Coconut date coffee forage grass interplanting cultivation method

Abstract

The present application relates to the technical field of agricultural planting, in particular to a coconut date coffee forage grass compound interplanting cultivation method, during 5-8 years before canopy formation after coconut date is planted in single planting with a plant row spacing of 6-10 m, a three-layer stereoscopic ecological niche complementary system is constructed in the row: the upper layer coconut date provides 30%-50% shading; the middle layer is a small-grain coffee planted in a strip outside the trunk at a distance of greater than or equal to 2 m; the lower layer is a strip-sowing creeping tropical leguminous forage grass, which reduces the ground surface temperature from greater than or equal to 55 DEG C to less than or equal to 35 DEG C, and is combined with three-track layered irrigation and mowing residual stubble ground surface coverage management, so that the irrigation water use efficiency is increased from less than 30% to greater than or equal to 65%, and the soil organic matter is accumulated from less than 0.5% to greater than or equal to 1.2%.

Description

Technical Field

[0001] This invention relates to the field of agricultural planting technology, specifically to a method for intercropping and relay cultivation of dates, coffee, and forage grasses. Background Technology

[0002] Dates ( Phoenix dactylifera L. Date palms (Phoenix palmatum) are evergreen trees belonging to the genus Date Palm in the family Arecaceae. Native to arid desert regions of West Asia and North Africa, they are one of the most important fruit trees in tropical arid and semi-arid regions. Since the 20th century, my country has gradually established a date palm cultivation system based on introductions from Yuanmou, Yunnan, and Pakistan. Currently, large-scale date palm plantations have been established in the dry-hot valleys of Yuanjiang and Baoshan in Yunnan, as well as Hainan and southern Sichuan. A single date palm tree can yield over 200 kg annually, making it an important crop for the transition from ecological restoration to economic cultivation in dry-hot valleys. It plays a significant role in promoting the coordinated upgrading of agricultural industries and ecological restoration in these regions.

[0003] However, as a typical deep-rooted, tall palm tree, the date palm requires a spacing of 6-10 meters between plants for commercial cultivation to meet the needs of canopy expansion and root development in mature plants. This spacing characteristic creates a structural contradiction with the canopy formation cycle of date palms. Date palms require a canopy formation period of 5-8 years from planting, during which the canopy projection area slowly increases from less than 10% initially to over 80% eventually. However, large areas of bare land remain between the rows throughout this entire 5-8 year period. In tropical hot and dry valleys, intense direct sunlight causes soil temperatures in bare areas to reach or even exceed 55°C during peak dry seasons, resulting in significant water evaporation and irrigation water utilization efficiency of less than 30%. Simultaneously, due to the lack of vegetation cover and root input between rows, soil organic matter content continuously declines to below 0.5%, further inhibiting root development and delaying the date palms' entry into the production period, hindering the release of their yield potential. This constitutes the core ecological and economic dual constraint of date palm monoculture in hot and dry valleys.

[0004] To alleviate the above problems, existing technologies have proposed a variety of solutions. US Patent US7634869B1 (Combined intercropping and mulching method) discloses a method of intercropping annual legumes with commercial cereal crops and combining it with green manure mulching. This method relies on the mechanized operation system of commercial field in temperate and subtropical regions. The intercropping combination is limited to two-dimensional planar intercropping of annual legumes and cereal crops, and cannot provide a spatiotemporally matched three-dimensional configuration for the 5-8 year long canopy formation period of date palm plantations in tropical dry and hot valleys. Although the green manure mulching can improve surface moisture conditions, it lacks perennial mid-level economic crops that can simultaneously utilize the shading resources of the upper canopy, so that the ecological resources between rows are still in a two-dimensional rather than a three-dimensional utilization state.

[0005] Chinese patent CN108738974A (A Method for Intercropping and Relay Cultivation of Bletilla striata and Kiwifruit) discloses a two-layer intercropping method, using kiwifruit as the upper trellis vine crop and planting Bletilla striata, a shade-tolerant medicinal plant, in the lower layer, forming a complementary utilization system of two layers of medicinal crops. Although this method proposes a design concept of complementary ecological niches between the upper and lower layers, its upper layer consists of artificially trellised vine crops rather than tall trees in arid and hot river valleys, and its lower layer consists of shade-tolerant medicinal herbs rather than creeping leguminous forage grasses. The irrigation and fertilization structure is also designed for the temperate and humid climate of the Qinling-Bashan Mountains. This method does not involve date palm plantations in arid and hot river valleys, nor does it solve the problem of water and soil waste in the bare land between rows during the 5-8 year canopy formation period.

[0006] Chinese patent application CN105191654A discloses a method for intercropping corn and beans. The method employs a wide-narrow row layout and staggered sowing dates to address the problem of insufficient accumulated temperature in high-latitude regions of Northeast China. This method is a two-dimensional intercropping within a single time dimension (within one year), and does not involve multi-year three-dimensional configurations during the canopy formation period of perennial woody crops. It offers no technical inspiration for the 5-8 year time window management of date palm plantations.

[0007] Chinese patent application CN110810250B discloses a method for rapid propagation of dates in tissue culture, which solves the problem of long natural propagation cycle of dates. This method belongs to date propagation technology, which reflects the high demand for high-quality seedlings for large-scale orchard establishment under the date monoculture planting model. However, it does not involve the land use between rows after date planting.

[0008] International patent WO2016103162A2 (Method and fertilizer compositions for treating a plant and plant growth medium) discloses a method for applying nitrogen, phosphorus and potassium fertilizers in a ratio for date palms and other fruit trees. It mainly addresses the problem of nutrient deficiency in sandy soils under date palm monoculture. Its essence is an external fertilizer supply path, and it does not provide a solution to improve soil fertility through ecological configuration between rows. The two problems of continuous input of external fertilizers and soil organic matter degradation coexist under this method.

[0009] In non-patent literature, traditional oasis agriculture systems, as a recognized three-tiered planting model, consist of a date palm canopy, a middle layer of fruit trees, and annual crops on the ground. However, the middle layer consists of conventional fruit trees with seasonal phenology similar to date palms, rather than perennial economic shrubs with semi-shade requirements; the lower layer consists of annual crops, lacking perennial creeping cover and nitrogen-fixing functions. The silvopastoral system constructed from Macauba palm and Brachiaria grass confirmed the feasibility of a two-tiered symbiosis between palm crops and lower grasses, but the middle layer was completely empty, failing to utilize the middle-layer light environment provided by the palm canopy. A study on the application of four leguminous forage crops in an ecological mango orchard in the Yunnan dry-hot valley demonstrated the feasibility of leguminous forage crops as lower-layer cover crops in dry-hot valley orchards, but it is a two-tiered structure (fruit trees + forage), with the upper layer not being date palms and lacking middle-layer economic crops. Both the coffee-banana intercropping model in the East African highlands and the coffee-camphor / autumn maple intercropping model in Yunnan place coffee as a shade-tolerant understory crop under shade trees, without integrating coffee as a middle-layer economic shrub into a three-tiered structure with date palms as the top layer.

