Double-layer planting method for alfalfa in dry terrace

Abstract

The invention discloses a dry terrace alfalfa double-layer planting method, and relates to the technical field of dry farming planting.The method includes the specific steps that soil preparation and ridging are conducted on a target dry terrace, ridge type upper-layer planting belts and ditch type lower-layer planting belts are formed, and a photo-thermal bearing area and a rainfall runoff collecting area are arranged respectively; layering root limiting arrangement is conducted, and a root system growth area is divided; fully covering a film for water retention laying, and constructing a water collection and supply channel; sowing double-layer alfalfa in the same period; starting a four-dimensional cooperative regulation and control unit, collecting data, and performing unified scheduling on water, fertilizer, gas and heat by using an algorithm; by constructing a furrow double-layer three-dimensional planting structure and matching with full-film-covering water retention, three-dimensional efficient utilization of dry terrace resources is achieved, water and fertilizer competition is avoided, and the water and fertilizer retention capacity is enhanced; through synchronous sowing, four-dimensional cooperative regulation and control, an exclusive water supplementing amount algorithm and synchronous peak shifting harvesting, mechanical harvesting operation requirements are met, damage of mechanical rolling to plants and ridge body structures is avoided, and support is provided for large-scale and mechanical planting of dry terrace alfalfa.

Description

Technical Field

[0001] This invention relates to the field of dryland farming technology, specifically a method for double-layer planting of alfalfa on dry terraces. Background Technology

[0002] Dry terraces are a typical type of arable land in semi-arid regions. Their high elevation, shallow soil layer, uneven rainfall distribution, and poor water retention capacity, coupled with low efficiency in light and heat resource utilization, are key bottlenecks restricting large-scale alfalfa cultivation. Alfalfa, as a high-quality forage crop, has a well-developed root system and water requirements that are poorly suited to dry terrace habitats. Conventional flat-planting methods easily lead to root competition and low water and fertilizer utilization efficiency. Furthermore, the lack of targeted water collection and retention techniques and stratified planting methods on dry terraces results in low alfalfa yields and unstable quality, making it difficult to meet the forage needs of livestock development.

[0003] Current alfalfa cultivation on dry terraces mostly employs traditional flat or single-ridge cultivation models, failing to achieve efficient stratified utilization of light, heat, and fertilizer, resulting in numerous technical shortcomings: The planting structure is simplistic, lacking a three-dimensional planting system, with light and heat resources only utilized on the surface, leading to low space utilization; the absence of root isolation measures results in disordered and intertwined root growth, significantly reducing water and fertilizer absorption efficiency; water retention and collection methods are inadequate, with mulching often being partial, leading to severe runoff loss and difficulty in maintaining soil moisture; water, fertilizer, air, and heat regulation lacks synergy, relying mostly on single-factor regulation without real-time adaptation to alfalfa growth dynamics and soil environment, failing to meet the habitat characteristics of dry terraces; and field harvesting methods are not adapted to the needs of mechanized operations, with batch harvesting easily causing repeated machinery entry and compaction of ridges and plants, increasing operational difficulty and impacting alfalfa regeneration and yield.

[0004] In summary, existing planting techniques cannot solve core problems such as insufficient utilization of light and heat resources, weak water retention capacity, competition among alfalfa roots, and inefficient water and fertilizer regulation in arid terraces. Furthermore, they are unsuitable for large-scale mechanized planting operations, thus hindering yield increases and industrial development in alfalfa cultivation on arid terraces. Therefore, there is an urgent need to develop an alfalfa planting method adapted to the arid terrace habitat. This method should involve constructing a double-layered, three-dimensional planting structure, achieving root layer isolation, strengthening water retention and collection through full mulching, and implementing four-dimensional synergistic regulation. Optimizing field harvesting patterns to adapt to mechanized operations will improve the comprehensive utilization efficiency of light, heat, water, and fertilizer resources on arid terraces, ultimately achieving high-quality, high-yield, and stable alfalfa cultivation. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a double-layer planting method for alfalfa on dry terraces. This method involves preparing the land by ridging it to form a ridge-type upper layer and a furrow-type lower layer planting zone, which serve as light and heat bearing areas and rainwater collection areas, respectively; layered root-limiting layout to limit the vertical distribution of the root system; full mulching for water retention to construct water collection channels; simultaneous double-layer sowing of alfalfa; and activation of a four-dimensional collaborative control unit to collect soil moisture and other data in real time, using algorithms to calculate the amount of water replenishment, and uniformly scheduling water, fertilizer, air, and heat to achieve efficient planting of alfalfa on dry terraces.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for double-layer planting of alfalfa on dry terraces, the specific steps of which are as follows:

[0007] S100, Land preparation and ridging: Deep plowing and leveling of the target dry terraces and ridging and ditching are carried out to form the upper planting zone of the ridge and the lower planting zone of the ditch in sequence. The high position of the ridge is set as the light and heat bearing zone, and the low position of the ditch is set as the rainwater runoff collection zone.

[0008] S200, Layered Root Limitation Layout: Install layered root limiting devices within the furrow structure formed by S100. Utilize the root spatial isolation degree calculation algorithm to calculate the spatial isolation degree of alfalfa roots in the upper and lower planting strips and adjust the layout parameters of the layered root limiting devices. Divide the soil profile into an upper shallow root growth zone and a lower deep root growth zone to limit the vertical distribution range of alfalfa roots in the upper and lower planting strips.

[0009] S300, full-film water-retaining laying: The ridge surface and ridge slope of the S100 formed ridge-type upper planting strip, as well as the bottom of the furrow-type lower planting strip, are fully covered without any gaps in the ground surface. A full-film water-retaining structure is laid to construct a water collection and supply channel for rainwater to flow into the furrow-type lower planting strip along the film surface.

[0010] S400, double-layer alfalfa sowing: On the fully covered water-retaining structure laid by S300, alfalfa is sown simultaneously in the upper planting strip of the ridge and the lower planting strip of the furrow, respectively, to construct a double-layer three-dimensional planting group with a high upper layer and a low lower layer.

