Method for improving planting effect of populus simonii forest protection in desert oasis area

Abstract

The application provides a method for improving the planting effect of Populus alba in a desert oasis area, and belongs to the technical field of farmland shelter forest afforestation in a dry area. The method for improving the planting effect of Populus alba in a desert oasis area provided by the application comprises the following steps: after Populus alba seedlings are transplanted, nitrogen-containing fertilizer is applied at an amount of 5-7 g of nitrogen per plant, irrigation is performed at an amount of 3200-3800 m 3 / hm 2 of total annual irrigation amount, and the soil volume water content of the root distribution layer (0-40 cm) is maintained at 12%-16%. The method has the advantages of water saving, nitrogen saving, high survival rate of planting, good growth in the seedling stage, and high water and nitrogen utilization efficiency. The method solves the problems of extensive irrigation, blind fertilization, disconnection between water and nitrogen management, low survival rate of planting, weak growth in the seedling stage, and low water and fertilizer utilization efficiency in the traditional mode, significantly improves the planting effect and growth performance in the seedling stage of Populus alba in a desert oasis area, and realizes the comprehensive goal of water saving, fertilizer saving, high efficiency and stable yield.

Description

Technical Field

[0001] This invention belongs to the field of afforestation technology for farmland shelterbelts in arid areas, specifically relating to a method for improving the planting effect of Populus tomentosa shelterbelts in desert oasis areas. Background Technology

[0002] Desert oasis areas suffer from sparse rainfall, intense evaporation, scarce water resources, and insufficient soil moisture supply. Some areas also suffer from low soil fertility, poor rhizosphere environment, poor soil structure, and salinization, resulting in a fragile ecological environment. This directly leads to low survival rates and weak growth in the early stages of transplanting Populus tomentosa. Populus tomentosa, due to its strong resistance, rapid growth, and outstanding windbreak and sand-fixing effects, has become a core afforestation species in farmland shelterbelt systems in desert oasis areas. Ensuring its afforestation effectiveness and growth performance is of great practical significance for the sustainable development of regional agriculture and ecological security. However, current artificial afforestation and establishment of Populus tomentosa still widely adopts traditional flood irrigation and experience-based fertilization management models. Irrigation and fertilization are independent and lack coordinated control, resulting in extensive water and fertilizer management, low resource utilization efficiency, and low transplant survival rates, severely restricting the quality of shelterbelt construction.

[0003] In the field of irrigation technology, drip irrigation, with its advantages of water conservation, high efficiency, and strong controllability, has been widely used in agriculture, fruit tree cultivation, and ecological forestry in arid and semi-arid regions. Drip irrigation can precisely supply water according to the water requirements of plants, significantly reducing soil ineffective evaporation and deep seepage, improving water use efficiency, and improving soil aeration in the root zone, thus promoting root development. However, in the planting and management of young poplar trees in Xinjiang desert oases, the adoption rate of drip irrigation is still low. Most afforestation plots still use traditional flood irrigation, which not only consumes a huge amount of water and has extremely low water use efficiency, but also easily causes soil compaction, nutrient leaching, and exacerbates forest salinization, further reducing seedling survival rate and growth quality.