[0010] The common limitations of the above-mentioned schemes are: they fail to recognize the vertical ecological niche mismatch vacuum characteristic of the 5-8 year time window of date palm canopy formation, which is characterized by horizontal canopy not being closed while vertical canopy is partially occupied; they fail to simultaneously incorporate the natural ecological niche of the middle light environment (30%-50% shading) in this vacuum window, which precisely matches the semi-shade requirement of small-bean coffee, and the resource gap of the 0.3-1.0 m soil volume of leguminous forage nitrogen fixation site into the composite structure for three-dimensional coupling utilization; and they fail to propose a three-track stratified irrigation topology and a cyclical management path for stubble surface mulching that matches the three-layer three-dimensional structure. As a result, the five types of resources of water, heat, light, nitrogen, and organic matter in existing date palm plantations are simultaneously in a state of inefficiency or even loss in monoculture mode during the 5-8 year canopy formation period. Therefore, there is an urgent need in this field for a composite cultivation method that can simultaneously incorporate the above five types of resources into three-dimensional coupling utilization within the 5-8 year time window and can naturally transition to a permanent two-layer symbiotic mode after the date palm canopy closes. Summary of the Invention

[0011] To address the problems existing in the prior art, the present invention aims to provide a method for intercropping and replanting dates and coffee with forage. This method involves constructing a three-tiered, complementary ecological niche system between date palm rows during the 5-8 years before the date palm canopy matures. Combined with a three-track stratified irrigation system and stubble mulching management, the 30%-50% shading environment in the middle layer, resulting from the phased increase in the date palm canopy projection area, and the nitrogen-fixing potential of the lower soil leguminous plants are simultaneously incorporated into resource utilization. This reduces the surface temperature between rows from ≥55°C in bare date palm monoculture to ≤35°C, increases irrigation water use efficiency from <30% to ≥65%, and accumulates soil organic matter content from ≤0.5% to ≥1.2% by the end of the 5-8 year period.

[0012] To achieve the aforementioned objectives, the date palm-coffee intercropping method of this invention constructs a three-tiered, complementary ecological niche intercropping system between the date palm rows during the 5-8 years after date palms are planted as a monoculture at a spacing of 6-10 m and before the canopy has fully formed. The upper layer consists of the already planted date palms, providing canopy support and continuously offering 30%-50% shade to the area below during these 5-8 years. The middle layer is planted in strips outside the main trunk of the date palms at a safe distance of ≥2 m, with small-bean coffee plantations arranged in double rows. The lower layer consists of creeping tropical legumes sown in rows on the remaining ground between the middle coffee rows. These creeping legumes cover the remaining ground surface with their stolons, reducing the ground temperature between rows from ≥55°C in bare date palm fields to ≤35°C. The method of this invention employs a three-track stratified irrigation structure for the upper, middle, and lower layers: drip irrigation is used for the base of the main stems of the upper layer of date palms; independent micro-sprinkler irrigation is used for the middle layer of coffee plants; and the lower layer of forage relies on lateral infiltration through the independent micro-sprinklers and natural rainfall for moisture. At the end of each dry season, the lower layer of forage is harvested, and the harvested stubble is used to cover the ground between rows, forming an organic mulch layer.

[0013] In the method of this invention, the starting point of the 5-8 year period is defined as the point when the projected area of ​​the date palm canopy reaches 30% of the ground surface area between rows, and the ending point is defined as the point when the projected area of ​​the date palm canopy reaches 80% of the ground surface area between rows. The planting time for mid-layer small-bean coffee is within 18-30 months after date palm monoculture planting, falling within a 0-6 month window before the starting point of the 5-8 year period. For creeping tropical leguminous forage, purple-flowered large-winged bean (Vigna purpurea) is selected based on local annual rainfall and winter low temperature conditions. Macroptilium atropurpureum ) or glossy purple sweet potato ( Vicia villosa subsp.varia) When the date palm canopy projection area reaches 80% and the period of 5-8 years ends, a system conversion will be carried out: the middle layer coffee belt and independent micro-sprinkler belt will be removed, and the lower layer forage will be replaced by creeping leguminous forage with shade-tolerant grass perennial forage, and a two-layer permanent symbiotic model of date palm and forage will be adopted.

[0014] The beneficial effects of this invention are as follows: First, this invention transforms the 5-8 year window of date palm canopy formation from a period of resource idleness into a period of efficient and coordinated utilization of water and soil resources. The surface temperature between rows decreases from ≥55°C in bare date palm monoculture to ≤35°C (temperature drop ≥20°C), irrigation water utilization efficiency increases from <30% to ≥65%, and soil organic matter content accumulates from ≤0.5% to ≥1.2% by the end of the 5-8 year period. Second, during the 5-8 year period before date palm production, this invention provides stable mid-layer economic benefits through mid-layer small-bean coffee cultivation and stable lower-layer livestock feed benefits through the harvesting of fresh grass. The annual yield of fresh grass is 1500-2500 kg per mu, structurally alleviating the cash flow pressure on date palm plantations before production begins. Third, the three-track stratified irrigation architecture of this invention, together with the nitrogen fixation by the rhizobia of the lower forage (8-12 kg N per mu per growing season) and the on-site decomposition of harvested stubble, forms a dual source of nitrogen input (40-72 kg N per mu accumulated over 5-8 years), which supports the root development and release of yield potential of date palms after they enter the production period. It also enables the date palm plantation to naturally transition to a permanent two-layer symbiotic mode through system transformation after the date palm canopy closes, achieving ecological and economic synergy throughout the entire life cycle of the date palm plantation without increasing additional investment. Attached Figure Description

[0015] Figure 1 This is a horizontal top view of the three-layered, three-dimensional, complementary ecological niche composite cultivation system constructed between the rows of date palms in the date palm-coffee intercropping and relay cultivation method of the present invention.

[0016] Figure 2 This is a cross-sectional elevation view of the three-layer structure and shading light path of the date palm, coffee and forage intercropping cultivation method of the present invention.

[0017] Figure 3 This is a schematic diagram of the three-track stratified irrigation structure of the date palm, coffee and forage intercropping cultivation method of the present invention.

[0018] Figure 4 This is a graph showing the relationship between the change in the projected area of ​​the date palm canopy and the trigger point of system transformation during the 5-8 year period of the date palm-coffee-forage intercropping cultivation method of the present invention.

[0019] Figure 5 This is a bar chart comparing the surface temperature, irrigation water use efficiency, and soil organic matter content data of various embodiments and comparative examples of the date palm, coffee, and forage intercropping cultivation method of the present invention. Detailed Implementation

[0020] The present invention will be further described below through specific embodiments. The specific methods, parameters, varieties, and test data described in the embodiments are for illustrative purposes only and should not be regarded as limiting the scope of protection of the present invention. Equivalent substitutions, parameter adjustments, and combination extensions made by those skilled in the art based on the technical solutions disclosed in the present invention without departing from the design concept of the present invention are all within the scope of protection of the present invention.

[0021] The date palm-coffee intercropping method of this invention follows the basic framework in its implementation. First, date palms are planted monoculture at a spacing of 6-10 m. Then, within a 0-6 month window before the date palm canopy projection area reaches 30% of the ground surface area between rows, small-bean coffee is planted in a strip area outside the main stem of the date palm to form the middle layer. In the remaining ground area between the middle coffee strips, creeping tropical leguminous forage is sown in rows at the beginning of the rainy season to form the lower layer. For example... Figure 1 As shown, the three-layer structure exhibits a hierarchical layout in a horizontal, top-down view, with a dotted distribution of dates, a double-row strip configuration of coffee in the middle layer, and continuous coverage of forage in the lower layer; as... Figure 2 As shown, the three-layer structure occupies vertical height segments of 2–6 m, 0.5–2 m, and 0–0.5 m respectively, and the peak periods of photosynthesis and water transpiration in the three layers do not conflict phenologically. Figure 3 As shown, the three-tiered irrigation system employs drip irrigation, micro-sprinkler belts, and lateral infiltration for stratified water supply. Subsequently, the irrigation scheduling, harvesting management, and system conversion path described in this invention are implemented, as follows: Figure 4 As shown, the projected area of ​​the date palm canopy increases according to a typical S-shaped curve over a period of 5 to 8 years, and the system conversion conditions are triggered when the projected area reaches 80%.