[0011] S500, Four-Dimensional Collaborative Regulation: The four-dimensional collaborative regulation unit is activated to collect real-time data on soil moisture, canopy light, and root distribution in the upper planting zone of the ridge-type planting zone and the lower planting zone of the furrow-type planting zone; the water replenishment algorithm of the two-layer planting system is used to calculate the single water replenishment volume corresponding to the water replenishment scheduling, and the water, fertilizer, air, and heat in the two-layer planting system are uniformly scheduled according to the collected data.

[0012] Furthermore, the ridge height of the upper planting strip is set to 15-25cm, the ridge width is set to 50-70cm, the center-to-center distance between adjacent ridges is set to 80-120cm, and the bottom width of the furrow of the lower planting strip is set to 20-30cm.

[0013] Furthermore, the layered root-limiting device uses an aging-resistant porous elastic root-septum, which is only placed in the soil layer corresponding to the upper planting strip of the ridge, with an installation depth of 15cm, consistent with the lower limit of alfalfa root distribution in the upper planting strip of the ridge; the pore size of the root-septum is set to 0.5-1.0mm, limiting the alfalfa root distribution range of the upper planting strip of the ridge to 0-15cm soil layer, and the alfalfa root distribution range of the lower planting strip of the furrow to 20-60cm soil layer.

[0014] Furthermore, the root spatial isolation degree calculation algorithm is used to determine the layout parameters of the stratified root-limiting device before sowing by calculating the spatial isolation degree of alfalfa roots in the upper and lower planting layers; during the growth period, the algorithm monitors changes in isolation degree and uses water and fertilizer regulation to constrain root distribution. The formula is:

[0015]

[0016] in, Root spatial isolation, expressed as % The sum of the cross-sectional areas of the alfalfa roots in the upper and lower planting strips that penetrate the stratified root-limiting device within the corresponding calculation period, expressed in cm². The total root cross-sectional area of ​​alfalfa in the upper planting strip of the ridge is the total root cross-sectional area of ​​alfalfa of the same variety in the 0-15cm soil layer during the entire growth period before sowing. During the growth period, it is the sum of the root cross-sectional area of ​​alfalfa in the 0-15cm soil layer in the upper planting strip and the upper root cross-sectional area of ​​the penetrating the stratified root limiting device up to the monitoring time point, in cm². The total root cross-sectional area of ​​alfalfa in the trench-type lower planting strip within the corresponding calculation period; before sowing, it is the historical preset value of the total root cross-sectional area of ​​the same variety of alfalfa in the 20-60cm soil layer throughout the entire growth period; during the growth period, it is the sum of the root cross-sectional area of ​​alfalfa in the 20-60cm soil layer in the lower planting strip and the root cross-sectional area of ​​the lower layer that penetrates the stratified root limiting device up to the monitoring time point, in cm².

[0017] The root system spatial isolation The preset minimum threshold is 90%; calculated before sowing When the value is lower than the preset minimum threshold, adjust the aperture of the stratified root-limiting device; the value obtained during the growth period is monitored. When the value is lower than the preset minimum threshold, water and fertilizer regulation is used to limit the root system from exceeding the preset distribution range.

[0018] Furthermore, the fully covered water-retaining structure uses a black polyethylene mulch film with a thickness of 0.010-0.012mm to provide 100% full surface coverage of the target plot; the overlap width of adjacent mulches is not less than 10cm, the overlap is continuously compacted with soil strips, and the mulch film edges on both sides of the ridge and at both ends of the ditch are buried in the soil to a depth of not less than 5cm.

[0019] Furthermore, in the sowing operation, the sowing time difference between the upper planting strip of the ridge type and the lower planting strip of the furrow type shall not exceed 24 hours; sowing and mulch film perforation shall be carried out simultaneously, the row spacing of the upper planting strip of the ridge type shall be 15-20 cm, the sowing depth shall be 1-2 cm, and the sowing rate shall be 15-18 kg / hm². 2 The sowing row spacing for the furrow-type lower planting strip is 20-25cm, the sowing depth is 2-3cm, and the sowing rate is 12-15kg / hm. 2 After sowing, cover with soil and compact.

[0020] Furthermore, the four-dimensional collaborative control unit includes soil moisture sensors, light sensors, root monitoring tubes, data processing terminals, and water, fertilizer, and air integrated actuators deployed in the upper planting strip of the ridge type and the lower planting strip of the furrow type.

[0021] The real-time collected parameters of the four-dimensional collaborative control unit include: relative soil moisture content and soil aeration porosity in the 0-15cm and 20-60cm soil layers, photosynthetically active radiation at the top of the canopy of the ridge-type upper planting strip, and root distribution depth and root vitality in the upper and lower planting strips.

[0022] The scheduling logic of the four-dimensional collaborative regulation unit is as follows: when the relative soil moisture content is lower than the preset lower threshold of 55%, water replenishment scheduling is initiated; when the soil aeration porosity is lower than the preset threshold of 15%, soil aeration regulation is initiated through the integrated water, fertilizer and air actuator without damaging the water-retaining structure of the full-coverage film; when the canopy photosynthetically active radiation is higher than the preset threshold of 1200 μmol / m², soil aeration regulation is initiated. 2 • Start water and fertilizer synchronous regulation at s, and apply water-soluble nitrogen, phosphorus and potassium fertilizer with irrigation water, with a single application rate not exceeding 75 kg / hm. 2 When the root system distribution exceeds the preset range, adjust the depth and frequency of water and fertilizer supply to constrain the root growth range.

