Methods for Improving Perennial Cool-Season Grasslands through Differentiated Mixing and Fertilization of Annual Forage Grasses

Abstract

This invention relates to the field of agricultural planting technology, specifically a method for improving perennial cool-season grasslands through differentiated mixed sowing and fertilization of annual forage grasses in multiple seasons, comprising the following steps: S1, grassland selection; S2, sowing and mowing times: three sowing times are set, namely May, August, and November of each year; S3, sowing ratio and sowing amount: sowing amount: the differentiated combination sowing amount is determined according to the degree of degradation of perennial grass grasslands and the season, and the sowing amount in May and August is: rye / oats 60-65 kg / hm. ‑2 Variegated purple vetch / arrow-leaved pea 45-50 kg / hm ‑2 The sowing rate in November is 45-50 kg / hm² for rye / oats. ‑2 40-45 kg / hm of *Vigna angularis* var. *gloriosa*. ‑2 Sowing time: In May and August, sowing is generally done after an effective rainfall when the soil moisture is suitable. Break the sod and sow shallowly for 1-2 cm. In November, sowing is done before rainfall, with a sowing depth of 2-3 cm. S4. Fertilization.

Description

Technical Field

[0001] This invention relates to the field of agricultural planting technology, specifically a method for improving perennial cool-season grasslands through multi-season differentiated mixed sowing and fertilization of annual forage grasses. Background Technology

[0002] There are approximately 2,000 contiguous grasslands in southern China, each exceeding 80,000 mu (about 5,333 hectares), totaling about 300 million mu (about 20 million hectares). The abundant rainfall in the south provides ample water for grassland growth, a unique advantage for grassland agriculture. Perennial grasslands do not require annual tillage, reducing labor and machinery inputs while mitigating soil erosion and structural damage, thus excelling in water conservation and soil and water retention. However, long-term improper management practices (fertilization methods and mowing) have negatively impacted the quality and productivity of perennial grasslands. This manifests primarily as reduced annual vegetation cover, poor water and fertilizer retention capacity, soil nutrient loss, and structural deterioration. Over time, this exacerbates soil erosion, further decreases soil nutrient content, reduces forage yield and quality, and makes it difficult to provide high-quality forage resources, creating a vicious cycle.

[0003] Furthermore, the monoculture of perennial grasses results in low nutrient content and high levels of indigestible substances; the crude protein content in dry matter is generally 3.5%-10.5%, and the crude fiber content is generally 30-50%. In contrast, annual legumes / grasses are considered an effective way to improve perennial grass pastures due to their rapid growth, nitrogen-fixing ability, and potential to improve soil structure. In southern regions, abundant rainfall from July to September creates favorable conditions for the growth of annual legumes and grasses. Therefore, multi-season planting of annual legumes / grasses in perennial grass pastures can increase land value, crop yield, and soil fertility.

[0004] Fertilization is a crucial way to improve plant productivity. Inorganic fertilizers act quickly but have short-lived effects, while organic fertilizers, on the other hand, offer long-lasting, mild, and balanced benefits. The combined application of organic and inorganic fertilizers leverages the advantages of both, and long-term application can improve soil structure, increase soil fertility, and boost crop yields. Furthermore, water availability is a key factor for plant growth. In southern regions, rainfall is unevenly distributed, with an average annual precipitation of approximately 1000 mm, of which 73% occurs from June to September. Therefore, adjusting the ratio of compound fertilizers and organic fertilizers based on rainfall, along with scientific reseeding and fertilization, is essential to ensuring that cool-season grasslands improve soil quality while simultaneously increasing productivity, creating a virtuous cycle. This is crucial for promoting the quality and efficiency of herbivorous livestock farming in southern China and enhancing agricultural sustainability. Summary of the Invention

[0005] To address the above problems, this invention provides a method for improving perennial cool-season grasslands through multi-season differentiated sowing and fertilization of annual forage grasses.

[0006] To achieve the above objectives, the following technical solution is provided:

[0007] A method for improving perennial cool-season grasslands through multi-season differentiated intercropping and fertilization of annual forage grasses, characterized by the following steps:

[0008] S1. Grassland Selection

[0009] In Yunnan Province, a grassland with soils mainly composed of dry red soil and red soil was selected (longitude: 103°13'57.8845"E, latitude: 25°36'57.7590"N); the annual precipitation is between 610 and 817 mm, mainly concentrated in summer, with distinct dry and wet seasons, and the water and heat contradiction is particularly prominent in the spring and early summer growing seasons;

[0010] S2, Sowing and Harvesting Time

[0011] Three sowing times were set: May, August, and November each year.

