A nutrient regulating agent for promoting the recovery of toxic grass type degraded grassland and a method for applying the same

Abstract

The application discloses a nutrient regulation agent for promoting recovery of toxic grass type degraded grassland and a method for applying the nutrient regulation agent. The toxic grass type degraded grassland is an alpine degraded grassland with reduced native excellent grasses and with Ligusticum chuanxiong as dominant species. The application applies ammonium nitrogen fertilizer and nitrification inhibitor to the degraded grassland, adds insect pathogenic fungi Metarhizium anisopliae, and sprays pac in the plant growing season. The application utilizes the difference between the excellent grasses and Ligusticum chuanxiong in the tolerance to ammonium nitrogen, i.e. the excellent grasses have strong tolerance to ammonium nitrogen while the growth of Ligusticum chuanxiong is inhibited in the ammonium nitrogen environment, and the different characteristics of the two in the sensitivity to pac, and through the synergistic regulation of the soil and the leaf surface, the native grass recovery is selectively promoted and the growth of toxic grass is inhibited. The examples show that after the combined treatment, the aboveground biomass of the grass is increased by about 141.4% compared with the no-pac group, the biomass of Ligusticum chuanxiong is reduced by about 89.8%, and the ratio of grass to toxic grass is increased from 1.11 to 26.43. The application does not need to introduce exogenous grass species and chemical herbicides, has small disturbance to the native vegetation, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of ecological restoration technology for degraded grasslands, specifically relating to a nutrient regulator that promotes the restoration of degraded grasslands with toxic weeds and its application method. Background Technology

[0002] Alpine grasslands are the most important ecosystem type on the Qinghai-Tibet Plateau, covering more than 70% of its total area. They play irreplaceable ecological and economic functions in climate regulation, water conservation, soil and water conservation, soil improvement, biodiversity protection, and livestock production. Grasses such as *Elymus nutans* and *Poa crymophila* are native dominant plants of the alpine grasslands of the Qinghai-Tibet Plateau, and have significant ecological and production value in maintaining grassland biodiversity and ensuring a supply of high-quality forage.

[0003] In recent years, affected by both global climate change and human activities (especially overgrazing), the degradation of alpine grasslands on the Qinghai-Tibet Plateau has become increasingly severe. Statistics show that Qinghai Province has over 800,000 hectares of moderately or severely degraded grassland. 4 This area covers nearly 20% of the province's usable grassland area, spanning hm². Typical manifestations of grassland degradation include: a decrease in the proportion of high-quality forage grasses, a decline in vegetation cover, soil nutrient loss, and the proliferation of poisonous weeds. Among these, degraded grasslands with poisonous weeds are the most difficult to manage and have the highest restoration costs.

[0004] Ligularia virgaurea is a perennial poisonous weed belonging to the genus Ligularia in the family Asteraceae. It is one of the most typical dominant poisonous weeds in the degraded grasslands of the Qinghai-Tibet Plateau. Its expansion mechanism mainly includes: (1) resource acquisition advantage: Ligularia virgaurea has a well-developed root system and a large leaf area, and its ability to compete for soil moisture, nutrients and light is significantly stronger than that of most grasses; (2) allelopathic effect: its root exudates and aboveground litter contain allelopathic substances such as alkaloids and terpenes, which can inhibit the germination of seeds and seedling growth of neighboring grasses; (3) difference in sensitivity to ammonium environment: existing studies have shown that broadleaf poisonous weeds such as Ligularia virgaurea are prone to ammonium ion accumulation in ammonium nitrogen environment, leading to metabolic disorders and inhibited growth, while grasses are more tolerant to ammonium nitrogen and can grow normally - this difference has not been effectively utilized in existing grassland restoration studies. The yellow broom ligustrum also contains toxic alkaloids, which can easily cause poisoning symptoms such as fever and diarrhea in cattle and sheep after they eat it, seriously restricting the sustainable development of local animal husbandry.

[0005] Currently, the following technical methods are mainly used for the restoration and management of degraded grasslands affected by poisonous weeds:

[0006] (1) Physical removal method: Remove poisonous weeds by manual digging or mechanical cutting. This method is labor-intensive and inefficient. Large-scale soil disturbance will damage the surface crust and root network, which will stimulate the regeneration and germination of the roots and stems of poisonous weeds, leading to a vicious cycle of "the more you dig, the more you get".

[0007] (2) Chemical weeding: spraying broad-spectrum herbicides such as 2,4-D butyl ester and glyphosate. Although this method is relatively quick, it has significant drawbacks: First, the herbicides have a killing effect on non-target plants (especially the remaining high-quality forage grasses), further damaging the grassland community structure; second, chemical residues pollute soil microorganisms and groundwater; and third, degradation is slow in the low-temperature environment of high-altitude and cold regions, and the ecological safety risks exist for a long time.

