Planting method for young orchards in middle and lower reaches of Yangtze River and giving consideration to environment and income increase

Abstract

The invention belongs to the technical field of agricultural planting, and particularly relates to a planting method giving consideration to environment and income increase in young orchards in the middle and lower reaches of the Yangtze River, citrus is planted in the young orchards, citrus and watermelons are intercropped, compound fertilizer is applied during planting, and the compound fertilizer comprises inorganic fertilizer, organic fertilizer, a soil conditioner and bacterial manure. According to the planting method, organic and inorganic combined application and water and fertilizer integrated cooperation are adopted, soil conditioner and microbial fertilizer application are integrated, a virtuous circle of soil improvement, quality improvement and efficiency improvement is formed, and the win-win situation of the environment benefit and the economic benefit of the young orchard is achieved.

Description

Technical Field

[0001] This invention belongs to the field of agricultural planting technology, specifically relating to a planting method for young orchards in the middle and lower reaches of the Yangtze River that takes into account both environmental protection and increased income. Background Technology

[0002] The continued growth of the global population places higher demands on agricultural systems to ensure food security. Given limited arable land resources, agricultural production increases output through higher input intensity, but this often comes at a high environmental cost. Agriculture contributes approximately 11% of anthropogenic greenhouse gas emissions, and improper fertilization can lead to nitrate pollution in groundwater and eutrophication of surface water; the production of agricultural chemicals also exacerbates global warming, acidification, and eutrophication, posing potential threats to ecosystems and human health.

[0003] The citrus industry is China's largest fruit industry and a pillar industry in southern China. The middle and lower reaches of the Yangtze River are one of the main citrus-growing areas. The middle and lower reaches of the Yangtze River are typical red soil hilly sloping farmland with a subtropical monsoon climate. The average annual temperature is 18.2℃, the average annual precipitation is 1254.20 mm, and the average annual sunshine duration is 1623.40h.

[0004] From an economic perspective, orchards typically experience a 3-5 year non-productive period in their initial establishment. During this phase, significant upfront costs are incurred in labor, agricultural chemicals, and irrigation facilities, with no economic return. Therefore, intercropping watermelons and other cash crops in young citrus orchards becomes a crucial means of generating short-term income. However, watermelon production requires substantial nutrient and water inputs, and sloping orchards often suffer from poor soil conditions and high runoff risk. Insufficient nutrient input can lead to resource competition between watermelons and citrus, resulting in reduced yields. In practice, farmers often address this issue by overusing chemicals, but this excessive use of agricultural chemicals in orchards causes soil and water pollution and increases greenhouse gas emissions. Furthermore, inappropriate irrigation methods such as flood irrigation further exacerbate nutrient loss and water waste, ultimately leading to low resource utilization efficiency, significant environmental pressure, and a decline in both watermelon yield and income. Therefore, optimizing management models is crucial for achieving a win-win situation for both the environment and the economy in this system. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a planting method for young orchards in the middle and lower reaches of the Yangtze River that balances environmental protection and income growth. By combining organic and inorganic fertilizers with integrated water and fertilizer management, and integrating soil conditioners and microbial fertilizers, a virtuous cycle of soil improvement, quality enhancement, and efficiency enhancement is formed, achieving a win-win situation for both environmental and economic benefits in young orchards.

[0006] The specific technical solution adopted in this invention is as follows:

[0007] A planting method for young orchards in the middle and lower reaches of the Yangtze River that takes into account both environmental protection and income increase, wherein citrus is planted in the young orchard, and the citrus is intercropped with watermelon. During the planting period, compound fertilizer is applied, which includes inorganic fertilizer, organic fertilizer, soil conditioner and microbial fertilizer.

[0008] The inorganic fertilizer contains 15-17% N, 15-17% P2O5, and 15-17% K2O.

[0009] The organic fertilizer contains 18-25 g·kg⁻¹ of total nitrogen, 30-35 g·kg⁻¹ of total phosphorus, and 3-4 g·kg⁻¹ of total potassium.

[0010] The soil conditioner contains K2O ≥ 4.0%, CaO > 30%, MgO ≥ 16.0%, SiO2 ≥ 12.0%, and has a pH value of 11.0-12.0.

[0011] The microbial fertilizer is a granular formulation, wherein the microorganisms include any one or more of Bacillus subtilis, Bacillus mucilaginosus, Bacillus megaterium, Streptomyces, arbuscular mycorrhizal fungi, Trichoderma, and Azotobacter chrysophyte, and the content of microorganisms in the microbial fertilizer has an effective viable count ≥ 500 million CFU / g.

