A method for integrated drip irrigation and fertigation of corn grown under plastic film mulch

Abstract

This invention belongs to the field of agricultural planting technology and proposes a method for integrated drip irrigation and fertigation of corn using mulch-side planting. The method includes: employing a wide-narrow row planting method; laying mulch film above the narrow rows; pressing the edges of the mulch film into the soil and covering them with soil; sowing corn seeds 4-5 cm outside the edge of the mulch film exposed on the ground; and laying drip irrigation tape under the mulch film. Irrigation is controlled by monitoring the soil matrix potential at a depth of 20-25 cm below the drippers of the drip irrigation tape, initiating irrigation when the soil matrix potential is ≤-15 kPa. During irrigation, all phosphate fertilizer is applied as base fertilizer; a portion of nitrogen fertilizer is applied as base fertilizer, with the remainder applied in multiple top dressings; and all potassium fertilizer is applied as base fertilizer, or a portion is applied as base fertilizer, with the remainder applied in multiple top dressings. This method significantly improves the mulch film recycling rate while ensuring stable and high corn yields, achieving the goals of water conservation, emission reduction, and efficiency improvement in arid areas.

Description

Technical Field

[0001] This invention belongs to the field of agricultural planting technology and relates to a method for integrated drip irrigation and fertilization of corn grown under plastic film. Background Technology

[0002] Mulching technology has significant effects such as increasing soil temperature, conserving water and moisture, suppressing weed growth, and controlling soil salinity. It can effectively promote crop growth and increase crop yield, and has been widely used in arid and semi-arid regions of Northwest China. With the development of agricultural water-saving irrigation technology, drip irrigation under mulch combines mulching with drip irrigation, achieving simultaneous water and fertilizer supply and further improving water and fertilizer utilization efficiency. It has become one of the main modes of corn planting in this region.

[0003] However, existing drip irrigation technology under plastic film faces a long-standing technical challenge in practical applications: due to the extensive and well-developed root system of corn, the roots easily become entangled with the plastic film laid on the soil surface during growth, making it difficult to completely recover the film after harvest. Studies have shown that residual plastic film can damage soil structure, reduce the physical, chemical, and biological properties of the soil, cause soil productivity obstacles, and affect crop yield and the sustainable use of farmland.

[0004] To address the low recycling rate of plastic film mulch, existing technologies mainly explore improvements in mulch materials or recycling machinery, such as using biodegradable mulch. However, biodegradable mulch is costly, its degradation time is difficult to control precisely, and the long-term effects of degradation products on the soil remain unclear. Furthermore, simply improving recycling machinery cannot fundamentally solve the problem of root entanglement with the mulch, and the recycling rate still falls short of ideal levels. In response, existing technologies have proposed side-planting techniques. For example, Chinese patent CN107360828A discloses a method for planting with plastic film mulch that eliminates the need for seedlings and facilitates easy recycling of residual film. This method sows corn 3-5 cm from the side of the mulch, achieving both seedling-free planting and easy film recycling. However, this technical solution still has the following drawbacks in practical applications: it relies entirely on natural rainfall, and in arid, semi-arid regions or years with insufficient rainfall, crop growth and yield cannot be guaranteed. Especially in the irrigated areas of Northwest my country, annual rainfall is generally below 200 mm, while evaporation exceeds 2000 mm. Relying solely on mulch-side planting without supporting irrigation measures makes it difficult to achieve high and stable crop yields. Secondly, research has not been conducted on water and fertilizer supply methods under mulch-side planting conditions, resulting in a lack of operational technical support for the practical application of this technology. Furthermore, no research has been conducted on irrigation control. In irrigated agricultural areas, the continued use of traditional surface irrigation or empirical irrigation methods not only wastes water resources but may also lead to nutrient leaching and secondary soil salinization.

[0005] In summary, while existing film-side planting technology provides a useful approach to solving the problem of film recycling, it still falls short of meeting the comprehensive needs of arid and semi-arid irrigated agricultural areas for water conservation, increased yield, and environmental protection. Summary of the Invention

[0006] This invention proposes a method for integrated drip irrigation and fertigation of corn grown under plastic film. This method significantly improves the plastic film recycling rate while ensuring stable and high corn yields, thus achieving the goal of water conservation, emission reduction and efficiency improvement in arid areas.

[0007] The technical solution of this invention is implemented as follows:

[0008] A method for integrating drip irrigation and fertigation in corn mulch-side planting includes the following steps:

[0009] Using a wide-narrow row planting method, a plastic film is laid on top of the narrow row, the two edges of the plastic film are pressed into the soil and covered with soil, the corn is sown 4-5 cm outside the edge of the part of the plastic film exposed on the ground surface, and the drip irrigation tape is laid under the plastic film.

[0010] The irrigation is controlled by monitoring the soil matrix potential at a depth of 20-25cm below the dripper of the drip irrigation tape. Irrigation is started when the soil matrix potential is ≤-15 kPa, and the water volume for a single irrigation is 10-18 m³ / mu.

[0011] During this period, all phosphate fertilizer is applied as base fertilizer; part of the nitrogen fertilizer is applied as base fertilizer, and the remainder is applied in several applications during the corn jointing stage to the grain filling stage; all potassium fertilizer is applied as base fertilizer; or, part of the potassium fertilizer is applied as base fertilizer, and the remainder is applied in several applications during the small trumpet stage to the tasseling stage.

[0012] Preferably, the mulch film is 40-50cm wide, with each side edge of the mulch film pressed obliquely into the soil for 4-5cm and then covered with soil; the corn seeds are sown in a position that avoids the obliquely pressed part of the mulch film.