[0004] In the field of fertilization technology, precision fertilization techniques such as quantitative fertilization, formula fertilization, deep application of base fertilizer, and fertigation have been widely used in economic forests and facility agriculture, effectively improving fertilizer utilization, reducing nutrient loss, and mitigating the risk of non-point source pollution. However, in the actual production of poplar shelterbelts in Xinjiang, traditional methods such as empirical fertilization, surface application, and broadcasting are still commonly used. Nitrogen application is highly arbitrary, and the timing and location of application are not standardized. This often results in insufficient growth due to low nitrogen levels and low utilization rates of high nitrogen levels, leading to severe nitrogen loss, high environmental pollution risks, and difficulty in achieving synergistic effects with water supply. More importantly, in the current process of artificial afforestation and establishment of poplar forests in Xinjiang, irrigation and fertilization are disconnected and lack coupled and coordinated regulation. Water and fertilizer management is extensive, water and nitrogen resource utilization efficiency is low, transplant survival rates are low, and young forest growth is uneven, severely restricting the quality of shelterbelt construction and the realization of comprehensive ecological and economic benefits. Although some studies on the effects of water and nitrogen as single factors on forest growth have been conducted both domestically and internationally, and there are also a few reports on the effects of water-nitrogen coupling on the growth of crops and economic forests and water and fertilizer utilization, there is still a lack of water-nitrogen coupling regulation mechanisms, precise quantitative parameters, and standardized supporting cultivation methods specifically for the planting period of one-year-old Xinjiang poplar in desert oases. A unified, standardized, and scalable technical system has not yet been formed, making it difficult to meet the practical needs of high-quality farmland shelterbelt construction in arid areas. Desert oasis areas are characterized by aridity, barrenness, intense water evaporation, and easy nitrogen loss. Current management methods for one-year-old Xinjiang poplar trees in these areas suffer from the following shortcomings: Existing irrigation methods are extensive, primarily relying on flood irrigation, resulting in high water consumption, significant ineffective evaporation, and extremely low water resource utilization, exacerbating the water shortage problem in arid regions; fertilization is haphazard and lacks standards, with nitrogen application determined by experience, leading to insufficient growth due to low nitrogen levels and decreased utilization, high leaching risk, and significant environmental pollution due to high nitrogen levels; water and nitrogen management are disconnected, with irrigation and fertilization operating independently without a synergistic coupling mechanism, failing to achieve the synergistic effect of water promoting nitrogen and nitrogen conserving water; planting survival rates are unstable, with water stress and nutrient imbalances leading to slow seedling establishment and weak growth, making it difficult to guarantee planting effectiveness and seedling growth performance; a suitable quantitative plan for arid regions is lacking, with no clear and stable ranges for irrigation and nitrogen application, making it difficult to guide actual production. Therefore, developing a water-saving, nitrogen-saving, high-survival-rate, seedling-growth-promoting, and highly efficient water and nitrogen utilization method for planting poplar in Xinjiang has become an urgent need for the construction of farmland shelterbelts in desert oasis areas. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method that can improve the planting effect of Populus tomentosa shelterbelts in desert oases. This method has the advantages of water conservation, nitrogen conservation, high survival rate of transplanted plants, good seedling growth, and high efficiency of water and nitrogen utilization. It fundamentally solves the technical problems of extensive irrigation, blind fertilization, disconnect between water and nitrogen management, low survival rate of transplanted plants, weak seedling growth, and low efficiency of water and fertilizer utilization under the traditional model. It significantly improves the planting effect and seedling growth performance of Populus tomentosa in desert oases, and achieves the comprehensive goals of water conservation, fertilizer conservation, high efficiency, and stable yield.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for improving the establishment effect of Populus tomentosa shelterbelts in desert oases, comprising the following steps: after transplanting and planting Populus tomentosa seedlings, applying nitrogen-containing fertilizer at a rate of 5-7g nitrogen per seedling, and irrigating a total annual area of ​​3200-3800 m³. 3 / hm 2 Irrigate with sufficient water to ensure that the soil volumetric moisture content of the root distribution layer (0-40 cm) is maintained at 12%-16%.

[0007] Preferably, the planting is 5,000 plants per hectare.

[0008] Preferably, the row spacing for planting is 2 m and the plant spacing is 1 m.

[0009] Preferably, the Xinjiang poplar seedlings are 1-year-old Xinjiang poplar cuttings, with a plant height of 110-115 cm and a ground diameter of 17-19 mm.

[0010] Preferably, the method of applying nitrogen-containing fertilizer includes applying base fertilizer and top dressing in multiple applications, applying base fertilizer once at the time of transplanting, or applying it with water drip.

[0011] Preferably, the method of applying nitrogen-containing fertilizer includes hole application, ring application, or strip application.

[0012] Preferably, the irrigation method includes drip irrigation, tap irrigation, sprinkler irrigation, or seepage irrigation.

[0013] Preferably, when performing drip irrigation, the drip irrigation system is laid in a manner that includes laying drip irrigation tape along the column direction, with one row of drip irrigation tape per column; the flow rate of the drip irrigation system is 4 L / h, and the spacing between drippers is 20 cm.

