Corn stalks rotten organic fertilizer and its preparation method and application

Abstract

The application provides corn straw matured organic fertilizer and a preparation method and application thereof, and belongs to the technical field of organic fertilizer.The application uses cow dung and straw as raw materials to prepare biogas slurry through anaerobic fermentation, pretreats corn straw with the prepared biogas slurry, and mixes with EM microbial agent to carry out compost fermentation to prepare matured organic fertilizer.The method can effectively recycle agricultural and forestry wastes such as cow dung and straw, the prepared organic fertilizer can improve the problem of a large decrease of organic matter in the northeast black soil, improves the total organic carbon content, total nitrogen content and crop yield in the soil, and effectively reduces the emission of greenhouse gases when the organic fertilizer is applied, thereby providing technical support for green agricultural production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic fertilizer, more particularly to a corn straw composted organic fertilizer and a preparation method and application thereof. BACKGROUND

[0002] As the largest corn production area in China, Northeast China can produce about 170 million tons of corn straw every year, accounting for 48% of the total corn straw resources in China and 1 / 3 of all straw resources. At the same time, with the increasing requirements of economic development, the content of organic matter in the black soil of Northeast China has decreased significantly due to overuse for a long time. The protection of the black soil is becoming increasingly severe. The use of straw returning to field can greatly utilize straw resources and improve soil quality and environmental problems. The existing technology mainly uses direct straw returning to field or straw returning to field after composting. However, direct straw returning to field can cause the growth of pests and diseases, which is harmful to seed germination and growth, and the utilization rate of straw is low. The existing straw composting returning to field has low fertilizer efficiency and low utilization rate.

[0003] The livestock and poultry breeding industry is gradually changing from the traditional free-range mode to intensive feeding. The breeding scale has increased significantly compared with the traditional mode, and a large amount of livestock and poultry manure is produced and concentrated. However, the livestock and poultry manure has not been effectively utilized, and the pollution caused by livestock and poultry breeding has become a major source of agricultural pollution. Anaerobic digestion process is an efficient way to treat poultry manure, and the produced biogas is a clean energy with high comprehensive utilization value. The treatment and disposal of biogas slurry is one of the key problems to be solved in biogas engineering.

[0004] Therefore, it is a technical problem to be solved by those skilled in the art to provide an organic fertilizer with high fertilizer efficiency prepared by using biogas slurry and EM microbial agent to promote the rapid composting of corn straw. SUMMARY

[0005] Therefore, the present application provides a corn straw composted organic fertilizer and a preparation method and application thereof. The agricultural and forestry wastes such as cow dung and straw are resourceized and reused, and the prepared organic fertilizer can effectively improve the problem of the significant decrease of organic matter in the black soil of Northeast China, increase the total organic carbon and total nitrogen content in the soil, and improve the crop yield. The use of the organic fertilizer can effectively reduce the emission of greenhouse gases, and provide technical support for green agricultural production.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] A preparation method of a corn straw composted organic fertilizer, comprising the following steps:

[0008] (1) Collecting corn straw, drying, and crushing, and reserving for use;

[0009] (2) Collecting cow dung, removing impurities, and preparing for use;

[0010] (3) Mixing the cow dung, crushed corn stalks, and biogas slurry to prepare anaerobic fermentation materials, carrying out anaerobic fermentation, extracting biogas slurry after gas production;

[0011] (4) Preparing compost materials by pretreating the corn stalks with the extracted biogas slurry and adding EM bacterial agent, carrying out compost fermentation, and obtaining corn stalks mature organic fertilizer.

[0012] Preferably, the moisture content of the air-dried corn stalks in step (1) is 8-11%, and the particle size after crushing is 1mm-3.5cm.

[0013] Preferably, the moisture content of the cow dung in step (2) is 60-63%.

[0014] Preferably, the carbon-nitrogen ratio of the anaerobic fermentation materials in step (3) is 28-30:1, and the carbon-nitrogen ratio is balanced by using urea; the total solid content in the anaerobic fermentation materials is 7-9%; the addition amount of the biogas slurry accounts for 8%-12% of the total volume of the fermentation materials; and the temperature of the anaerobic fermentation is 33-38℃.