[0008] (3) Reseeding Improvement Method: As disclosed in Chinese patents CN109041624A, CN118614333A and CN119422503A, degraded grasslands are restored by reseeding superior forage grasses such as *Leymus chinensis*, *Poa glabra*, and *Festuca sinensis*. However, the core idea of ​​this type of method is to "introduce exogenous grass species." Without changing the competitive advantage of toxic grasses, the reseeded grass species are difficult to successfully establish due to their inability to compete with toxic grasses, resulting in poor sustainability of the restoration effect. At the same time, reseeding requires tilling or breaking the sod of the native vegetation, which causes significant disturbance to the grassland ecosystem.

[0009] (4) Ecological factor regulation method: As disclosed in Chinese patent CN115462289A, different forms of nitrogen are applied to promote the conversion of nitrogen forms in degraded alpine grassland soil. However, this method mainly focuses on soil nitrogen management and does not involve measures to inhibit the growth of poisonous weeds themselves, nor does it consider the synergistic application of plant growth regulators and nitrogen regulation. Therefore, the restoration effect on degraded grasslands where poisonous weeds are the dominant species is limited.

[0010] In summary, current technologies lack a green restoration method that can selectively promote the recovery of native grasses and inhibit the spread of toxic weeds without introducing exogenous species or using chemical herbicides. The fundamental reason is that current technologies fail to recognize that the difference in ammonium tolerance between grasses and toxic weeds can serve as a target for selective regulation, and they also fail to synergistically combine soil nitrogen form regulation with plant endogenous hormone regulation to achieve the targeted restoration goal of supporting grasses and suppressing weeds. Summary of the Invention

[0011] To address the above problems, this invention provides a nutrient regulator for promoting the restoration of degraded grasslands with poisonous weeds and its application method.

[0012] The applicant discovered that native grasses in alpine grasslands (such as *Leymus chinensis* and *Poa chinensis*) exhibit strong tolerance to ammonium nitrogen, while the dominant poisonous weed *Ligustrum lucidum* is prone to ammonium poisoning in ammonium nitrogen environments, manifesting as leaf chlorosis, decreased root activity, and inhibited growth. Utilizing this selective difference, by applying ammonium fertilizer in combination with nitrification inhibitors to maintain the dominant ratio of ammonium nitrogen in the soil, the growth of poisonous weeds can be selectively inhibited while promoting the growth of grasses. Simultaneously, *Ligustrum lucidum* shows a higher dependence on gibberellin synthesis than grasses; spraying an appropriate amount of paclobutrazol can selectively inhibit its vegetative growth without significantly affecting grasses. Based on the above dual selectivity principle, this invention proposes the following technical solution:

[0013] A nutrient regulator for promoting the restoration of degraded grasslands with poisonous weeds, wherein the degraded grasslands are alpine degraded grasslands with reduced native superior grasses and dominated by Ligularia virgaurea, the nutrient regulator comprises ammonium nitrogen fertilizer, nitrification inhibitor, entomopathogenic fungi, and plant growth retardant; optionally, the nutrient regulator further comprises an auxiliary synergist, which is one or a combination of two or more of micronutrient fertilizers, soil conditioners, or plant immune inducers.

[0014] The present invention also provides a method for applying the nutrient regulator, comprising the following steps: during the grassland greening period, applying the ammonium nitrogen fertilizer, nitrification inhibitor and insect pathogenic fungi to the degraded grassland; and during the plant growing season, spraying the plant growth retardant onto the degraded grassland.

[0015] Preferably, the native superior grasses include Elymus nutans and / or Poa crymophila.

[0016] Preferably, the ammonium nitrogen fertilizer is selected from at least one of ammonium sulfate, ammonium chloride, or ammonium bicarbonate, and the application rate is 2-6 g / m³ (calculated as N). 2 The nitration inhibitor is 3,4-dimethylpyrazole phosphate (DMPP), and the application rate is 2-6 mg / m³. 2 The entomopathogenic fungus is *Metarhizium spp.*, and the addition amount is 1-10 g / m³. 2 .

[0017] Preferably, the plant growth retardant is paclobutrazol, and its application method is as follows: paclobutrazol wettable powder or suspension is diluted with water to a concentration of 50-500 mg / L, and a surfactant or adjuvant is added before uniformly spraying it onto the plant leaves; the surfactant is selected from at least one of organosilicon and Tween-80, and the amount added is 0.05%-0.3% of the spray solution volume; the adjuvant is urea, and the amount added is 0.5%-2% of the spray solution mass; the application period of paclobutrazol is from June to mid-July, during the peak plant growth season, and it is applied in 1-3 applications, with each application amount being 1-15 mg / m³ based on the active ingredient. 2 .

