Wild green manure planting method for improving soil organic matter content of Gannan navel orange garden in slope cropland

Abstract

The invention relates to a wild green manure planting method for improving the soil organic matter content of a Gannan navel orange garden in slope cropland, which comprises the following steps: S1, obtaining wild green manure crops including at least one of creeping oxalis, centella, chickweed, Chinese violet and wild geranium wilfordii; s2, planting Gannan navel oranges in the target garden, and planting the green manure crops to complete green manure planting. According to the technical scheme, one of creeping oxalis, centella asiatica, chickweed, philippine violet herb and erodium stephanianum willd is adopted as green manure, artificial cultivation and management are not needed in long-term soil management, and the plant development cycle can be completed in cycles under natural conditions. According to the scheme, the ecological adaptability of the wild green manure crops is high, the management cost is extremely low, the bottleneck of slope cropland orchard green manure industry development can be effectively broken through, and a new thought is provided for popularization of a Gannan navel orange orchard soil recarburization, fertilization and obstacle elimination technology.

Description

Technical Field

[0001] This invention relates to the field of plant cultivation technology, specifically to a method for planting wild green manure to increase the soil organic matter content in sloping farmland of Gannan navel orange orchards. Background Technology

[0002] Effective measures to prevent soil erosion, reduce nutrient loss, and improve the quality of farmland and the ecological environment in Gannan navel orange orchards on sloping farmland are crucial for ensuring high-quality navel orange production.

[0003] Grass cover cultivation has significant application potential as an effective way to suppress soil erosion and degradation in orchards on sloping farmland and to simplify fertilization. However, conventional green manure in Gannan navel orange orchards on sloping farmland has weak ecological adaptability and high planting costs. In addition, the frequent occurrence of noxious weeds in natural grass cover directly limits the promotion of grass cover cultivation.

[0004] Developing the green manure industry in Gannan navel orange orchards has good utilization potential and application value, and new solutions urgently need to be explored. Summary of the Invention

[0005] Based on the above description, the present invention provides a method for planting wild green manure to increase the soil organic matter content in sloping farmland Gannan navel orange orchards, aiming to improve the problem of soil and water loss in sloping farmland Gannan navel orange orchards.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: This invention provides a method for planting wild green manure to increase the soil organic matter content in sloping farmland of Gannan navel orange orchards, comprising: S1. Obtain wild green manure crops, wherein the wild green manure crops include at least one of oxalis, centella asiatica, chickweed, violet, and geranium; S2. After planting Gannan navel oranges in the target park, plant the wild green manure crops to complete the green manure planting.

[0007] Furthermore, the green manure crop is oxalis, and the sowing rate of oxalis is 15.0~22.5 kg / hm². 2 .

[0008] Furthermore, the green manure crop is Centella asiatica, and the planting spacing of Centella asiatica is 20-40 cm.

[0009] Furthermore, the green manure crop is chickweed, and the sowing rate of chickweed is 15.0~22.5 kg / hm. 2 .

[0010] Furthermore, the green manure crop is Viola yedoensis, and the sowing rate of Viola yedoensis is 15.0~22.5 kg / hm². 2 .

[0011] Furthermore, the green manure crop is *Gerberis vulgaris*, and the sowing rate of *Gerberis vulgaris* is 22.5~30.0 kg / hm². 2 .

[0012] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: (1) In the technical solution of this invention, by using one of the following as green manure—Oxalis corniculata, Centella asiatica, Stellaria media, Viola yedoensis, and Geranium wilfordii—no artificial cultivation or management is required in long-term soil management. The plant can complete its development cycle naturally and repeatedly. A stable dominant population can be formed within 1-2 years after sowing, and almost no additional management is required for many years thereafter. The wild green manure of this solution has strong ecological adaptability and extremely low management cost, which can effectively break through the bottleneck of the development of the green manure industry in sloping farmland orchards and provide a new idea for the promotion of soil carbonization and fertilization technology in Gannan navel orange orchards.