[0013] Preferably, when the soil moisture is below 80% of the field capacity after sowing, 1-2 irrigations should be carried out first, with a total irrigation volume of 20-30 m³ / mu.

[0014] Ideally, irrigation should be stopped 30-45 days before corn harvest.

[0015] Preferably, irrigation is limited to 95% of field capacity, and irrigation is stopped when the soil matric potential recovers to the value corresponding to this limit.

[0016] Preferably, in the wide-narrow row planting method, the width of the wide row is 60-70 cm and the width of the narrow row is 40-50 cm.

[0017] Preferably, the soil matrix potential is monitored at a depth of 20 cm directly below the dripper of the drip irrigation tape.

[0018] Preferably, the corn is planted 5 cm away from the edge of the mulch film.

[0019] Preferably, the drip irrigation tape is laid under the mulch film, located in the middle of the narrow row, and one drip irrigation tape controls the irrigation and fertilization of two rows of corn on both sides.

[0020] Preferably, a portion of the nitrogen fertilizer is applied as base fertilizer, with the base fertilizer amount being 20%-25% of the total fertilizer application. The remaining nitrogen fertilizer is applied as top dressing in 3-4 applications from the jointing stage to the grain-filling stage. A portion of the potassium fertilizer is applied as base fertilizer, with the remaining potassium fertilizer applied as top dressing in 2-3 applications from the small trumpet stage to the tasseling stage.

[0021] Preferably, the plastic film and drip irrigation tape are mechanically recycled after the corn harvest.

[0022] Preferably, the dripper flow rate of the drip irrigation tape is 1.0-2.0 L / h, and the dripper spacing is 20-25 cm.

[0023] Preferably, the corn planting density is 5,500-6,500 plants per mu.

[0024] The working principle and beneficial effects of this invention are as follows:

[0025] 1. This invention sows corn 4-5 cm outside the edge of the exposed portion of the mulch film, while controlling irrigation by monitoring the soil matrix potential at a depth of 20-25 cm below the dripper. This avoids the problem of root entanglement with the mulch film in traditional under-mulch planting, creating a prerequisite for efficient mulch film recycling. Simultaneously, precise irrigation ensures water supply to the corn outside the mulch film, avoiding the unstable yields in arid regions caused by reliance on natural rainfall in existing mulch-side planting techniques. This significantly improves irrigation water utilization efficiency. This invention integrates mulch-side planting, precision irrigation, and fertigation, forming a mutually supportive and synergistic whole. Experimental results show that this invention increases the mulch film recycling rate to over 80%, while maintaining a stable corn yield of 1394-1400 kg / mu, achieving a balance between high recycling and stable yield. This invention significantly improves the mulch film recycling rate and irrigation water utilization efficiency while ensuring crop yield, which is of great significance for alleviating water shortages in arid and semi-arid regions and reducing soil mulch film residue.

[0026] 2. This invention moves corn planting from inside to outside the plastic film, while simultaneously ensuring sufficient and timely water and fertilizer supply through complementary irrigation and fertilization methods. Experimental results show that this method has stronger resilience and yield stability, with more significant yield increases in drought years or under extensive management conditions. Specifically, this invention organically combines the irrigation initiation threshold with the timing of multiple topdressing applications of nitrogen and potassium fertilizers. The irrigation threshold setting ensures that soil moisture in the root zone remains within a suitable range, providing conditions for fertilizer dissolution and nutrient migration. The multiple topdressing fertilization system is combined with the nutrient requirements of corn from the jointing to the grain-filling stage. Through a drip irrigation fertigation system, fertilizer is applied to the root zone simultaneously with water, achieving temporal and spatial coupling of water and fertilizer supply, avoiding nutrient leaching or nutrient deficiency caused by water and fertilizer separation in traditional management. This coordinated water and fertilizer supply is key to the stable yield and increased yield potential of this invention.

[0027] 3. This invention employs a wide-narrow row planting method (wide rows 60-70 cm, narrow rows 40-50 cm), concentrating the mulch film and drip irrigation tape within the narrow rows, with corn planted outside the mulch film on both sides of the narrow rows. The wide row design ensures canopy ventilation and light penetration, reduces field humidity, and minimizes the occurrence of pests and diseases; the concentrated mulch film coverage in the narrow rows reduces the amount of mulch film used, while also facilitating the placement and retrieval of the drip irrigation tape. This layout allows mechanized sowing, inter-row cultivation and fertilization, and mulch film retrieval to all be carried out along the wide rows, achieving synergy between agronomic measures and mechanized operations, and reducing labor intensity and operating costs.

[0028] 4. The method of this invention is simple to operate, requiring no complex calculations or precision instruments, and can be mechanized using existing agricultural machinery, thus lowering the barrier to technology promotion. Compared with traditional under-film planting, this invention also eliminates the seedling placement step, reducing labor input and lowering production costs. Attached Figure Description

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] Figure 1 This is a schematic diagram of the corn wide and narrow row planting mode of the present invention, wherein 100 represents drip irrigation tape, 200 represents mulch film, 300 represents corn, L1 represents the width of the narrow row, L2 represents the width of the wide row, L3 represents the width of the mulch film, L4 represents the distance between the corn planting point and the outer edge of the mulch film, and L5 represents the width of the two sides of the mulch film pressed into the soil and covered with soil.