[0018] Preferably, the application rate of the ammonium nitrogen fertilizer, calculated as N, is 3-5 g / m³. 2 The dosage of the nitration inhibitor DMPP is 2-6 mg / m³. 2 The dosage of the entomopathogenic fungus *Metarhizium anisopliae* is 3-8 g / m³. 2 The plant growth retardant mentioned is paclobutrazol, and its total application rate, based on the active ingredient, is 5-25 mg / m³. 2 .

[0019] More preferably, the application rate of the ammonium nitrogen fertilizer is 4 g / m³ (calculated as N). 2 The dosage of the nitration inhibitor DMPP is 4 mg / m³. 2 The entomopathogenic fungus is *Metarhizium anisopliae*, and the addition amount is 5 g / m³. 2 The plant growth retardant mentioned is paclobutrazol, applied in two applications, with each application at a dosage of 11 mg / m³ based on the active ingredient. 2 The total application rate was 22 mg / m³. 2 .

[0020] Preferably, the application method further includes a feedback control step: after applying the ammonium nitrogen fertilizer, nitrification inhibitor, and entomopathogenic fungi, monitoring the concentration ratio of ammonium nitrogen to nitrate nitrogen in the soil; when the ammonium nitrogen / nitrate nitrogen ratio is lower than a set threshold, supplementing the nitrification inhibitor; and after spraying the plant growth retardant, monitoring the plant height ratio or cover ratio of grasses to Ligustrum lucidum in degraded grassland; when the grass / poisonous weed plant height ratio or cover ratio is lower than a set threshold, supplementing the plant growth retardant.

[0021] Preferably, the ammonium nitrogen fertilizer, nitrification inhibitor, and insect pathogenic fungi are applied at the end of May to the beginning of June during the grassland greening period; the plant growth retardant is sprayed twice, in mid-June and mid-July.

[0022] Preferably, the application method further includes a compensation and regulation step: when excessive dwarfing symptoms are detected in grasses, a gibberellin (GA3) solution is sprayed onto the degraded grassland at a concentration of 0.01~0.1 mg / L.

[0023] Preferably, the application method further includes a step of determining the basic physicochemical properties of the degraded grassland soil before applying the ammonium nitrogen fertilizer; the basic physicochemical properties include soil pH, soil moisture content, soil ammonium nitrogen content, nitrate nitrogen content and soil organic matter content; based on the determination results, the initial application amount of the ammonium nitrogen fertilizer, nitrification inhibitor and entomopathogenic fungi is determined.

[0024] The present invention also provides the use of the above method in promoting the restoration of degraded grasslands with poisonous weeds.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) This invention utilizes the difference between grasses' strong tolerance to ammonium nitrogen and the inhibited growth of Ligustrum lucidum in an ammonium nitrogen environment. By using ammonium fertilizer in combination with nitrification inhibitors to maintain the dominant ratio of ammonium nitrogen in the soil, the growth of poisonous weeds is selectively inhibited and native grasses are promoted to recover. Example 1 shows that after applying ammonium fertilizer + DMPP + Metarhizium anisopliae, the aboveground biomass of grasses increased by about 100.9% compared with the control group (see Table 1).

[0027] (2) This invention utilizes the difference in sensitivity of grasses and poisonous weeds to paclobutrazol to selectively inhibit the vegetative growth of Ligustrum lucidum by spraying an appropriate amount of paclobutrazol. Example 2 shows that the biomass of poisonous weeds was reduced by 45% to 55% after paclobutrazol treatment, and there was no significant inhibition on the growth of grasses (see Table 2).

[0028] (3) This invention combines the regulation of ammonium nitrogen form with the foliar regulation of paclobutrazol to form a synergistic effect of "promoting grass underground and suppressing weeds above ground". Example 3 shows that after the combined treatment, the biomass of poisonous weeds decreased by about 89.8% compared with the control group, the biomass of grass increased by about 141.4%, and the grass / poisonous weed biomass ratio increased from 1.11 to 26.43 (see Table 3).

[0029] (4) This invention uses Metarhizium anisopliae for biological control of underground pests, protecting the roots of grasses from insect damage and further enhancing the competitiveness of grasses. Example 5 shows that the underground biomass of grasses increased by about 38.5% after adding Metarhizium anisopliae.