[0023] Furthermore, the water replenishment algorithm for the dual-layer planting system determines the single water replenishment amount through layered calculation and summation when the four-dimensional collaborative control unit initiates water replenishment scheduling. The water replenishment operation is then executed based on the calculated value, as shown in the formula:

[0024]

[0025] in, This refers to the volume of water replenished in a single instance, expressed in m³. , These are the target volumetric moisture contents for the upper and lower layers of alfalfa during their respective growth stages, expressed in cm³ / cm³. They are calculated by multiplying the target relative soil moisture content for the corresponding growth stage by the field capacity. The target relative soil moisture content ranges from 60% to 75%, with 60%-65% for the seedling stage, 70%-75% for the branching to budding stage, and 65%-70% for the regeneration stage after mowing. , These are the average volumetric water content of the 0-15cm and 20-60cm soil layers, respectively, as monitored in real time by the four-dimensional collaborative control unit, in cm³ / cm³. The planned wetting layer depth for the upper planting strip of the ridge is set at 0.15m. The planned wetting layer depth for the lower planting strip in the trench is set at 0.60m. , These represent the water replenishment and control areas corresponding to the upper and lower planting zones, respectively, in m². The field water use coefficient for the fully covered water-retaining structure is 0.95, since the plot has 100% full surface coverage.

[0026] Within 24 hours after the water replenishment operation is completed, the four-dimensional collaborative control unit collects soil relative moisture content data again to verify whether the soil relative moisture content after water replenishment has reached the target range. If it does not reach the target, the water replenishment amount is recalculated and water replenishment is performed.

[0027] Furthermore, during the alfalfa growing season, simultaneous staggered harvesting operations are implemented for the upper planting strips of ridges and the lower planting strips of furrows. The harvesting window is based on the initial flowering stage of alfalfa. The harvesting time for the upper planting strips of ridges is delayed by 2-3 days compared to the initial flowering stage, while the harvesting time for the lower planting strips of furrows is advanced by 2-3 days compared to the initial flowering stage. The harvesting time difference between the upper and lower planting strips is controlled within 3-5 days, completing continuous mechanized harvesting of the same batch. The stubble height after cutting the upper planting strips of ridges is 8-10 cm, and the stubble height after cutting the lower planting strips of furrows is 5-8 cm. After all harvesting operations of the upper and lower planting strips are completed, water-soluble fertilizer is applied uniformly through a four-dimensional collaborative control unit. The amount of fertilizer is determined comprehensively based on the overall growth of alfalfa in the upper and lower planting strips and the soil nutrient status.

[0028] Compared with existing technologies, this method for double-layer planting of alfalfa on dry terraces has the following advantages:

[0029] I. This invention constructs a double-layered, three-dimensional planting structure with furrows, combined with a layered root-limiting layout to achieve spatial isolation and control of alfalfa roots. Simultaneously, it utilizes a fully covered, water-retaining structure to create dedicated water collection and supply channels, achieving efficient three-dimensional utilization of light, heat, land, and water resources in arid terraces. This effectively avoids water and fertilizer competition between upper and lower alfalfa root systems, allowing alfalfa roots from different planting zones to grow within their designated soil layers, thus optimizing the efficiency of stratified distribution of soil water and fertilizer resources. The fully covered layout reduces ineffective evaporation of soil moisture, improves the collection and utilization efficiency of natural rainfall, and strengthens the soil's water and fertilizer retention capacity. From a resource utilization perspective, it adapts to the shallow soil layer and water-scarce planting conditions of arid terraces, reducing water and fertilizer loss.

[0030] II. This invention constructs a three-dimensional planting community by simultaneous sowing, and achieves unified and precise scheduling of water, fertilizer, air, and heat within the planting system through a four-dimensional collaborative control unit. Combined with a water replenishment algorithm, it provides scientific water replenishment. Furthermore, it incorporates a simultaneous, staggered harvesting method in the field, forming a refined, full-cycle management system adapted to alfalfa growth in dry terraces while also meeting the needs of mechanized operations. It captures real-time environmental and physiological data on alfalfa growth, adjusts water, fertilizer, air, and heat supply as needed, and precisely constrains the root growth range. Simultaneous, staggered harvesting adapts to the growth rhythm of both upper and lower layers of alfalfa, balancing alfalfa regeneration capacity and yield formation, while also reducing the difficulty of mechanized harvesting and avoiding damage to the ridge structure and alfalfa plants from multiple batches of machinery. It meets the needs of large-scale, mechanized planting, effectively solving the problems of extensive management, poor growth stability, and weak mechanization adaptability in traditional planting methods. This improves alfalfa yield and quality per unit area, providing reliable technical support for large-scale alfalfa planting in dry terraces.

[0031] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A flowchart illustrating the steps of a double-layer alfalfa planting method on dry terraces;

[0034] Figure 2 A flowchart for calculating and controlling the root spatial isolation of a double-layer alfalfa planting method on dry terraces;

[0035] Figure 3 This is a flowchart illustrating the four-dimensional coordinated regulation and water replenishment process of a double-layer alfalfa planting method on dry terraces. Detailed Implementation

[0036] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structure, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0037] Example 1:

[0038] The arid terraces underwent comprehensive deep tillage and leveling to break up soil compaction, optimize soil aggregate structure, and improve soil permeability. Following this, standardized ridge and furrowing operations were carried out according to plan, systematically forming ridge-type upper planting zones and furrow-type lower planting zones. Light and heat carrying areas were scientifically designed in the higher areas of the ridges to maximize the reception of natural sunlight and heat, meeting the photosynthetic and accumulated temperature requirements of alfalfa. Rainfall collection areas were rationally designed in the lower areas of the furrows to achieve efficient collection and convergence of natural rainfall, reducing water loss. Specifically, the ridge height of the ridge-type upper planting zone was precisely set to 20cm, the ridge width to 60cm, and the center-to-center distance between adjacent ridges to 100cm. The furrow bottom width of the lower planting zone was precisely set to 25cm. This standardized ridge-furrow structure enabled the efficient zoning and utilization of light and heat resources and rainfall runoff, allowing the upper planting zone to fully utilize light and heat conditions, while the lower planting zone efficiently absorbs runoff water, adapting to the natural environmental characteristics of the arid terraces.