[0014] Preferably, when the irrigation method is drip irrigation, a soil moisture monitoring device is installed in the root distribution layer of 0-40 cm to monitor the soil volumetric moisture content in real time. When the soil volumetric moisture content is detected to be lower than 12%, irrigation is started and stopped when the soil volumetric moisture content reaches 16%. A phased and balanced water replenishment method is adopted, with each irrigation amount applied in two separate applications, with an interval of 12-24 hours between the two applications.

[0015] Preferably, the nitrogen-containing fertilizer includes urea, ammonium chloride, ammonium sulfate, or ammonium nitrate.

[0016] The beneficial effects of this invention are: This invention proposes for the first time a regulatory approach based on the coupling of water-saving irrigation supply and quantitative nitrogen application. Targeting the site characteristics of arid and barren desert oasis areas, characterized by intense water evaporation and easy nitrogen loss, this invention uses one-year-old Xinjiang poplar as the research object. By setting appropriate deficit irrigation intervals and medium nitrogen application intervals, a precise management model of water and nitrogen synergistic coupling under water-saving irrigation conditions is established. The entire process of setting irrigation quotas, soil moisture control thresholds, nitrogen application amount, fertilization methods, and fertilization timing is quantitatively and standardized, forming a complete, replicable, and scalable planting and cultivation technology scheme. This fundamentally solves the technical problems of extensive irrigation, blind fertilization, disconnect between water and nitrogen management, low planting survival rate, weak seedling growth, and low water and fertilizer utilization efficiency under the traditional model. It significantly improves the planting effect and seedling growth performance of Xinjiang poplar, achieving the comprehensive goals of water saving, fertilizer saving, high efficiency, and stable yield.

[0017] The method provided by this invention has the following advantages: it can significantly improve the planting success and seedling growth vigor of one-year-old Xinjiang poplar, with a significant increase in plant height, ground diameter, and biomass; it can optimize the rhizosphere environment, enhancing soil water retention, fertilizer retention, aeration, and drought resistance; it can improve leaf photosynthetic efficiency and carbon assimilation capacity, fully realizing photosynthetic physiological potential; it enables water use efficiency and nitrogen use efficiency to reach their optimal levels simultaneously; under the premise of significant water saving, the biomass is not significantly different from that of fully irrigated treatment; it increases costs slightly and has a significant water-saving effect, making it suitable for large-scale promotion in desert oasis areas. Attached Figure Description

[0018] Figure 1 These are pictures showing the actual field application of the method of the present invention.

[0019] Figure 2 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0020] This invention provides a method for improving the establishment effect of Populus tomentosa shelterbelts in desert oases, comprising the following steps: after transplanting and planting Populus tomentosa seedlings, applying nitrogen-containing fertilizer at a rate of 5-7g nitrogen per seedling, and irrigating a total annual area of ​​3200-3800 m³. 3 / hm 2 Irrigate with sufficient water to ensure that the soil volumetric moisture content of the root distribution layer (0-40 cm) is maintained at 12%-16%.

[0021] In this invention, the desert oasis area refers to a green agricultural area in a desert context, replenished by snowmelt, suitable for cultivation and habitation. Xinjiang poplar is a unique protective forest species in desert oasis areas, sensitive to water stress, and its survival rate is significantly affected by water control. The method provided by this invention aims to improve the formation speed of Xinjiang poplar protective forests during the first year of establishment, ensuring rapid seedling establishment while achieving water conservation and efficient nitrogen utilization. In this invention, the Xinjiang poplar seedlings are preferably one-year-old Xinjiang poplar pruning seedlings, with a preferred height of 110-115 cm, more preferably 113 cm, and a preferred ground diameter of 17-19 mm, more preferably 18 mm. The planting density is preferably 5000 seedlings per hectare, more preferably with a row spacing of 2 m and a plant spacing of 1 m. The planting depth is preferably 25-35 cm, with the rootstock level with the ground surface and uniform soil compaction.