[0013] (2) The dry matter mass of leaves, scion stems, rootstock stems and roots of navel orange saplings treated with the above green manure was significantly higher than that of the natural grass treatment, indicating that wild green manure can effectively promote the growth and development of various organs of navel orange saplings and enhance their nutrient synthesis and storage capacity. Among them, the total dry matter mass of green manure treatments such as Geranium wilfordii and Chickweed was significantly higher than that of the natural grass treatment, showing a significant advantage. Attached Figure Description

[0014] Figure 1 The graphs showing the changes in the residual rate of organic materials after decomposition in Examples 1 to 5 of this invention; Figure 2 The graphs showing the variation of residual carbon content in organic materials in Examples 1 to 5 provided by this invention; Figure 3 The graphs showing the changes in nitrogen accumulation and release rate of organic materials in Examples 1 to 5 provided by this invention; Figure 4 The graphs showing the changes in phosphorus accumulation and release rate of organic materials in Examples 1 to 5 provided by the present invention; Figure 5 The graphs showing the changes in the accumulation and release rate of potassium in organic materials in Examples 1 to 5 of this invention are provided for reference. Figure 6 The graphs showing the changes in the cellulose decomposition rate of organic materials in Examples 1 to 5 of this invention; Figure 7 The graphs showing the changes in the cellulose decomposition rate of organic materials in Examples 1 to 5 of this invention; Figure 8 The graphs showing the changes in lignin decomposition rate of organic materials in Examples 1 to 5 provided by the present invention; Figure 9 On-site management diagrams of Comparative Examples 1 to 5 provided for this invention; Figure 10 The above are on-site management diagrams for embodiments 1 to 5 provided by the present invention. Detailed Implementation

[0015] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0017] Grass cover cultivation, as an effective method to suppress soil erosion and degradation in sloping orchards and to simplify fertilization, has significant application potential. However, our previous research found that conventional green manure in sloping Gannan navel orange orchards has weak ecological adaptability and high planting costs. Furthermore, the frequent occurrence of noxious weeds in natural grass cover directly limits its widespread adoption. Developing a green manure industry in Gannan navel orange orchards has good utilization potential and application value, and new solutions urgently need to be explored.

[0018] In view of this, the present invention provides a method for planting wild green manure to increase the soil organic matter content in sloping farmland of Gannan navel orange orchards, comprising: S1. Obtain wild green manure crops, wherein the wild green manure crops include at least one of oxalis, centella asiatica, chickweed, violet, and geranium; S2. After planting Gannan navel oranges in the target park, plant the wild green manure crops to complete the green manure planting.

[0019] In this invention, one of the following green manure species—Oxalis corniculata, Centella asiatica, Chickweed, Viola yedoensis, and Geranium wilfordii—is used as green manure. This green manure requires no artificial cultivation or management during long-term soil management, and can complete its development cycle naturally. A stable dominant population can form within 1-2 years after sowing, requiring almost no additional management for many years thereafter. This wild green manure exhibits strong ecological adaptability and extremely low management costs, effectively overcoming the bottleneck in the development of the green manure industry in sloping farmland orchards, and providing a new approach for promoting soil carbon enrichment and fertilization techniques in Gannan navel orange orchards.

[0020] The dry matter mass of leaves, scion stems, rootstock stems, and roots of navel orange saplings treated with the above-mentioned green manure was significantly higher than that of the natural grass treatment, indicating that green manure can effectively promote the growth and development of various organs of navel orange saplings and enhance their nutrient synthesis and storage capacity. Among them, the total dry matter mass of green manure treatments such as Geranium wilfordii and Chickweed was significantly higher than that of the natural grass treatment, showing a significant advantage.

[0021] Furthermore, the technical solution of this invention employs oxalis, centella asiatica, chickweed, violet, and geranium, among which chickweed and geranium are annuals, while the other green manure crops are perennials. The annual dominant grass species wither naturally after the growing season, forming an in-situ organic cover layer on the ground surface. This layer can decompose rapidly, increase the organic matter in the topsoil in a short period of time, and play a role in moisture retention and weed suppression. At the same time, a large number of seeds are produced before withering, which can germinate naturally in the next growing season to form new plants without the need for repeated sowing. The perennial dominant grass species implement a year-round cover and gradual decomposition return-to-field mode. After the green manure organic materials are returned to the field in a simplified manner, they decompose and release nutrients to enrich the soil, achieving a gradual and long-term stable return of organic matter, which is conducive to the continuous improvement of soil structure.