[0022] Example 1: The date palm-coffee intercropping cultivation method described in Example 1 was implemented in a date palm plantation in Ganzhuang Street, Yuanjiang Hani, Yi and Dai Autonomous County, Yuxi City, Yunnan Province. The plantation site is at an altitude of 420 m, with an average annual temperature of 24.1°C, an annual precipitation of 820 mm, and a dry season lasting 5 months (November to April of the following year). The soil is hot and dry red soil, and the organic matter content of the 0-30 cm soil layer measured before the plantation was 0.46%, the pH was 6.7, and the average annual sunshine duration was 2370 h. The site conditions meet the selection criteria for the purple-flowered large-winged bean variety in claim 5 of this invention, which requires an annual precipitation of 600-1200 mm and a dry season lasting ≥5 months.

[0023] The date palms were selected from tissue-cultured seedlings of mature Medjool mother trees. Monoculture planting was completed in June 2018, with a spacing of 8 m × 8 m, and 10 date palms planted per acre. For the first 18 months after planting, conventional date palm management was implemented for survival and maintenance. By January 2020 (19 months after planting), the measured canopy projection area reached approximately 18% of the ground surface area between rows, placing the plant in the 0-6 month preparatory window before the start of the 5-8 year period, thus entering the stage of constructing a multi-cropping system. Before the rainy season began in February 2020, a mid-level coffee strip was marked out along the date palm rows, 2.5 m away from the main trunk of each date palm tree. The strip was 2.0 m wide, and two rows of small-bean coffee were planted in each strip, with a plant spacing of 1.5 m and a row spacing of 2.0 m. The small-bean coffee variety selected was Catimor P5, which is highly adaptable to Yunnan. 120 coffee trees were planted per acre, and the distance between two adjacent coffee strips was 3.5 m.

[0024] In May 2020, at the beginning of the rainy season, purple-flowered large-winged bean (Macroptilium atropurpureum) was sown in rows between the remaining rows of mid-layer coffee plants as understory forage. Before sowing, the seed coat was pretreated with 0.2 mol / L sulfuric acid for 5 minutes, rinsed with water, and then treated with rhizobium inoculant. The sowing rate was 1.2 kg per acre, with a row spacing of 30 cm and a sowing depth of 1–2 cm. Uniform emergence was observed 10 days after sowing, and the aboveground stolon coverage reached 92% after 60 days. The measured thickness of the understory stolon layer was 6–10 cm.

[0025] The three-track, tiered irrigation system of this embodiment is implemented according to the parameters described in claim 4 of this invention. The upper layer, the date palm main trunk base, is equipped with 6 L / h pressure-compensated drippers, with four drippers per date palm plant arranged in a square around the trunk base. Irrigation duration is 7 hours per day during the dry season and activated as needed during the rainy season. The middle layer, the coffee belt, is laid with independent micro-sprinklers along a strip-like direction, with a sprinkler spacing of 0.7 m and an operating pressure of 0.15 MPa. Irrigation duration is 2.0 hours per day during the dry season and suspended during the rainy season. The lower layer, the purple-flowered winged bean, only activates the coffee micro-sprinklers for a 15-minute delay for lateral infiltration irrigation when there is no continuous rainfall for more than 15 days. The three-layer irrigation schedule is staggered: the upper layer from 22:00 to 5:00 the next day; the middle layer twice a day (6:00 to 7:00 and 18:00 to 19:00); and the lower layer irrigation is scheduled immediately after the middle layer irrigation ends, avoiding mutual interference in water transport.

[0026] At the end of the dry season each year (late April), the lower layer of purple-flowered winged beans is harvested, leaving a stubble height of 8-10 cm to maintain regeneration capacity. The annual yield of fresh grass harvested is 2018 kg / mu (actual measurement in 2023), and the fresh grass is used as feed for cattle and sheep of nearby livestock farmers. The harvested stubble is used as ground cover between rows, with an actual stubble coverage of 390 kg / mu. At the end of the rainy season each year (late October), old leaves of the upper layer of date palms are thinned out, removing 1-2 yellowed or semi-yellowed old leaves from each date palm plant. After thinning, the middle layer is maintained at 30%-50% shade.

[0027] This embodiment operated completely for 5 years from 2020 to 2025 without any significant pests or diseases. By December 2025 (90 months after date palm planting), the measured canopy projection area of ​​the date palms reached approximately 75% of the ground surface area between rows, approaching the 80% system conversion trigger condition described in claim 8 of this invention. The system conversion is expected to be implemented in the second quarter of 2026: the middle layer coffee belt and independent micro-sprinkler belt will be removed, and the lower layer of purple-flowered winged beans will be replaced with shade-tolerant perennial forage grass, African foxtail grass (Setaria sphacelata cv. Kazungula), transitioning to a two-layer permanent symbiotic relationship between date palms and forage grass.

[0028] In this embodiment, conventional monoculture management of date palms was implemented during the initial maintenance phase from the first to the 18th month after planting. Each date palm plant was fertilized monthly with 150 g of compound fertilizer (N15-P15-K15) and 3 kg of organic fertilizer. Weeding was carried out 3-4 times throughout the year, and approximately 5 kg of pruned leaf debris per plant was used to cover the rootstock to maintain soil moisture. No significant pests or diseases occurred during this period. From 2018 to 2019, the date palm survival rate was 100%, and the annual shoot length was 19.6 cm, meeting the conventional growth standards for the Medjool variety introduced in this region. This laid a normal foundation for the normal date palm growth of the 5-8 year compound cultivation system described in this invention.

[0029] This embodiment describes a three-layer cultivation management system implemented annually for five years starting from the establishment of the integrated cultivation system in 2020. The middle layer of small-bean coffee began flowering 18 months after planting in June 2020 (December 2021), and began producing beans for the first time in March 2022. From 2022 to 2025, the cumulative green coffee bean yield increased year by year across four production seasons (98 kg / mu in 2022, 142 kg / mu in 2023, 168 kg / mu in 2024, and 186 kg / mu in 2025), showing a good synergistic relationship with the annual expansion of the middle canopy and the annual optimization of the shading provided by the date palm canopy. The lower layer of purple-flowered large-winged coffee was harvested once a year at the end of April. Regeneration was rapid after harvesting, and by the beginning of the rainy season, the runner coverage had recovered to over 85%.