[0030] (5) This invention does not require the introduction of exogenous grass species or the use of chemical herbicides, and causes little disturbance to native vegetation. It is a green and sustainable method for restoring degraded grasslands. Attached Figure Description

[0031] Figure 1The effects of ammonium fertilizer combined with DMPP and Metarhizium anisopliae on the aboveground biomass of grasses and Ligustrum lucidum;

[0032] Figure 2 The effects of different concentrations of paclobutrazol on the aboveground biomass of grasses and Ligustrum lucidum;

[0033] Figure 3 The effects of ammonium fertilizer combined with DMPP, Metarhizium anisopliae and paclobutrazol treatment on the aboveground biomass of grasses and Ligustrum lucidum;

[0034] Figure 4 These are comparative photos of the field growth of plants treated with ammonium fertilizer in combination with DMPP, Metarhizium anisopliae, and paclobutrazol. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0036] The detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] Experiment on combined treatment of ammonium fertilizer, DMPP and Metarhizium anisopliae.

[0039] 1. Overview of the test site

[0040] The experimental plot for this study was located in an alpine meadow in Haiyan County, Haibei Tibetan Autonomous Prefecture, Qinghai Province, at an altitude of approximately 3100 m. The climate is a plateau continental climate, characterized by drought and strong winds, with an average annual temperature of 0.20–3.4 ℃, average annual sunshine of 2750–2580 h, and average annual precipitation of 277.8–499.5 mm. The vegetation type of the experimental plot was a degraded alpine grassland dominated by poisonous weeds, with *Ligularia virgaurea* as the dominant species. The main native superior grasses in the plot were *Elymus nutans* and *Poa crymophila*, with a vegetation cover of approximately 35%–45%, and *Ligularia virgaurea* cover of approximately 40%–50%, indicating a clear dominance of poisonous weeds.

[0041] 2. Experimental Design

[0042] The experiment consisted of two treatments: a control group and an experimental group. Each group had four biological replicates, with a plot area of ​​4m × 4m.

[0043] Control group: Degraded grassland of the poisonous weed type in its natural state, without any treatment.

[0044] Experimental group: At the end of May, during the grassland greening period, ammonium sulfate was applied to the degraded grassland at a rate of 4 g / m² (calculated as nitrogen); simultaneously, nitrification inhibitor DMPP (3,4-dimethylpyrazole phosphate) was added at a rate of 4 mg / m². 2 It also added Metarhizium spp. spore powder (purchased from Ningxia Lvbaike Biotechnology Co., Ltd., active ingredient 10 billion spores / gram, pesticide registration certificate number: PD20220377, product implementation standard: Q / ZWO01-2025), at a dosage of 5 g / m³. 2 The spore powder of Metarhizium anisopliae is mixed evenly with ammonium sulfate and DMPP and then applied together.

[0045] 3. Specific operating steps

[0046] (1) Apply the product between May 25 and May 31, either before rain or when the soil moisture is suitable;

[0047] (2) Weigh out ammonium sulfate, DMPP and Metarhizium anisopliae spore powder, and mix them evenly according to the proportion;

[0048] (3) Spread the mixture evenly on the surface of the test plot;

[0049] (4) No tilling is required after application; rainwater will carry the material into the soil surface.

[0050] 4. Sample Collection and Measurement

[0051] From August 25th to August 31st (peak growing season), three 0.5 m × 0.5 m quadrats were randomly selected from each plot, and the aboveground parts of all plants within each quadrat were cut at ground level. The collected plant samples were categorized into grasses (Leymus chinensis and Kentucky bluegrass) and Ligustrum lucidum, and placed separately in kraft paper bags, which were then brought back to the laboratory. The samples were blanched at 105℃ for 3 hours, then dried at 65℃ for 48 hours until constant weight, and weighed. The aboveground biomass (g / m³) of the grasses and Ligustrum lucidum was recorded. 2 ).

[0052] 5. Test Results

[0053] The results are shown in Table 1 and... Figure 1 .

[0054] Table 1. Effects of ammonium fertilizer + DMPP + Metarhizium anisopliae treatment on aboveground biomass of grasses and Ligustrum lucidum.

[0055] Note: Different lowercase letters in the same column indicate significant differences between treatments (P < 0.05), the same applies below.

[0056] The results showed that the aboveground biomass of the experimental grass group was 162.71 g / m². 2 Compared with the control group (81.00 g / m²), 2 The biomass of *Ligularia zebrina* increased by approximately 100.9%; the biomass of *Ligularia zebrina* was 49.25 g / m³. 2 Compared with the control group (68.25 g / m²), 2 The biomass ratio of grasses to poisonous weeds decreased by approximately 27.8%. The grass / poisonous weed biomass ratio reversed from 1.19 to 3.30, indicating a significant increase in the competitive advantage of grasses in the community.