[0022] In this invention, the preferred methods of applying nitrogen-containing fertilizers include multiple applications of basal fertilizer and topdressing, one-time basal application at planting, or drip application with irrigation water. Preferred methods of applying nitrogen-containing fertilizers include hole application, ring application, or strip application. When applying nitrogen-containing fertilizers in a single hole application at planting, the preferred location is 10-15 cm from the roots and 5-10 cm deep, with the fertilizer evenly applied, covered with soil, and compacted, without direct contact with the roots. In this invention, the preferred nitrogen-containing fertilizers include urea, ammonium chloride, ammonium sulfate, ammonium nitrate, slow-release nitrogen fertilizer, polypeptide nitrogen fertilizer, or water-soluble fertilizer. The application amount, calculated at 5-7g of nitrogen per plant, can meet the nutrient requirements of Xinjiang poplar during the establishment stage (one growing season after planting), without the need for additional topdressing. In this invention, the preferred amount of nitrogen applied per plant is 6g. After the Xinjiang poplar has successfully entered the normal growth stage, routine nutrient management can be carried out according to the local farmland shelterbelt management technical regulations, combined with drip irrigation and fertigation.

[0023] In this invention, the preferred irrigation methods include drip irrigation, small-pipe irrigation, sprinkler irrigation, or seepage irrigation. In this invention, the preferred annual total irrigation volume is 3400-3700 m³. 3 / hm 2 More preferably 3500~3600 m 3 / hm 2This invention employs an irrigation method that achieves precise water control, thereby improving water use efficiency and promoting seedling survival and growth. When drip irrigation is used, it essentially applies a farmland irrigation system to forestry and shelterbelt construction. For drip irrigation, the preferred method of laying the system includes laying drip tape along the row direction, one row per row; the flow rate of the drip irrigation system is 4 L / h, the dripper spacing is 20 cm, and the pipeline is sealed to prevent leakage. When drip irrigation is used, it is preferable to install a soil moisture monitoring device in the root distribution layer (0-40 cm) to monitor the soil volumetric moisture content in real time. Irrigation is initiated when the soil volumetric moisture content is below 12% and stopped when the soil volumetric moisture content reaches 16%. A phased, balanced water replenishment method is adopted, with each irrigation dose applied in two separate applications, 12-24 hours apart, to reduce the risk of deep seepage and nutrient loss. A field application diagram of this invention is shown below. Figure 1 As shown.

[0024] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0025] Unless otherwise specified, the following embodiments are all conventional methods.

[0026] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0027] Example 1 A method for improving the establishment effect of Populus tomentosa shelterbelts in desert oases includes the following steps: (1) Preparation of transplanting site: The original soil of the experimental site, 0-40 cm silty loam, with a bulk density of 1.18 g / cm³. 3 The field water holding capacity is 23.5%, total nitrogen is 0.26 g / kg, and pH is 8.5. In mid-April each year, remove weeds, stones, and root debris, and level the land with a height difference of ≤5cm.

[0028] (2) Transplanting and planting of Xinjiang poplar seedlings: In mid-April each year, dig planting pits, straighten the seedlings, backfill with the original soil, compact in layers, and plant at a depth of 30 cm, with the root collar level with the ground surface, and ensure uniform soil compaction. The seedlings mentioned are 1-year-old Xinjiang poplars ( Populus alba var. Pyramidalis (Bge.) Cut-off seedlings, average plant height 110 cm, ground diameter 18 mm. Planting density: row spacing 2 m, plant spacing 1 m, 5000 plants per hectare.

[0029] (3) Quantitative application of base fertilizer: Calculate the amount of urea (total nitrogen ≥46.0%) based on 6 g of nitrogen per plant. Apply 13.04 g of urea per plant. Apply the fertilizer in one hole at the time of planting. Apply the fertilizer evenly, cover with soil and tamp it down. The fertilizer position is 13 cm away from the root system and 8 cm deep, without direct contact with the root system.

[0030] (4) Drip irrigation system installation: Drip irrigation tape is laid along the column direction, one row of drip irrigation tape per column, and the water pump is 4m long. 3 The main pipeline uses 90×6.7 PE water supply pipe (3-inch pipe national standard), and the straight pipe uses 32×3.0 PE water supply pipe (1-inch pipe national standard). The drip irrigation tape is a patch type with a flow rate of 4 L / h and a dripper spacing of 20 cm. The pipeline is sealed without leakage.