[0039] A layered root-limiting device is precisely installed inside the standardized ridge and furrow structure. This device uses an aging-resistant, porous, elastic root-limiting pad, which is placed in the soil layer corresponding to the upper planting strip of the ridge. The installation depth is strictly controlled at 15cm, which is highly consistent with the lower limit of the alfalfa root distribution in the upper planting strip, thus precisely limiting the downward growth range of the upper roots. The pore size of the root-limiting pad is precisely set to 0.8mm, which ensures normal water and nutrient infiltration in the soil while effectively preventing the penetration of upper alfalfa roots. The spatial isolation degree of the alfalfa roots between the upper and lower planting strips is calculated using a root spatial isolation degree calculation algorithm. The formula is as follows: ,in, Root spatial isolation; The sum of the cross-sectional areas of the alfalfa roots in the upper and lower planting strips that penetrate the stratified root-limiting device within the corresponding calculation period; This refers to the total root cross-sectional area of ​​alfalfa in the upper planting strip of the ridge within the corresponding calculation period; This calculation calculates the total root cross-sectional area of ​​alfalfa in the furrow-type lower planting strip within the corresponding calculation period; and adjusts the layout parameters of the stratified root-limiting device in a timely manner based on the calculation results. The soil profile is scientifically divided to create an upper shallow-root growth zone and a lower deep-root growth zone. The distribution area of ​​alfalfa roots in the ridge-type upper planting strip is strictly limited to the 0-15cm soil layer, and the distribution area of ​​alfalfa roots in the furrow-type lower planting strip is strictly limited to the 20-60cm soil layer. This effectively isolates the upper and lower layers of alfalfa roots spatially, avoiding competition for nutrients and water caused by root cross-growth, ensuring that the spatial isolation between the upper and lower layers of roots meets the preset requirements, allowing each layer of alfalfa roots to grow healthily within its designated zone, and fully utilizing the nutrient and water resources of different soil layers.

[0040] A seamless full-surface covering operation was carried out on the ridge surface and slope of the upper planting strip and the bottom of the furrow of the lower planting strip. A full-coverage water-retaining structure was laid, using a 0.011mm thick black polyethylene film, which has excellent water-proofing, heat-insulating, and weed-suppressing properties. It can effectively reduce soil moisture evaporation, increase soil temperature, and inhibit weed growth, achieving 100% full surface coverage of the target plot. The overlap width of adjacent films was precisely set to 12cm, and the overlap was continuously compacted with soil strips to ensure a tight seal and no air or water leakage. The depth of the film edges buried in the soil on both sides of the ridge and at both ends of the furrow was precisely set to 6cm, allowing the film to adhere tightly to the soil, enhancing the stability of the covering structure, and preventing the film from being damaged or lifted by natural factors such as strong winds. This fully covered membrane structure creates a water collection and supply channel where rainwater flows along the membrane surface into the trench-like lower planting zone. This allows natural rainwater to quickly converge into the lower planting zone along the smooth membrane surface, improving the utilization rate of rainwater. At the same time, the heat preservation effect of the mulch film can effectively increase the soil temperature, promote alfalfa seed germination and root growth, and the weed suppression function reduces the competition between weeds and alfalfa for nutrients, water and light.

[0041] On the completed fully mulched water-retaining structure, alfalfa was simultaneously sown in both the ridge-type upper planting strip and the furrow-type lower planting strip, with the sowing time difference strictly controlled within 18 hours to maximize the synchronization of the growth periods of the upper and lower alfalfa layers. This created a double-layered, three-dimensional planting community with a high upper layer and a low lower layer, fully utilizing the vertical space resources of the dry terraces and increasing planting density and yield per unit area. Sowing and mulch perforation were carried out simultaneously, with the spacing and depth of the perforations matching the sowing parameters to avoid affecting seed germination due to improper perforation. The row spacing for the ridge-type upper planting strip was precisely set to 18cm, the sowing depth to 1.5cm, and the sowing rate to 16.5kg / hm². 2These parameters are adapted to the characteristics of the shallow-rooted upper growth zone, ensuring reasonable spacing between upper alfalfa plants and making full use of light, heat, and shallow soil nutrients; the sowing row spacing of the furrow-type lower planting zone is precisely set to 22cm, the sowing depth to 2.5cm, and the sowing rate to 13.5kg / hm. 2 This method is adapted to the water and nutrient distribution characteristics of the lower deep-root growth zone, ensuring sufficient growing space for the alfalfa plants. After sowing in all planting strips, standardized soil covering and compaction are carried out to effectively reduce seed suspension, improve seed water absorption and germination rate, and at the same time, the compacted soil forms a good water-retaining layer, providing a stable moisture environment for seed germination.

[0042] The four-dimensional collaborative control unit has been officially launched. This unit includes soil moisture sensors, light sensors, and root monitoring tubes deployed at key points in the upper planting strip of the ridge-type planting system and the lower planting strip of the furrow-type planting system, as well as supporting high-performance data processing terminals and intelligent water, fertilizer, and air integrated actuators. All components work together to achieve precise monitoring and control of the planting system. This unit collects real-time and precise data on soil relative moisture content and soil aeration porosity in the 0-15cm and 20-60cm soil layers, photosynthetically active radiation at the top of the canopy in the upper planting strip of the ridge-type planting system, and root distribution depth and root activity in both planting strips. The water replenishment algorithm for the two-layer planting system is used to accurately calculate the single water replenishment volume corresponding to the water replenishment schedule. The formula is: ,in, This refers to the amount of water replenished in a single instance. , These are the target volumetric moisture contents for the upper and lower layers of alfalfa during their growth period, respectively. , These are the average volumetric water content of the 0-15cm and 20-60cm soil layers, respectively, as monitored in real time by the four-dimensional collaborative control unit. The planned wetting layer depth corresponds to the upper planting strip of the ridge; The planned depth of the wetting layer corresponds to the lower planting zone of the trench type; , These are the water replenishment and control areas corresponding to the upper and lower planting zones, respectively. This system aims to optimize the field water use efficiency of the fully mulched water-retaining structure; prevent excessive watering leading to water waste and soil waterlogging, or insufficient watering to meet alfalfa growth needs; and intelligently manage water, fertilizer, air, and heat within the double-layer planting system based on real-time data to ensure optimal growth conditions for alfalfa. When the relative soil moisture content falls below 55%, water replenishment is immediately initiated, precisely supplying water according to the calculated amount to quickly increase soil moisture. When soil aeration porosity falls below 15%, soil aeration is regulated via an integrated water, fertilizer, and air system to improve soil aeration without disrupting the fully mulched water-retaining structure, ensuring alfalfa root respiration. The system also ensures that the canopy's photosynthetically active radiation exceeds 1200 μmol / m². 2 • Start water and fertilizer synchronous regulation at s, apply water-soluble nitrogen, phosphorus and potassium fertilizer with irrigation, and precisely control the amount of fertilizer applied at 70 kg / hm. 2 With ample sunlight, alfalfa can fully absorb and utilize nutrients, improving photosynthetic efficiency and growth rate. When root distribution exceeds the preset range, the depth and frequency of water and fertilizer supply are adjusted promptly. Through targeted nutrient and water supply, roots are guided to grow within the preset range, constraining their growth area and maintaining spatial isolation between upper and lower root layers. Within 24 hours of watering, the four-dimensional collaborative control unit comprehensively collects soil relative moisture data again to accurately verify whether the soil relative moisture content has reached the target range. If it does not, the watering amount is recalculated using the two-layer planting system watering algorithm, and supplementary watering is executed promptly to ensure that the soil moisture content always meets the actual needs of alfalfa growth. Figure 1 As shown.