[0015] Further preferably, the carbon-nitrogen ratio of the anaerobic fermentation materials is 28:1, and the total solid content is 8%; and the temperature of the anaerobic fermentation is 35℃.

[0016] Preferably, the pretreatment process of the biogas slurry on the corn stalks in step (4) is as follows: mixing the biogas slurry with the corn stalks, the volume of the biogas slurry being 28-32% of the volume of the corn stalks, and placing the mixture in a sealed state for 7d after fully mixing.

[0017] Further preferably, the volume of the biogas slurry is 30% of the volume of the corn stalks.

[0018] Preferably, the addition amount of the EM bacterial agent in step (4) is 6mL / kg of corn stalks; the moisture content of the compost materials is 60-65%, and the carbon-nitrogen ratio is 25-30:1; the compost fermentation time is 22-26d, the initial temperature of the compost fermentation is 25℃, and the initial pH value is 6.5-7.0.

[0019] Preferably, ventilation is carried out during the compost fermentation in step (4), and the center temperature of the pile is maintained at 42-53℃.

[0020] Preferably, the ventilation rate is 0.4-0.5L / min, and the ventilation time is 10-15min / h.

[0021] Still another purpose of the present application is to provide corn stalks mature organic fertilizer prepared by the above method.

[0022] Still another object of the present application is to provide the use of the corn stalk composted organic fertilizer in soil improvement, crop planting and / or greenhouse gas emission reduction.

[0023] Through the above technical solution, compared with the prior art, the present application has the following beneficial effects:

[0024] The present application uses cow dung and straw as raw materials to prepare biogas slurry through anaerobic fermentation, pretreats corn stalks with the prepared biogas slurry, and mixes with EM microbial agent for composting fermentation to prepare composted organic fertilizer. The agricultural and forestry wastes such as cow dung and straw are resourcefully utilized. The prepared organic fertilizer can effectively improve the problem of large decrease of organic matter in the northeast black soil, increase the total organic carbon and total nitrogen content in the soil, and increase crop yield. In addition, the application of the organic fertilizer can effectively reduce the emission of greenhouse gases, and provides technical support for green agricultural production. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0026] Figure 1 C / N change of straw pretreated by different proportions of biogas slurry;

[0027] Figure 2 Temperature change during composting process under different treatments;

[0028] Figure 3 Change of moisture content during composting process under different treatments;

[0029] Figure 4 Change of pH during composting process under different treatments;

[0030] Figure 5 Change of electrical conductivity during composting process under different treatments;

[0031] Figure 6 Change of total organic carbon during composting process under different treatments;

[0032] Figure 7 Change of total nitrogen during composting process under different treatments;

[0033] Figure 8 Change of C / N ratio during composting process under different treatments;

[0034] Figure 9 Total organic carbon (TOC) in soil under different field treatments;

[0035] Figure 10 Total nitrogen (TN) in soil under different field treatments;

[0036] Figure 11 TOC and TN in corn under different field treatments;

[0037] Figure 12 CO2 emission in soil under different field treatments;

[0038] Figure 13 CH4 emission in soil under different field treatments;

[0039] Figure 14 N2O emission in soil under different field treatments. DETAILED DESCRIPTION

[0040] The technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0041] Embodiment 1

[0042] A corn straw rapid composting method for preparing organic fertilizer comprises the following steps:

[0043] (1) drying corn straw to a moisture content of 8-11%, a carbon-nitrogen ratio of 67-69:1, and then crushing to 1mm-3.5cm for standby;

[0044] (2) collecting cow dung, removing impurities in the cow dung, the cow dung having a moisture content of 60-63% and a carbon-nitrogen ratio of 40-43:1 for standby;

[0045] (3) mixing the cow dung and the crushed corn straw uniformly and placing them in a fermentation container, controlling the carbon-nitrogen ratio of the cow dung and the straw anaerobic co-fermentation to be 28, the total solid content to be 8%, adding 10% of the total volume of the fermentation material of biogas slurry to introduce methanogenic bacteria, and performing anaerobic fermentation in a 35℃ water bath, and extracting biogas slurry after gas production.