[0057] This demonstrates that soil treatment using only ammonium fertilizer, DMPP, and Metarhizium anisopliae can effectively reverse the dominance of toxic weeds without introducing exogenous species or using chemical herbicides. The mechanism is as follows: ammonium fertilizer maintains a high level of ammonium nitrogen in the soil, while DMPP inhibits the conversion of ammonium nitrogen to nitrate nitrogen, thus maintaining a high ammonium nitrogen environment in the soil over a long period. In this environment, *Ligularia zebrina* experiences growth inhibition due to ammonium ion accumulation, while grasses, due to their strong tolerance to ammonium nitrogen, can grow normally and gradually gain a competitive advantage. Metarhizium anisopliae simultaneously controls underground pests from feeding on grass roots, protecting the grass roots and ensuring normal nutrient absorption.

[0058] Example 2

[0059] Foliar spraying experiments with different concentrations of paclobutrazol.

[0060] 1. Overview of the test site

[0061] Same as Example 1.

[0062] 2. Experimental Design

[0063] The experiment included four treatments: a control group, a PAC100 group, a PAC200 group, and a PAC500 group. Each group had four biological replicates, with a plot size of 4 m × 4 m.

[0064] Control group: Sprayed with an equal amount of water, without the addition of paclobutrazol.

[0065] PAC100 group: Paclobutrazol was applied twice, in mid-June and mid-July, with each application at a dose of 2.2 mg / m³ based on the active ingredient. 2 Total application rate: 4.4 mg / m³ 2 .

[0066] PAC200 group: Paclobutrazol was applied twice, in mid-June and mid-July, with each application at a dose of 4.4 mg / m³ based on the active ingredient. 2 Total application rate: 8.8 mg / m³ 2 .

[0067] PAC500 group: Paclobutrazol was applied as a foliar spray twice, in mid-June and mid-July, with each application at a dose of 11 mg / m³ based on the active ingredient. 2 Total application rate: 22 mg / m³ 2 .

[0068] 3. Specific operating steps

[0069] (1) Dilute paclobutrazol (PAC, 15% wettable powder) with water to 200 mg / L and add 0.1% (volume ratio) of organosilicon surfactant;

[0070] (2) The first spraying was carried out from June 15 to 20, and the second spraying was carried out from July 15 to 20;

[0071] (3) Use a backpack sprayer to spray evenly on both sides of the plant leaves until the leaves are moist but not dripping.

[0072] (4) The control group was sprayed with an equal amount of water (containing the same concentration of organosilicon surfactant).

[0073] 4. Sample Collection and Measurement

[0074] Same as Example 1.

[0075] 5. Test Results

[0076] The results are shown in Table 2 and Figure 2 .

[0077] Table 2. Effects of different concentrations of paclobutrazol on the aboveground biomass of grasses and Ligustrum lucidum.

[0078] The results showed that paclobutrazol had a significant inhibitory effect on *Ligularia zebrina*, but this inhibitory effect did not increase simply with increasing concentration. Under the concentration settings of this experiment, the PAC100 group showed the best inhibitory effect on the poisonous plant, with a *Ligularia zebrina* biomass of 31.00 g / m³. 2 Compared with the control group (68.25 g / m²), 2 The concentration decreased by approximately 54.6%; simultaneously, this concentration significantly promoted the growth of grasses, with grass biomass reaching 143.25 g / m³. 2Compared to the control group, the inhibition rate of grasses was increased by approximately 76.9%, and the grass / poisonous weed biomass ratio reached 4.62. Meanwhile, the poisonous weed inhibition rates in the PAC200 and PAC500 groups were 45.4% and 36.6%, respectively, with grass biomass of 71.75 g / m³. 2 (Slightly lower than control) and 91.50 g / m 2 (Higher than control).

[0079] This indicates that within the concentration range selected in this invention, low concentrations of paclobutrazol can strongly inhibit the growth of *Ligularia zebrina* while simultaneously promoting the growth of grasses. The mechanism is that paclobutrazol dwarfs the plant by inhibiting gibberellin synthesis. Broadleaf plants such as *Ligularia zebrina* have a significantly higher dependence on gibberellin than grasses; therefore, low concentrations of paclobutrazol can selectively inhibit the vegetative growth of poisonous weeds without significantly affecting grasses, and may even indirectly promote grass development by reducing competition from poisonous weeds. The PAC100 group exhibited the best selective regulatory effect.

[0080] Example 3

[0081] Experiment on combined treatment of ammonium fertilizer and paclobutrazol.

[0082] 1. Overview of the test site

[0083] Same as Example 1.

[0084] 2. Experimental Design

[0085] The experiment consisted of two treatments: a control group and a combined treatment group. Each group had four biological replicates, with a plot area of ​​4 m × 4 m.