[0043] During the alfalfa growing season, based on the growth characteristics of the upper and lower layers of alfalfa, the spatial characteristics of three-dimensional planting, and the operational requirements of mechanized harvesting, a scientific, simultaneous, and staggered harvesting operation is implemented for the upper planting strips of ridges and the lower planting strips of furrows. This avoids the problems of repeated mechanical entry and crushing of the ridges and plants, and low operational efficiency caused by batch harvesting. Using the initial flowering stage of alfalfa as the harvesting window, the harvesting time for the upper planting strips of ridges is delayed by 2-3 days compared to the initial flowering stage, while the harvesting time for the lower planting strips of furrows is advanced by 2-3 days. The harvesting time difference between the upper and lower planting strips is precisely controlled within 4 days, achieving continuous mechanized harvesting of the same batch. This approach balances the nutritional quality and biomass accumulation of alfalfa while reducing the difficulty of mechanized operations and avoiding damage to the ridge structure and alfalfa plants caused by mechanical crushing. The stubble height for the upper planting strip in the ridge system is set at 9cm. This reasonable stubble height ensures that the regenerated buds of the alfalfa roots are not damaged, preserving sufficient nutrients and growth points for subsequent regeneration. The stubble height for the lower planting strip in the furrow system is set at 6cm, which is suitable for the deep root growth characteristics of the lower layer and ensures the nutrient supply for the regenerated root system. After the harvesting of both planting strips is completed, water-soluble fertilizer is precisely applied through a unified four-dimensional collaborative control unit, taking into account the soil nutrient status of both planting strips, the alfalfa regeneration needs, and the overall growth status. The water-soluble fertilizer dissolves quickly in water and is rapidly absorbed and utilized by the alfalfa roots, promptly replenishing the nutrients consumed during harvesting. The amount of fertilizer is precisely determined based on the actual growth of the alfalfa in the field. Less fertilizer is applied to areas with good growth, and more fertilizer is applied to areas with weaker growth, achieving precise fertilization, promoting synchronous and rapid regeneration of alfalfa in both planting strips, improving the growth rate and subsequent yield after harvest, and ensuring the continuous high yield of the double-layer planting system and its compatibility with mechanized operations.

[0044] Example 2:

[0045] Deep tillage and leveling are carried out on the dry terraces to break up deep soil compaction, improve soil permeability, promote soil microbial activity, and enhance soil fertility. Then, according to the established standards, ridge and furrow operations are carried out to form ridge-type upper planting strips and furrow-type lower planting strips. A light and heat carrying area is scientifically created at the high position of the ridges so that the upper planting strip can fully receive full sunlight and accumulate more heat to meet the light and heat requirements of alfalfa photosynthesis and growth. A rainwater runoff collection area is reasonably created at the low position of the furrows to achieve efficient collection of natural rainfall and field irrigation water, reduce ineffective water loss on the surface, and improve water use efficiency. The height of the upper planting strip in the ridge type is precisely set to 15cm, the width of the ridge is precisely set to 50cm, the center-to-center distance between adjacent ridges is precisely set to 80cm, and the bottom width of the lower planting strip in the furrow type is precisely set to 20cm. Based on this compact and reasonable ridge and furrow specification, the upper planting strip can make full use of light and heat resources to achieve robust plant growth, while the lower planting strip can efficiently absorb runoff water, which is suitable for the relatively water-scarce environment of dry terraces. At the same time, the compact ridge and furrow layout can improve the planting utilization rate per unit area and build a stable field structure for subsequent double-layer three-dimensional planting.

[0046] A tiered root-limiting device is precisely installed within the standardized ridge and furrow structure. The device utilizes a durable, porous, elastic root-blocking mat, whose porous structure ensures normal water and nutrient exchange in the soil. It is precisely placed only in the corresponding soil layer of the upper planting strip of the ridge, with the installation depth strictly controlled at 15cm, coinciding with the lower limit of alfalfa root distribution in the upper planting strip. This precise installation depth controls the growth boundary of the upper root system. The pore size of the root-blocking mat is precisely set to 0.5mm, effectively preventing the penetration and growth of upper alfalfa roots while not hindering the vertical movement of water and mineral nutrients in the soil, ensuring unaffected nutrient supply to the lower soil layers. A root spatial isolation calculation algorithm is used to calculate the degree of spatial isolation between the upper and lower planting strips of alfalfa roots, and the placement parameters of the tiered root-limiting device are adjusted promptly based on the calculation results. The soil profile is scientifically and clearly divided, creating distinct upper shallow-root growth zones and lower deep-root growth zones. In ridge-type planting, the alfalfa root distribution area in the upper layer is strictly limited to 0-15cm of soil, allowing the upper alfalfa to fully utilize the nutrients and water in the shallow soil and adapt to the abundant light and heat of the upper layer. In furrow-type planting, the alfalfa root distribution area in the lower layer is strictly limited to 20-60cm of soil, allowing the lower alfalfa to utilize the nutrients and water in the deeper soil and adapt to the relatively abundant water of the lower layer. This allows both upper and lower alfalfa to grow healthily within their respective dedicated root growth zones, improving the overall nutrient and water utilization efficiency of the planting system. Figure 2 As shown.