[0046] (4) The extracted biogas slurry was used to treat the corn straw. After treatment, 6 mL of microbial agent was added to each kilogram of corn straw and mixed with EM microbial agent to prepare compost material. The moisture content of the compost material was adjusted to 60% to 65%, and the carbon-nitrogen ratio was 25-30:1. Composting was carried out. The initial fermentation temperature was 25℃ and the fermentation pH was 6.5-7.0. During the composting fermentation process, an air pump was used to ventilate the compost. The ventilation rate of the air pump was 0.4 L / min, and ventilation was carried out for 15 minutes per hour to ensure that the center temperature of the compost was 42-53℃ during the composting process. Fermentation was carried out for 22-26 days to prepare corn straw decomposed organic fertilizer.

[0047] The experiment was conducted according to Table 1 based on Example 1 described above.

[0048] Table 1 Experimental Design for Rapid Straw Composting

[0049]

[0050]

[0051] Samples were taken on days 1, 3, 5, 8, 13, 16, and 26 of the composting process. Samples were taken from the top, middle, and bottom layers of the compost pile, using the quartering method, and then mixed thoroughly. The effects of the amount of biogas slurry added on the C / N ratio of straw, temperature, moisture content, pH, conductivity, TOC, TN, and the C / N ratio after composting startup were determined. The experimental results are shown below. Figures 1-8 And as shown in Table 2.

[0052] Results analysis:

[0053] like Figure 1 As shown, the C / N ratio of pretreated corn stalks decreased, and this decrease increased with the increase of the biogas slurry addition ratio. The C / N ratios decreased by 59.59% and 60.50% when the biogas slurry addition ratio was 30% and 40% of the total straw amount, respectively, indicating that 30% and 40% biogas slurry pretreatment of corn stalks had the best effect. With the increase of the biogas slurry addition ratio, the number of microorganisms introduced into the corn stalk treatment system increased. These microorganisms can efficiently degrade and utilize plant fibers such as cellulose, playing a key role in the composting and degradation process of corn stalks.

[0054] Figures 2-5 The changes in temperature, moisture content, pH, and conductivity during the composting process.

[0055] Temperature: After the start of composting, the temperature of the four groups of composting rose rapidly, and the maximum temperature of S2 and S3 experimental groups was higher than that of the other three groups, reaching 52.6℃ and 49.3℃ on D13 and D14 days, respectively. The high temperature of S2 experimental group lasted for a short time, and the maximum temperature of S4 experimental group was 46.3℃. The maximum temperature of the compost was S3(52.6℃)>S2(49.3℃)>S4(46.3℃)>S1(42.3℃)>Z(35.6℃). The addition of biogas slurry to the corn straw composting system provided more organic matter, so the temperature during the high temperature period was the highest. However, the maximum temperature of S4 experimental group was lower than that of S2 experimental group, which may be due to the excessive introduction of corn straw degradation related microorganisms, resulting in a certain degree of decomposition of organic matter and a decrease in the overall content.

[0056] Moisture content: During the high temperature period of composting (D5-D7), the moisture content of the five groups of compost showed a more obvious fluctuation. During the temperature decline process, the moisture content of the five groups of compost generally showed a trend of first increasing and then decreasing, but the overall moisture content value decreased.

[0057] pH: The pH of the five groups of compost ranged from 5.92 to 8.46, which was suitable for the survival of microorganisms. During the initial stage of composting (D3-D13), the pH of the compost mixture increased rapidly, with the highest value reaching 8.46 (CK). Subsequently, the pH of the five groups of compost decreased slowly. The final pH of the four groups of compost was S1(7.43)>S4(7.09)>CK(7.08)>S2(7.06)>S3(7.03), which was neutral to alkaline, and could slow down soil acidification.