[0086] Control group: Degraded grassland of the poisonous weed type in its natural state, without any treatment.

[0087] Joint processing group:

[0088] Soil treatment: Apply ammonium sulfate (4 g N / m³) at the end of May during the greening period. 2 ) + DMPP (4 mg / m 2 ) + Metarhizium anisopliae (5g / m 2 );

[0089] Foliar treatment: Apply paclobutrazol twice, in mid-June and mid-July, at a rate of 11 mg / m³ based on the active ingredient each time. 2 Total application rate: 22 mg / m³ 2 .

[0090] 3. Specific operating steps

[0091] (1) From May 25 to 31, soil treatment was completed according to the method of Example 1;

[0092] (2) From June 15 to 20, the first paclobutrazol spraying was completed according to the method in Example 2;

[0093] (3) From July 15 to 20, the second paclobutrazol spraying was completed according to the method in Example 2.

[0094] 4. Sample Collection and Measurement

[0095] Same as Example 1.

[0096] 5. Test Results

[0097] The results are shown in Table 3. Figure 3 and Figure 4 .

[0098] Table 3. Effects of combined ammonium fertilizer and paclobutrazol treatment on aboveground biomass of grasses and Ligustrum lucidum.

[0099] The results showed that the aboveground biomass of grass in the combined treatment group was 340.15 g / m². 2 Compared to the control group without PAC (140.88 g / m²), 2 The biomass of *Ligularia zebrina* increased by approximately 141.4%; the biomass of *Ligularia zebrina* decreased to 12.87 g / m³. 2 Compared to the control group without PAC (126.59 g / m³), 2 The biomass of grasses and poisonous weeds decreased by approximately 89.8%. The grass / poisonous weed biomass ratio reversed from 1.11 to 26.43, which is 23.8 times that of the control group.

[0100] Compared to single treatments: In the single ammonium fertilizer treatment (ammonium fertilizer without PAC, i.e., the enhanced treatment in Example 1), the grass content was 235.76 g / m³. 2 The concentration of poisonous plants was 37.87 g / m³. 2 The grass / toxicity ratio was 6.23; with single paclobutrazol treatment (control + PAC, i.e., the PAC group in Example 2), the grass concentration was 152.99 g / m³. 2 The concentration of poisonous plants was 10.99 g / m³. 2 The grass / toxic herb ratio reached 13.92; after combined treatment, the grass yield increased to 340.15 g / m³. 2 Meanwhile, the poisonous weeds were strongly suppressed at 12.87.

[0101] The combined treatment showed significantly better inhibitory effects on poisonous weeds and promoting effects on grasses than any single treatment, exhibiting a clear synergistic effect. The mechanism lies in the following: the soil treatment (ammonium fertilizer + DMPP + Metarhizium anisopliae) enhances the nutrient competition ability and root health of grasses at the underground level, while the foliar treatment (paclobutrazol) weakens the light competition ability and allelochemical output of poisonous weeds at the aboveground level. Through this synergistic effect, the competitive potential of grasses is "super-recovered," the competitive advantage of poisonous weeds is "multiple-fold suppressed," the direction of grassland community succession is completely reversed, and the community landscape undergoes a fundamental change. Figure 4 ).

[0102] Application Example 1

[0103] Example of feedback control application.

[0104] Based on Example 3, a dynamic feedback control group was set up to verify the effect of the feedback control steps described in Claim 6. The test location was the same as in Example 1.

[0105] 1. Soil feedback regulation

[0106] Soil samples from the 0–10 cm topsoil layer were collected from each plot on days 15, 30, and 45 after soil treatment to determine soil NH4 levels. + -N and NO3 - -N content, calculate the ammonium nitrogen / nitrate nitrogen ratio. Set a threshold: when NH4+... + / NO3 - When the ratio was below 0.6, DMPP 2 mg / m² was applied as a supplement. Results showed that the dynamic feedback control group maintained soil NH4 levels throughout the growing season. + / NO3 - The ratio remained stable between 0.8 and 1.2, while in the single-application group, the ratio dropped below 0.4 60 days after application. Ultimately, the biomass of grasses / poisonous weeds in the dynamic feedback control group was approximately 12% higher than that in the single-application group (Example 3).

[0107] 2. Plant feedback regulation

[0108] On days 20 and 40 after the first application of paclobutrazol, the average plant height ratio of grasses to *Ligularia zebrina* in each plot was measured. A threshold was set: when the grass / weed plant height ratio was below 0.5, paclobutrazol was applied again at a dose of 5 mg / m². 2 The results showed that dynamic plant feedback regulation could more precisely suppress the growth of poisonous weeds. While ensuring the normal growth of grasses, it further reduced the biomass of poisonous weeds by about 14.6% compared with the single-application group, and avoided the over-application of paclobutrazol.