[0012] The specific steps for intercropping citrus fruits and watermelons are as follows:

[0013] S1. Plant citrus in the orchard in the first year;

[0014] S2. Watermelon seedlings are raised in March of the following year, and base fertilizer is applied in furrows between the citrus rows. In April, watermelon seedlings are transplanted into furrows with base fertilizer. Topdressing is applied 1-3 weeks after transplanting. The mature watermelons are harvested in July.

[0015] The spacing between citrus plants is 300-400cm, the spacing between watermelon plants is 85-100cm, and the row spacing between watermelons and citrus plants is 140-260cm.

[0016] The base fertilizer includes 250-300 kg / hm2 of inorganic fertilizer, 30,000-35,000 kg / hm2 of organic fertilizer, 200-250 kg / hm2 of soil conditioner, and 100-125 kg / hm2 of microbial fertilizer. The top dressing includes 820-850 kg / hm2 of inorganic fertilizer.

[0017] The cost-benefit ratio of the watermelon is calculated using the following formula:

[0018] LCC = Environmental Emissions Cost Coefficient * Environmental Emissions Per Unit Output + Total Variable Costs + Total Fixed Costs

[0019] Cost-benefit ratio = (Total revenue - LCC) / LCC

[0020] In the formula, LCC is the life cycle cost (yuan / t); environmental emission cost coefficient (yuan / kg); environmental emissions per unit output (kg / t); total revenue (yuan / t); total variable cost (yuan / t); and total fixed cost (yuan / t).

[0021] The beneficial effects of this invention are:

[0022] 1. This invention integrates the application of organic and inorganic fertilizers with the synergistic effect of water and fertilizer integration, and combines soil conditioners with microbial fertilizers to form a virtuous cycle of synergistic regulation of soil improvement, quality enhancement and efficiency enhancement, thus achieving a win-win situation for both environmental and economic benefits in young orchards.

[0023] 2. This invention employs a fertilizer combination composed of inorganic fertilizer, organic fertilizer, soil conditioner, and microbial fertilizer. The components work synergistically to significantly improve nutrient utilization efficiency. Specifically, the inorganic fertilizer rapidly replenishes readily available nutrients such as nitrogen, phosphorus, and potassium required for the growth of citrus and watermelons; the organic fertilizer slowly releases nutrients, extending its effective period while increasing soil organic matter content; the soil conditioner specifically improves the soil structure of red soil hilly slopes in the middle and lower reaches of the Yangtze River, and its calcium, magnesium, and silicon content can increase soil pH, alleviate red soil acidification, and reduce the risk of soil nutrient loss; the beneficial microorganisms in the microbial fertilizer activate fixed nutrients in the soil, promoting nutrient absorption by crop roots. Attached Figure Description

[0024] Figure 1 For readily available nutrients in the soil under various technical models;

[0025] Figure 2 This refers to the total nutrient content of the soil under various technical models;

[0026] Figure 3 The soil microbial carbon and nitrogen content under various technical modes;

[0027] Figure 4 Characterization results of the global warming potential (GWP) for producing 1000 kg of watermelon;

[0028] Figure 5 Characterization results of acidification potential (AP) for producing 1000 kg of watermelon;

[0029] Figure 6 Characterization results of eutrophication potential (EP) for producing 1000 kg of watermelon;

[0030] Figure 7 Characterization results of water consumption (WD) for producing 1000 kg of watermelon;

[0031] Figure 8Characterization results of energy consumption (ED) for producing 1000 kg of watermelon;

[0032] Figure 9 The normalized results and environmental impact indices for each technology mode's environmental impact category;

[0033] Figure 10 Average annual yield of watermelon under different technological models;

[0034] Figure 11 The single fruit weight of watermelons under different technical conditions;

[0035] Figure 12 The sugar content at the edge and core of watermelons under different technical conditions. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments: I. Specific Implementation Methods

[0038] A planting method for young orchards in the middle and lower reaches of the Yangtze River that takes into account both environmental protection and income increase, wherein citrus is planted in the young orchard, and the citrus is intercropped with watermelon. During the planting period, compound fertilizer is applied, which includes inorganic fertilizer, organic fertilizer, soil conditioner and microbial fertilizer.

[0039] Compared with the traditional method of applying chemical fertilizers alone, the compound fertilizer solution of the present invention can reduce the amount of chemical fertilizers applied, avoid environmental problems such as groundwater nitrate pollution and surface water eutrophication caused by excessive application of chemicals, and at the same time reduce greenhouse gas emissions and mitigate the potential threat of agricultural production to the ecosystem.