[0047] The entire surface of the ridges and slopes of the upper planting strips, as well as the bottom of the furrows in the lower planting strips, is covered with a full-coverage water-retaining structure. This structure uses a 0.010mm thick black polyethylene film, which combines good tensile strength and water retention. The black film also provides significant shading and weed suppression, effectively inhibiting the germination and growth of weeds on the soil surface. This achieves 100% surface coverage of the target plot, ensuring no bare soil remains and completely blocking soil moisture loss through evaporation and surface runoff. The overlap width between adjacent films is precisely set at 10cm, and the overlap is continuously and tightly compacted with soil strips to ensure a seamless and airtight seal, effectively preventing water evaporation and wind-blown film. The edges of the film on both sides of the ridges and at both ends of the furrows are precisely buried 5cm into the soil, ensuring a tight fit between the film and the soil and enhancing the overall stability of the covering structure. This fully covered water-retaining structure creates a water collection and supply channel for rainwater to flow along the film surface into the trench-type lower planting zone. This allows natural rainwater to quickly and efficiently converge on the smooth surface of the film into the trench-type lower planting zone, improving the collection and utilization efficiency of natural rainwater. At the same time, the film can effectively increase soil temperature, especially during the germination and seedling growth stages of alfalfa seeds. Suitable soil temperature can promote rapid seed germination, accelerate the growth of seedling roots and plants, and shorten the seedling establishment period. In addition, the soil environment after film covering is relatively stable, which can reduce the loss of soil nutrients, improve the utilization rate of soil nutrients, and provide a stable and good soil environment for the entire growth of alfalfa.

[0048] On the completed and well-maintained fully mulched water-retaining structure, alfalfa was simultaneously sown in both the ridge-type upper planting strip and the furrow-type lower planting strip. The sowing time difference between the two was strictly controlled within 24 hours to ensure the germination and growth of alfalfa in both layers were synchronized to the greatest extent possible. This created a double-layered, three-dimensional planting community with a high upper layer and a low lower layer, making full use of the vertical space of the dry terraces, increasing the number of plants and photosynthetic area per unit area, and maximizing land utilization. Sowing and mulch perforation were carried out simultaneously. The perforation position was strictly matched with the row spacing and plant spacing, and the perforation depth was adapted to the sowing depth to avoid affecting seed germination due to excessively deep or shallow perforations. The row spacing for the ridge-type upper planting strip was precisely set to 15cm, the sowing depth to 1cm, and the sowing rate to 15kg / hm². 2 These parameters are perfectly suited to the soil conditions and light and heat resources of the upper shallow-root growth zone, ensuring good ventilation and light penetration among the upper alfalfa plants, allowing each plant to receive sufficient sunlight. At the same time, the reasonable seeding rate avoids internal competition caused by overcrowding. The row spacing for the furrow-type lower planting zone is precisely set to 20cm, the seeding depth to 2cm, and the seeding rate to 12kg / hm². 2These parameters are adapted to the water distribution and soil nutrient characteristics of the lower deep-root growth zone. Reasonable row spacing provides ample space for the deep growth of alfalfa roots, while appropriate seeding rate ensures the growth density of lower-level plants, balancing yield and growth quality. After sowing, standardized soil covering and compaction are performed on all planting strips to effectively eliminate soil gaps, improve seed water absorption and germination rate. Simultaneously, the compacted soil surface forms a dense water-retaining layer, effectively reducing soil moisture evaporation and providing a continuous and stable water supply for seed germination and seedling growth.

[0049] The four-dimensional collaborative control unit was officially launched. This unit consists of soil moisture sensors, light sensors, root monitoring tubes, high-performance data processing terminals, and intelligent water, fertilizer and air integrated actuators deployed at key monitoring points in the upper planting strip of the ridge planting system and the lower planting strip of the furrow planting system. The components are rationally arranged and work together to achieve full-dimensional, real-time and precise monitoring and control of the two-layer planting system. This unit collects real-time and precise data on soil relative moisture content and aeration porosity in the 0-15cm and 20-60cm soil layers, photosynthetically active radiation at the top of the canopy of the ridge-type upper planting strip, and root distribution depth and root vitality in both upper and lower planting strips. Using a water replenishment algorithm for the double-layer planting system, the unit accurately calculates the amount of water to be replenished at a time, achieving on-demand water supply. This ensures the alfalfa's water needs are met while avoiding water waste and root rot caused by waterlogging. Based on the collected real-time data, the system integrates and intelligently manages water, fertilizer, air, and heat within the double-layer planting system, allowing these four key growth factors to work synergistically and effectively. When the relative soil moisture content is detected to be below 55%, water replenishment is immediately initiated. Water is precisely supplied according to the calculated replenishment amount through an integrated water, fertilizer, and air system to quickly raise the soil moisture content to a suitable range. When soil aeration porosity is below 15%, soil aeration regulation is initiated through the integrated water, fertilizer, and air system to effectively improve soil aeration, ensure normal respiration of alfalfa roots, and promote root absorption of nutrients and water. The canopy photosynthetically active radiation is above 1200 μmol / m². 2 • Start simultaneous water and fertilizer regulation at s, taking advantage of the high light efficiency growth period, and apply water-soluble nitrogen, phosphorus, and potassium fertilizer with irrigation, with the single application rate precisely controlled at 60 kg / hm. 2Water-soluble fertilizers can be quickly absorbed and utilized by the root system, working in conjunction with high-efficiency photosynthesis to enhance alfalfa growth rate and biomass accumulation. When root distribution exceeds the preset range, the depth and frequency of water and fertilizer supply are adjusted promptly. Through targeted and precise nutrient and water supply, roots are guided to grow within the preset growth range, limiting disorderly root growth and maintaining spatial isolation between upper and lower root layers to avoid competition for nutrients and water. Within 24 hours of water replenishment, the four-dimensional collaborative control unit comprehensively and accurately collects soil relative moisture data, rigorously verifying whether the soil relative moisture content after water replenishment has entered the target range suitable for alfalfa growth. If it does not meet the target, the water replenishment amount is immediately recalculated using the double-layer planting system water replenishment algorithm, and replenishment is promptly implemented to provide stable water supply for the healthy growth of alfalfa throughout its lifespan. Figure 3 As shown.