[0031] (5) Precise water management during the growing season: After transplanting, drip irrigation should be carried out in stages according to the soil moisture conditions, with an irrigation quota of 3500 m³ / year. 3 / hm 2 The method of balanced drip irrigation based on soil moisture conditions is as follows: After planting the Xinjiang poplar, a soil moisture monitoring device is installed at a depth of 20 cm from the root system to monitor the soil volumetric moisture content in real time. Irrigation is started when the monitored soil volumetric moisture content is below 12% and stops when the soil volumetric moisture content reaches 16%. A balanced drip irrigation method is adopted, with each irrigation dose applied in two separate applications, 15 hours apart, to reduce the risk of deep seepage and nutrient loss.

[0032] (6) Unified nurturing and management: Weeding and loosening the soil twice during the entire growth period, without using herbicides or insecticides, and without additional topdressing or shading.

[0033] A schematic diagram of the above-described method flow of the present invention is shown below. Figure 2 As shown.

[0034] The results showed that the survival rate after transplanting was 96.2%. Cutting the seedlings back to their original height at the end of October of the same year (after the growing season) compared to transplanting had the following effects: Growth performance indicators: Plant height: increased by 82.4% compared to the planting height, reaching 204.6 cm; Ground diameter: increased by 76.7% compared to the planting time, reaching 31.6 mm; Aboveground biomass: 62.3% higher than the conventional control (Comparative Example 5 below).

[0035] Physiological indicators: Net photosynthetic rate (Pn): 31.5% higher than the conventional control (Comparative Example 5 below); Water use efficiency (WUE): up to 12.7 μmol / mmol; Nitrogen use efficiency (NUE): up to 28.3 g biomass / g N; Nitrogen fertilizer partial productivity (here, nitrogen fertilizer partial productivity refers to the biomass that can be produced by a unit input of nitrogen fertilizer, i.e., biomass / nitrogen application rate): 26.40 kg / kg; Nitrogen fertilizer absorption and utilization rate (nitrogen fertilizer absorption and utilization rate = (total nitrogen uptake by plants in nitrogen-applied areas - total nitrogen uptake by plants in nitrogen-free areas) / nitrogen application rate × 100%): 20.50%; Biomass: 3620.93 kg / hm 2 .

[0036] Example 2 A method for improving the establishment effect of Populus tomentosa shelterbelts in desert oases includes the following steps: (1) Clearing the transplanting site: In mid-April each year, remove weeds, stones and residual roots, level the site, and the drop should be ≤5 cm.

[0037] (2) Transplanting and planting of Xinjiang poplar seedlings: In mid-April each year, dig planting pits, straighten the seedlings, backfill with the original soil, compact in layers, and plant at a depth of 25 cm, with the root collar level with the ground surface, and ensure uniform soil compaction. The seedlings mentioned are 1-year-old Xinjiang poplars ( Populus alba var. Pyramidalis (Bge.) Cut-off seedlings, average plant height 115 cm, ground diameter 19 mm. Planting density: row spacing 2 m, plant spacing 1 m, 5000 plants per hectare.

[0038] (3) Quantitative application of base fertilizer: Calculate the amount of urea (total nitrogen ≥46.0%) based on 5 g of nitrogen per plant. Apply 10.87 g of urea per plant. Apply the fertilizer once in the hole when planting. Apply the fertilizer evenly, cover with soil and tamp it down. The fertilizer position is 10 cm away from the root system and 5 cm deep, without direct contact with the root system.

[0039] (4) Drip irrigation system installation: Drip irrigation tape is laid along the column direction, one row of drip irrigation tape per column, and the water pump is 4m long. 3 The main pipeline uses 90×6.7 PE water supply pipe (3-inch pipe national standard), and the straight pipe uses 32×3.0 PE water supply pipe (1-inch pipe national standard). The drip irrigation tape is a patch type with a flow rate of 4 L / h and a dripper spacing of 20 cm. The pipeline is sealed without leakage.