[0040] The inorganic fertilizer contains 15-17% N, 15-17% P2O5, and 15-17% K2O.

[0041] The organic fertilizer contains 18-25 g·kg⁻¹ of total nitrogen, 30-35 g·kg⁻¹ of total phosphorus, and 3-4 g·kg⁻¹ of total potassium.

[0042] The soil conditioner contains K2O ≥ 4.0%, CaO > 30%, MgO ≥ 16.0%, SiO2 ≥ 12.0%, and has a pH value of 11.0-12.0.

[0043] The microbial fertilizer is a granular formulation, wherein the microorganisms include any one or more of Bacillus subtilis, Bacillus mucilaginosus, Bacillus megaterium, Streptomyces, arbuscular mycorrhizal fungi, Trichoderma, and Azotobacter chrysophyte, and the content of microorganisms in the microbial fertilizer has an effective viable count ≥ 500 million CFU / g.

[0044] The acid-resistant strains contain ≥200 million CFU / g, and the survival rate of the strains in an environment of pH 4.0-6.0 is ≥80% to ensure their activity in acidic soil.

[0045] The specific steps for intercropping citrus fruits and watermelons are as follows:

[0046] S1. Plant citrus in the orchard in the first year;

[0047] S2. Watermelon seedlings are raised in March of the following year, and base fertilizer is applied in furrows between the citrus rows. In April, watermelon seedlings are transplanted into furrows with base fertilizer. Topdressing is applied 1-3 weeks after transplanting. The mature watermelons are harvested in July.

[0048] The citrus trees are planted with a spacing of 300-400cm between plants and a row spacing of 400-600cm. The rows of citrus trees are planted in raised beds 85-120cm wide and about 15-20cm high, with drainage ditches 30-40cm deep and 40-50cm wide dug around the edges. The watermelon trees are planted with a row spacing of 140-260cm between them, with deep furrows dug between the fruit trees, and watermelon plants spaced 85-100cm apart.

[0049] The base fertilizer includes 250-300 kg / hm2 of inorganic fertilizer, 30,000-35,000 kg / hm2 of organic fertilizer, 200-250 kg / hm2 of soil conditioner, and 100-125 kg / hm2 of microbial fertilizer. The top dressing includes 820-850 kg / hm2 of inorganic fertilizer.

[0050] II. Field Trials

[0051] 1. Test Plan

[0052] The experiment was conducted in a young citrus orchard in Yitang Town, Lengshuitan District, Yongzhou City, Hunan Province. The orchard was two years old, and the citrus variety was Chun Jian. At the beginning of the experiment, the average tree height was about 1 m, the average trunk diameter was about 2 cm, and the average canopy width was about 0.5 m3. The soil type was deep red soil developed from sandstone. The basic physicochemical properties of the soil before the experiment were as follows: pH 4.49, organic matter 18.99 g / kg, total nitrogen 1.00 g / kg, total potassium 13.65 g / kg, total phosphorus 0.64 g / kg, available nitrogen 74.13 mg / kg, available phosphorus 143.36 mg / kg, and available potassium 16.82 mg / kg.

[0053] The watermelon variety tested was Black Beauty. In this experiment, high-concentration potassium sulfate compound fertilizer (containing 17% N, 17% P2O5, and 17% K2O) was used as inorganic fertilizer, well-rotted pig manure (total nitrogen 22.27 g / kg, total phosphorus 32.71 g / kg, and total potassium 3.67 g / kg) was used as organic fertilizer, Yakefeng soil conditioner was used as soil conditioner, and the experimental fertilizer jointly developed by Yuanhe Biotechnology Co., Ltd. and the Chinese Academy of Agricultural Sciences was used as microbial fertilizer.

[0054] The experiment included five technical models for intercropping watermelons in young citrus orchards: no fertilizer (CK), inorganic fertilizer (NPK), combined application of organic and inorganic fertilizers (NPKM), NPKM combined with drip irrigation (NPKMW), and NPKMW combined with soil conditioner and microbial fertilizer (NPKMWC). The specific management measures for each technical model are shown in Table 1.

[0055] The experiment employed a completely randomized block design, with three replicates for each treatment. Each experimental plot was 64 m² (8 m × 8 m). A 1.5 m buffer zone was established at the edge of the experimental plot to avoid marginal effects. Basal fertilizer for each treatment was applied in 40 cm deep furrows in mid-to-late March each year, and topdressing was applied in batches in April each year. Watermelon seedlings were started in mid-March each year, transplanted in early April, and harvested in batches in July each year. Watermelons were planted using machine-ditched, mulched planting; plastic sheeting was used to separate experimental plots to ensure planting density. Irrigation of young citrus trees and watermelons was achieved using drip irrigation under the mulch film; other field management practices were carried out according to local customs.