[0031] Figure 2 This is a graph showing the changes in meteorological elements during the maize growing season in 2024, according to an embodiment of the present invention. In the graph, 2024a represents the average temperature, 2024b represents the relative humidity, 2024c represents the wind speed, 2024d represents the saturated vapor pressure difference, 2024e represents the net radiation, and 2024f represents the Eto (evapotranspiration) curve of the reference crop.

[0032] Figure 3 This is a graph showing the changes in meteorological elements during the maize growing season in 2025, according to an embodiment of the present invention. In this graph, 2025a represents the average temperature, 2025b represents the relative humidity, 2025c represents the wind speed, 2025d represents the saturated vapor pressure difference, 2025e represents net radiation, and 2025f represents the curve showing the change in Eto (evapotranspiration) of the reference crop. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] like Figure 1 As shown, this invention employs a wide-narrow row planting method. The narrow row width L1 is 40-50 cm, and the wide row width L2 is 60-70 cm. A plastic film 200 is laid over the narrow row, with a total width of 40-50 cm. Its two edges are obliquely pressed into the soil with a width L5 (4-5 cm) and covered with soil to fix the film and ensure it adheres tightly to the ground. The width L3 of the exposed portion of the plastic film 200 is the total width minus the width occupied by the soil-covered portions on both sides. A drip irrigation tape 100 is laid below the plastic film 200, located in the middle of the narrow row. The dripper flow rate is 1.0-2.0 L / h, and the dripper spacing is 20-25 cm. One drip irrigation tape simultaneously controls the irrigation and fertilization of two rows of corn on either side. Corn 300mm was sown on the outer edge of the exposed portion of the 200mm plastic film on the soil surface. The horizontal distance L4 between the sowing point and this edge was 4-5 cm, and the sowing position vertically avoided the part of the plastic film that was obliquely pressed into the soil, i.e., the area where L5 was located, to prevent the corn roots from entangled with the plastic film. Irrigation was controlled by monitoring the soil matrix potential at a depth of 20-25 cm directly below the dripper: irrigation was initiated when the soil matrix potential was ≤-15 kPa, with a single irrigation volume of 10-18 m³ / mu. All phosphate fertilizer was applied as base fertilizer; 20%-25% of the nitrogen fertilizer was applied as base fertilizer, with the remainder applied as top dressing in 3-4 applications from the jointing stage to the grain-filling stage; potassium fertilizer could be applied entirely or partially as base fertilizer, with the remainder applied as top dressing in 2-3 applications from the small trumpet stage to the tasseling stage. These parameters worked together to achieve spatial separation between water supply under the film and planting outside the film, significantly improving the plastic film recycling rate while ensuring stable and high corn yields.

[0035] Example 1

[0036] This embodiment takes the Hetao Irrigation District of Inner Mongolia as an example to provide a detailed description of the corn film-side planting drip irrigation and fertigation method provided by the present invention.

[0037] I. Experimental Background

[0038] The Hetao Irrigation District is located in the arid and semi-arid region of the upper reaches of the Yellow River, with abundant light and heat resources. In 2024, the corn planting area in the irrigation district was 4.78 million mu (approximately 385,000 hectares), accounting for about 42% of the total irrigation area. However, the irrigation district suffers from low rainfall and high evaporation, with an annual irrigation water consumption of up to 4.4 billion cubic meters, accounting for about 88% of the total water consumption. The average irrigation water consumption per mu (approximately 0.067 hectares) exceeds 400 cubic meters, which exacerbates secondary soil salinization, causes a large amount of nutrient leaching, and seriously restricts local agricultural production and ecological environmental protection.

[0039] To improve water and fertilizer use efficiency, the irrigation district has vigorously promoted the use of plastic film mulching. This method significantly increases early soil temperature, reduces surface evaporation and weed growth, and promotes crop growth and yield. However, after crop harvest, the plastic film has low strength and is easily broken, leading to difficulties in recycling and low recycling rates. Continuous monitoring at 22 monitoring points in the irrigation district from 2015 to 2021 showed that the average residual amount of plastic film increased from 7.25 kg / mu to 8.16 kg / mu, an increase of 13%, with some monitoring points reaching 14.8 kg / mu, more than doubling. Currently, even with improved plastic film quality, the seasonal recycling rate is only about 60%, and the residual amount of plastic film in the soil continues to increase.

[0040] The corn film-side planting drip irrigation and fertigation method proposed in this invention has been applied and verified in the National Agricultural High-tech Industrial Park in Chengguan Town, Linhe District, Bayannur City, Hetao Irrigation District.

[0041] II. Overview of the Experimental Site

[0042] 1. Year and season of the experiment

[0043] The trials will be conducted during the 2024 and 2025 maize trial seasons, specifically from April 20 to September 30 each year.

[0044] 2. Test Site and Regional Background

[0045] Experimental location: National Agricultural High-tech Industrial Park, Suhai Village, Chengguan Town, Linhe District, Bayannur City, Inner Mongolia Autonomous Region, 107°16′9.61″E, 40°40′55.57″N, altitude 1044 m.

[0046] Regional climate type: The experimental area has a typical temperate continental climate, characterized by long winters and short summers, distinct seasons, large diurnal temperature range, abundant sunshine but scarce annual precipitation. The average annual precipitation is about 140 mm, the average diurnal temperature range is 8.2 ℃, the average annual frost-free period is about 135 days, the average annual wind speed is 1.4-4.2 m / s, the maximum annual wind speed is 18-40 m / s, the average annual evaporation is 2032-3179 mm, the average annual temperature is 8.1 ℃, the frost-free period is about 140 days, and the average annual sunshine duration is 3230 h.