[0040] (5) Precise water management during the growing season: After transplanting, drip irrigation is carried out in stages according to the soil moisture conditions, with an irrigation quota of 3200 m³ / year. 3 / hm 2The method of balanced drip irrigation based on soil moisture conditions is as follows: After planting the Xinjiang poplar, a soil moisture monitoring device is installed at a depth of 40 cm from the root system to monitor the soil volumetric moisture content in real time. Irrigation is started when the monitored soil volumetric moisture content is below 12% and stops when the soil volumetric moisture content reaches 16%. A balanced drip irrigation method is adopted, with each irrigation dose applied in two separate applications, 24 hours apart, to reduce the risk of deep seepage and nutrient loss.

[0041] (6) Unified nurturing and management: Weeding and loosening the soil are carried out 3 times throughout the entire growth period. No herbicides or insecticides are used, and no additional topdressing or shading is required.

[0042] Example 3 A method for improving the establishment effect of Populus tomentosa shelterbelts in desert oases includes the following steps: (1) Clearing the transplanting site: In mid-April each year, remove weeds, stones and residual roots, level the site, and the drop should be ≤5 cm.

[0043] (2) Transplanting and planting of Xinjiang poplar seedlings: In mid-April each year, dig planting pits, straighten the seedlings, backfill with the original soil, compact in layers, and plant at a depth of 25 cm, with the root collar level with the ground surface, and ensure uniform soil compaction. The seedlings mentioned are 1-year-old Xinjiang poplars ( Populus alba var. Pyramidalis (Bge.) Cut-off seedlings, average plant height 115 cm, ground diameter 19 mm. Planting density: row spacing 2 m, plant spacing 1 m, 5000 plants per hectare.

[0044] (3) Quantitative application of base fertilizer: Calculate the amount of ammonium chloride to be applied according to the amount of 7 g nitrogen per plant. Apply the amount of base fertilizer and topdressing twice at the time of planting.

[0045] (4) Precise water management during the growing season: After transplanting, drip irrigation is carried out according to the soil moisture conditions, with an irrigation quota of 3800 m³ per year. 3 / hm 2 The drip irrigation method based on soil moisture conditions is as follows: After planting the Xinjiang poplar, a soil moisture monitoring device is installed at a depth of 15 cm from the root system to monitor the soil volumetric moisture content in real time. Drip irrigation is initiated when the monitored soil volumetric moisture content is below 12% and continues until the soil volumetric moisture content reaches 16%.

[0046] (5) Unified nurturing and management: Weeding and loosening the soil three times throughout the entire growth period, without using herbicides or insecticides, and without additional topdressing or shading.

[0047] Comparative Example 1 The difference from Example 1 is that in step (3), the nitrogen application rate is 2g of nitrogen per plant, which is converted to 4.35g of urea (total nitrogen ≥46.0%) per plant. The irrigation quota in step (5) is 4300 m³ per year. 3 / hm 2 The rest are the same as in Example 1.

[0048] The results show: Plant height and ground diameter were significantly higher than those of the unfertilized groups (Comparative Examples 6-8 below), and net photosynthetic rate was significantly increased. Nitrogen fertilizer partial productivity: 28.99 kg / kg; nitrogen fertilizer uptake and utilization rate: 13.80%; biomass: 3373.44 kg / hm² 2 Growth is mediocre, mainly due to low nitrogen supply.

[0049] Comparative Example 2 The difference from Example 1 is that the irrigation quota in step (5) is 4300 m³ per year. 3 / hm 2 The rest are the same as in Example 1.

[0050] The results show: The plant exhibited the fastest growth in plant height and diameter at ground level, and the highest net photosynthetic rate (relative to all examples and other comparative groups). Biomass: 3630.22 kg / hm² 2 Nitrogen fertilizer partial productivity: 18.67 kg / kg; nitrogen fertilizer absorption and utilization rate: 12.02%; although this comparative group showed the best growth performance, it consumed a lot of water and had low water use efficiency, making it unsuitable for promotion and application in desert oasis areas.

[0051] Comparative Example 3 The difference from Example 1 is that in step (3), the nitrogen application rate is 10g of nitrogen per plant, which is converted to 21.74g of urea (total nitrogen ≥46.0%) per plant. The irrigation quota in step (5) is 4300 m³ per year. 3 / hm 2 The rest are the same as in Example 1.