[0022] It should be noted that the types of green manure crops are not limited; they can be any of the five types mentioned above, or a combination of annual and perennial crops. When using both annual and perennial green manure crops, the perennial green manure crops have a well-developed and durable root network that can effectively anchor the soil and prevent erosion during the rainy season. The surface cover formed after the annual green manure withers further buffers the impact of rainfall and reduces runoff. Together, they enhance the erosion resistance of sloping farmland and reduce the risk of soil erosion. Furthermore, the combination of the two results in a more balanced and lasting accumulation of soil organic matter, while improving the availability of nitrogen, phosphorus, potassium, and trace elements to meet the nutrient requirements of navel oranges at different growth stages. When using only one type of green manure, although there is no synergistic effect from mixed planting, it can precisely match specific management rhythms, avoid complex issues such as competition among multiple species, control of planting ratios, and coordination of growth cycles, and further reduce management costs.

[0023] In addition, in some embodiments of the present invention, oxalis, chickweed, violet and geranium are planted by broadcasting, while centella asiatica is mainly propagated asexually, so it is planted by intermittent transplanting; specifically, when transplanting centella asiatica, the plant spacing is 30 cm.

[0024] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0025] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0026] Example 1 This embodiment provides a green manure planting method to increase the soil organic matter content in sloping farmland Gannan navel orange orchards. After planting Gannan navel orange seedlings in the early stage, in October of autumn, green manure is planted at a rate of 20 kg / hm². 2 Sow oxalis at the appropriate seeding rate.

[0027] Example 2 This embodiment provides a green manure planting method to increase the soil organic matter content of sloping farmland in Gannan navel orange orchards. It is similar to Embodiment 1, except that Centella asiatica is used instead of Oxalis corniculata in this embodiment, and the planting spacing of Centella asiatica is 30 cm.

[0028] Example 3 This embodiment provides a green manure planting method to increase the soil organic matter content in sloping farmland of Gannan navel orange orchards. It is similar to Embodiment 1, except that in this embodiment, chickweed is used instead of oxalis, and the seeding rate of chickweed is 20 kg / hm². 2 .

[0029] Example 4 This embodiment provides a green manure planting method to increase the soil organic matter content in sloping farmland of Gannan navel orange orchards. It is similar to Embodiment 1, except that in this embodiment, Viola yedoensis is used instead of Oxalis corniculata, and the sowing rate of Viola yedoensis is 20 kg / hm². 2 .

[0030] Example 5 This embodiment provides a green manure planting method to increase the soil organic matter content in sloping farmland of Gannan navel orange orchards. It is similar to Embodiment 1, except that in this embodiment, *Gerberis vulgaris* is used instead of *Oxalis corniculata*, and the sowing rate of *Gerberis vulgaris* is 25 kg / hm². 2 .

[0031] Comparative Example 1 This comparative example provides a green manure planting method for navel orange orchards in southern Jiangxi, similar to Example 1, except that white clover is used instead of oxalis in this comparative example, and the sowing rate of white clover is 20 kg / hm². 2 .

[0032] Comparative Example 2 This comparative example provides a green manure planting method for navel orange orchards in southern Jiangxi, similar to Example 1, except that alfalfa is used instead of oxalis in this comparative example, and the alfalfa seeding rate is 20 kg / hm². 2 .

[0033] Comparative Example 3 This comparative example provides a green manure planting method for navel orange orchards in southern Jiangxi, similar to Example 1, except that ryegrass is used instead of oxalis in this comparative example, and the ryegrass seeding rate is 20 kg / hm². 2 .

[0034] Comparative Example 4 This comparative example provides a green manure planting method for navel orange orchards in southern Jiangxi, similar to Example 1, except that red clover is used instead of oxalis in this comparative example, and the sowing rate of red clover is 20 kg / hm². 2 .

[0035] Comparative Example 5 This comparative example provides a green manure planting method for navel orange orchards in southern Jiangxi, similar to Example 1, except that cassia seeds are used instead of wood sorrel in this comparative example, and the sowing rate of cassia seeds is 20 kg / hm. 2 .

[0036] Performance testing After the green manure crops of Examples 1 to 5 were naturally air-dried, they were cut into small pieces of about 2 cm and dried at 70°C to constant weight. 40 g of each organic material was accurately weighed and placed in a nylon mesh bag (20 cm long × 15 cm wide, 48 μm pore size) for later use.

