Application of dragon fruit branch waste converted from hermetia illucens and chicken manure in preparation of organic fertilizer for dragon fruit planting

Abstract

According to the invention, the black soldier flies are converted into pitaya branch waste and chicken manure to prepare an organic fertilizer through aerobic fermentation, the organic fertilizer is applied to a pitaya field to verify the fertilization effect, and the pitaya is mature after about 40 days. Experimental results show that compared with a control group (applying a water-soluble fertilizer), the insect-sand organic fertilizer can improve the weight of a single pitaya fruit, and the number of fruits of 400 g or above is obviously higher than that of the control group. And the content of soluble solids in the center and the edge of the pitaya is remarkably increased by the medium-dose fertilization group. The result shows that the worm sand organic fertilizer has the potential of improving the fruit quality and yield, and a feasible way is provided for resource utilization of pitaya branch waste.

Description

Technical Field

[0001] This invention relates to the field of environmental protection and resource utilization, specifically to the application of black soldier fly larvae in converting dragon fruit branch waste and chicken manure into organic fertilizer for dragon fruit cultivation. Background Technology

[0002] Dragon fruit, as an important agricultural economic crop, is widely cultivated globally. However, the large amount of branch waste generated during dragon fruit cultivation and the manure from livestock farming have become significant issues in agricultural waste management. Improper disposal of these wastes not only leads to low resource utilization but also risks environmental pollution and ecological damage. Therefore, exploring efficient and environmentally friendly methods for treating dragon fruit branches and livestock manure has become a key issue in promoting sustainable agricultural development.

[0003] The residue produced by black soldier fly larvae after biotransformation of organic waste accounts for approximately 30-50% of the initial weight of the feeding substrate. This residue is a valuable byproduct. Because it shares similar characteristics with immature compost, recent research has focused on using black soldier fly larvae residue as a bio-organic fertilizer. These fertilizers can be used in agriculture to improve soil structure, enhance soil fertility, and promote plant growth, reducing the use of chemical fertilizers, further realizing resource recycling, and promoting sustainable agricultural development. The process of black soldier fly larvae transforming organic waste achieves a closed-loop cycle of "waste-resource-product," conforming to the basic principles of a circular economy. By converting organic waste into high-value insect bodies and residue, not only is resource waste reduced, but a sustainable source of feed and fertilizer is also provided for agricultural production, promoting the development of a circular economy in agriculture. Summary of the Invention

[0004] This invention aims to promote the resource utilization of dragon fruit branch waste and chicken manure treated by black soldier flies, and further prepare the insect excrement into organic fertilizer for use, thereby achieving resource recycling and promoting sustainable agricultural development.

[0005] To achieve the above objectives, the present invention adopts the following technical measures: This invention provides the application of black soldier fly larvae converting dragon fruit branch waste and chicken manure in the preparation of organic fertilizer for dragon fruit cultivation.

[0006] Furthermore, the aforementioned applications include the following steps: S1: Add rice bran to the converted black soldier fly sand to adjust the moisture content and carbon-nitrogen ratio; S2: The adjusted insect sand is piled into a cone shape for aerobic composting, and the dynamic changes of the physicochemical composition of the pile are monitored during the composting process. S3: Apply the prepared insect-sand organic fertilizer to the dragon fruit field at different dosages to verify its fertilizer effect; As a further improvement to the scheme, in steps S1 to S3, the insect sand used in the experiment was obtained by black soldier flies converting dragon fruit branch waste and chicken manure, and the ratio of dragon fruit branch waste and chicken manure in the conversion process was 3:2.

[0007] Technical effect Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention is based on the treatment of dragon fruit branch waste and chicken manure by black soldier flies to produce organic fertilizer. On the one hand, it realizes the utilization of waste, and on the other hand, the organic fertilizer produced can promote the quality of dragon fruit planting, which has dual economic benefits. Attached Figure Description

[0008] Figure 1 This is a flowchart of the experimental process of the present invention.

[0009] Figure 2-1 and Figure 2-2 The dynamics of physicochemical parameters during the secondary composting process of black soldier fly sand were analyzed. Among them, (a) temperature; (b) moisture content; (c) pH value; (d) organic matter; (e) total phosphorus; (f) total potassium; (g) total nitrogen; (h) ammonium nitrogen; (i) nitrate nitrogen; (j) carbon-to-nitrogen ratio; different lowercase letters indicate significant differences (P < 0.05).

[0010] Figure 3 The dynamic changes in enzyme activity during the composting of insect sand are shown; (a) urease activity; (b) peroxidase activity; error bar: standard error of the average of three replicates (n = 3).

[0011] Figure 4 The effect of different treatments on the weight of a single fruit. Detailed Implementation

[0012] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention. Unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods. Unless otherwise specified, the materials and reagents used in the embodiments of this invention are commercially available.