[0109] Application Example 2

[0110] Examples of compensation regulation applications.

[0111] Based on Example 3, on the 15th day after the second application of paclobutrazol, some plots of grasses showed slight stunting symptoms. Gibberellin (GA3) solution was then sprayed on the affected plots at a concentration of 0.05 mg / L, using the same application method as paclobutrazol. On the 20th day after spraying, the grass height recovered to over 90% of normal levels, and the inhibitory effect on *Ligularia cirrhosa* was not significantly affected. This indicates that GA3 compensatory spraying can act as an effective "safety net" when paclobutrazol excessively inhibits grasses.

[0112] Summary of test data.

[0113] Table 4. Summary of aboveground biomass of grasses and Ligustrum lucidum in each embodiment.

[0114] Table 4 provides a direct comparison of the data: the combined treatment (ammonium fertilizer + PAC) resulted in a grass biomass of 340.15 g / m³. 2 The concentration was significantly higher than any single treatment (ammonium fertilizer treatment: 235.76 g / m³). 2 Treatment with paclobutrazol PAC alone yielded 152.99 g / m³. 2 The combined treatment showed a strong synergistic effect; the biomass of the poisonous weeds was 12.87 g / m³. 2 The concentration was significantly lower than that of the single ammonium fertilizer treatment (37.87 g / m³). 2 ), and compared with single paclobutrazol treatment (10.99 g / m 2 The ratio of grass to poisonous weed biomass increased dramatically from 1.11 in the control group without PAC to 26.43, which is 23.8 times that of the control group.

[0115] This demonstrates that combining soil treatment (ammonium fertilizer + DMPP + Metarhizium anisopliae) with foliar treatment (paclobutrazol) significantly outperformed single treatments in both promoting grass growth and inhibiting the spread of poisonous weeds. The combined treatment not only enhanced the root nutritional competitiveness of grasses by utilizing the ammonium nitrogen environment, but also significantly weakened the plant height and allelochemical output of poisonous weeds through paclobutrazol. This combined niche regulation strategy fundamentally reversed the succession direction of the community, resulting in a remarkably significant recovery effect.

[0116] Example 4

[0117] Comparative experiment of different ammonium fertilizer application rates.

[0118] To verify the applicability of the ammonium fertilizer application range, different ammonium fertilizer application treatments were set up based on Example 1: 2g N / m 2 3 g N / m 2 4 g N / m 2 5 g N / m2 and 6 g N / m 2 DMPP was added at 0.1 wt% of the pure nitrogen content in the ammonium fertilizer, and Metarhizium anisopliae was added at 5 g / m³. 2 The experimental location and operating procedures were the same as in Example 1, with three biological replicates set up for each group.

[0119] The results showed that the application rate of ammonium fertilizer was 2-6 g N / m³. 2 Within the specified range, grass biomass increased with increasing application rate, but the rate of increase gradually slowed down; while the biomass of *Ligularia zebrina* decreased with increasing application rate. Among these, 3–5 g N / m³... 2 Within the range, the ratio of grasses to poisonous weeds was greater than 1.0, indicating a significant effect; 4 g N / m 2 For optimal application, continue increasing to 5-6 g N / m 2 The increase in grass biomass was not significant (P > 0.05), indicating that 4 g N / m³ was the optimal choice while ensuring effectiveness. 2 This can prevent fertilizer waste.

[0120] Example 5

[0121] Verification experiment on the effect of adding Metarhizium anisopliae.

[0122] To verify the independent contribution of Metarhizium anisopliae, a treatment group without Metarhizium anisopliae (ammonium fertilizer + DMPP only) was set up in Example 1 for comparison with the group with Metarhizium anisopliae (ammonium fertilizer + DMPP + Metarhizium anisopliae). The experimental location and operation procedures were the same as in Example 1, and four biological replicates were set up for each group.

[0123] The results showed that the underground biomass of grasses treated with Metarhizium anisopliae increased by approximately 38.5% compared to the group without Metarhizium anisopliae (P < 0.05), and the aboveground biomass also increased by approximately 15%. This indicates that Metarhizium anisopliae effectively protects the grass root system by controlling underground pests such as grubs, enhances the grass's ability to absorb and utilize ammonium nitrogen, and further amplifies the growth-promoting effect of ammonium fertilizer.

[0124] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0125] The above embodiments are a limited number of preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. 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.