[0047] Topography: The experimental site is a typical saline-alkali area in Northwest China, with an altitude of 1044 m and flat terrain.

[0048] 3. Basic physical and chemical properties of soil

[0049] Soil type: According to the Chinese soil classification, alluvial soil type.

[0050] Soil texture: silty loam at a depth of 0-100 cm.

[0051] Site shape: The experimental site is approximately 60 mu (about 4 hectares), rectangular, 200 m long and 200 m wide, with flat terrain.

[0052] Soil nutrient status: The physicochemical properties of the 0-40 cm soil layer measured before sowing in 2024 are as follows: pH 8.48, salt content 1.72 g / kg, and inorganic nitrogen content 5.96 mg / kg.

[0053] Trial year and season:

[0054] 4. Meteorological data:

[0055] Data source: Experimental station of China Agricultural University Hetao Irrigation District Research Institute, about 6 km from the experimental site.

[0056] Data period: Covering the entire corn growing season (April to October).

[0057] like Figure 2 and Figure 3 The study presents the meteorological parameters during the maize growing season in 2024 and 2025, including average temperature, relative humidity, wind speed, saturated vapor pressure difference, net radiation, and reference crop evapotranspiration (ETo). The two years of meteorological data indicate high evaporation during the experiment, with peak ETO reaching 6-8 mm / day, and scarce precipitation, with only 116-119 mm during the growing season, characteristic of a typical arid irrigated agricultural region.

[0058] 5. Test crops

[0059] Crop type and variety: Spring maize (Zea mays L.), variety 'Kehe 699'.

[0060] III. Test Treatment

[0061] The experiment was set up with two treatments:

[0062] Treatment 1: The present invention provides a method for corn film-side planting with drip irrigation and fertigation integration.

[0063] Treatment 2 (CK): Local corn drip irrigation method under plastic film, traditional control.

[0064] Each treatment consisted of 3 replicates, for a total of 6 cells, arranged in a completely randomized block layout to eliminate random errors. The data results were the average of the replicates. The area of ​​each replicate cell was 200 m × 33 m.

[0065] IV. Specific Planting Implementation Methods

[0066] (a) Planting pattern

[0067] Sowing and harvesting dates: May 7, 2024 and September 29, 2024, respectively; April 27, 2025 and September 26, 2025, respectively.

[0068] 1. Planting model of the present invention

[0069] like Figure 1 As shown, a wide-narrow row planting method is used for sowing: the wide row is 60 cm wide, and the narrow row is 50 cm wide. A plastic film is laid over the narrow rows, covering the soil surface corresponding to those rows. The plastic film is a 0.01 mm thick, 50 cm wide polyethylene film, laid over the narrow rows. The edges of the film are slanted 5 cm into the soil on both sides and covered with soil to a thickness of 2-3 cm. Corn seeds are sown 5 cm outside the edge of the exposed portion of the plastic film, ensuring the seeds do not overlap with the slanted portion of the film in the horizontal direction. The plant spacing is 20 cm, resulting in a planting density of 6064 plants per acre. The sowing method involves using a film-side seeder to complete the film laying, tape laying, sowing, and soil covering in one operation. The sowing depth is 5 cm.

[0070] The drip irrigation tape is laid under the mulch film. The drip irrigation tape is an inlaid patch type with a dripper flow rate of 1.5 L / h, a dripper spacing of 20 cm, a wall thickness of 0.20 mm, and a diameter of 16 mm. The drip irrigation tape is laid under the mulch film in the middle of the narrow row. One drip irrigation tape controls the irrigation and fertilization of two rows of corn on both sides.

[0071] 2. Traditional comparison: Local corn planting method using drip irrigation under plastic film.

[0072] The similarities between this control method and the planting mode of this invention are as follows: both adopt wide and narrow row planting, with a wide row width of 60 cm and a narrow row width of 50 cm; the planting density is 6064 plants / mu and the plant spacing is 20 cm; the drip irrigation tape is laid in the middle of the narrow row, the dripper flow rate is 1.5 L / h and the dripper spacing is 20 cm; irrigation and fertilization management follow the local conventional mode.

[0073] The core difference between this comparative method and the planting model of this invention lies in the width of the mulch film and the corn planting location, as detailed below:

[0074] Mulch film specifications and laying: Use polyethylene mulch film with a width of 70 cm, covering the narrow row (50 cm wide). When laying, stretch the mulch film flat, leaving 10 cm on each side, and press it diagonally into the soil, then cover it with 2-3 cm of soil and compact it to ensure that the mulch film is tightly attached to the ground.

[0075] Corn planting location: Plant two rows of corn on the narrow row, with both rows directly below the plastic film. Specifically, using the center line of the narrow row as a reference, plant the two rows of corn on either side of the center line, with a row spacing of 50 cm, which is the same as the width of the narrow row, and each row is 25 cm away from the center line of the narrow row.

[0076] (ii) Irrigation system

[0077] 1. Irrigation system of this invention

[0078] In each replicate plot, a negative pressure gauge (tensimeter) is installed at a depth of 20 cm directly below the dripper of the drip irrigation tape at a typical location to monitor the soil matrix potential in real time.

[0079] Irrigation start-up conditions: Take a negative pressure count twice a day, at 8:00 AM and 6:00 PM. Start drip irrigation when any reading is ≤ -15 kPa.

[0080] Irrigation water volume: The single irrigation water volume is 10-18 m³ / mu, which is 15-27 mm.