[0013] Example 1: Preparation of Black Soldier Fly Sand Organic Fertilizer To further verify the promoting effect of compound microbial agents on the transformation of dragon fruit branches by black soldier fly larvae on a small-scale basis, we considered conducting pilot-scale amplification of black soldier fly transformation of dragon fruit branches and chicken manure. For large-scale black soldier fly transformation, we used a canvas tank with dimensions of 3 m × 2 m × 0.5 m (length × width × height) for the experiment. The total mixture of dragon fruit branches and chicken manure was 150 kg, the insect-to-material ratio was 1:1, the amount of microbial agent added was 150 mL, and the chicken manure accumulation thickness was 5 cm-10 cm. The group with microbial agent addition was named the microbial agent addition group (BA), and the group without microbial agent addition was named (NBA). Each treatment was performed in triplicate, and the transformation time was 8 days.

[0014] After conversion, the aggregation characteristics of black soldier fly larvae were utilized to separate them from the residue, obtaining mature larvae and frass. To further decompose the frass and obtain high-value organic fertilizer, the black soldier fly frass prepared using the above-mentioned microbial agent addition group (BA) treatment method was piled into three heaps for secondary composting in a rain-sheltered and ventilated factory building, named the microbial agent composting treatment group (BAC). The heaps were turned and the organic fertilizer was harvested according to the material temperature. Samples were stored at -20℃ for physicochemical composition analysis, and the remaining compost samples were used for dragon fruit planting and returning to the field experiment.

[0015] 1.1 Dynamic monitoring of physicochemical parameters during composting: Temperature: Before stirring or turning the compost every day, use a 60 cm electronic thermometer to measure the temperature 25 cm below the surface of the compost, and take the average value of the three temperature measurements.

[0016] Moisture content: Weigh 15 g of each stage of material every 4 days, divide it into three portions, dry it at 105 ℃ to constant weight, and determine the moisture content of the material.

[0017] pH value: Weigh 5 g of each stage of material every 4 days, add it to 45 mL of sterile distilled water, shake and soak for 30 min, centrifuge at 4000 r / min for 15 min, and measure the pH value of the supernatant with a pH meter.

[0018] Nutritional composition: Materials were collected every 4 days at each stage, and the contents of total organic matter, total nitrogen, total phosphorus (as P2O5), and total potassium (as K2O) were tested according to the method in national standard NY525-2012. ω (N) + ω (P2O5) + ω (K2O) is used as the total nutrient content. ω (Total organic matter) / 1.724 is used as the total carbon. ω (C) Content; The content of humus composition was determined according to the method of national standard NY / T 1867-2010; the contents of ammonium nitrogen and nitrate nitrogen were determined by Solarbio soil ammonium nitrogen and nitrate nitrogen detection kits, respectively.

[0019] Results analysis: After the pilot-scale conversion was completed, the converted black soldier fly larvae sand was further composted to prepare black soldier fly organic fertilizer. During the composting process, the material temperature rose from an initial 29.57℃ to a high of 51.96℃ on day 8, and reached a maximum composting temperature of 66.10℃ on day 12. The entire high-temperature stage (>50℃) was maintained for about 14 days. After 24 days of composting, the temperature of the compost pile dropped to below 40℃. Figure 2-1 a). The moisture content of the compost pile decreased slowly in the first 6 days, from 64.72% to 61.32%. This was due to the low microbial activity and slow reproduction rate in the early stages of composting, while the temperature of the pile was gradually rising. However, by day 8, the temperature of the pile reached a high-temperature stage, and the moisture content began to decrease rapidly. By day 26, the moisture content of the pile had decreased to about 30% (Figure 2b-1). The pH first decreased and then increased from day 0 to day 8, and then remained stable between 9.0 and 9.5 until the end of composting. This result differs from the previous observation that the pH after black soldier fly chicken manure composting was between 8.0 and 8.5, and the national standard for organic fertilizer pH being between 5.5 and 8.5. This may be because the initial C / N ratio of the compost substrate was relatively low, and the large release of ammonia during decomposition led to an increase in pH. Figure 2-1 c).

[0020] observe Figure 2-1 As shown in d and j, the changes in organic matter content and carbon-nitrogen ratio during composting exhibit similar trends: an initial decrease followed by an increase, then a further decrease before stabilizing. The organic matter content decreased from an initial 754.4 g / kg to 524.6 g / kg after 26 days of composting, while the carbon-nitrogen ratio eventually stabilized at around 17.2. At the beginning of composting, microorganisms rapidly decompose easily degradable carbon-containing organic matter, releasing carbon dioxide and reducing carbon content, leading to a decrease in both organic matter content and carbon-nitrogen ratio. As carbon-containing organic matter decreases, the accumulation of recalcitrant substances (such as lignin) and the enhanced mineralization of nitrogen increase the relative levels of organic matter content and carbon-nitrogen ratio. When easily degradable substances are exhausted and the decomposition of recalcitrant substances slows down, the organic matter content and carbon-nitrogen ratio tend to stabilize. Throughout the composting process, the total phosphorus and total potassium contents generally show an increasing trend, reaching 0.6525% and 3.82% respectively after composting. Figure 2-1(e and f). This may be due to the concentration effect. During composting, the evaporation of water and the decomposition of organic matter lead to a decrease in the total volume of the raw materials, resulting in the concentration of phosphorus and potassium. Therefore, although the absolute mass may not increase significantly, the relative concentration will increase, leading to an upward trend in the measured total phosphorus and total potassium content. The total nitrogen content decreased and then increased during composting, stabilizing at around 1.778% after composting. The ammonium nitrogen content fluctuated due to various factors such as organic matter decomposition, microbial activity, temperature changes, nitrification, and ammonia volatilization during composting. The nitrate nitrogen content generally increased, and may have decreased slightly in the later stages due to denitrification. At the end of composting, the nitrate nitrogen and ammonium nitrogen contents were 262.23 µg / g and 84.22 µg / g, respectively. Figure 2-2 g, h, and i).