[0030] The cumulative economic benefits achieved by this implementation model up to 2025 are as follows: A cumulative yield of 594 kg / mu of mid-layer small-bean coffee beans (calculated at a local green coffee bean purchase price of 32 yuan / kg, resulting in a cumulative mid-layer economic benefit of 19,008 yuan / mu); a cumulative yield of 9,824 kg / mu of fresh grass from the lower layer of purple-flowered winged beans (calculated at a local livestock fresh grass purchase price of 0.6 yuan / kg, resulting in a cumulative lower-layer economic benefit of 5,894 yuan / mu). The total economic benefits from the mid- and lower layers amount to 24,902 yuan / mu, equivalent to a stable additional income of 4,980 yuan / mu per year, effectively alleviating the cash flow pressure on date palm plantations before production commences. In terms of ecological indicators, a cumulative soil organic matter return of approximately 2,150 kg / mu over the five years (1,925 kg / mu of stubble cover + 225 kg / mu of fallen coffee leaves), effectively supporting the accumulation of soil organic matter from an initial 0.46% to the measured 1.28% in 2025.

[0031] The integrated pest management in this embodiment was carried out according to local ecological planting practices. For the upper-layer date palms, Bordeaux mixture (1:1:200) was sprayed twice annually, once in early (May) and once in mid-July, to control the date palm weevil, with no significant infestation reported. For the middle-layer small-bean coffee, the coffee longhorn beetle (Xylotrechus quadripes) was controlled using a combination of manual capture and yellow sticky traps; over five years, no more than 3% of coffee plants were damaged. The lower-layer purple-flowered winged bean pest and disease incidence was extremely low; only one mild aphid infestation occurred in mid-2022 (approximately 8 aphids per plant), which was largely controlled within 14 days after the release of ladybugs as a natural enemy. This embodiment did not use any highly toxic chemical pesticides throughout the process, ensuring the safety of the freshly cut forage for cattle and sheep, and avoiding the potential inhibition of chemical pesticide residues on the lower-layer soil microbial community and nitrogen-fixing activity of rhizobia in the date palm plantation.

[0032] Example 2: The date palm-coffee intercropping cultivation method described in Example 2 was implemented in a date palm plantation in Lujiang Town, Longyang District, Baoshan City, Yunnan Province. The plantation site is at an altitude of 660 m, with an average annual temperature of 22.8°C, annual precipitation of 710 mm, and a dry season lasting 6 months (October to March of the following year). The soil is sandy red soil, and the organic matter content of the 0-30 cm soil layer was 0.51% and the pH was 6.5, as measured before the plantation was established. The site conditions meet the selection criteria for the purple-flowered large-winged bean variety in claim 5 of this invention, which requires an annual precipitation of 600-1200 mm and a dry season lasting ≥5 months, but are drier than in Example 1.

[0033] The date palm variety was selected from tissue-cultured seedlings of mature Khalas mother trees. Monoculture planting was completed in May 2019, with a spacing of 6 m × 10 m (10 m row spacing along contour lines and 6 m plant spacing perpendicular to contour lines, adapting to sloping terrain), resulting in 11 date palm trees per acre. In March 2021 (22 months after date palm planting), the intercropping system was established, with the measured canopy projection area of ​​the date palms reaching approximately 22% of the ground surface area between rows. The mid-layer small-bean coffee variety was the same Catimor P5 lineage, planted before the rainy season began in April 2021, 2.2 m from the date palm trunk, with a plant spacing of 1.5 m and a row spacing of 2.0 m. The distance between adjacent coffee strips was adjusted to 3.0 m due to the smaller plant spacing of the date palms, resulting in 130 coffee trees per acre.

[0034] The lower-layer purple-flowered winged beans were sown in rows at the beginning of the rainy season in May 2021, with sowing parameters consistent with Example 1. Due to the relatively dry site in this example, the lower-layer purple-flowered winged beans experienced mild water stress twice, on days 30 and 60 after emergence. This was alleviated once each by lateral infiltration watering with a 20-minute delay using the middle-layer coffee micro-sprinkler belt. After 60 days, the aboveground runner coverage still reached 88%.

[0035] In this embodiment, the three-track tiered irrigation system is appropriately adjusted according to the arid conditions of the orchard site. The drip flow rate at the base of the main trunk of the upper-layer date palm is adjusted to 8 L / h (6 L / h in Example 1), and the daily irrigation duration is extended to 8 h during the dry season; the sprinkler spacing of the independent micro-sprinkler belt in the middle-layer coffee belt is maintained at 0.7 m, the working pressure is increased to 0.20 MPa, and the daily sprinkler irrigation duration is extended to 2.5 h during the dry season; the lateral infiltration water replenishment trigger condition for the lower-layer purple winged bean is adjusted from 15 consecutive days without precipitation to 12 days, and the water replenishment time is delayed by 20 min each time.

[0036] The mowing management and system conversion path are the same as in Example 1. This example ran completely for approximately four and a half years from 2021 to 2025, during which the annual fresh yield of purple winged bean grass was 1742 kg / mu (measured in 2024), and the stubble coverage was 340 kg / mu. By October 2025, the measured canopy projection area of ​​date palms reached approximately 62% of the ground surface area between rows, and it is expected to reach 80% by 2027, triggering system conversion. The comparison between this example and Example 1 verifies the adaptability of this invention to different dry and hot valley regions with different date palm row spacings, and verifies that the parameters of the three-track stratified irrigation structure can be finely adjusted within the range defined in claim 4 of this invention according to the drought level of the orchard site.

[0037] In this embodiment, due to the relatively dry site, a shallow circular pit (approximately 15 cm deep) with a diameter of 2.5 m was set up around each date palm plant as a micro-water collection basin during the early maintenance phase. Rainwater and irrigation water could be temporarily concentrated in the shallow pit and slowly seep in, ensuring a 100% survival rate and an annual shoot length of 18.4 cm for the first 18 months. This micro-water collection measure was retained after the middle-layer coffee plants were planted and removed after two years of establishment and maintenance. For the first 6 months after planting the middle-layer coffee plants, each plant was fertilized weekly with diluted liquid fertilizer (10 g of N6-P6-K6 water-soluble fertilizer dissolved in 10 L of water). After 6 months, the application was reduced to once a month, resulting in a 98.5% survival rate for the coffee plants.

[0038] The cumulative annual yield of green coffee beans from the middle layer, as recorded in this embodiment up to 2025, is as follows: 82 kg / mu in 2022 (first harvest), 128 kg / mu in 2023, 149 kg / mu in 2024, and 162 kg / mu in 2025. The annual yield of fresh grass from the lower layer of purple-flowered winged beans is recorded as follows: 1356 kg / mu in 2021 (first year), 1632 kg / mu in 2022, 1748 kg / mu in 2023, 1742 kg / mu in 2024, and 1810 kg / mu in 2025. The fresh grass yield stabilized after the third year (2023), indicating that the root system and symbiotic rhizobium system of the lower-layer creeping leguminous forage grass completed colonization in the third year. The comparison between this embodiment and Embodiment 1 shows that, under more arid conditions, the method of the present invention can still stably achieve three core indicators: ≥1.2% soil organic matter accumulation, ≥65% irrigation water use efficiency, and ≤35°C surface temperature.

[0039] Example 3: The date palm-coffee intercropping cultivation method described in Example 3 was implemented in a date palm plantation in Laocheng Township, Yuanmou County, Chuxiong Yi Autonomous Prefecture, Yunnan Province. The plantation site is at an altitude of 1180 m, with an average annual temperature of 21.9°C, annual precipitation of 1310 mm, a dry season lasting approximately 4 months (December to March of the following year), an average temperature of 12.3°C in the coldest month (January), and a continuous period of low temperatures (daily minimum temperature <10°C) lasting approximately 45 days. The soil is mountain red soil, and the organic matter content of the 0-30 cm soil layer measured before the plantation was 0.62%, with a pH of 6.4. The plantation site conditions meet the selection criteria for the *Sweet Potato* cultivar of claim 5 of this invention, which requires an annual precipitation of 1200-1800 mm or ≥1 month of low temperatures in winter.

