.

[0068] Comparative Example 5 The difference from Example 4 is that the amount of recycled organic fertilizer returned to the field, the application rates of nitrogen, phosphorus, and potassium fertilizers, and the urea topdressing ratio remain constant throughout each crop rotation cycle, without feedback adjustments based on IFI, pH value, available phosphorus, and available potassium test results. The amount of recycled organic fertilizer returned to the field remains at 6.0 t / hm². 2 The application rates of nitrogen, phosphorus, and potassium fertilizers should be maintained at 150 kg / hm². 2 25 kg / hm 2 and 60kg / hm 2 The proportion of urea top dressing should be maintained at 40%.

[0069] Table 5 Comparison of Feedback Control and Non-Feedback Control Treatments

[0070] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for the combined application of chemical fertilizers and recycled organic fertilizers based on comprehensive soil fertility feedback, characterized in that, Includes the following steps: S1. Detect the organic carbon, total nitrogen, available nitrogen, total phosphorus, total potassium, available phosphorus, available potassium, and pH value of the topsoil layer (0-20 cm) of the target farmland to obtain basic soil quality data; S2. Establish a crop planting management unit in the target farmland. The crop planting management unit is a grain-legume rotation, grain crop rotation, or grain crop continuous planting management unit. S3. Apply chemical fertilizers before, during, or during the crop growth period; The fertilizer is at least one of nitrogen fertilizer, phosphorus fertilizer, or potassium fertilizer; For gramineous grain crops, the nitrogen fertilizer application rate, calculated by mass of nitrogen, phosphorus, and potassium elements, is 120-180 kg / hm². 2 The application rate of phosphate fertilizer is 20-35 kg / hm. 2 Potassium fertilizer application rate is 45-90 kg / hm. 2 ; For legume crops, the nitrogen fertilizer application rate, calculated by mass of nitrogen, phosphorus, and potassium, is 0-45 kg / hm². 2 The application rate of phosphate fertilizer is 15-35 kg / hm. 2 Potassium fertilizer application rate is 30-75 kg / hm. 2 ; S4. After the crop is harvested, 30%-100% of the crop straw is crushed and used as bedding material for livestock and poultry pens. Livestock and poultry manure and used straw bedding material are collected and aerobically decomposed to obtain recycled organic fertilizer. The initial moisture content of the material during the aerobic composting process is 50%-65%, the composting time is 40-90 days, and the material is turned over 1-5 times during the composting process. The recycled organic fertilizer has a C / N ratio of 15-25, a seed germination index of not less than 70%, and no obvious fresh manure odor; S5. Apply the recycled organic fertilizer obtained in step S4 to the target farmland before the next crop season sowing, or during land preparation in the following spring or autumn. The amount of recycled organic fertilizer returned to the field is 3.0-10.0 t / hm² (dry matter weight). 2 And mix it into the 0-25 cm topsoil layer by plowing or rotary tillage; S6. Retest the soil indicators described in step S1 every 1-3 years, calculate the membership degree Ui and weight Wi of each indicator, and calculate the comprehensive fertility index IFI according to the formula IFI=Σ(Wi×Ui), where ΣWi=1; Positive membership functions were applied to organic carbon, total nitrogen, alkaline-available nitrogen, total phosphorus, total potassium, available phosphorus, and readily available potassium: When Xi ≤ Ai, Ui = 0; When Ai<Xi<Bi, Ui=(Xi-Ai) / (Bi-Ai); When Xi ≥ Bi, Ui = 1; Where Xi is the measured value of the i-th soil index, and Ai and Bi are the lower limit evaluation boundary value and upper limit evaluation boundary value of the i-th soil index, respectively. Membership function applied to pH value: UpH = 0 when pH ≤ 5.0 or pH ≥ 8.5; When 5.0 < pH < 6.5, UpH = (pH - 5.0) / (6.5 - 5.0); When 6.5 ≤ pH ≤ 7.2, UpH = 1; When 7.2 < pH < 8.5, UpH = (8.5 - pH) / (8.5 - 7.2); S7. Based on the test results of IFI, pH value, available phosphorus and available potassium, feedback regulation is carried out on the amount of recycled organic fertilizer returned to the field and the ratio of chemical fertilizer in the next crop cycle. When IFI < 0.60 or the current monitored pH value decreases by more than 0.30 compared to the pH value in the baseline soil quality data, the amount of recycled organic fertilizer returned to the field in the next cropping cycle should be increased by 10%-25%, based on the amount returned in the previous cropping cycle, and the adjusted amount of recycled organic fertilizer returned to the field should not exceed 10.0 t / hm. 2 ; When the available phosphorus is below 15 mg / kg, the application rate of phosphate fertilizer should be increased by 10%-20% based on the application rate of the phosphate fertilizer in the immediate preceding crop cycle. When the available potassium is below 100 mg / kg, the potassium fertilizer application rate should be increased by 10%-20% based on the potassium fertilizer application rate of the crop cycle immediately preceding the previous one. When urea is used as nitrogen fertilizer, and the pH is below 5.8 or the current pH is more than 0.30 lower than the baseline pH, the proportion of urea top dressing should be reduced by 10 percentage points compared with the previous crop cycle, while keeping the total amount of urea applied unchanged. When multiple control conditions are met simultaneously, the increase in the amount of recycled organic fertilizer returned to the field is taken as the larger value among the increase values ​​corresponding to each triggering condition, without repeated accumulation.