[0081] Post-sowing irrigation: If soil moisture is below 80% of field capacity after sowing, irrigate 1-2 times, with a total irrigation volume of 20-30 m³. 3 / mu (30-45 mm).

[0082] Irrigation limit: Irrigation should be based on 95% of the field capacity. Irrigation should be stopped when the soil matric potential recovers to the value corresponding to this limit. At this time, the irrigation water volume is generally in the range of 10-18 m³ / mu.

[0083] Irrigation should be stopped one month before the corn harvest.

[0084] Actual irrigation records are shown in Tables 1-1 and 1-2:

[0085] 2024: Irrigation began on June 14 and ended on August 20, with a total of 12 irrigations. Each irrigation was about 16 mm-27 mm, with a total irrigation volume of 250.4 mm (167 m³ / mu). Rainfall during the growing season was 116.8 mm.

[0086] 2025: Irrigation began on May 21 and ended on August 13, with a total of 16 irrigations and a total irrigation volume of 280.3 mm (187 m³ / mu). Rainfall during the growing season was 119.3 mm. Because the top 20 cm soil moisture content at sowing was 67% of field capacity, which was lower than the suitable water volume for emergence (80% of field capacity), two emergence irrigations were carried out, on May 21 and June 1, respectively.

[0087] Table 1-1 Irrigation Time and Irrigation Water Volume in 2024

[0088]

[0089] Table 1-2 Irrigation Time and Irrigation Water Volume in 2025

[0090]

[0091] 2. Traditional Comparison: Local Maize Drip Irrigation System under Plastic Film

[0092] The local area is irrigated approximately every 7-10 days, with each irrigation providing 45mm (30 m) of water. 3 / mu). During the two-year trial period, irrigation was carried out 7 times in 2024 and 8 times in 2025, with irrigation amounts of 315 mm (210 m³) respectively. 3 / mu) and 360mm (240 m) 3 / mu). In 2025, due to the soil moisture content of the top 20 cm layer being only 67% of the field weight at sowing time, which was lower than the suitable water volume for seedling emergence (80% of the field weight), irrigation was carried out once on May 21st, with an irrigation volume of 45 mm. The specific drip irrigation tape arrangement is the same as in this invention: the drip irrigation tape adopts an inlaid patch type, with the following specifications: dripper flow rate 1.5 L / h, dripper spacing 20 cm, wall thickness 0.20 mm, and diameter 16 mm. The drip irrigation tape is laid directly below the mulch film, in the middle of the narrow row. Control method: one drip irrigation tape simultaneously controls the irrigation and fertilization of two rows of corn on both sides.

[0093] (III) Fertilization System

[0094] 1. Fertilization system of this invention

[0095] In the Hetao Irrigation District of Inner Mongolia, where the surface soil salinity is below 2‰ and the corn grain yield is 1000-1200 kg / mu (15-18 tons / hectare), the recommended fertilizer application rates for corn are: 250 kg / hectare for nitrogen (pure nitrogen), 120-150 kg / hectare for phosphorus (P2O5), and 75-90 kg / hectare for potassium (K2O). This translates to 16.7 kg / mu for nitrogen (pure nitrogen), 8-10 kg / mu for phosphorus (P2O5), and 5-6 kg / mu for potassium (K2O).

[0096] All phosphate fertilizer can be used as base fertilizer, applied directly to the soil using sowing machinery during corn planting. Part of the nitrogen fertilizer is used as base fertilizer, with the remainder applied in 3-4 applications during the jointing to grain-filling stage using a fertigation system. Potassium fertilizer can be used entirely as base fertilizer, or partially as base fertilizer, with the remainder applied in 2-3 applications during the small trumpet stage to tasseling stage using a fertigation system. For topdressing, choose easily soluble fertilizers: nitrogen fertilizers such as urea or water-soluble nitrogen fertilizers; potassium fertilizers such as easily soluble potassium sulfate or water-soluble potassium fertilizers.

[0097] The total fertilizer application rate for this experiment was set according to the high-yield target of 1000-1200 kg / mu: nitrogen fertilizer (pure N): 16.7 kg / mu (250 kg / ha); phosphorus fertilizer (P2O5): 10 kg / mu (150 kg / ha); potassium fertilizer (K2O): 5 kg / mu (75 kg / ha).

[0098] (1) Application of base fertilizer:

[0099] In both 2024 and 2025, compound fertilizer was used as basal fertilizer. The selected compound fertilizer had N, P2O5, and K2O nutrient contents of 10%, 27%, and 10%, respectively, with an application rate of 40 kg per mu (approximately 0.067 hectares). This translates to N, P2O5, and K2O application rates of 4.0 kg / mu, 10.8 kg / mu, and 4.0 kg / mu, respectively. It can be seen that nitrogen fertilizer was deficient by 12.7 kg / mu, phosphorus fertilizer exceeded the planned application rate, therefore no further phosphorus fertilizer was added, and potassium fertilizer was deficient by 1.0 kg / mu. Nitrogen fertilizer applied as basal fertilizer accounted for 24% of the total nitrogen fertilizer application, and potassium fertilizer accounted for 80% of the total potassium fertilizer application.

[0100] (2) Topdressing plan:

[0101] During topdressing, the remaining nitrogen fertilizer is applied in four applications using urea; potassium fertilizer is applied twice, at the small and large bell-shaped inlets, using potassium sulfate. Specific topdressing times are shown in Table 2.