[0050] Throughout the alfalfa growth cycle, based on the growth rhythms of the upper and lower layers of alfalfa, the spatial characteristics of three-dimensional planting, the nutrient accumulation patterns of alfalfa, and the operational requirements of large-scale mechanized planting, scientific and precise simultaneous staggered harvesting operations are implemented for the upper planting strips in ridges and the lower planting strips in furrows. This avoids the problems of multiple mechanical entries and trampling, increased field management difficulty, low operational efficiency, and yield loss caused by batch harvesting. Using the initial flowering stage of alfalfa as the harvesting window, the harvesting time for the upper planting strips in ridges is delayed by 2-3 days compared to the initial flowering stage, while the harvesting time for the lower planting strips in furrows is advanced by 2-3 days. The harvesting time difference between the upper and lower planting strips is precisely controlled within 3-5 days, achieving continuous mechanized harvesting of the same batch. At this time, the crude fiber content of alfalfa is moderate, the content of crude protein and other nutrients reaches its peak, and the biomass of both upper and lower alfalfa layers is at its optimal level, balancing nutritional quality and mechanized operational efficiency. The stubble height for the upper planting strip in the ridge type is set at 8cm. This stubble height effectively protects the regenerated buds and growing points of the alfalfa roots, avoiding harvesting damage. At the same time, the retained stems can provide certain nutrients for regeneration and promote rapid regeneration of alfalfa. The stubble height for the lower planting strip in the furrow type is set at 5cm, which is suitable for the deep root growth characteristics of the lower layer. This ensures the normal germination and growth of the root regenerated buds, while reducing the ineffective consumption of nutrients. After the harvesting of both the upper and lower planting strips is completed, a unified four-dimensional collaborative control unit is used to apply water-soluble fertilizer in a targeted manner, taking into account the regeneration needs of alfalfa after harvesting, the remaining soil nutrients, and the overall growth status of the plants. Water-soluble fertilizer has the characteristics of rapid dissolution and high absorption and utilization rate, which can quickly replenish the nutrients consumed by alfalfa after harvesting and meet the nutrient needs of synchronous regeneration and growth in a timely manner. The amount of fertilizer is determined according to the actual growth status of alfalfa in the field. Appropriate amount of fertilizer is applied to areas with vigorous growth and fast regeneration, while the amount of fertilizer is increased to areas with weak growth and slow regeneration, so as to achieve precise and differentiated fertilizer application. This effectively promotes the synchronous and rapid regeneration and robust growth of alfalfa in both upper and lower layers, improves the yield and quality of fresh grass after harvesting, and ensures the continuous and efficient production of the entire double-layer planting system and its high degree of compatibility with mechanized operations.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for double-layer planting of alfalfa on dry terraces, characterized in that, The specific steps of this method are as follows: S100, Land preparation and ridging: Deep plowing and leveling of the target dry terrace and ridging and ditching are carried out to form the upper planting strip of the ridge and the lower planting strip of the ditch in sequence. The high position of the ridge is set as the light and heat bearing area, and the low position of the ditch is set as the rainwater runoff collection area. S200, Layered Root Limitation Layout: Install layered root limiting devices within the furrow structure formed by S100. Utilize the root spatial isolation degree calculation algorithm to calculate the spatial isolation degree of alfalfa roots in the upper and lower planting strips and adjust the layout parameters of the layered root limiting devices. Divide the soil profile into an upper shallow root growth zone and a lower deep root growth zone to limit the vertical distribution range of alfalfa roots in the upper and lower planting strips. S300, full-film water-retaining laying: The ridge surface and ridge slope of the S100 formed ridge-type upper planting strip, as well as the bottom of the furrow-type lower planting strip, are fully covered without any gaps in the ground surface. A full-film water-retaining structure is laid to construct a water collection and supply channel for rainwater to flow into the furrow-type lower planting strip along the film surface. S400, double-layer alfalfa sowing: On the fully film-covered water-retaining structure laid by S300, alfalfa is sown simultaneously in the upper planting strip of the ridge and the lower planting strip of the furrow, respectively, to construct a double-layer three-dimensional planting group with a high upper layer and a low lower layer. S500, Four-Dimensional Collaborative Regulation: The four-dimensional collaborative regulation unit is activated to collect real-time data on soil moisture, canopy light, and root distribution in the upper planting zone of the ridge-type planting zone and the lower planting zone of the furrow-type planting zone; the water replenishment algorithm of the two-layer planting system is used to calculate the single water replenishment volume corresponding to the water replenishment scheduling, and the water, fertilizer, air, and heat in the two-layer planting system are uniformly scheduled according to the collected data.

2. The method for double-layer planting of alfalfa on dry terraces according to claim 1, characterized in that, In step S100, the ridge height of the upper planting strip is set to 15-25cm, the ridge width is set to 50-70cm, the center-to-center distance between adjacent ridges is set to 80-120cm, and the bottom width of the furrow of the lower planting strip is set to 20-30cm.

3. The method for double-layer planting of alfalfa on dry terraces according to claim 1, characterized in that, In step S200, the layered root-limiting device uses an aging-resistant porous elastic root-separating pad, which is only placed on the soil layer corresponding to the upper planting strip of the ridge, with an installation depth of 15cm, consistent with the lower limit of alfalfa root distribution in the upper planting strip of the ridge; the pore size of the root-separating pad is set to 0.5-1.0mm, the alfalfa root distribution range of the upper planting strip of the ridge is limited to the 0-15cm soil layer, and the alfalfa root distribution range of the lower planting strip of the furrow is limited to the 20-60cm soil layer.