[0012] S3, sowing ratio and sowing amount

[0013] Seeding rate: Differentiated seeding rates were determined based on the degree of degradation of perennial grasses and the season. The seeding rates for May and August were: rye / oats 60–65 kg / hm². -2 Purple sweet potato with glossy leaves / arrow-leaved pea 45~50 kg.hm -2 The sowing rate in November is 45-50 kg / hm for rye / oats. -2 Purple sweet potato with glossy leaves / arrow-leaved pea 40~45 kg.hm -2 ;

[0014] Sowing time: In May and August, sowing is generally done after an effective rainfall when the soil moisture is suitable. Break the sod and sow shallowly for 1-2 cm. In November, sowing is done before rainfall, with a sowing depth of 2-3 cm.

[0015] S4, Fertilization

[0016] Based on the proportion of the average monthly effective rainfall over many years to the average annual effective rainfall, and the proportion of the average monthly effective precipitation over many years to the effective precipitation during the growing season (a), the amount of fertilizer applied this time = a × the annual compound fertilizer application amount + ((100%-a) / 2) × the annual organic fertilizer application amount.

[0017] The beneficial effects of this invention are as follows: by reseeding annual legumes / grass forage and fertilizing according to local rainfall characteristics, the orchardgrass grassland can be improved. The mixed sowing of annual legumes and grasses can increase grassland yield, improve grassland quality and improve soil fertility. Differentiated fertilization can adjust the ratio of compound fertilizer and organic fertilizer in a timely manner according to rainfall to ensure the supply of nutrients during plant growth and ensure efficient use of nutrients. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method for improving perennial cool-season grasslands through multi-season differentiated sowing and fertilization of annual forage grasses, provided by the present invention. Detailed Implementation

[0019] 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. 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.

[0020] Example 1

[0021] A method for improving perennial cool-season grasslands through multi-season differentiated intercropping and fertilization of annual legumes / grasses includes the following steps:

[0022] S1, Grassland Selection

[0023] A degraded orchard grassland (103°18'47.2020"E, 25°38'34.7412"N) was selected in Xundian County, Kunming City, Yunnan Province, at an altitude of 2500 m and covering an area of ​​approximately 20 mu.

[0024] S2, Sowing Time

[0025] For sowing in May and August, broadcast sowing should be done before rainfall, with a shallow sowing depth, just enough to break the turf (1-2 cm). For November sowing, it is generally done after an effective rainfall, when the grassland soil moisture is suitable, by breaking the turf and sowing shallowly (2-3 cm).

[0026] S3, rebroadcast volume

[0027] The sowing rate in May and August is 60-65 kg / hm. -2 (Oats) and 45~50 kg.hm -2 (Arrowhead pea), sowing rate in November is 45-50 kg / hm. -2 (Oats) and 40~45 kg.hm -2 (Egg pea).

[0028] S4, Fertilizer application rate

[0029] Step A1: Differentiated fertilization was conducted based on the proportion of monthly average rainfall to annual average rainfall during the periods of May-July (43%), August-October (45.5%), and November-April of the following year (11.5%) from 2010 to 2022 (Table 2). The fertilization amount during May-July was 96.8 kg / hm². -2 Urea + 309.6 kg.hm -2 Calcium magnesium phosphate compound fertilizer and 2565 kg.hm -2 Organic fertilizer; the application rate from August to October is 102.4 kg / hm². -2 Urea + 327.6 kg.hm -2 Calcium magnesium phosphate compound fertilizer and 2452.5 kg.hm -2 Organic fertilizer; the amount applied from November to May of the following year was 25.9 kg / hm. -2 Urea + 82.8 kg.hm -2 Calcium magnesium phosphate compound fertilizer and 3982.5 kg.hm -2 Organic fertilizer.

[0030] Step A2: First apply urea and calcium magnesium phosphate compound fertilizer, then apply organic fertilizer.

[0031] Example 2

[0032] A method for improving perennial cool-season grasslands through multi-season differentiated intercropping and fertilization of annual legumes / grasses includes the following steps:

[0033] S1, Grassland Selection

[0034] A degraded orchardgrass grassland (103°21′18.40″E, 25°18′29.95″N), at an altitude of 2038 m and covering an area of ​​approximately 6 mu, was selected in Xundian County, Kunming City, Yunnan Province. Its soil nutrient background values ​​are shown in Table 1.

[0035] Table 1. Background values ​​of soil nutrients

[0036]

[0037] S2, rebroadcast time

[0038] For sowing, in May and August, sowing should be done before rainfall, with a relatively deep sowing depth (1-2 cm). In November, sowing is generally done after a significant rainfall, when the soil moisture in the grassland is suitable, by breaking the sod and sowing shallowly (2-3 cm).