[0102] Table 2. Application time and amount of experimental fertilizers

[0103]

[0104] Topdressing methods:

[0105] Fertilizer is dissolved and applied with irrigation water through the fertilizer tank installed at the head of the drip irrigation system, achieving integrated water and fertilizer management.

[0106] 2. Traditional Comparison: Local Corn Drip Irrigation Fertilizer System

[0107] The base fertilizer used was compound fertilizer with N, P2O5, and K2O nutrient contents of 10%, 27%, and 10%, respectively. The application rate was 40 kg per mu (approximately 0.067 hectares), which translates to N, P2O5, and K2O application rates of 4.0 kg / mu, 10.8 kg / mu, and 4 kg / mu, respectively. Nitrogen fertilizer was applied three times during the tasseling, tasseling, and grain-filling stages, with each application of 10 kg / mu of urea, equivalent to an N content of 4.6 kg / mu. The total nitrogen fertilizer application for the three applications was 13.8 kg / mu. No potassium fertilizer was applied during the growing season. Therefore, the total N, P2O5, and K2O application rates during the corn growing season were 17.8 kg / mu, 10.8 kg / mu, and 4.0 kg / mu, respectively.

[0108] (iv) Field management

[0109] Both methods employ the same field management pattern, as detailed below:

[0110] Check and replant seedlings: Check seedlings promptly after emergence and replant any missing seedlings to ensure full germination.

[0111] Cultivation and weeding: During the growing season, cultivate the bare ground between the plastic film mulch in conjunction with topdressing to remove weeds and loosen the soil.

[0112] Pest and disease control: Take timely control measures based on the occurrence of pests and diseases in the field.

[0113] (v) Harvesting and Plastic Film Recycling

[0114] Harvest dates: September 29, 2024; September 26, 2025.

[0115] Harvesting method: Mechanical harvesting, using a high stubble retention method (stubble height 10-15 cm) to avoid damaging the plastic film during the harvesting process.

[0116] Plastic film recycling: After the corn harvest, professional plastic film recycling machinery is used to recycle the plastic film. The recycled plastic film and drip irrigation tape are collected and handed over to plastic recycling companies for processing.

[0117] IV. Measurement Indicators and Methods

[0118] (a) Corn yield

[0119] Sampling method: Three representative sampling points were randomly selected within each treatment plot, and 20 corn ears were harvested consecutively from each point.

[0120] Threshing and weighing: Threshing was done manually. The total weight of all kernels from 20 ears of grain was measured. The total weight of kernels from the 20 ears at the i-th sampling point was recorded as . In this embodiment, the term is referred to as grain weight, and the unit is g / 20 ears.

[0121] Moisture content determination: The moisture content of corn kernels was measured three times using a grain moisture meter, and then the average kernel moisture content at each point was calculated. The average kernel moisture content at point i was... In this embodiment, the term is abbreviated as grain moisture, in units of %.

[0122] Standard moisture yield conversion: The grain weight converted to 14% standard moisture content is calculated by taking the average total grain weight of 20 ears from the i-th sampling point, converted to 14% standard moisture content, and denoted as [missing information]. In this embodiment, the yield is calculated based on 14% moisture content, in g / 20 ears, using the following formula:

[0123] ; In the formula:

[0124] : The total weight of grains from 20 ears of grain at the i-th sampling point, converted to 14% standard moisture content, in g / 20 ears, or can be converted to kg / 20 ears;

[0125] : Total weight of grains from 20 ears of grain at the i-th sampling point, in g / 20 ears;

[0126] : Average moisture content of grains at the i-th sampling point.

[0127] Theoretical yield calculation: Based on the row spacing and plant spacing, calculate the planting density PD (plants / acre), with a correction factor of 0.85, and calculate the theoretical yield using the following formula:

[0128]

[0129] In the formula:

[0130] Theoretical yield of corn under standard moisture content, kg / mu;

[0131] : The average grain weight per ear at the i-th sampling point, converted to 14% standard moisture content, in kg / ear; ;

[0132] Corn planting density, plants per acre.

[0133] (ii) Irrigation water use efficiency

[0134] Calculate irrigation water use efficiency (IWP) using the following formula:

[0135]

[0136] In the formula:

[0137] IWP: Irrigation Water Use Efficiency, kg / m³. The higher the value, the higher the irrigation water use efficiency.

[0138] Theoretical yield of corn under standard moisture content, kg / mu;

[0139] Total irrigation water volume during the growing season, m³ / mu.

[0140] (III) Mulch Film Recycling Rate

[0141] The plastic film recycling rate is the ratio of the mass of plastic film that is mechanically or manually recycled after crop harvest to the mass of plastic film laid before sowing.

[0142] Sampling method: After corn harvest, 3-5 sampling points are randomly selected in each treatment plot, and a 2-meter length is measured at each point along the direction of the mulch film laying.

[0143] Recycled plastic film weighing: Plastic film up to 2 meters in length is collected manually, only the visible portion on the surface is collected; fragments remaining in the soil are not collected. The collected film is washed, dried, weighed, and recorded. (g) Calculate the average recovery mass at each sampling point. .

[0144] Weighing the new plastic film: Take 3-5 pieces of the same type of new plastic film, each piece 2 m long, weigh them, and calculate the average mass. .

[0145] Recovery rate calculation: The plastic film recovery rate is calculated using the following formula:

[0146] ;

[0147] Wherein, Rec: plastic film recycling rate, %

[0148] The mass of the plastic film recovered at the i-th sampling point is in g, which is the measured mass of the plastic film over a length of 2m.