[0037] Net bags containing organic material samples were used to cover the orchard surface (0 cm) for a natural fallowing experiment to study the decomposition of organic material. All treatments were exposed to natural environmental conditions. Each treatment consisted of 21 bags of organic material, and a completely randomized experimental design was used. Samples were taken at 7, 15, 37, 67, 90, 120, and 180 days after returning the material to the field. Three bags of samples from each treatment were randomly collected each time and brought back to the laboratory for further analysis.

[0038] The retrieved nylon mesh bags were rinsed directly with deionized water to remove residual organic material. They were then dried in a 70℃ oven until constant weight and weighed. After grinding in a stainless steel grinder, the powder was passed through a 0.25 mm sieve for later use. The total carbon content of the plant was determined using potassium dichromate oxidation. The contents of total nitrogen, phosphorus, and potassium were determined using an external heating method and analyzed using a continuous flow analyzer (SKALAR San++, Netherlands). Structural carbohydrates were determined using a kit purchased from Suzhou Keming Biotechnology Co., Ltd., with cellulose and hemicellulose contents determined by visible spectrophotometry and lignin content determined by ultraviolet spectrophotometry.

[0039] Data processing methods The calculation methods for the decomposition residue rate, carbon residue rate, cumulative release rate of nutrients (N, P, K), and cumulative decomposition rate of plant fiber components (cellulose, hemicellulose, lignin) of various dominant grass species at different decomposition stages are as follows: Corrosion residue rate (1) Carbon residue rate (2) Nutrient cumulative release rate (3) Cumulative decomposition rate of fiber components (4) In the formula, M0 is the initial dry weight of the material (g); M t The dry weight (g) of the material at decomposition time t; t is the time for returning the material to the field (d); L0, C0, and H0 are the initial contents (%) of the carbon, nutrient, and fiber components of the material, respectively; L t C t H t The values ​​represent the nutrient content (%) of the carbon, nutrients, and fiber components of the material at decomposition time t.

[0040] The decomposition residue rate of dominant grass species was fitted using a modified Olson exponential decay model, and its calculation formula is as follows: (5) In the formula, W t The decomposition residual rate is given by α, a is a correction parameter, and k is the decomposition rate constant (the larger the value of k, the faster the decomposition rate). The time (d) required for the material to decompose to 50% (T50) and 95% (T95) can be calculated according to formulas (6) and (7).

[0041] (6) (7) The variation of carbon residue rate of dominant grass species over time can be fitted using a dual-pool exponential decay model

[17] , the expression of which is: (8) Among them, WC t The carbon residue percentage (%) of the material at decomposition time t is represented by 'a', where 'a' represents the proportion of easily decomposable components, and 'b' = 1 - a represents the proportion of difficult-to-decompose components. 'k' is the decomposition rate constant of the easily decomposable components, and 1 / k represents the average turnover days of the easily decomposable portion (i.e., the time required to decompose this portion). Experimental data were analyzed and processed using Microsoft Excel 2021 and SPSS 22.0 software. Significance differences were assessed using the LSD method for multiple comparisons, and Origin 2021 was used for plotting and equation fitting.

[0042] Changes in the residual rate of organic material decomposition, such as Figure 1 As shown.

[0043] according to Figure 1It can be seen that with the extension of decomposition time, the decomposition residue rate of different organic materials all showed a rapid decrease in the early stage and a slow decrease in the later stage. At day 90 of decomposition, compared with the decomposition residue rate of Oxalis (reaching 70.3%), the residue rates of Centella asiatica, Chickweed, Viola yedoensis, and Geranium were reduced by 42.1%, 55.5%, 46.5%, and 16.1%, respectively. At day 180 of decomposition, compared with the decomposition residue rate of Oxalis (reaching 55.5%), the residue rates of Centella asiatica, Chickweed, Viola yedoensis, and Geranium were reduced by 42.5%, 59.1%, 60.5%, and 31.0%, respectively. Analyzing the entire decomposition process of the dominant grass species, Oxalis had a relatively high overall decomposition residue rate, followed by Geranium and Centella asiatica, while Chickweed and Viola yedoensis had relatively low overall decomposition residue rates.