[0039] S3, rebroadcast volume

[0040] The sowing rate in May and August is 60-65 kg / hm. -2 (Rye) and 45~50 kg.hm -2(Glossy-leaved purple sweet potato), sowing rate in November is 45-50 kg / hm. -2 (Rye) and 40~45 kg.hm -2 (Glossy-leaved purple sweet potato).

[0041] S4, Fertilizer application rate

[0042] Step A1: Differentiated fertilization was conducted based on the proportion of monthly average rainfall to annual average rainfall during the periods of May-July (43%), August-October (45.5%), and November-April of the following year (11.5%) from 2010 to 2022 (Table 2). The fertilization amount during May-July was 96.8 kg / hm². -2 Urea + 309.6 kg.hm -2 Calcium magnesium phosphate compound fertilizer and 2565 kg.hm -2 Organic fertilizer; the application rate from August to October is 102.4 kg / hm². -2 Urea + 327.6 kg.hm -2 Calcium magnesium phosphate compound fertilizer and 2452.5 kg.hm -2 Organic fertilizer; the amount applied from November to May of the following year was 25.9 kg / hm. -2 Urea + 82.8 kg.hm -2 Calcium magnesium phosphate compound fertilizer and 3982.5 kg.hm -2 Organic fertilizer.

[0043] Step A2: First apply urea and calcium magnesium phosphate compound fertilizer, then apply organic fertilizer.

[0044] Table 2. Average Monthly Rainfall in Kunming City, 2010-2022

[0045]

[0046] Experimental Design

[0047] The experiment was conducted on flat grassland in the study area, with each plot measuring 4m × 4m and 1m intervals between plots. First, the orchardgrass in the experimental plots was mowed to a depth of 3cm. After rainfall in May 2023, the soil surface was broken to a depth of 1-2cm for sowing. The sowing rates for rye and vetch were 60 kg / hm². -2 and 45 kg.hm -2 Fertilize 10 days after seedling emergence. First, weigh out urea (96.8 kg / hm²). -2 ), magnesium phosphate compound fertilizer (309.6 kg.hm) -2 Mix thoroughly and sprinkle in, then add the weighed organic fertilizer (2565 kg / hm). -2The fertilizer was evenly applied to the experimental plot, and the land was mowed at the end of July and the beginning of August 2023. Three to five days after mowing, sowing was carried out after rainfall, using the same sowing rate, method, and fertilization method as in May. The fertilizer application rate in August was 102.4 kg / hm². -2 Urea, 327.6 kg.hm -2 And calcium magnesium phosphate compound fertilizer and 2452.5 kg.hm -2 Organic fertilizer. After harvesting at the ground level at the end of October, sow seeds 2-3 cm below the surface before rainfall in early November. The sowing rate for rye and glossy purple vetch is 45 kg / hm². -2 and 35 kg.hm -2 Fertilize 10 days after emergence, using the same method as in May and August, but at a rate of 5.9 kg / hm. -2 Urea, 82.8 kg.hm -2 Calcium magnesium phosphate compound fertilizer and 3982.5 kg.hm -2 Organic fertilizer will be used, and harvesting will take place at the end of April 2024.

[0048] Indicator Measurement

[0049] Vegetation sampling: Plant samples were collected using quadrats (1×1m) at the end of July, the end of October 2023 and the end of April 2024. After the plant samples were brought back to the laboratory, they were blanched in an oven at 108℃ for one hour. The oven temperature was then adjusted to 75℃ until the samples were dried. The biomass was weighed, and the dried plant samples were crushed into powder using a small grinder. Nutritional indicators were then measured.

[0050] Soil sampling: Soil sampling was conducted after the plant sampling was completed using quadrat frames. Following the quadrat survey at the end of April 2024, soil samples were taken from each plot using a soil auger via the cross-sampling method, with a total of 5 samples taken from each plot. The soil samples were placed in sealed plastic bags (0-10cm deep). After being brought back to the laboratory for natural air drying and sieving, the samples were analyzed.

[0051] Data Analysis

[0052] Sample data analysis was performed using SPSS 23.0.

[0053] Results Analysis

[0054] Differential reseeding and fertilization of grassland biomass in different growing seasons

[0055] Table 3. Effects of Differentiated Reseeding and Fertilization on Biomass of Perennial Grasslands

[0056]

[0057] Table 3 shows that the biomass of the differentiated fertilization and mixed sowing treatments was higher than that of the other treatments in all three time periods. The biomass of the grassland community under the differentiated fertilization and mixed sowing treatments and the fertilization treatments increased by 2.99 times and 2.29 times, respectively, compared with the control treatment. Moreover, the total biomass of the differentiated fertilization and mixed sowing treatments was higher than that of the fertilization-only treatment and the differentiated fertilization-only treatment.