[0058] Conductivity (EC): The initial EC of each group of compost was similar, except that the minimum EC of S4 experimental group appeared on D8, and that of the other four groups appeared on D3. Subsequently, it rose again and then stabilized. The EC of CK was basically higher than that of the other experimental groups during the composting process. The change in EC of the biogas slurry pretreated corn straw during the composting process was inhibited. The final EC of the four groups of compost was less than 9000 μm / s, which could be considered as having no growth inhibition effect on plants.

[0059] Figures 6-7 For the change of total organic carbon and total nitrogen during composting, the TOC of the five groups of compost fluctuated in the early high temperature period (D1-D5), and generally showed a trend of first decreasing and then increasing in the high temperature period (D9-D17). The TOC reduction rate of the five groups of compost was S3(7.14%)>S1(7.05%)>S4(5.25%)>CK(3.32%)>S2(1.92%), among which the 30% biogas slurry addition had the highest organic carbon degradation rate, indicating that the microbial activity in the system was relatively strong.

[0060] TN: The TN content of the five compost groups fluctuated significantly during the high-temperature composting period, except for the CK and S4 experimental groups, which generally showed an upward trend. The final increase in TN content for the five compost groups was: S3 (5.33 g / kg) > S4 (2.62 g / kg) > CK (1.58 g / kg) > S1 (0.91 g / kg) > S2 (0.63 g / kg). TN content increased with the addition of biogas slurry and the degradation of lignocellulose.

[0061] C / N: By Figure 8 It can be seen that after composting started, the C / N ratio of the five compost groups showed an overall decreasing trend. At the end of composting, the C / N ratios of each group were S2 (29.47) > S1 (28.40) > S4 (24.60) > CK (22.74) > S3 (21.63). The S3 experimental group had the lowest C / N ratio, and therefore had the best composting effect.

[0062] Example 3

[0063] The straw after composting was returned to the field, and the experimental groups are shown in Table 2.

[0064] Table 2 Field Experiment Design for Straw Composting and Returning to the Field

[0065]

[0066] Note: Conventional fertilization refers to the replacement of urea with urea in the nitrogen provided by straw compost in the base fertilizer.

[0067] Results analysis:

[0068] Figures 9-10 This study investigated the changes in soil SOC and TN content under the following conditions in 2023: addition of corn stalks, replacement of chemical fertilizers with composted corn stalks, and conventional fertilization in black soil. The SOC content increased under the corn stalk composting treatment, with a 15.14% increase, but the effect was not as significant as conventional fertilization. The TN content in the soil of all three experimental groups showed an upward trend after the start of the experiment. Conventional fertilization, due to the direct addition of chemical fertilizers, showed a more pronounced upward trend in soil TN content in the early stages, but there was no significant difference compared to the other treatment groups at each stage (P<0.05). After the experiment, the TN content in the corn stalk composting treatment increased to a certain extent, with an increase of 16.67%.

[0069] Table 3 is the change of soil microbial diversity index under different field treatments. The comprehensive analysis of soil bacterial Alpha diversity under two years of continuous cultivation in 2022-2023 shows that the Chao1 index of Z1 and Z2 experimental groups increases by 52.82% and 41.53% respectively, and the Shannon index of Z1 and Z2 experimental groups increases by 10.98% and 10.40% respectively. In summary, the soil microbial community diversity under straw composting and returning to field increases the most, straw composting accelerates straw decomposition, promotes more straw to be degraded into small molecular organic matter, and increases the energy and nutrients required for soil organisms in the early growth stage of spring maize.