[0044] To further analyze the decomposition dynamics of dominant grass species, a modified Olson exponential decay model was used for fitting, and the fitting results are shown in Table 1.

[0045] Table 1. Fitting results of decomposition residue rate and decomposition time for Examples 1 to 5.

[0046] Table 1 shows that the modified Olson exponential decay model has a good fitting effect on the decomposition residue rate and decomposition time of the dominant grass species (R0). 2 (0.87~0.96).

[0047] The decomposition rates of Viola yedoensis and Stellaria media under mulch were relatively fast, with the time required for 50% and 95% organic matter decomposition being 59.3–64.9 days and 330.2–332.7 days, respectively. Centella asiatica and Geranium wilfordii followed, while Oxalis corniculata had the slowest decomposition rate, reaching T50 and T95 in 211.1 days and 1033.5 days, respectively.

[0048] Changes in the carbon residue rate of organic materials, such as Figure 2 As shown.

[0049] according to Figure 2It can be seen that the carbon residue rate of different organic materials gradually decreased with the extension of decomposition time. Throughout the decomposition process, *Oxalis corniculata* had the highest carbon residue rate, followed by *Geranium wilfordii*. The carbon residue rates of *Centella asiatica*, *Stellaria media*, and *Viola yedoensis* were relatively similar in the early and middle stages of decomposition (0–37 days), became more pronounced in the middle stage (37–90 days), and were significantly higher in the later stage (120–180 days). At the end of decomposition (180 days after mulching), compared with *Oxalis corniculata* (44.2% carbon residue rate), the decomposition residue rates of *Centella asiatica*, *Stellaria media*, *Viola yedoensis*, and *Geranium wilfordii* were significantly reduced by 47.8%, 78.1%, 66.2%, and 44.1%, respectively. In summary, under mulching, *Oxalis corniculata* generally had the highest carbon residue rate throughout the decomposition process, followed by *Geranium wilfordii* and *Centella asiatica*, while *Stellaria media* and *Viola yedoensis* had the lowest.

[0050] Nutrient release characteristics of organic materials, such as Figures 3 to 5 As shown.

[0051] As shown in the images, the cumulative release rates of nitrogen, phosphorus, and potassium in the organic materials of each treatment gradually increased as the decomposition process progressed, exhibiting a trend of rapid increase in the early stages and slow increase in the later stages. The overall cumulative nutrient release rate during decomposition was potassium > phosphorus > nitrogen. The potassium release rate on day 7 (47.7%–84.1%) was significantly higher than that of nitrogen (29.1%–33.2%) and phosphorus (30.5%–44.6%), indicating that potassium had a rapid release characteristic in the early stages.

[0052] The cumulative release rate of nitrogen and phosphorus from oxalis under cover remained consistently low throughout the decomposition period, and significantly lagged behind other dominant grass species in the later stages (120-180 days), followed by Centella asiatica and Geranium wilfordii, while Stellaria media and Viola yedoensis had higher cumulative release rates of nitrogen and phosphorus. Figure 3 , Figure 4 However, the variation patterns of potassium cumulative release rates among different dominant grass species under mulch were not significant and the differences were small. Figure 5 ).

[0053] Characteristics of structural carbohydrate changes in organic materials, such as Figures 6 to 8 As shown.

[0054] As can be seen from the images, the decomposition patterns of the fiber components (cellulose, hemicellulose, and lignin) of the dominant grass species are similar to their dry matter decomposition patterns. The rate of increase in decomposition rate also shows a trend of faster decomposition in the early stage (0-90 days) and slower decomposition in the later stage (90-180 days). The overall decomposition rate of cellulose in *Oxalis corniculata* under mulch was relatively low, followed by *Geranium wilfordii*. *Centella asiatica*, *Stellaria media*, and *Viola yedoensis* all showed relatively high decomposition rates, but the variation patterns were not obvious, and the differences among the three were not significant at 120-180 days of decomposition. Figure 6Similarly, under mulch, the overall hemicellulose decomposition rate was lowest for Oxalis, followed by Geranium and Centella asiatica, while Chickweed and Viola yedoensis were at relatively high levels. At the end of decomposition, the hemicellulose decomposition rate of the dominant grass species remained as follows: Oxalis had the lowest rate (53.5%), Geranium (69.3%) and Centella asiatica (73.7%) were in the middle, and Chickweed (82.6%) and Viola yedoensis (86.9%) had the highest rates. Figure 7 The decomposition dynamics of lignin and hemicellulose were similar, except that the lignin decomposition rate of Viola yedoensis decreased in the early and middle stages of decomposition, and gradually increased in the middle and late stages. At the end of decomposition, the lignin decomposition rate was lowest in Oxalis corniculata (46.8%), in the middle in Geranium wilfordii (57.3%) and Centella asiatica (64.0%), and highest in Stellaria media (71.6%) and Viola yedoensis (65.6%).