Claims

1. A nutrient regulator for promoting the restoration of degraded grasslands of the poisonous grass type, wherein the degraded grassland of the poisonous grass type is an alpine degraded grassland with reduced native superior grasses and Ligularia virgaurea as the dominant species, characterized in that, The nutrient regulator comprises ammonium nitrogen fertilizer, nitrification inhibitor, insect pathogenic fungi, and plant growth retardant; optionally, the nutrient regulator further comprises an auxiliary synergist, which is one or a combination of two or more of micronutrient fertilizers, soil conditioners, or plant immune inducers.

2. The method for applying the nutrient regulator as described in claim 1, characterized in that, Includes the following steps: During the grassland greening period, the ammonium nitrogen fertilizer, nitrification inhibitor and insect pathogenic fungi are applied to the degraded grassland; During the growing season, the plant growth retardant is sprayed onto the degraded grassland.

3. The application method according to claim 2, characterized in that, The native superior grasses include Elymus nutans and / or Poa crymophila. The ammonium nitrogen fertilizer is selected from at least one of ammonium sulfate, ammonium chloride, or ammonium bicarbonate, and the application rate is 2-6 g / m³ (calculated as N). 2 ; The nitration inhibitor is 3,4-dimethylpyrazole phosphate (DMPP), applied at a rate of 2–6 mg / m³. 2 ; The entomopathogenic fungus is *Metarhizium spp.*, and the addition amount is 1~10 g / m³. 2 .

4. The application method according to claim 2, characterized in that, The plant growth retardant is paclobutrazol, and its application method is as follows: paclobutrazol wettable powder or suspension is diluted with water to a concentration of 50-500 mg / L, and a surfactant or adjuvant is added before uniformly spraying it onto the plant leaves; the surfactant is selected from at least one of organosilicon and Tween-80, and the amount added is 0.05%-0.3% of the spray solution volume; the adjuvant is urea, and the amount added is 0.5%-2% of the spray solution mass; The application period for paclobutrazol is from June to mid-July, during the peak growing season for plants. It is applied in 1 to 3 sprays, with each application at a dosage of 1 to 15 mg / m³ based on the active ingredient. 2 .

5. The nutrient regulator according to claim 1, characterized in that, The application rate of the ammonium nitrogen fertilizer, calculated as N, is 3-5 g / m³. 2 The dosage of the nitration inhibitor DMPP is 2-6 mg / m³. 2 The dosage of the entomopathogenic fungus *Metarhizium anisopliae* is 3-8 g / m³. 2 ; The plant growth retardant is paclobutrazol, and its total application rate, based on the active ingredient, is 5-25 mg / m³. 2 .

6. The nutrient regulator according to claim 1, characterized in that, The application rate of the ammonium nitrogen fertilizer, calculated as N, is 4 g / m³. 2 The dosage of the nitration inhibitor DMPP is 4 mg / m³. 2 The entomopathogenic fungus mentioned is *Metarhizium anisopliae*, and the addition amount is 5 g / m³. 2 The plant growth retardant mentioned is paclobutrazol, applied in two applications, with each application at a dosage of 11 mg / m³ based on the active ingredient. 2 The total application rate was 22 mg / m³. 2 .

7. The application method according to claim 2, characterized in that, It also includes feedback control steps: After applying the ammonium nitrogen fertilizer, nitrification inhibitor and entomopathogenic fungi, monitor the concentration ratio of ammonium nitrogen to nitrate nitrogen in the soil. When the ammonium nitrogen / nitrate nitrogen ratio is lower than the set threshold, apply the nitrification inhibitor. Furthermore, after spraying the plant growth retardant, the plant height ratio or cover ratio of grasses to Ligustrum lucidum in the degraded grassland is monitored. When the grass / poisonous grass plant height ratio or cover ratio is lower than a set threshold, the plant growth retardant is sprayed again.

8. The application method according to claim 2, characterized in that, The ammonium nitrogen fertilizer, nitrification inhibitor, and insect pathogenic fungi are applied at the end of May to the beginning of June during the grassland greening period; the plant growth retardant is sprayed twice, in mid-June and mid-July.

9. The application method according to claim 2, characterized in that, It also includes a compensation and regulation step: when excessive dwarfing symptoms are detected in grasses, a gibberellin solution is sprayed onto the degraded grassland to relieve the excessive inhibition of grasses by the plant growth retardant; the spraying concentration of the gibberellin solution is 0.01~0.1 mg / L.

10. The application method according to any one of claims 2 to 9, characterized in that, It also includes a step of determining the basic physicochemical properties of degraded grassland soil before applying ammonium nitrogen fertilizer; the basic physicochemical properties include soil pH, soil moisture content, soil ammonium nitrogen content, nitrate nitrogen content and soil organic matter content; based on the test results, the initial application amount of the ammonium nitrogen fertilizer, nitrification inhibitor and entomopathogenic fungi is determined.

Images