[0040] The date palms were selected from tissue-cultured seedlings of mature Deglet Noor mother trees. Monoculture planting was completed in July 2017, with a spacing of 10m x 8m (arranged along the prevailing wind direction for good ventilation), and 8 date palms per acre. In May 2019 (22 months after planting), the integrated cultivation system was established, with the actual measured canopy projection area reaching approximately 25% of the ground surface area between rows. The mid-layer small-bean coffee was selected from the Yunnan local Typica strain (more adapted to higher altitude, semi-shaded environments). Planting was completed in June 2019 at the beginning of the rainy season, with a spacing of 3.0m from the main trunk of the date palms (the safety distance could be appropriately increased due to the larger spacing between date palms), a plant spacing of 1.5m, a row spacing of 2.0m, and a spacing of 4.5m between adjacent coffee strips, with 100 coffee trees per acre.

[0041] The lower-layer Vicia villosa subsp. varia was sown in autumn in September 2019 to adapt to the phenological rhythm of overwintering growth under the low winter conditions of this region. The sowing rate was 1.0 kg per mu (approximately 0.067 hectares), with a row spacing of 25 cm and a sowing depth of 1.5 cm. Before sowing, the seeds were treated with rhizobium inoculum. Due to the overwintering habits of Vicia villosa, a shallow covering was applied in early December of the sowing year (approximately 200 kg / mu of date palm leaf trimmings) for frost protection and insulation. The covering was removed in February of the following year after the temperature rose. The aboveground runner coverage of Vicia villosa in this orchard reached a peak of 95% in spring. In summer, due to higher temperatures and the semi-dormant state of Vicia villosa, the coverage dropped to 75%–80%.

[0042] The three-track tiered irrigation system is implemented according to the parameters described in claim 4 of this invention. The upper layer, the dripper at the base of the date palm trunk, has a flow rate of 5 L / h and a daily irrigation duration of 6 h during the dry season; the middle layer, the coffee belt, has independent micro-sprinklers with a sprinkler spacing of 0.5 m (suitable for densely planted coffee), an operating pressure of 0.10 MPa, and a daily sprinkler irrigation duration of 1.5 h during the dry season; the lower layer, the lateral infiltration irrigation for the purple sweet potato is only activated during the spring dry period. Due to the high annual precipitation at the orchard site in this embodiment, the frequency of lower layer irrigation activation is significantly lower than in Embodiments 1 and 2.

[0043] In this embodiment, mowing management is adjusted to once a year in early May (late dry season, late spring) according to the biennial phenology of *Stylos sphacelata*. The annual yield of fresh grass is 2317 kg / mu (measured in 2023), and the stubble coverage is 460 kg / mu. Since *Stylos sphacelata* re-germinates in autumn after a semi-dormant period in summer, the mowing frequency in this embodiment remains once a year. By July 2025, the measured canopy projection area of ​​date palms reached approximately 68% of the ground surface area between rows. It is expected to reach 80% by the third quarter of 2026, triggering the system conversion. At that time, the lower layer of *Stylos sphacelata* will be replaced with a mixed sowing combination of shade-tolerant grasses and perennial forage grasses (Stylos sphacelata × Setaria sphacelata).

[0044] Due to the high altitude of the site and the continuous 45-day low-temperature period in winter, during the early maintenance phase of the date palms, a layer of straw (approximately 3 cm thick) was wrapped around the base of the main stem for frost protection for two consecutive months from December to January of the following year. This was removed after the temperature rose in February of the following year. This frost protection measure ensured a 100% survival rate of the date palms over winter in Yuanmou at an altitude of 1180 m. The Typica variety from Yunnan was selected for the middle layer of coffee because this variety exhibits superior coffee bean quality (cherry fullness and cup flavor) compared to the Catimor variety in semi-shaded environments at altitudes of 1000-1500 m, making it more suitable for the high-altitude climate of this embodiment.

[0045] Due to its biennial biological characteristics, the lower layer of *Solanum glabra* in this embodiment reaches its biomass peak in April-May of the following year after autumn sowing in September. The annual fresh grass yield recorded at this time is as follows: 1842 kg / mu in 2020 (first year), 2156 kg / mu in 2021, 2218 kg / mu in 2022, 2317 kg / mu in 2023, and 2289 kg / mu in 2024. The fresh grass yield of *Solanum glabra* in this embodiment stabilizes after the third year (2022). After entering a semi-dormant state during the high-temperature summer period from June to September each year, the aboveground cover of *Solanum glabra* drops to 75%-80%. However, because its stolons and shallow root system still maintain the physical structure of the soil, its function of regulating surface temperature is not significantly affected. The measured peak surface temperature in summer of 2024 was still 32.1°C, meeting the requirement of ≤35°C as described in claim 1 of this invention. The cumulative green bean yield of Typica coffee in the middle layer over 5 years was 786 kg / mu. Based on the local purchase price of Typica coffee green beans of 35 yuan / kg, the cumulative economic benefit of the middle layer was 27,510 yuan / mu, which is about 44.7% higher than the benefit of Catimor coffee green beans in Example 1.

[0046] During the five years of operation of this embodiment, due to the latitudinal difference between the Yuanmou dry-hot valley region and traditional coffee-producing areas, the flowering period of Typica coffee was delayed from the usual April-May to May-June, thus delaying the ripening period of the coffee berries to December of the current year to February of the following year. This misalignment with the basic irrigation period during the dry season for date palms further reduced the competition for water demand between the middle-layer coffee plants and the upper-layer date palms. This phenological misalignment is an additional favorable factor under the high-altitude site conditions of this embodiment, which did not occur in Embodiments 1 and 2, reflecting that the method described in this invention can naturally generate additional synergistic promoting mechanisms under different geographical and climatic conditions.

[0047] To fully verify the beneficial effects of the present invention, three independent comparison areas were delineated within the same date palm plantation, each approximately 3 acres in size, based on the site conditions and planting stage of Example 1. The date palm varieties, planting time, row spacing, and routine date palm management were completely consistent with Example 1, but the inter-row management paths adopted the different patterns described in Comparative Examples 1, 2, and 3, respectively. The detection time period, sampling sites, and detection methods in the three comparison areas were completely synchronized with those in Example 1 to eliminate interference from environmental and time factors.

[0048] Comparative Example 1 is a date palm monoculture (bare ground between rows) model. No mid- or low-lying crops are planted between the date palm rows; only conventional date palm monoculture management, including weeding and basal fertilization, is implemented. This comparative example represents the date palm monoculture model defined in claim 1 of this invention as a baseline control. Cumulative monitoring data from Comparative Example 1 over a 5-year period showed: peak ground surface temperature between rows during the dry season was 58.2°C; actual irrigation water utilization efficiency was 28.4%; soil organic matter content after 5 years was 0.42% (a decrease of 8.7% from the initial value); average annual shoot length for date palms was 23.1 cm; and there were no economic benefits from mid- or low-lying crops in the date palm plantation during the 5-8 year period.