2. The method for combined application of chemical fertilizers and cyclic organic fertilizers based on comprehensive soil fertility feedback according to claim 1, characterized in that, The target farmland is dryland farmland, grain production farmland, crop rotation farmland, or grain-legume rotation farmland.

3. The method for combined application of chemical fertilizers and cyclic organic fertilizers based on comprehensive soil fertility feedback according to claim 1, characterized in that, The crop planting management unit is continuous corn planting, wheat-corn rotation, soybean-corn rotation, soybean-corn-corn rotation, peanut-corn rotation, or rotation of legumes with gramineous food crops.

4. The method for applying chemical fertilizers and cyclic organic fertilizers in combination based on comprehensive soil fertility feedback according to claim 1, characterized in that, The nitrogen fertilizer is at least one of urea, ammonium sulfate, and calcium ammonium nitrate; the phosphate fertilizer is at least one of superphosphate, triple superphosphate, diammonium phosphate, and monoammonium phosphate; and the potassium fertilizer is at least one of potassium sulfate and potassium chloride.

5. The method for combined application of chemical fertilizers and cyclic organic fertilizers based on comprehensive soil fertility feedback according to claim 1, characterized in that, For gramineous grain crops, 50%-70% of nitrogen fertilizer should be applied as basal fertilizer, and the remaining nitrogen fertilizer should be applied as top dressing during the jointing stage, booting stage, or rapid growth stage; all phosphorus fertilizer should be applied as basal fertilizer; all potassium fertilizer should be applied as basal fertilizer; or, 20%-40% of the total potassium fertilizer application should be applied as top dressing during the rapid growth stage of the crop.

6. The method for combined application of chemical fertilizers and cyclic organic fertilizers based on comprehensive soil fertility feedback according to claim 1, characterized in that, 50%-100% of the legume crop straw is crushed and used as bedding material for livestock and poultry pens, and 30%-70% of the gramineous grain crop straw is crushed and used as bedding material for livestock and poultry pens.

7. The method for combined application of chemical fertilizers and cyclic organic fertilizers based on comprehensive soil fertility feedback according to claim 1, characterized in that, The Ai of organic carbon is 6 g / kg and the Bi is 18 g / kg; the Ai of total nitrogen is 0.5 g / kg and the Bi is 1.5 g / kg; the Ai of alkaline-available nitrogen is 40 mg / kg and the Bi is 120 mg / kg; the Ai of total phosphorus is 0.20 g / kg and the Bi is 0.80 g / kg; the Ai of total potassium is 8 g / kg and the Bi is 25 g / kg; the Ai of available phosphorus is 5 mg / kg and the Bi is 35 mg / kg; and the Ai of available potassium is 40 mg / kg and the Bi is 150 mg / kg.

8. The method for combined application of chemical fertilizers and cyclic organic fertilizers based on comprehensive soil fertility feedback according to claim 1, characterized in that, The weights of each indicator are as follows: organic carbon weight 0.20, total nitrogen weight 0.15, alkaline nitrogen weight 0.15, total phosphorus weight 0.10, total potassium weight 0.10, available phosphorus weight 0.15, available potassium weight 0.10, and pH value weight 0.05.

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