[0056] Table 1

[0057]

[0058] 2. Sample collection and measurement methods

[0059] 2.1 Soil Sample Collection and Testing

[0060] After the watermelon harvest in mid-to-late July each year, soil samples were randomly taken and mixed in each plot according to field sampling methods. Since the depth of trench fertilization before watermelon transplanting is 40cm, the sampling depth was 0-40cm. Watermelon vines on the soil surface were removed before sampling. Soil samples for determining soil bulk density were taken in each plot using a 100cm³ ring sampler. Soil samples for determining soil aggregates were collected in undisturbed soil at each sampling point. The remaining soil samples were air-dried after sampling and used to determine soil pH, organic matter, available nutrients (alkaline nitrogen, available phosphorus, available potassium), total nutrients (total nitrogen, total phosphorus, total potassium), and soil heavy metals (chromium Cr, copper Cu, zinc Zn, cadmium Cd, and lead Pb).

[0061] Soil pH was determined using a potentiometric method (soil-to-water ratio 1:5, glass electrode); organic matter content was determined using the potassium dichromate-external heating method; available nitrogen content was determined using the NaOH-alkaline diffusion method; available phosphorus content was determined using the sodium bicarbonate extraction-molybdenum-antimony colorimetric method; available potassium content was determined using the ammonium acetate extraction-flame photometry method; total nitrogen content was determined using the Kjeldahl method; total phosphorus content was determined using the NaOH fusion-molybdenum-antimony colorimetric method; total potassium content was determined using the NaOH fusion-flame photometry method; the number and stability of soil aggregates were determined using the wet sieving method; and soil bulk density was determined using the ring sampler method. Soil heavy metal concentrations were determined using nitric acid-hydrofluoric acid microwave digestion and ICP-MS.

[0062] The formula for calculating the soil aggregate index used in the experiment is as follows:

[0063] The formulas for calculating the weight-mean diameter (MWD, mm) and geometric mean diameter (GMD, mm) are as follows:

[0064]

[0065]

[0066] In the formula: Xi is the average diameter (mm) of aggregates within the i-th particle size range; Wi is the percentage (%) of aggregates in the i-th particle size range; and M is the total mass (g) of the soil sample.

[0067] The formula for calculating the content of aggregates larger than 0.25 mm (R0.25,%) is as follows:

[0068]

[0069] In the formula: Mr < 0.25 is the mass (g) of soil aggregates with a diameter < 0.25 mm; MT is the total mass (g) of soil aggregates.

[0070] 2.2 Collection and Measurement of Watermelon Samples

[0071] Each time watermelons ripen, they are weighed individually in each plot, and the yield per hectare is calculated based on the plot yield. Watermelons are harvested 3 to 4 times during the fruit ripening period from mid-June to mid-July each year. At the time of each harvest, three fully ripe watermelons are randomly selected from each plot for weighing, and the average weight is used to represent the weight of a single watermelon in that plot. A sugar content meter is used to determine the sugar content at the edge and core of the watermelon.

[0072] 2.3 Life Cycle Assessment (LCA)

[0073] Life cycle assessment (LCA) is a widely used method globally to evaluate and analyze the resource consumption and environmental load of a product throughout its entire lifecycle, from raw material acquisition to production and disposal, and to systematically analyze its ecological impacts. The LCA calculations in this study were performed using SimaPro software and the ReCiPe 2016 midpoint (H) method. The evaluation was conducted according to the International Organization for Standardization (ISO) standard 14040 (ISO 14040, 2006).

[0074] Life Cycle Inventory Analysis (LCI) is a stage in life cycle assessment used to compile and quantify the resource consumption and environmental emissions of a product throughout its entire life cycle. This experiment focuses on collecting relevant background and real-world data from the two major stages of watermelon production: agricultural input production and crop cultivation. Based on this, a life cycle inventory of watermelon production under five typical technological models was constructed. Table 2 shows the economic input inventory for each technological model.

[0075] Table 2

[0076]

[0077] Life Cycle Impact Assessment (LCIA) is the stage in the LCA methodology that categorizes and interprets environmental emissions and resource inputs identified in the inventory analysis phase. It includes three steps: characterization, normalization, and weighted assessment. This study selected five environmental impact categories for environmental benefit assessment: energy consumption (ED), water consumption (WD), acidification potential (AP), eutrophication potential (EP), and global warming potential (GWP). The equivalent coefficients of specific emissions for the AP, EP, and GWP categories are shown in Table 3.