[0070] Table 3 Influence of different treatments on soil microbial diversity

[0071]

[0072]

[0073] The prepared organic fertilizer of the S3 experimental group of the application is used for full amount of straw returning to field, and corn planting is carried out after returning to field, and the controls are set according to Table 2 during the planting process. The total nitrogen application amount during the whole growth period is 180 kg / hm 2 , the bottom fertilizer nitrogen application amount accounts for 60-70% of the whole growth period, the nitrogen application amount of the corn straw composting organic fertilizer in the bottom fertilizer is 65-70 kg / hm 2 , the nitrogen amount carried by phosphorus fertilizer is 45-50 g / hm 2 , urea is used to supplement the nitrogen amount of the bottom fertilizer, and the application amount of diammonium phosphate and potassium chloride is 90 kg / hm 2 , 100 kg / hm 2 . The changes of TOC content and TN content in the early growth stage of the planted corn and after autumn harvest are determined Figure 11 , the effects of different soil treatment conditions on ear weight, ear number, hundred-grain weight and yield of corn are determined (Table 4), the greenhouse gas emission conditions under different soil treatment conditions are determined Figures 12-14 , and the global warming potential (GWP) during the growth period of corn is determined (Table 5).

[0074] Result analysis:

[0075] Figure 11 For the TOC content and TN content of the planted corn, it can be seen that compared with the blank experimental group, the two groups of treatments increase the carbon and nitrogen content of the corn, straw composting and returning to field more improves the TOC content of the corn by 2.80 mg / kg, and conventional fertilization is beneficial to improve the TN content of the corn by 6.14 mg / kg.

[0076] As shown in Table 4, the yield of maize under different soil treatments was calculated. The ear weight of different treatments was Z1>Z2>CK, the number of ears was CK>Z1>Z2, and the weight of 100 kernels was Z1>Z2>CK. The effects of straw composting and returning to the field and returning to the field with constant fertilizer on the weight of 100 kernels of maize were comparable. At the same time, the maize yield of the straw composting and returning to the field treatment was higher, exceeding that of the CK group by 1.06%.

[0077] Table 4. Maize yield under different treatments

[0078]

[0079] Note: Different letters indicate that the difference is significant at the 5% level.

[0080] Several quadrats are randomly selected in the cornfield, with each quadrat typically having an area of ​​1-10 m². 2 Greenhouse gases were collected and measured using a static chamber-gas chromatography method. Sampling was conducted between 10:00 AM and 12:00 PM, with each chamber session lasting 30 minutes. Experimental data were statistically analyzed using SPSS 21.0 and plotted using Origin 2018. The results are as follows:

[0081] like Figure 12 As shown, the soil CO2 emission patterns were basically consistent across different field treatments. Soil CO2 emission flux was low in May, a period immediately following fertilization and during the early growth stage of maize. During this stage, the differences in soil CO2 emissions among different treatments were relatively small. Comparatively, soil CO2 emission flux was higher when straw compost was returned to the field, with an average emission flux of 7.62 mg / m³. 2 / h, the soil CO2 emission flux under conventional fertilization is 6.52 mg / m³. 2 / h, this is because straw composting and nitrogen fertilizer application provide direct carbon and nitrogen sources to the soil, thus increasing the soil respiration rate. Soil CO2 emissions reach a relatively high peak in June and July, coinciding with the early stages of maize growth and periods of high rainfall. Both straw composting and conventional fertilization significantly increase soil CO2 emission flux, but the increase is smaller under the maize straw composting and returning treatment. Throughout the crop growing season, the soil CO2 emission flux is CK(69.16 mg / m³). 2 / h)>Z2(63.02mg / m 2 / h)>Z1(60.55mg / m 2 / h).

[0082] like Figure 13 As shown, during field fertilization and the early stages of maize growth, the CH4 gas emission flux in the soil increased with both conventional fertilization and straw composting treatments. During this period, the CH4 gas emission flux Z2 in the three experimental groups was -0.11 mg / m³.2 / h)>CK(-0.12mg / m 2 / h)>Z1(0.20mg / m 2 Although the total CH4 gas emission flux was less than zero during June and July, the average emission flux during this period was Z2 (0.15 mg / m³). 2 / h), Z1 (0.11mg / m 2 The CH4 gas emission flux was greater than zero during the entire crop growing season. This was because the organic fertilizer introduced a large amount of easily soluble organic matter, and the increased content of easily decomposable organic matter in the soil provided more reaction substrates for methanogenic bacteria, thus promoting CH4 emissions. Ultimately, the soil CH4 emission flux during the entire crop growing season was Z2(-0.11 mg / m³). 2 / h)>Z1(-0.63mg / m 2 / h)>CK(-9.79×10 -4 mg / m 2 / h).