[0149] n: The number of sampling points for recycled plastic film;

[0150] The mass of the new plastic film in the i-th segment is in g, which represents the measured mass of the new plastic film within a 2m length.

[0151] m: Number of sampling sections for the new plastic film.

[0152] Residual rate calculation: The residual rate of mulch film is calculated according to the following formula:

[0153] .

[0154] V. Test Results

[0155] (a) Corn yield

[0156] Results for 2024:

[0157] Table 3 shows the yield measurement results of the corn film-side planting drip irrigation and fertigation method of the present invention and the local corn film-under-film drip irrigation method (CK) in 2024.

[0158] Table 3. Maize Yield Assessment Results in 2024

[0159]

[0160] As shown in Table 3, the corn yield of the method of the present invention in 2024 was 1400 kg / mu, while that of the control method was 1443 kg / mu. The yield of the method of the present invention was 3.0% lower than that of the control, but the difference was not significant (P>0.05).

[0161] Table 4 shows the yield measurement results of the corn film-side planting drip irrigation and fertigation method of this invention and the local corn film-under-film drip irrigation method (CK) in 2025.

[0162] Table 4. Maize Yield Assessment Results in 2025

[0163]

[0164] As shown in Table 4, the maize yield using the method of this invention in 2025 was 1394 kg / mu, while the yield using the control method was 1246 kg / mu. The yield of the method of this invention was 11.9% higher than that of the control, and the difference was significant (P<0.05). Looking at the yield results over the two years, the yield of the method of this invention remained stable at 1394-1400 kg / mu, while the yield of the control method fluctuated more significantly, ranging from 1246-1443 kg / mu. The results indicate that the method of this invention has stronger yield stability, and the yield increase effect is more significant in drought years.

[0165] (ii) Irrigation water use efficiency

[0166] Table 5 shows the irrigation water volume, yield, and irrigation water use efficiency results of the method of the present invention and the control method in 2024 and 2025.

[0167] Table 5 Results of Irrigation Water Use Efficiency

[0168]

[0169] As can be seen from Table 5:

[0170] In 2024, the irrigation water use efficiency of the method of this invention was 8.39 kg / m³, while that of the control method was 6.87 kg / m³, representing a 22% improvement. In 2025, the irrigation water use efficiency of the method of this invention was 7.46 kg / m³, while that of the control method was 5.19 kg / m³, representing a 44% improvement. The results show that the method of this invention can significantly improve irrigation water use efficiency, producing the same or even more grain with less water.

[0171] (III) Mulch Film Recycling Rate

[0172] The results of the plastic film recovery rate of the method of the present invention and the control method in 2024 and 2025 are shown in Table 6.

[0173] Table 6 Results of plastic film recycling rate

[0174]

[0175] As can be seen from Table 6:

[0176] In 2024, the plastic film recovery rate of the method of this invention was 81.7%, while that of the control method was 39.3%, representing an improvement of 42.4 percentage points. In 2025, the plastic film recovery rate of the method of this invention was 84.4%, while that of the control method was 46.7%, representing an improvement of 37.7 percentage points. The average recovery rate over the two years was 83.1%, compared to 43.0% for the control method, nearly double the rate of the control method. These results demonstrate that the method of this invention can significantly improve the plastic film recovery rate, effectively reduce plastic film residue, and protect the soil ecological environment.

[0177] Based on the results of field trials conducted in 2024 and 2025, it can be concluded that: the method of this invention maintains a stable corn yield of 1394-1400 kg / mu, with no decrease or even an increase in yield compared to traditional drip irrigation under mulch film; the irrigation water use efficiency of this invention is 22%-44% higher than that of traditional methods, demonstrating significant water-saving effects; and the mulch film recycling rate of this invention reaches 83.1%, nearly double that of traditional methods, effectively solving the problem of difficult mulch film recycling. This embodiment fully verifies the feasibility and superiority of the technical solution of this invention.

[0178] The traditional practice of drip irrigation under plastic film involves planting corn directly beneath the film to fully utilize its water-retention effect. However, this is the root cause of root entanglement and low film recycling rates. This invention breaks with this practice by shifting the corn planting position from under the film to 4-5 cm outside the edge of the film, thus completely avoiding physical contact between the roots and the film in terms of planting layout.

[0179] However, planting on the side of the mulch film is not simply a matter of relocation. In arid and semi-arid regions, soil moisture evaporates rapidly on the side of the mulch film. Without simultaneous and precise water and fertilizer supply to the root zone, crops are highly susceptible to drought and yield reduction. This invention lays drip irrigation tape under the mulch film in the middle of narrow rows, utilizing the lateral diffusion of drip irrigation water to precisely supply corn roots 4-5 cm from the mulch film. Simultaneously, the water-loving nature of corn roots causes them to tend to grow into the soil on the mulch side, mitigating the impact of insufficient water and fertilizer distribution outside the mulch film on crop growth. This spatially separated design of water supply under the mulch film and planting outside the mulch film retains the water-retention function of the mulch film while avoiding root contact with the mulch film, achieving precise water and fertilizer supply to the roots. This spatially separated, functionally synergistic method has not been reported in existing drip irrigation planting technology under mulch film.

[0180] The soil matrix potential selected for irrigation in this invention is -15 kPa, which is the optimal water-saving threshold under the premise of ensuring stable corn yield. Deviating from this threshold will not achieve the water-saving without yield reduction objective of this invention. If it is too high, such as -10 kPa, the soil moisture content will be too high, resulting in insufficient oxygen in the soil, affecting root development and crop growth, significantly reducing water use efficiency, and generally leading to excessive irrigation water consumption and resource waste. If it is too low, such as below -25 kPa, the soil moisture content on the root side will be too low, causing water stress on the crop, resulting in reduced photosynthetic product accumulation and a significant decrease in yield. Therefore, -15 kPa is the key parameter for achieving the balance point of water saving without yield reduction in this invention.