[0078] Table 3

[0079]

[0080] (1) Characterization: By using specific models and category indicators, various environmental emissions and resource consumption in the inventory analysis are converted into common units of measurement under the corresponding impact categories. For example, carbon dioxide, methane, and other greenhouse gases can be uniformly converted into carbon dioxide equivalent (CO2-eq) to measure their contribution to global warming potential. The calculation formula is as follows:

[0081] EP(x)i=∑[Q(x)i·EF(x)i]

[0082] In the formula, EP(x)i refers to the potential value of the i-th type of impact factor on the x-th type of environment throughout the entire life cycle, i.e., the characteristic result; Q(x)i refers to the emission of the i-th type of impact factor; EF(x)i refers to the equivalent coefficient of the i-th type of impact factor on the x-th type of environment (Table 3).

[0083] The formula for calculating water resource consumption is as follows:

[0084] WD=Σ[Qw(p)]

[0085] In the formula, WD refers to the total water consumption of a unit of function throughout the entire process, in m3; Qw(p) is the water input of the p-th unit process, in m3. Since the recycling rate of agricultural irrigation water is low, this study assumes a reuse rate of 0.

[0086] The formula for calculating energy consumption is as follows:

[0087] ED = ∑[QE(ip)]

[0088] In the formula, ED represents the total energy consumption of a unit of function throughout the entire process, MJ; QE(ip) is the energy consumption of the i-th substance in the p-th unit process, MJ.

[0089] (2) Normalization: The characteristic results of each environmental impact category are transformed into standardized indicators relative to a reference benchmark (such as per capita emissions) to achieve comparability evaluation between different environmental impact categories. The selection of the normalization benchmark needs to consider factors such as regional economic development level, population, and policies. The benchmark values ​​and weights for environmental impact categories are shown in Table 4. The calculation formula is as follows:

[0090] Rx=Ep(x) / S

[0091] In the formula, Rx is the normalization result of the xth environmental impact category; Ep(x) is the characteristic result of the xth environmental impact category; and S is the per capita environmental impact potential value of Chinese people.

[0092] (3) Weighted Assessment: The impact categories are weighted according to the relative importance of the environmental issues to obtain a comprehensive environmental impact score, namely the Environmental Impact Index (EI). The calculation formula is as follows:

[0093] EI=Σ(Wx*Rx)

[0094] In the formula, EI is the environmental impact index; Wx is the weight of the x-th environmental impact category; and Rx is the normalization result of the x-th environmental impact category.

[0095] Table 4

[0096]

[0097] Life cycle outcome interpretation is a systematic process that uses characteristic calculations to derive the potential values ​​of each environmental impact category, analyzes the contribution of different production stages and different production inputs (such as electricity and fuel oil) to each environmental impact category throughout the entire life cycle system, and ultimately draws conclusions, explains current limitations, proposes improvement suggestions, and reports the results of life cycle interpretation. Sensitivity analysis is a method used to quantitatively assess the influence of input variables on the output results of a mathematical model. Its purpose is to examine the degree of influence of a specific input on the overall environmental outcomes of certain specific environmental impact categories, thereby helping researchers identify environmental hotspots in their research objectives. The sensitivity of this experiment is defined as:

[0098] Smn=(△Om / Om) / (△In / In)

[0099] In the formula, Smn represents the sensitivity of Om to changes in In; Om is the value of the m-th LCA outcome index, and In is the value of the n-th process inventory data. With all other parameters held constant, the sensitivity of each input is assessed by increasing the input parameter In by 20%.

[0100] 2.4 Life Cycle Cost Calculation

[0101] The seasonal selling price of watermelons was determined. Fixed costs were calculated based on the proportion of economic depreciation of assets over the analysis period (3 years), while variable costs were quantified based on the unit cost of consumables (pesticides, fertilizers, etc.). The environmental emission costs per unit yield (1000 kg) of watermelons produced under each technical model in this experiment were calculated using the LCA environmental emission inventory and emission cost coefficients, as shown in Table 5.