[0083] like Figure 14 As shown, soil N2O emissions showed a slight decreasing trend in the blank control group and the conventional fertilization group during field fertilization and the early stages of maize growth, but this trend was not significant. The soil N2O emission flux in the straw composting and returning-to-the-field treatment also showed a decreasing trend. From June to September and from the maize jointing stage to maturity, the soil N2O emission flux in the conventional fertilization treatment showed a trend of first decreasing and then increasing, while the soil N2O emission flux in the straw composting and returning-to-the-field treatment showed a trend of first increasing and then decreasing. The application of organic fertilizer introduces a large amount of soluble organic matter into the soil, increasing the substrate for denitrifying bacteria. Some studies also suggest that farmland N2O emissions are mainly affected by the content of nitrate nitrogen and ammonia nitrogen in the soil; the content of nitrate nitrogen and ammonia nitrogen in the soil decreased under straw composting and returning-to-the-field treatment. Ultimately, the soil N2O emission flux during the entire crop growing period was Z2 (0.63 mg / m³). 2 / h)>Z1(0.43mg / m 2 / h)>CK(0.37mg / m 2 / h).

[0084] The global warming potential (GWP) during the growth period of corn was calculated, and the total GWP during the growth period of corn was mainly contributed by CO2, followed by CH4, and N2O had little contribution to the total GWP. The conventional fertilization treatment increased the total GWP during the growth period of corn by 10.96% compared with the blank group, and the straw composting and returning treatment reduced the total GWP during the growth period of corn by 0.99% compared with the blank group. The greenhouse gas emission intensity was calculated, and the results are shown in the table. The soil greenhouse gas emission intensity under the conventional fertilization was the largest, which was 10.96% higher than that of the blank group, and the soil greenhouse gas emission intensity under the straw composting and returning treatment was reduced by 0.99% compared with the blank group.

[0085] Table 5 Greenhouse gas warming effect of soil under different treatments

[0086]

[0087] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the embodiments can be referred to each other.

[0088] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a corn stalk humus organic fertilizer, characterized by, It comprises the following steps: ​ (1) Collect corn stalks to dry to a moisture content of 8-11%, crush to 1mm-3.5cm, and reserve; (2) Collect cow dung with a moisture content of 60-63%, remove impurities, and reserve; (3) Mix the cow dung, crushed corn stalks, and biogas slurry, use urea to balance the carbon-nitrogen ratio to prepare anaerobic fermentation material with a carbon-nitrogen ratio of 28-30:1 and a total solid content of 7%-9%, carry out anaerobic fermentation at 33-38℃, extract biogas slurry after gas production; the addition amount of the biogas slurry is 8%-12% of the total volume of the fermentation material; (4) Add the extracted biogas slurry to the corn stalks at 30% of the volume of the corn stalks, mix thoroughly, place in a sealed state for 7d, add EM bacterial agent to prepare compost material, carry out compost fermentation to prepare corn stalks matured organic fertilizer; The addition amount of the EM bacterial agent is 6mL / kg of corn stalks; the moisture content of the compost material is 60-65%, and the carbon-nitrogen ratio is 25-30:1; the compost fermentation time is 22-26d, the initial temperature is 25℃, and the initial pH value is 6.5-7.0; During the compost fermentation, the pile is ventilated at a rate of 0.4-0.5L / min for 10-15min / h, and the center temperature of the pile is maintained at 42-53℃.

2. Corn stalks matured organic fertilizer prepared by the method of claim 1.

3. Application of the corn stalks matured organic fertilizer of claim 2 in soil improvement, crop planting, and / or reduction of greenhouse gas emissions.

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