[0049] Comparative Example 2 was a two-layer system consisting of date palm monoculture and purple winged bean understory mulch (without mid-layer coffee). Mid-layer coffee was not planted between the date palm rows, but purple winged beans were sown as understory mulch using the same parameters as in Example 1. The purpose of this comparative example was to isolate and test the contribution of the presence or absence of mid-layer coffee to the overall system. Data from Comparative Example 2 showed that the peak ground surface temperature between rows was 40.6°C (a decrease of 17.6°C compared to Comparative Example 1), irrigation water use efficiency was 48.7%, soil organic matter content after 5 years was 0.85%, and the annual shoot length of the date palm was 28.6 cm. Although Comparative Example 2 was significantly better than Comparative Example 1 in three key indicators—surface temperature regulation, water use efficiency, and soil organic matter—the date palm plantation had no mid-layer economic benefits during the 5-8 year period, except for the income from fresh grass feed in the lower layer (measured at 1856 kg / mu·year). Moreover, the cumulative nitrogen input per unit area came only from nitrogen fixation in the lower layer (accumulated at only 31 kg N per mu over 5 years).

[0050] Comparative Example 3 uses a three-layer pattern of date palm, mango, and purple winged bean (the middle layer is mango, not small-bean coffee). Mango trees are planted in a strip 2.5 m outside the main stem between the date palm rows. Mangifera indica L.The middle layer was planted with purple-flowered winged beans in rows below. The purpose of this comparative study was to isolate and test the non-equivalence of the middle layer of small-bean coffee varieties relative to the middle layer of conventional fruit trees (mango). Since mango is a conventional fruit tree with similar seasonal phenology to date palms, deep root systems, and peak summer water requirements that overlap with date palms, the test data of Comparative Study 3 showed that: the annual shoot length of date palms was only 24.3 cm (15.0% lower than Comparative Study 2), the total irrigation water consumption of date palm orchards increased by about 38% over 5 years compared to Comparative Study 2, the middle layer of mangoes could not enter the stable production period due to insufficient canopy, and the annual yield was only 98 kg / mu, and the annual yield of fresh purple-flowered winged beans in the lower layer dropped to 1320 kg / mu (28.9% lower than Comparative Study 2). Comparative Example 3 verifies from the opposite perspective that during the formation period of the date palm canopy, the mid-layer crop must be a perennial economic shrub (i.e., small-bean coffee) that requires partial shade, has shallow roots, and is out of sync with the phenology of date palms in terms of time and space, rather than a conventional fruit tree that is synchronized with the phenology of date palms and has intense root competition.

[0051] The annual peak surface temperature variations of Comparative Examples 1, 2, and 3 over the 5-year period exhibit the following patterns: In Comparative Example 1, the annual peak surface temperature remained relatively stable between 56.8 and 58.9°C over the 5 years, showing no significant interannual variation trend, reflecting the persistently harsh thermal environment of the bare geothermal environment between rows under the date palm monoculture model. In Comparative Example 2, the annual peak surface temperature decreased from 45.2°C in the first year to 40.6°C in the fifth year, reflecting the cumulative effect of the increasing ground cover of the underlying creeping forage grasses with increasing growth years. In Comparative Example 3, the annual peak surface temperature decreased from 42.1°C in the first year to 37.4°C in the fifth year, a smaller decrease than in Comparative Example 2, reflecting that water competition between the middle mango and the underlying forage grasses inhibited the development of the underlying forage cover. The annual peak surface temperature of Example 1 decreased from 38.6°C in the first year to 33.8°C in the fifth year. The decrease was similar to that of Comparative Example 2, but the absolute value was significantly lower than that of Comparative Example 2 and Comparative Example 3. This further verifies the nonlinear synergistic advantage of the three-layer structure of the present invention in the regulation of the surface thermal environment.

[0052] The detection items, detection methods, and sampling specifications of each embodiment and comparative example of the present invention shall be uniformly implemented in accordance with the following specifications to ensure the comparability and repeatability of the detection data.

[0053] The surface temperature between rows was continuously monitored using a T-type thermocouple sensor in conjunction with a data logger. The sensor was placed at two fixed measuring points: one 2.5 m away from the main trunk of the date palm (edge ​​of the middle coffee belt) and the other at the center of the two adjacent coffee belts (center of the lower forage cover). The sensor was buried at a depth of 1 cm and the sampling frequency was 1 time / min. The highest surface temperature was recorded during the peak period at the end of the dry season from April to May each year (14:00 to 16:00). The arithmetic mean of the highest values ​​within the 30-day measurement cycle each year was taken as the annual peak surface temperature.

[0054] Irrigation water use efficiency was calculated using the water balance method. The total irrigation water volume was determined by the cumulative readings of the flow meters in each irrigation branch. The actual water absorption of the date palms was calculated by continuous monitoring using a stem flow meter (Heat Pulse method). The actual water absorption of the middle-layer coffee and lower-layer forage crops was inversely estimated by combining soil moisture changes in the coffee strip and forage plots (FDR soil moisture sensor, 0-30 cm soil layer) with reference crop evapotranspiration (FAO Penman-Monteith method). Irrigation water use efficiency was defined as the ratio of the sum of the actual water absorption of the three crop layers to the total irrigation water volume.

[0055] Soil organic matter content was determined using the potassium dichromate external heating method according to GB 9834-1988 "Soil Organic Matter Determination Method". Sampling depth was 0–30 cm. Five sampling points were randomly selected within the area of ​​each example or comparative example, with three parallel samples collected from each point. The samples were then mixed and the mean was taken. Sampling was conducted annually around the anniversary of the park's founding, with the sampling season fixed in the middle of the dry season (February each year) to eliminate seasonal fluctuations.

[0056] The nitrogen fixation rate of rhizobia in the lower layer of creeping tropical leguminous forage grasses was determined by... 15 Nitrogen isotope dilution method was used for determination. Application was performed in experimental plots during the forage sowing season. 15 Ammonium sulfate with an nitrogen abundance of 4.0% was used as a tracer (application rate of 4 kg N per acre). Samples were collected from the upper part of forage grass during the harvest season, dried, pulverized, and sent to an isotope mass spectrometer for analysis. 15 N abundance, using non-nitrogen-fixing reference plants (non-leguminous grass seedlings planted concurrently in the same plot) as the reference plants. 15 Nitrogen abundance was used as a reference to calculate the nitrogen fixation rate, and nitrogen fixation per unit area was calculated by combining forage biomass data.

[0057] The photosynthetic rate of mid-layer small-bean coffee was measured using a LI-6800 portable photosynthesis measurement system on sunny mornings between 10:00 and 11:00 AM during the middle of the rainy season (July) each year. Light intensity was set to 1500 μmol / (m²) saturation light. 2 ·s), CO2 concentration was set to the environmental value of 400 μmol / mol, leaf temperature was set to 28°C, 5 coffee plants were randomly selected for each example, and the 3rd to 5th mature leaves in the middle of the main stem of each plant were measured 3 times, and the average value was taken.

[0058] The annual yield of fresh forage in the lower layer was determined using a 5 m × 5 m quadrat weighing method. Three quadrats were randomly arranged for each example or comparative example. The fresh weight was weighed immediately at the time of harvesting, and the average fresh weight of the three quadrats was converted to the yield per acre. The amount of stubble cover was weighed within the same quadrat within 24 hours after harvesting to confirm that the stubble was evenly distributed on the ground surface between rows.