4. The method for double-layer planting of alfalfa on dry terraces according to claim 1, characterized in that, In step S200, the root spatial isolation degree calculation algorithm is used to determine the layout parameters of the stratified root-limiting device before sowing by calculating the spatial isolation degree of alfalfa roots in the upper and lower planting layers; during the growth period, the algorithm monitors changes in isolation degree and uses water and fertilizer regulation to constrain root distribution. The formula is: in, Root spatial isolation; The sum of the cross-sectional areas of the alfalfa roots in the upper and lower planting strips that penetrate the stratified root-limiting device within the corresponding calculation period; This refers to the total root cross-sectional area of ​​alfalfa in the upper planting strip of the ridge within the corresponding calculation period; This refers to the total root cross-sectional area of ​​alfalfa in the lower planting strip of the trench within the corresponding calculation period; The root system spatial isolation The preset minimum threshold is 90%; calculated before sowing When the value is lower than the preset minimum threshold, adjust the aperture of the stratified root-limiting device; the value obtained during the growth period is monitored. When the value is lower than the preset minimum threshold, water and fertilizer regulation is used to limit the root system from exceeding the preset distribution range.

5. The method for double-layer planting of alfalfa on dry terraces according to claim 1, characterized in that, In step S300, the full-coverage water-retaining structure uses a black polyethylene mulch film with a thickness of 0.010-0.012mm to cover the target plot 100% of the ground surface; the overlap width of adjacent mulches is not less than 10cm, the overlap is continuously compacted with soil strips, and the mulch film edges on both sides of the ridge and at both ends of the ditch are buried in the soil layer to a depth of not less than 5cm.

6. The method for double-layer planting of alfalfa on dry terraces according to claim 1, characterized in that, In step S400, during the sowing operation, the sowing time difference between the upper planting strip of the ridge type and the lower planting strip of the furrow type does not exceed 24 hours; sowing and mulch film perforation are carried out simultaneously, the row spacing of the upper planting strip of the ridge type is 15-20 cm, the sowing depth is 1-2 cm, and the sowing rate is 15-18 kg / hm. 2 The sowing row spacing for the furrow-type lower planting strip is 20-25cm, the sowing depth is 2-3cm, and the sowing rate is 12-15kg / hm². 2 After sowing, cover with soil and compact.

7. The method for double-layer planting of alfalfa on dry terraces according to claim 1, characterized in that, In step S500, the four-dimensional collaborative control unit includes soil moisture sensors, light sensors, root monitoring tubes, data processing terminals and water, fertilizer and air integrated actuators deployed in the upper planting strip of the ridge and the lower planting strip of the furrow. The real-time acquisition parameters of the four-dimensional collaborative control unit include: relative soil moisture content and soil aeration porosity in the 0-15cm and 20-60cm soil layers, photosynthetically active radiation at the top of the canopy of the ridge-type upper planting strip, and root distribution depth and root vitality in the upper and lower planting strips. The scheduling logic of the four-dimensional collaborative regulation unit is as follows: when the relative soil moisture content is lower than the preset lower threshold of 55%, water replenishment scheduling is initiated; when the soil aeration porosity is lower than the preset threshold of 15%, soil aeration regulation is initiated through the integrated water, fertilizer and air actuator without damaging the water-retaining structure of the full-coverage film; when the canopy photosynthetically active radiation is higher than the preset threshold of 1200 μmol / m², soil aeration regulation is initiated. 2 • Start water and fertilizer synchronous regulation at s, and apply water-soluble nitrogen, phosphorus and potassium fertilizer with irrigation water, with a single application rate not exceeding 75 kg / hm. 2 When the root system distribution exceeds the preset range, adjust the depth and frequency of water and fertilizer supply to constrain the root growth range.

8. The method for double-layer planting of alfalfa on dry terraces according to claim 1, characterized in that, In step S500, the water replenishment algorithm for the two-layer planting system determines the single water replenishment amount by calculating and summing the values ​​in layers when the four-dimensional collaborative control unit starts water replenishment scheduling. The water replenishment operation is then executed based on the calculated values. The formula is as follows: in, This refers to the amount of water replenished in a single instance. , These are the target volumetric moisture contents for the upper and lower layers of alfalfa during their growth period, respectively. , These are the average volumetric water content of the 0-15cm and 20-60cm soil layers, respectively, as monitored in real time by the four-dimensional collaborative control unit. The planned wetting layer depth corresponds to the upper planting strip of the ridge; The planned depth of the wetting layer corresponds to the lower planting zone of the trench type; , These are the water replenishment and control areas corresponding to the upper and lower planting zones, respectively. The field water use coefficient of the fully covered water-retaining structure; Within 24 hours after the water replenishment operation is completed, the four-dimensional collaborative control unit collects soil relative moisture content data again to verify whether the soil relative moisture content after water replenishment has reached the target range. If it does not reach the target, the water replenishment amount is recalculated and water replenishment is performed.

9. A method for double-layer planting of alfalfa on dry terraces according to claim 1, characterized in that, During the alfalfa growing season, simultaneous staggered harvesting operations are implemented for the upper planting strips of ridges and the lower planting strips of furrows. The harvesting window is based on the initial flowering stage of alfalfa. The harvesting time for the upper planting strips of ridges is delayed by 2-3 days compared to the initial flowering stage, while the harvesting time for the lower planting strips of furrows is advanced by 2-3 days compared to the initial flowering stage. The harvesting time difference between the upper and lower planting strips is controlled within 3-5 days, and continuous mechanized harvesting of the same batch is completed. The stubble height after cutting the upper planting strips of ridges is 8-10 cm, and the stubble height after cutting the lower planting strips of furrows is 5-8 cm. After all the harvesting operations of the upper and lower planting strips are completed, water-soluble fertilizer is applied uniformly through the four-dimensional collaborative control unit. The amount of fertilizer is determined comprehensively based on the overall growth of alfalfa in the upper and lower planting strips and the soil nutrient status.

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