[0052] Compared with Example 1, the growth was reduced, high nitrogen inhibition was observed, and the net photosynthetic rate decreased. Nitrogen fertilizer partial productivity was extremely low at 5.29 kg / kg; nitrogen fertilizer uptake and utilization rate was 7.44%; and biomass was 3349.52 kg / hm². 2 Nitrogen was wasted seriously, and its utilization rate dropped significantly.

[0053] Comparative Example 4 The difference from Example 1 is that the amount of nitrogen applied in step (3) is 2g of nitrogen per plant. After conversion, the amount of urea (total nitrogen ≥46.0%) applied is 4.35g per plant. The rest is the same as in Example 1.

[0054] At the same time, a control group without nitrogen application was set up (this control group refers to the one that is different from Example 1 in that the amount of nitrogen applied in step (3) is 0g of nitrogen per plant, and the rest is the same as Example 1).

[0055] The experimental results showed that the growth (referring to comprehensive indicators including plant height, diameter at root, and photosynthetic indicators) was significantly higher than that of the control group. Compared with the control group, the nitrogen fertilizer absorption and utilization rate was greatly improved: 29.42%; nitrogen fertilizer partial productivity: 27.52 kg / kg; biomass: 3129.81 kg / hm². 2 However, it still shows nitrogen deficiency and moderate growth.

[0056] Comparative Example 5 The method used was local flood irrigation and fertilization, differing from Example 1 in that it employed flood irrigation, with an annual water consumption of approximately 9000 m³. 3 / hm 2 The fertilization method was conventional nitrogen application by farmers, mainly by broadcasting. The amount of fertilizer applied was much higher than the 6g of nitrogen per plant in Example 1. There was no drip irrigation system or soil moisture testing device. Everything else was the same as in Example 1.

[0057] The results showed that the survival rate of the poplar shelterbelt in Xinjiang was low, only 84%, the aboveground biomass was only about 60% of that in Example 1, and the water use efficiency was less than 50% of that in Example 1. It required a large amount of labor, had high costs, and posed a high risk of ecological pollution, and could not achieve the synergistic goal of water conservation, fertilizer conservation, efficient planting and stable growth.

[0058] As can be seen from the comparison between Example 1 and this comparative example, the present invention effectively solves the prominent problems in the prior art, such as extensive irrigation, serious water waste, low nitrogen fertilizer utilization, disconnect between water and nitrogen management, poor planting effect, and weak seedling growth, through precise regulation of water and nitrogen coupling, quantitative drip irrigation, and quantitative fertilization. Compared with existing conventional irrigation and fertilization methods, the present invention can significantly improve the planting effect of Populus tomentosa in Xinjiang, enhance seedling growth, improve photosynthetic efficiency and dry matter accumulation, and simultaneously achieve efficient utilization of water and nitrogen, while saving more than 60% of water. Its comprehensive benefits are outstanding, making it suitable for large-scale promotion and application in desert oasis areas.

[0059] Comparative Example 6 The difference from Example 1 is that the nitrogen application rate in step (3) is 0g of nitrogen per plant, which is converted to 0g of urea (total nitrogen ≥46.0%) per plant. The irrigation quota in step (5) is 4300 m³ per year. 3 / hm 2 The rest are the same as in Example 1.

[0060] The experimental results showed that the plant height and diameter at ground level grew slowly, the net photosynthetic rate was low, the leaves were prone to yellowing, and the water use efficiency was low. The biomass was 3097.95 kg / hm². 2 The survival rate after transplanting is low, and the plants grow weakly.

[0061] Comparative Example 7 The difference from Example 1 is that the amount of nitrogen applied in step (3) is 0 g of nitrogen per plant. After conversion, the amount of urea (total nitrogen ≥ 46.0%) applied is 0 g per plant. The rest is the same as in Example 1.

[0062] The experimental results showed that the plant exhibited the weakest growth among all the implemented and comparative groups, with significant leaf yellowing and the lowest net photosynthetic rate. The biomass was 2868.36 kg·hm². -2 The transplanting effect was poor.