[0181] This invention sows corn 4-5 cm outside the edge of the plastic film, utilizing the lateral diffusion of moisture from the drip irrigation-created under-film moist zone to precisely supply water to the roots outside the film. This design places specific requirements on the width of the plastic film—too narrow or too wide a film will disrupt the synergistic balance between sowing location, moist zone coverage, and film recyclability. If the film is too narrow, even with 5 cm sowing on the side, the moist zone becomes too small, failing to provide sufficient water and fertilizer to the roots on the side, leading to reduced yield. If the film is too wide, even with 5 cm sowing on the side to prevent root entanglement, the drip irrigation tape is too far from the corn roots, requiring increased irrigation water to allow water to seep into the roots, resulting in excessive irrigation water, greater deep leakage, reduced water use efficiency, increased film usage, increased agricultural production costs, and increased film residue. The film width and side planting distance set by this invention ensure that the moist zone precisely covers the 5 cm of roots on the side of the film, while maintaining a moderate film width and good strength, achieving a synergistic effect of stable and high yield and easy film recycling.

[0182] In summary, this invention addresses the long-standing technical challenge of synergistically achieving water conservation, stable yield, and pollution reduction in maize cultivation in arid and semi-arid regions. It breaks through the traditional inertia of drip irrigation under plastic film, which involves planting maize under the film, and proposes a spatially separated layout of subsurface water supply and external planting. A corresponding precision irrigation method integrating drip irrigation with fertigation, featuring irrigation threshold control and high-frequency, low-volume irrigation, is also established. In this invention, parameters such as planting location, film width, monitoring depth, irrigation threshold, single irrigation volume, fertilizer application rate, and fertilization regime are not selected independently. Instead, they are based on a holistic system optimization of the drip irrigation wetting body morphology, maize root distribution, and film-side planting layout. These parameters are interconnected and synergistic, jointly achieving a comprehensive technical effect of stable and high yield, water conservation and efficiency improvement, and easy film recycling.

[0183] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for integrated drip irrigation and fertigation of corn grown under plastic film, characterized in that, Includes the following steps: Using a wide-narrow row planting method, a plastic film is laid on top of the narrow row, the two edges of the plastic film are pressed into the soil and covered with soil, the corn is sown 4-5 cm outside the edge of the part of the plastic film exposed on the ground surface, and the drip irrigation tape is laid under the plastic film. The irrigation is controlled by monitoring the soil matrix potential at a depth of 20-25cm below the dripper of the drip irrigation tape. Irrigation is started when the soil matrix potential is ≤-15 kPa, and the water volume for a single irrigation is 10-18 m³ / mu. During this period, all phosphate fertilizer is applied as base fertilizer; part of the nitrogen fertilizer is applied as base fertilizer, and the remainder is applied in several applications during the corn jointing stage to the grain filling stage; all potassium fertilizer is applied as base fertilizer; or, part of the potassium fertilizer is applied as base fertilizer, and the remainder is applied in several applications during the small trumpet stage to the tasseling stage.

2. The method for integrated drip irrigation and fertigation of corn grown under plastic film as described in claim 1, characterized in that, When the soil moisture is below 80% of the field capacity after sowing, irrigate 1-2 times, with a total irrigation volume of 20-30 m³ / mu.

3. The method for integrated drip irrigation and fertigation of corn grown under plastic film as described in claim 1, characterized in that, Stop irrigation 30-45 days before corn harvest.

4. The method for integrated drip irrigation and fertigation of corn grown under plastic film as described in claim 1, characterized in that, In the wide-narrow row planting method, the width of the wide row is 60-70 cm, and the width of the narrow row is 40-50 cm.

5. The method for integrated drip irrigation and fertigation of corn grown under plastic film as described in claim 1, characterized in that, The soil matrix potential is monitored at a depth of 20 cm directly below the dripper of the drip irrigation tape.

6. The method for integrated drip irrigation and fertigation of corn grown under plastic film as described in claim 1, characterized in that, The corn was planted 5 cm away from the edge of the plastic film.

7. The method for integrated drip irrigation and fertigation of corn grown under plastic film as described in claim 1, characterized in that, The drip irrigation tape is laid under the mulch film, in the middle of the narrow row, and one drip irrigation tape controls the irrigation and fertilization of the two rows of corn on both sides.

8. The method for integrated drip irrigation and fertigation of corn grown under plastic film as described in claim 1, characterized in that, A portion of the nitrogen fertilizer is applied as base fertilizer, accounting for 20%-25% of the total fertilizer application. The remaining nitrogen fertilizer is applied as top dressing in 3-4 applications from the jointing stage to the grain-filling stage. A portion of the potassium fertilizer is applied as base fertilizer, and the remaining potassium fertilizer is applied as top dressing in 2-3 applications from the small trumpet stage to the tasseling stage.

9. A method for integrated drip irrigation and fertigation of corn grown under plastic film as described in claim 1, characterized in that, The drip irrigation tape has a drip flow rate of 1.0-2.0 L / h and a drip spacing of 20-25 cm.

10. A method for integrated drip irrigation and fertigation of corn grown under plastic film as described in claim 1, characterized in that, The corn planting density is 5,500-6,500 plants per mu.

Images