[0102] Table 5

[0103]

[0104] In summary, the formula for calculating net income in this experiment is as follows:

[0105] Total revenue = Selling price * Watermelon yield

[0106] Total emission cost = Environmental emission cost coefficient * Environmental emissions per unit output

[0107] LCC = Total Variable Costs + Total Fixed Costs + Total Emissions Costs

[0108] Net income = Total revenue - LCC

[0109] In the formula, total production revenue is RMB / t; sales price is RMB; watermelon yield is t; total emission cost is the gas emission cost during the planting stage of agriculture, RMB / t; environmental emission cost coefficient is RMB / kg; environmental emissions per unit yield is the gas emission of watermelon production during the planting stage per unit yield, kg / t; LCC is the life cycle cost, RMB / t; total variable cost includes fertilizer, agricultural film, pesticides, labor and other field management costs, RMB / t; total fixed cost includes drip irrigation facilities, RMB / t; net profit is RMB / t; and total revenue is RMB / t.

[0110] This study uses the cost-benefit ratio to measure the relationship between the net benefit per unit yield of watermelons and the life cycle cost under five technological models. The calculation formula is as follows:

[0111] Cost-benefit ratio = Net income / Lifetime cost = (Total revenue - LCC) / LCC

[0112] 3. Experimental Results and Analysis

[0113] 3.1 Impacts of different technology models on soil

[0114] 3.1.1 Soil pH and organic matter

[0115] The test results are shown in Table 6. The results show that the NPK, NPKM and NPKMWC models all significantly increased the soil pH. In addition, the three optimized technology models all significantly increased the soil organic matter content, with an increase of 12%-18%.

[0116] Table 6

[0117]

[0118] Note: The values ​​in the table are expressed as mean ± standard deviation for each treatment. Different lowercase letters indicate significant differences between different patterns (P < 0.05).

[0119] 3.1.2 Soil Nutrients and Microbial Biomass (Carbon and Nitrogen)

[0120] Figure 1 For readily available nutrients in the soil under various technical models, Figure 2 This refers to the total nutrient content of the soil under various technical models. Figure 3 The soil microbial carbon and nitrogen content under various technical modes.

[0121] Depend on Figure 1It was found that by the third year of the experiment, compared with the NPK model, the soil available nitrogen content in the NPKMW model decreased significantly by 18.72%. The soil available nitrogen content in the other two optimized technical models did not differ significantly from that in the NPK model. Compared with NPK, the NPKMW and NPKMWC models significantly increased the soil available phosphorus content, increasing by 76.24% and 132.85% respectively, with the NPKMWC model showing the highest content at 60.93 mg / kg.

[0122] Figure 2 The results showed that, compared with the NPK model, only the NPKMWC model significantly increased the total nitrogen, total phosphorus and total potassium contents in the soil, by 10.91%, 28.91% and 9% respectively. The total nutrient contents of the other optimized technical models did not differ significantly from those of the NPK model.

[0123] like Figure 3 As shown, MBC represents microbial biomass carbon, and MBN represents microbial biomass nitrogen. The NPKMWC model had the highest MBC content at 217.41 mg / kg, which was significantly higher than the NPK model by 102.26%. The NPKMW model had the highest MBN content at 46.39 mg / kg, but the MBN content in the NPKMWC model was also significantly higher than that in the NPK model.

[0124] 3.1.3 Main components of soil

[0125] Table 7 shows the principal components, comprehensive scores, and rankings of soil quality under different technical models. As shown in Figure 3, ten indicators were selected for dimensionality reduction: soil pH and nine soil nutrient indicators (organic matter, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus, available potassium, microbial biomass carbon, and microbial biomass nitrogen). Principal component analysis was then performed. Three principal components (F1, F2, and F3) meeting the eigenvalue > 1 standard were extracted, with eigenvalues ​​of 5.139, 1.515, and 1.288, respectively, and variance contribution rates of 51.39%, 15.15%, and 12.89%, respectively, reflecting 79.42% of the original information. Among the five technical models, the NPKMWC model had high scores in both the first principal component (F1) and the second principal component (F2), and the highest comprehensive score of 1.217, indicating the best effect on improving soil quality. In contrast, the CK model had the lowest comprehensive score of -1.020, making it the most unfavorable model for soil quality. The results indicate that intercropping watermelons in young orchards on sloping farmland with a reasonable optimized technical model can effectively improve soil quality, and the NPKMWC model is the technical model with the best effect on improving soil quality.

[0126] Table 7

[0127]

[0128] 3.2 Environmental Impacts of Watermelon Production under Different Technological Modes

[0129] 3.2.1 LCA Characterization Results of Watermelon Production under Different Technical Modes

[0130] LCA characterization results for producing 1000 kg of watermelon using different typical technical methods are as follows: Figure 4-8 As shown, where Figure 4-8 The results are characterized for the global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), water consumption (WD), and energy consumption (ED) of producing 1000 kg of watermelon.