[0063] Comparative Example 8 The difference from Example 1 is that the nitrogen application rate in step (3) is 0g of nitrogen per plant, which is converted to 0g of urea (total nitrogen ≥46.0%) per plant. The irrigation quota in step (5) is 3000 m³ per year. 3 / hm 2 The rest are the same as in Example 1.

[0064] The experimental results showed that the survival rate after transplanting was 79.3%. Long-term insufficient soil moisture led to a high risk of plant wilting, severely inhibited plant height and diameter growth, and a significant decrease in net photosynthetic rate. The biomass was 2672.4 kg·hm². -2 This indicates that when the moisture content is lower than that in Example 1 of this invention, normal establishment and growth cannot be guaranteed.

[0065] Comparative Example 9 The difference from Example 1 is that the amount of nitrogen applied in step (3) is 10g of nitrogen per plant. After conversion, the amount of urea (total nitrogen ≥46.0%) applied is 21.74g per plant. The rest is the same as in Example 1.

[0066] The experimental results showed that, compared with Example 1, the growth of *Populus thunbergii* in this comparative example was inhibited, lower than that in Example 1, and the net photosynthetic rate decreased. Nitrogen fertilizer partial productivity was extremely low at 5.47 kg·kg⁻¹. -1 The nitrogen fertilizer absorption and utilization rate was 7.17%, and the biomass was 3128.20 kg·hm². -2 This indicates that high nitrogen levels lead to waste and inhibition, making them unsuitable for production applications.

[0067] The comparison of the above comparative examples and embodiments shows that when the irrigation volume is lower or higher than 3500 m³, 3 ·hm -2When nitrogen application rates are lower or higher than 6 g N / plant, the survival rate, growth vigor, photosynthetic performance, biomass, and water and nitrogen use efficiency of *Populus xinanense* all show a significant decrease. Only within the water-nitrogen coupling parameters described in this invention can optimal synergy between planting effect and growth performance be achieved, resulting in better technical outcomes.

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving the establishment effect of Populus tomentosa shelterbelts in desert oasis areas, characterized in that, It comprises the following steps: after the seedling transplanting of Xinjiang poplar, nitrogen-containing fertilizer is applied at the amount of 5-7 g of nitrogen per plant, irrigation is carried out at the total amount of 3200-3800 m 3 / hm 2 per year, and the soil volume water content in the root distribution layer of 0-40 cm is maintained at 12%-16%.

2. The method according to claim 1, characterized in that, The planting density is 5,000 plants per hectare.

3. The method according to claim 1, characterized in that, The row spacing for planting is 2 m, and the plant spacing is 1 m.

4. The method according to claim 1, characterized in that, The Xinjiang poplar seedlings mentioned are one-year-old Xinjiang poplar cuttings, with a plant height of 110-115 cm and a ground diameter of 17-19 mm.

5. The method according to claim 1, characterized in that, The methods of applying nitrogen-containing fertilizers include applying base fertilizer and top dressing in multiple applications, applying base fertilizer once at the time of transplanting, or applying it with water drip.

6. The method according to claim 1, characterized in that, The methods of applying nitrogen-containing fertilizers include hole application, ring application, or strip application.

7. The method according to claim 1, characterized in that, The irrigation methods include drip irrigation, tap irrigation, sprinkler irrigation, or seepage irrigation.

8. The method according to claim 7, characterized in that, When implementing drip irrigation, the drip irrigation system is laid out by laying drip tape along the column direction, with one row of drip tape per column; the flow rate of the drip irrigation system is 4 L / h, and the spacing between drippers is 20 cm.

9. The method according to claim 7, characterized in that, When the irrigation method is drip irrigation, a soil moisture monitoring device is installed in the root distribution layer of 0~40 cm to monitor the soil volumetric moisture content in real time. When the soil volumetric moisture content is detected to be lower than 12%, irrigation is started and stopped when the soil volumetric moisture content reaches 16%. A phased and balanced water replenishment method is adopted, with each irrigation amount applied in two separate applications, with an interval of 12~24 hours between the two applications.

10. The method according to claim 1, characterized in that, The nitrogen-containing fertilizers include urea, ammonium chloride, ammonium sulfate, or ammonium nitrate.

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