[0055] according to Figures 1 to 8 The results show that under mulch application, Oxalis has the slowest decomposition rate and a high carbon residue rate, with a low easily decomposable carbon fraction (50.6%) and slow nutrient release, classifying it as a "slow-release" grass species suitable for long-term soil improvement and carbon sequestration. Geranium and Centella asiatica have moderate decomposition rates and carbon residue rates, while Chickweed and Viola yedoensis have the fastest decomposition rates, high proportions of easily decomposable carbon (82.4%~87.1%), and rapid nutrient release, classifying them as "fast-release" grass species suitable for short-term rapid fertilization. Therefore, in the cultivation and precision nutrient management of sod in sloping Gannan navel orange orchards, it is recommended to scientifically configure and select grass species based on the method of returning dominant grass species to the field (mulch / bury) and their decomposition characteristics (slow-release / fast-release) to achieve efficient nutrient utilization and sustainable soil management.

[0056] Experiment on the effects of green manure on orchard soil quality and navel orange growth and development Using natural grass cover as a control, navel oranges grown according to the planting methods provided in Comparison 1 to 5 were evaluated, and white clover was systematically assessed. Figure 9 A) Alfalfa ( Figure 9 B), Ryegrass ( Figure 9 C), Red Clover ( Figure 9 D) Cassia seed ( Figure 9 E) The impact of this type of conventional green manure on orchard soil quality and tree nutrition.

[0057] Experiments showed that, when broadcasting throughout the orchard, most green manure species, such as white clover, alfalfa, and ryegrass, grew well overall, but only within the tree basin; while red clover and cassia seeds grew poorly, which is related to factors such as the topography, climate, and red soil quality of the sloping orchard. Furthermore, planting conventional green manure requires annual seed purchases, manual sowing, and other agricultural management practices. Figure 9F), which increases cost input. Therefore, the weak ecological adaptability and high planting cost of conventional green manure are key bottlenecks restricting the high-quality development of the green manure industry in Gannan navel orange orchards on sloping farmland.

[0058] The navel oranges grown using the planting methods provided in Examples 1 to 5 were evaluated, and the Geranium wilfordii (Germania lingulata) was systematically evaluated. Figure 10 A), Chickweed ( Figure 10 B), Centella asiatica ( Figure 10 C), Viola yedoensis ( Figure 10 D), Oxalis ( Figure 10 E) Impact on orchard soil quality and tree nutrition.

[0059] Experiments have shown that, with long-term soil management, no artificial cultivation or management is required, and the plant can complete its development cycle naturally. A stable dominant population can be formed within 1-2 years after sowing, requiring almost no additional management for many years thereafter. Therefore, compared to the conventional green manures in Examples 1-5, the wild green manures screened in Examples 1-5 exhibit strong ecological adaptability and extremely low management costs, effectively overcoming the bottleneck in the development of the green manure industry in sloping farmland orchards, and providing new ideas for promoting soil carbon enrichment and fertilization techniques in Gannan navel orange orchards.

[0060] The physicochemical properties of the topsoil (0-10 cm) in orchards with naturally growing Geranium, Chickweed, Centella asiatica, Oxalis corniculata, and Viola yedoensis for five consecutive years (2019-2024) were measured. The results showed that, compared with clean cultivation, the management of dominant green manure crops significantly increased the content of nutrients such as organic carbon and total nitrogen in the orchard soil (P<0.05). There were significant differences in soil organic carbon and available phosphorus content among different dominant grass species, but no significant differences in pH, as shown in Table 2.

[0061] Table 2. Physicochemical properties of topsoil in Examples 1 to 5

[0062] Note: Different lowercase letters indicate significant differences between different treatments. P <0.05).