[0131] Among the three optimized technical models, the NPKMWC model produced the lowest GWP (Gross Potential) at 399.64 kg CO2-eq / t, significantly lower than the NPK model by 39.30%. In the AP (Acidity Per Year) impact category, the NPKMWC model produced the lowest life-cycle acidification potential at 1.62 kg SO2-eq / t, significantly lower than the NPK model by 67.76%. In the EP (Environmental Impact Per Year) impact category, the NPKMWC model (0.2152 kg PO4-eq / t) produced the lowest environmental impact potential. Regarding resource consumption, the NPKMWC model consumed the least water resources among the three optimized technical models, at only 3.51 m3; the NPKMWC model also consumed the least energy among the optimized technical models, at 2764.42 MJ / t.

[0132] 3.2.2 Standardization Results and Environmental Impact Index of Different Technical Modes

[0133] Figure 9 The normalized results and environmental impact indices for each technology mode's environmental impact category are derived from... Figure 9 It is evident that, compared to the NPK model, all three optimized technology models significantly reduced the negative environmental impact of producing 1000kg of watermelon, with the NPKMWC model performing the best and having the lowest environmental impact index.

[0134] 3.3 Economic Benefits of Intercropping Watermelon in Young Citrus Orchards under Different Technical Modes

[0135] 3.3.1 Yield and quality of watermelons under different technical modes

[0136] Figure 10 The average annual yield of watermelons under different technological models. Figure 11 The single fruit weight of watermelons under different technical modes, Figure 12 The sugar content at the edge and core of watermelons under different technical conditions.

[0137] Depend on Figure 10It can be seen that, compared with the control (CK), all the technical modes after fertilization significantly increased watermelon yield. Compared with the NPK mode, all three optimized modes significantly increased watermelon yield per unit area, with the NPKMWC mode having the highest average annual yield per unit area over three years, at 42661.42 kg·hm⁻².

[0138] Depend on Figure 11-12 It can be seen that, compared with the control (CK), all other technical modes can significantly increase the weight of individual watermelons, with the NPKMWC technical mode producing the highest weight. Furthermore, the NPKMWC technical mode also resulted in higher levels of core sugar and edge sugar content in the watermelons.

[0139] 3.2.2 Economic Benefits of Watermelons under Different Technological Modes

[0140] The life cycle cost of producing 1000 kg of watermelon was calculated based on the input costs of agricultural materials, irrigation facilities, labor, and environmental emissions. The results are shown in Table 8.

[0141] Among them, the seedlings are priced at 2 yuan per plant, and the replanting rate is calculated at 5%; the cost is calculated as 1 year based on the 5-year service life of the drip irrigation facilities; the CK watermelon is small and the purchase price is 1.2 yuan / kg, while the purchase price of watermelons under other technology models is 1.4 yuan / kg; the greenhouse gas emission reduction revenue is calculated based on the greenhouse gas emission reduction of watermelon production life cycle under the three optimized technology models, and the carbon trading price is 91.8 yuan / t. The values ​​in the table are expressed as the average value ± standard deviation of each treatment.

[0142] Table 8 shows that the NPK model has the highest lifecycle cost, at RMB 1074.10 / t. Compared with NPK, both the NPKMW and NPKMWC models significantly reduce LCC, and both have higher overall net benefits. Among them, the NPKMW model has slightly better economic benefits than the NPKMWC model.

[0143] This invention uses the life cycle assessment (LCA) method to conduct qualitative and quantitative analysis of resource consumption and environmental emissions in each stage of watermelon production under different typical technical models. The functional unit is set as the production of 1000 kg of watermelon.

[0144] The LCA system boundary begins with the extraction of raw materials required for agricultural input production and ends with the production of watermelons from farmland (excluding subsequent watermelon sales, vine disposal, etc.), and is divided into the agricultural input production stage and the cropping stage. The agricultural input production stage refers to the process of extracting, producing, and transporting raw materials for various agricultural inputs (mainly including fertilizers, organic fertilizers, pesticides, agricultural films, and resources such as fuel oil and electricity) during watermelon production. The cropping stage mainly includes the environmental impacts of fertilizers and organic fertilizers, such as greenhouse gases, nutrient leaching, and ammonia volatilization, released into the air, water, and soil after being applied to farmland, as well as the impacts of diesel combustion during the use of agricultural machinery.