[0021] 1.2 Determination of enzyme activity indicators during composting: Urease: Urease promotes nitrogen conversion and regulates pH value in composting by decomposing urea, thus affecting composting efficiency and nitrogen retention. By monitoring urease content, the composting process can be optimized, and composting quality and efficiency can be improved.

[0022] Peroxidase: Peroxidase participates in the oxidative decomposition of organic matter. During composting, the activity of peroxidase is related to the activity of microorganisms and can reflect the intensity of microbial activity to a certain extent.

[0023] Urease and peroxidase contents were determined using Solarbio soil urease (S-UE) and peroxidase (S-POD) detection kits, respectively.

[0024] Results analysis: Urease is closely related to nitrogen metabolism during composting. In the early stages of composting, urease activity decreases from 477.92 U / g to 164.42 U / g due to factors such as rapid temperature increases and the production of acidic substances from organic matter decomposition. As composting progresses to the middle stage, mesophilic bacteria are gradually replaced by thermophilic bacteria. These microorganisms can produce urease, and the accumulation of urea from the decomposition of nitrogenous organic matter further induces the microorganisms to produce even more urease, increasing enzyme activity to 635.95 U / g. In the later stages of composting, as urea and other substrates in the compost pile are gradually depleted, microbial activity weakens, and enzyme activity decreases again.

[0025] Peroxidases participate in the degradation of complex organic matter by catalyzing the reaction of hydrogen peroxide with organic substrates. Their activity is influenced by microbial abundance and organic matter content. During composting, peroxidase activity generally shows an initial increase followed by a decrease, eventually stabilizing at 106.50 U / g. This may be because, with increasing temperature, thermophilic bacteria replace mesophilic bacteria as the dominant bacteria, enhancing the biochemical and metabolic activity of the compost. In the later stages of composting, recalcitrant organic matter such as lignin gradually decomposes, the compost stabilizes, and the reduced substrate leads to decreased microbial activity, reduced reactive oxygen species and free radicals, and a decreased demand for peroxidases. Figure 3 ).

[0026] Example 2: The impact of applying black soldier fly larvae sand organic fertilizer to the field for dragon fruit cultivation on dragon fruit products and quality. Black soldier fly larvae sand-based organic fertilizer was prepared in a pilot-scale test, with four groups containing 0.25, 0.5, and 1 kg / m³ of black soldier fly larvae sand-based organic fertilizer. 2 Apply water-soluble fertilizer alone (CK). After the dragon fruit matures, analyze the growth, yield, and quality of the dragon fruit to evaluate whether the organic fertilizer made from the waste of black soldier flies—chicken manure—is suitable for dragon fruit cultivation and determine the appropriate application rate.

[0027] Results Analysis Figure 4 This study statistically analyzed the weight of individual dragon fruit after approximately 40 days of ripening, comparing different fertilization doses and the control group (CK) treated with water-soluble fertilizer alone. The results showed that, compared to the CK, the number of dragon fruits weighing over 400g harvested from the three doses of insect-sand organic fertilizer was significantly higher than the control group, indicating that black soldier fly insect-sand organic fertilizer can significantly increase the weight of individual dragon fruit. Table 1 shows that insect-sand organic fertilizer significantly increased the soluble solids content in the center and periphery of dragon fruit, with the medium-dose fertilization group showing the best effect. The soluble solids content in the center and periphery of the dragon fruit in this group was 16.77% and 8.35%, respectively, representing increases of 7.57% and 11.63% compared to the control. Soluble solids are one of the core factors affecting fruit quality, directly determining the fruit's taste, flavor, nutritional value, storability, and processing characteristics. This result indicates that black soldier fly insect-sand has the potential to become a high-quality organic fertilizer, promoting fruit growth and improving product quality under appropriate fertilization amounts.

[0028] Table 1 Effects of different treatments on fruit internal quality Note: Different lowercase letters indicate significant differences (p<0.05).

[0029] Note: Different lowercase letters indicate significant differences (p<0.05)。

Claims

1. Application of black soldier fly larvae in converting dragon fruit branch waste and chicken manure into organic fertilizer for dragon fruit cultivation.

2. The application according to claim 1, characterized in that, The mass ratio of dragon fruit branch waste to chicken manure is 3:

2.

3. The application according to claim 1, characterized in that, The mass ratio of black soldier fly larvae and dragon fruit branch waste is 1:0.5~2.

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