[0059] The annual shoot length of date palms was measured according to the routine management specifications for date palms. Five date palms were randomly selected for each example or comparative example. Two representative new leaves from the second to third layer at the top of the main axis of each date palm were selected, and the total length of the leaf from the base to the top was measured. The difference was taken once at the beginning of the year and once at the end of the year. The average value of the five date palms was taken as the annual shoot length.

[0060] Table 1 summarizes the core detection indicators of the three embodiments and three comparative examples of the present invention at the end of year 5 (i.e., the end point of the 5-8 year period). For ease of horizontal comparison, all data have been converted to a uniform unit.

[0061] Table 1. Summary of core detection indicators for the three examples and three comparative examples at year 5 (i.e., the end point of the 5-8 year period).

[0062] Table 1 shows that Examples 1, 2, and 3 of this invention are significantly superior to Comparative Example 1 (date palm monoculture), Comparative Example 2 (date palm + lower forage layer), and Comparative Example 3 (date palm + middle mango + lower forage layer) in all seven core detection indicators. Further analysis of the data reveals three sets of nonlinear synergistic effects. These nonlinear effects emerge as a whole from the three-layered, three-dimensional niche-complementary composite cultivation system of this invention and cannot be explained by the simple summation of contributions from a single layer.

[0063] First, the nonlinear decrease in surface temperature between rows. The surface temperature in Comparative Example 1 dropped from 58.2°C to 40.6°C in Comparative Example 2, a decrease of 17.6°C, which can be attributed to the single factor of the underlying creeping forage surface cover. However, in Example 1, after adding mid-layer small-bean coffee to Comparative Example 2, the surface temperature further decreased to 33.8°C, a further decrease of 6.8°C. If the mid-layer coffee only provides independent shading, linear extrapolation based on its shading coverage (mid-layer coffee coverage is approximately 35%) should only result in a decrease in surface temperature of about 2.0°C. The actual temperature decrease is 3.4 times the linearly extrapolated value. This superlinear drop is due to the airflow vortex blocking effect formed between the middle coffee canopy and the lower stolon layer. The middle canopy slows down the horizontal flow of air close to the ground, allowing the low-temperature water vapor formed by evaporation from the lower stolon layer to remain stably near the surface, forming a continuous local low-temperature microclimate. This is a coupling effect that cannot be produced by a single layer.

[0064] Second, the non-linear improvement in irrigation water use efficiency. Comparative Example 1 showed an efficiency of 28.4%, and Comparative Example 2 showed an efficiency of 48.7%, an increase of 20.3 percentage points; Example 1 showed an efficiency of 68.5%, an increase of 19.8 percentage points compared to Comparative Example 2. If the middle layer of coffee trees only plays an independent water-using role, based on its water-using proportion (the middle layer of coffee trees accounts for about 40% of the total irrigation water), the linear prediction could increase the overall efficiency to a maximum of about 60%; the actual efficiency of Example 1, 68.5%, exceeded the linear prediction by 8.5 percentage points. The mechanism is as follows: the three-track layered irrigation architecture of this invention allows the three layers of water input to operate in staggered phases according to phenological time. A small amount of water lost from the upper layer's nighttime drip irrigation can be partially absorbed by the leaves of the middle layer of coffee trees. About 15% of the atomized water from the middle layer's morning and evening micro-sprinklers is laterally drifted to supplement the root zone of the lower forage grasses. The high surface coverage of the lower stolon layer significantly reduces the secondary evaporation loss of soil moisture during the upper layer's drip irrigation and the middle layer's micro-sprinkler process. The mutual reuse of water flow among the three layers is something that a single irrigation system cannot achieve.

[0065] Third, the nonlinear superposition of soil organic matter accumulation. Comparative Example 1 showed a 5-year soil organic matter content of 0.42% (a decrease from the initial level), Comparative Example 2 showed 0.85% (an increase of approximately 0.3 percentage points from the initial level), and Example 1 showed 1.28% (an increase of approximately 0.8 percentage points from the initial level). If the middle-layer coffee trees only act as an independent input of organic matter (coffee fallen leaves and pruning residue), based on the linear superposition of approximately 0.15%~0.20% organic matter accumulation in pure coffee plantations over 5 years according to the literature, the organic matter content in Example 1 should reach approximately 1.00%~1.05%; the actual 1.28% exceeded the linear prediction by 0.23~0.28 percentage points. The mechanism is as follows: the organic acid secretion from the roots of the middle-layer coffee plant activates the insoluble organic nitrogen formed by nitrogen fixation in the lower-layer forage, transforming nitrogen from a microbially held state to a plant-available state. This indirectly promotes a further increase in the biomass of the lower-layer forage. The increased lower-layer biomass then flows back into the soil as additional organic matter during the stubble harvesting stage, forming a positive feedback loop between the middle-layer coffee plant, the lower-layer forage, and the soil organic matter. Although Comparative Example 3 used a three-layer structure, the root characteristics of the middle-layer mango plant were significantly different from those of the coffee plant, and the above positive feedback loop was not formed, with soil organic matter accumulating to only 0.96%.

[0066] Three sets of nonlinear synergistic effects collectively support the core technical effects defined in the claims of this invention: the inter-row surface temperature decreased from ≥55°C to ≤35°C in date palm monoculture bare land, irrigation water use efficiency increased from <30% to ≥65%, and soil organic matter accumulated from <0.5% to ≥1.2%. Further data show that the three embodiments robustly achieved the above effects under different geographical and climatic conditions, demonstrating that the method of this invention has good adaptability to different sub-climatic zones in hot and dry valley regions.

[0067] Further analysis at the mechanistic level reveals that the reason why the date palm-coffee intercropping cultivation method of this invention can achieve a nonlinear synergistic effect that surpasses the comparative ratio lies in the fact that this invention identifies and utilizes the vertical ecological niche mismatch vacuum existing between rows within the 5-8 year time window of the date palm canopy formation period. This vacuum has a dual spatiotemporal mismatch characteristic: in the horizontal direction, the projected area of ​​the date palm canopy has reached 30%-80% but has not yet reached complete closure, so that the 30%-50% shading light environment in the middle layer just matches the semi-shade ecological requirements of small-bean coffee; in the vertical direction, the date palm root system has penetrated to a depth of 2-3 m, but the horizontal root system has not yet occupied the entire soil volume between rows, so that there is a vacancy for nitrogen fixation sites associated with leguminous plants in the 0.3-1.0 m soil layer. The three-layer structure of this invention precisely fills this vacuum: the middle layer of small-bean coffee occupies the central photonic niche, the lower layer of creeping tropical leguminous forage occupies the surface cover and shallow nitrogen-fixing niche, and the upper layer of date palm occupies the deep root system and canopy photosynthetic niche. The three layers exhibit a completely complementary rather than competitive coupling relationship in four dimensions: phenological rhythm, root zone distribution, peak photosynthetic period, and seasonality of water requirements.

[0068] Crucially, the vacuum window of this invention has a naturally defined time endpoint: the starting point is when the date palm canopy projection reaches 30% (approximately month 18-30), and the ending point is when the date palm canopy projection reaches 80% (approximately month 60-96). Before the starting point, the dates themselves require sufficient resource maintenance; after the ending point, the closing of the date palm canopy naturally compresses the light ecological space of the middle coffee plant. This time endpoint characteristic enables the composite cultivation system of this invention to self-terminate upon reaching the endpoint, naturally transitioning to a permanent two-layer symbiotic mode through the system transformation path described in claim 8, avoiding resource conflicts or economic losses that may be caused by artificial forced termination. Therefore, the method of this invention constitutes a complete cultivation system with a definable start and end time, quantifiable spatial niche complementarity, and simultaneous release of economic and ecological benefits.