[0145] Life cycle cost (LCC) calculation includes all costs related to a system, product, or structure throughout the life cycle of the investigated target, including fixed costs (such as labor), variable costs (such as fertilizers, pesticides, seeds, and agricultural films), and environmental emissions costs. The functional unit of LCC is the annual production of 1000 kg of watermelons in an orchard. Since the purchase price of agricultural inputs already includes their production costs, the system boundary of LCC involves the direct costs of materials such as fertilizers, pesticides, and diesel fuel paid during the watermelon field production stage, as well as the environmental emissions costs during that stage. LCC is an economic indicator used to calculate different technological models. First, the seasonal selling price of the watermelons should be determined. Fixed costs are calculated as a percentage of the economic depreciation of assets over the analysis period (3 years), and variable costs are quantified based on the unit cost of consumables (pesticides, fertilizers, etc.).

[0146] The environmental emission costs per unit yield (1000 kg) of watermelon under various technical modes in this study were calculated using the LCA environmental emission inventory and emission cost coefficients, with the cost coefficients converted to RMB.

[0147] Table 8

[0148]

[0149] 4. Conclusion

[0150] Considering soil improvement, environmental impact, and crop economics, the planting method (NPKMWC model) in this invention, through the synergistic application of organic and inorganic fertilizers and integrated water and fertilizer management, and the application of soil conditioners and microbial fertilizers, forms a virtuous cycle of "soil improvement-quality enhancement-efficiency enhancement," achieving a win-win situation for both environmental and economic benefits in young orchards.

Claims

1. A planting method for young orchards in the middle and lower reaches of the Yangtze River that balances environmental protection and income generation, wherein the young orchards are planted with citrus, characterized in that... The intercropping of citrus and watermelon involves applying compound fertilizer during the planting period. The compound fertilizer includes inorganic fertilizer, organic fertilizer, soil conditioner, and microbial fertilizer.

2. The planting method for young orchards in the middle and lower reaches of the Yangtze River that balances environmental protection and income generation, as described in claim 1, is characterized in that... The inorganic fertilizer contains 15-17% N, 15-17% P2O5, and 15-17% K2O. The organic fertilizer contains 18-25 g·kg⁻¹ of total nitrogen, 30-35 g·kg⁻¹ of total phosphorus, and 3-4 g·kg⁻¹ of total potassium. The soil conditioner contains K2O ≥ 4.0%, CaO > 30%, MgO ≥ 16.0%, SiO2 ≥ 12.0%, and has a pH value of 11.0-12.

0. The microbial fertilizer is a granular formulation, wherein the microorganisms include any one or more of Bacillus subtilis, Bacillus mucilaginosus, Bacillus megaterium, Streptomyces, arbuscular mycorrhizal fungi, Trichoderma, and Azotobacter chrysophyte, and the content of microorganisms in the microbial fertilizer has an effective viable count ≥ 500 million CFU / g.

3. A planting method for young orchards in the middle and lower reaches of the Yangtze River that balances environmental protection and income generation, as described in claim 1, is characterized in that... The specific steps for intercropping citrus fruits and watermelons are as follows: S1. Plant citrus in the orchard in the first year; S2. Watermelon seedlings are raised in March of the following year, and base fertilizer is applied in furrows between the citrus rows. In April, watermelon seedlings are transplanted into furrows with base fertilizer. Topdressing is applied 1-3 weeks after transplanting. The mature watermelons are harvested in July.

4. A planting method for young orchards in the middle and lower reaches of the Yangtze River that balances environmental protection and income generation, as described in claim 3, is characterized in that... The spacing between citrus trees is 300-400cm, the spacing between watermelon trees is 85-100cm, and the row spacing between watermelons and citrus trees is 140-260cm.

5. A planting method for young orchards in the middle and lower reaches of the Yangtze River that balances environmental protection and income generation, as described in claim 3, is characterized in that... The base fertilizer includes 250-300 kg / hm2 of inorganic fertilizer, 30,000-35,000 kg / hm2 of organic fertilizer, 200-250 kg / hm2 of soil conditioner, and 100-125 kg / hm2 of microbial fertilizer. The top dressing includes 820-850 kg / hm2 of inorganic fertilizer.

6. A planting method for young orchards in the middle and lower reaches of the Yangtze River that balances environmental protection and income generation, as described in claim 1, is characterized in that... The cost-benefit ratio of the watermelon is calculated using the following formula: LCC = Environmental Emissions Cost Coefficient * Environmental Emissions Per Unit Output + Total Variable Costs + Total Fixed Costs Cost-benefit ratio = (Total revenue - LCC) / LCC In the formula, LCC is the life cycle cost (yuan / t); environmental emission cost coefficient (yuan / kg); environmental emissions per unit output (kg / t); total revenue (yuan / t); total variable cost (yuan / t); and total fixed cost (yuan / t).

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