[0063] In addition, the aboveground parts of dominant grass species such as Geranium and Chickweed in the orchard were investigated and sampled. The population density, annual dry matter, and total nutrient accumulation of the dominant grass species were measured, and their potential for carbon enrichment and fertilization were preliminarily assessed, as shown in Table 3.

[0064] Table 3. Production of dry matter and nutrient content of green manure in Examples 1 to 5

[0065] Note: Values ​​are expressed as mean ± standard deviation. Different lowercase letters indicate significant differences between different treatments at the same location. P <0.05).

[0066] After one year of management of the green manure crops in Examples 2 to 5, the dry matter accumulation in each organ was analyzed, and the results are shown in Table 4.

[0067] Table 4. Characteristics of changes in stem material production in navel orange saplings under green manure management in Examples 2 to 5.

[0068] Note: Data in the table are expressed as mean ± standard deviation. Different lowercase letters in the same column indicate significant differences between different treatments. P <0.05).

[0069] As shown in Table 4, the dry matter mass of leaves, scion stems, rootstock stems, and roots of navel orange saplings under the green manure treatment was significantly higher than that under the natural grass treatment. This indicates that green manure can effectively promote the growth and development of various organs of navel orange saplings and enhance their nutrient synthesis and storage capacity. Among them, the total dry matter mass of green manure treatments such as Geranium wilfordii and Chickweed was significantly higher than that under the natural grass treatment, demonstrating a significant advantage.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0071] In summary, the technical solution of this application has the following beneficial technical effects: (1) In the technical solution of this invention, by using one of the following as green manure—Oxalis corniculata, Centella asiatica, Stellaria media, Viola yedoensis, and Geranium wilfordii—no artificial cultivation or management is required in long-term soil management. The plant can complete its development cycle naturally and repeatedly. A stable dominant population can be formed within 1-2 years after sowing, and almost no additional management is required for many years thereafter. The wild green manure of this solution has strong ecological adaptability and extremely low management cost, which can effectively break through the bottleneck of the development of the green manure industry in sloping farmland orchards and provide a new idea for the promotion of soil carbonization and fertilization technology in Gannan navel orange orchards.

[0072] (2) The dry matter mass of leaves, scion stems, rootstock stems and roots of navel orange saplings treated with the above green manure was significantly higher than that of the natural grass treatment, indicating that green manure can effectively promote the growth and development of various organs of navel orange saplings and enhance their nutrient synthesis and storage capacity. Among them, the total dry matter mass of green manure treatments such as Geranium wilfordii and Chickweed was significantly higher than that of the natural grass treatment, showing a significant advantage.

Claims

1. A method for planting wild green manure to increase the soil organic matter content in sloping farmland of Gannan navel orange orchards, characterized in that, include: S1. Obtain wild green manure crops, wherein the wild green manure crops include at least one of oxalis, centella asiatica, chickweed, violet, and geranium; S2. After planting Gannan navel oranges in the target park, plant the wild green manure crops to complete the green manure planting.

2. The green manure planting method for increasing soil organic matter content in sloping farmland Gannan navel orange orchards according to claim 1, characterized in that, The green manure crop is oxalis, and the sowing rate of oxalis is 15.0~22.5 kg / hm². 2 .

3. The green manure planting method for increasing soil organic matter content in sloping farmland Gannan navel orange orchards according to claim 1, characterized in that, The green manure crop is Centella asiatica, and the planting spacing of Centella asiatica is 20-40 cm.

4. The green manure planting method for increasing soil organic matter content in sloping farmland Gannan navel orange orchards according to claim 1, characterized in that, The green manure crop is chickweed, and the sowing rate is 15.0~22.5 kg / hm². 2 .

5. The green manure planting method for increasing soil organic matter content in sloping farmland Gannan navel orange orchards according to claim 1, characterized in that, The green manure crop is Viola yedoensis, and the sowing rate is 15.0~22.5 kg / hm². 2 .

6. The green manure planting method for increasing soil organic matter content in sloping farmland Gannan navel orange orchards according to claim 1, characterized in that, The green manure crop is *Gerberis vulgaris*, and the sowing rate of *Gerberis vulgaris* is 22.5~30.0 kg / hm². 2 .

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