[0069] Further analysis of the energy and material flow in the ecosystem reveals that the three-layer structure of this invention constitutes a micro-ecosystem with multi-level energy interception and material cycling. Light energy from solar radiation is first intercepted by the upper date palm canopy (approximately 30%–50% of the shading value), the remaining light energy penetrates the canopy and enters the middle layer of small-bean coffee canopy for secondary photosynthetic interception, and the remaining light energy then enters the lower stolon layer for tertiary photosynthetic interception. This results in the total photosynthetic utilization rate of solar radiation by the three-layer structure of this invention being approximately 2.3 times higher than that of date palm monoculture. Regarding material flow, fallen leaves and crop residues in the three layers decompose on-site during the rainy season, releasing organic carbon and nitrogen. Some of this is directly absorbed by the lower root system, some is absorbed by the middle layer of coffee rhizosphere microorganisms and converted into forms usable by plants, and some reaches the depth of the upper date palm root system through deep hydrological flow, forming a vertical nutrient cycle between the upper, middle, and lower layers. This vertical nutrient cycle is not present in date palm monoculture or simple two-layer intercropping, and it is also the fundamental mechanism that distinguishes the three-layer structure of this invention from any existing two-layer intercropping model.

[0070] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. The method of the present invention, without departing from the core architecture of the three-layer three-dimensional ecological niche complementary composite cultivation system and the three-track stratified irrigation topology, can be adapted and selected by those skilled in the art according to the specific site conditions for date palm varieties, coffee strains, forage types and specific parameters. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for intercropping and relay cultivation of date palms, coffee, and forage grasses, characterized in that... In the date palm plantation, during the 5-8 years after the date palms are planted as a monoculture with a spacing of 6-10 m between plants and before the canopy is formed, a three-tiered, complementary ecological niche composite cultivation system is constructed between the rows of date palms: the upper layer consists of the planted date palms as the canopy supply crop, and the upper layer continuously provides 30%-50% shade to the areas below during the 5-8 years; the middle layer is located at a distance of ≥2 meters from the main trunk of the date palms. Small-bean coffee is planted in a double-row strip configuration within a safety spacing of m. The lower layer, between the middle coffee strips, is planted with creeping tropical legumes, which cover the remaining ground surface between rows with their above-ground stolons, reducing the ground temperature between rows from ≥55°C in bare date palm fields to ≤35°C. The method employs a three-track stratified irrigation system for the upper, middle, and lower layers. The base of the main stem of the upper date palm is irrigated by drip irrigation, the middle coffee strip is irrigated by independent micro-sprinklers, and the lower forage relies on lateral infiltration from the independent micro-sprinklers and natural rainfall for moisture. At the end of each dry season, the lower forage is harvested, and the stubble is used to cover the ground surface between rows to form an organic mulch layer.

2. The method for intercropping and relay cultivation of date palms and coffee with forage grasses according to claim 1, characterized in that, The starting point of the 5-8 year period is when the projected area of ​​the date palm canopy reaches 30% of the ground area between the rows, and the ending point of the 5-8 year period is when the projected area of ​​the date palm canopy reaches 80% of the ground area between the rows.

3. The method for intercropping and relay cultivation of date palms and coffee with forage grasses according to claim 2, characterized in that, The planting time for the mid-layer small-bean coffee variety is within 18 to 30 months after the date palm monoculture planting, and falls within the 0 to 6 month window before the start of the 5 to 8 year period.

4. The method for intercropping and relay cultivation of date palms and coffee with forage grasses according to claim 3, characterized in that, The drip irrigation system at the base of the upper date palm trunk has a flow rate of 4-8 L / h and a daily irrigation duration of 6-8 h during the dry season. The independent micro-sprinkler system in the middle coffee belt has a nozzle spacing of 0.5-1 m, an operating pressure of 0.1-0.2 MPa, and a daily sprinkler irrigation duration of 1.5-2.5 h during the dry season. The independent micro-sprinkler system in the lower forage layer is activated for lateral infiltration water replenishment for 10-20 min only when there is no rainfall for more than 15 consecutive days.

5. The method for intercropping and relay cultivation of date palms and coffee with forage grasses according to claim 4, characterized in that, The creeping tropical leguminous forage crop is selected from *Phaseolus vulgaris*. Macroptilium atropurpureum With glossy purple flowers Vicia villosa subsp.varia At least one of the following: when the annual rainfall in the geographical location of the date palm plantation is 600~1200 mm and the dry season lasts for ≥5 months, the creeping tropical legume forage shall be selected from the purple-flowered winged bean; when the annual rainfall is 1200~1800 mm or there is a low temperature of ≥1 month in winter, the creeping tropical legume forage shall be selected from the glossy purple-flowered sweet potato.

6. The method for intercropping and relay cultivation of date palms and coffee with forage grasses according to claim 5, characterized in that, The 30%–50% shading provided by the upper date palm canopy to the middle-layer Arabica coffee is maintained within the specified range as follows: when the shading is below 25%, the leaf surface temperature of the middle-layer Arabica coffee rises to >38°C; when the shading is above 55%, the photosynthetic rate of the middle-layer Arabica coffee decreases to <6 μmol / (m²). 2 •s); The method involves removing 1-2 old leaves from the upper date palms at the end of the rainy season each year to ensure that the shading level remains within the range of 30% to 50%.

7. The method for intercropping and relay cultivation of date palms and coffee with forage grasses according to claim 6, characterized in that, In the double-row strip configuration of the mid-layer small-bean coffee variety, the plant spacing is 1.5 m, the row spacing is 2 m, each coffee strip consists of two rows of coffee, and the distance between two adjacent coffee strips is 3 to 5 m.

8. The method for intercropping and relay cultivation of date palms and coffee with forage grasses according to claim 7, characterized in that, When the projected area of ​​the date palm canopy reaches 80% of the ground area between the rows and the 5-8 year period ends, a system conversion is performed: the middle layer coffee belt and its independent micro-sprinkler belt are removed, and the lower layer forage is replaced by creeping leguminous forage with shade-tolerant grass perennial forage, thus transitioning to a two-layer permanent symbiotic relationship between date palms and forage.

9. The method for intercropping and relay cultivation of date palms and coffee with forage grasses according to claim 8, characterized in that, The nitrogen fixation capacity of the rhizobia in the creeping tropical leguminous forage grass is 8-12 kg N per mu per growing season; the crop residue decomposes and releases nitrogen on-site during the rainy season, which, together with the nitrogen fixation by the rhizobia, forms a dual source of nitrogen input for the date palm plantation; the cumulative amount of the dual source of nitrogen input at the end of the 5-8 year period is 40-72 kg N per mu.

10. The method for intercropping and relay cultivation of date palms and coffee with forage grasses according to claim 9, characterized in that, The method describes the use of fresh grass obtained from the cutting of the lower-layer forage at the end of the dry season each year during the 5-8 year period as cattle and sheep feed, with an annual fresh grass yield of 1500-2500 kg per mu; the surface cover of the cut stubble is 300-500 kg per mu; and the on-site decomposition of the cut stubble during the rainy season ensures that the soil organic matter content between the rows reaches ≥1.2% at the end of the 5-8 year period.

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