[0058] Table 4. Impact of Differentiated Overseeding and Fertilization on Grassland Quality Throughout the Year

[0059]

[0060] Table 4 shows that in 2022, compared with the control treatment, the CP content of the mixed seeding treatment, differentiated mixed seeding treatment, and differentiated fertilization and mixed seeding increased by 42%, 46%, and 62.5%, respectively. Compared with the control treatment, the crude fiber and crude ash content of the differentiated mixed seeding treatment increased by 4.5% and 28.8%, respectively. Acid detergent fiber and neutral detergent fiber decreased by 18.9% and 6.2%, respectively.

[0061] Table 5. Effects of Differentiated Reseeding and Fertilization on Grassland Quality and Soil Nutrient Content

[0062]

[0063] As shown in Table 5, compared with the control treatment, soil pH, soil organic matter, total nitrogen and total phosphorus, hydrolyzable nitrogen and available phosphorus all increased under both fertilization and mixed seeding treatments. Specifically, soil pH increased by 4.8% and 10% under differentiated fertilization and mixed seeding treatments, respectively; soil organic matter increased by 2% and 14.9%; total nitrogen increased by 9.9% and 42.4%; total phosphorus increased by 11.1% and 22.8%; hydrolyzable nitrogen increased by 16.5% and 40.9%; and available phosphorus increased by 45.2% and 115%, respectively.

[0064] Summarize

[0065] 1) After multi-season differentiated sowing and fertilization of perennial orchardgrass, the aboveground biomass of orchardgrass increased, the crude protein content of forage decreased, the content of crude fiber, acid detergent fiber, neutral detergent fiber and crude ash in forage decreased, the soil pH and soil organic matter content increased, and the total nitrogen and total phosphorus content, as well as the hydrolyzable nitrogen and available phosphorus content in the soil increased.

[0066] 2) The biomass, forage quality and soil nutrient status of the multi-season differentiated mixed sowing and fertilization treatment were higher than those of the fertilization-only, differentiated fertilization-only, mixed sowing-only and differentiated reseeding-only treatments.

[0067] 3) Compared with the control treatment, fertilization-only treatment, and mixed seeding-only treatment, the biomass of grassland increased by 229%, 21.3%, and 243%, respectively; crude protein increased by 62.6%, 49.7%, and 11.5%, respectively; soil pH increased by 13.8%, 4.8%, and 10%, respectively; soil organic matter increased by 19.9%, 2.03%, and 14.9%, respectively; total nitrogen increased by 54.8%, 9.9%, and 42.4%, respectively; total phosphorus increased by 29.6%, 11.1%, and 22.8%, respectively; hydrolyzable nitrogen increased by 80.4%, 16.5%, and 41%, respectively; and available phosphorus increased by 188%, 45.2%, and 115%, respectively.

[0068] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for improving a perennial cool-season grassland by mixed sowing and fertilization of annual forage grasses in different seasons, characterized by, Comprising the following steps: S1, grassland selection In Yunnan Province, choose the soil of cocksfoot grassland mainly with dry red soil and red soil, the annual precipitation is between 610-817 mm, mainly concentrated in summer, the dry and wet seasons are distinct, and the water-heat contradiction in plant growth season of spring and early summer is particularly prominent; S2, sowing time Set 3 sowing times, May, August and November every year; Sowing in May and August is generally after an effective rainfall, and the grassland soil moisture is suitable, and the grass is shallowly sown 1-2 cm; Sowing in November is selected before rainfall, and the sowing depth is 2-3 cm; S3, sowing amount Seeding rate: according to the degree of perennial grassland degradation and season to determine the different combination of seeding rate, the seeding rate in May and August is: rye / oat 60~65 kg.hm -2 and light purple flower / arrowhead pea 45~50 kg.hm -2 ; the seeding rate in November is: rye / oat 45~50 kg.hm -2 and light purple flower / arrowhead pea 40~45 kg.hm -2 ; S4, fertilization The fertilization time is May, August and November every year; The fertilization amount in May is: according to the proportion a1 of the total monthly average rainfall in May to the total annual average rainfall in many years, the fertilization amount = a1×total annual compound fertilizer application amount + ((100%-a1) / 2)×total annual organic fertilizer application amount; The fertilization amount in August is: according to the proportion a2 of the total monthly average rainfall in August to the total annual average rainfall in many years, the fertilization amount = a2×total annual compound fertilizer application amount + ((100%-a2) / 2)×total annual organic fertilizer application amount; The fertilization amount in November is: according to the proportion a3 of the total monthly average rainfall from November to the next April to the total annual average rainfall in many years, the fertilization amount = a3×total annual compound fertilizer application amount + ((100%-a3) / 2)×total annual organic fertilizer application amount.

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