Soil conditioner as well as preparation method and application thereof

Abstract

The invention relates to the technical field of soil conditioning, and particularly discloses a soil conditioner and a preparation method and application thereof.The soil conditioner is prepared from, by weight, 160-200 parts of volcanic ash modified biochar, 50-70 parts of straw leavening and 50-70 parts of animal dung; the volcanic ash modified biochar is obtained by mixing volcanic slag and crop straw according to a mass ratio of 1: (4-5) and then carrying out carbonization reaction at 450-650 DEG C. According to the soil conditioner provided by the invention, the content of organic matters in black soil is increased, the content of water-stable large aggregates in the soil is increased, and the effects of recarburizing and improving the soil are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil conditioning, and specifically relates to a soil conditioner, a preparation method thereof, and an application thereof. Background Art

[0002] The black soil is a high-quality soil resource in the Northeast region and enjoys the reputation of "giant panda in cultivated land". Relevant research shows that after years of high-intensity utilization, the black soil is facing varying degrees of degradation. Due to differences in climate, location, development years, resource endowment, and utilization methods, the degrees and manifestations of the degradation of the Northeast black soil are not the same, but the common feature is that the black soil layer is "becoming thinner, poorer, and harder". The thickness of the black soil layer decreases by 2 - 10 mm every year, the organic matter content in the plough layer has decreased by more than 40% compared with the initial stage of reclamation, and 50% of the farmland has obstructive horizons such as a compacted plough sole layer and albic horizon. Excessive reclamation, urbanization, etc. will damage the soil structure, reduce the input of soil organic carbon, and at the same time increase the decomposition and loss of organic carbon. Frequent tillage will damage the soil aggregate structure, accelerate the mineralization decomposition of organic carbon, and reduce the content of organic carbon and water-stable macroaggregates in the soil. Long-term excessive application of chemical fertilizers will lead to insufficient input of soil organic carbon, affecting the formation and stability of soil aggregates. The soil conditions urgently need to be improved. Improving the content of soil organic carbon and water-stable macroaggregates is crucial for improving soil conditions.

[0003] Soil organic carbon is one of the important indicators of soil fertility. It can provide essential nutrients for plants, such as nitrogen, phosphorus, potassium, etc. At the same time, organic carbon can also improve the physical properties of the soil, such as soil structure, air permeability, and water retention, thereby improving soil fertility. Organic carbon combines with soil mineral particles to form stable organic-inorganic aggregates, enhancing the soil's erosion resistance and reducing soil erosion. Organic carbon can improve the water retention and air permeability of the soil, enabling the soil to have better water regulation ability, which is beneficial to plant growth.

[0004] Soil aggregates refer to structural units in the soil with different sizes, shapes, porosities, and mechanical and water stabilities. Usually, the structural units with a particle size > 0.25 mm are called macroaggregates. Water-stable aggregates are those soil structural bodies that do not immediately disperse after being soaked in water and maintain the morphological integrity of the soil structural bodies without breaking. At present, the products of biochar have weak targeting for reducing the obstacles in black soil, and have weak effects on soil organic carbon and water-stable aggregates in black soil. Therefore, it is necessary to develop a soil conditioner suitable for black soil to increase the content of soil organic carbon and water-stable aggregates. Summary of the Invention

[0005] To develop a soil conditioner suitable for black soil and used to increase the content of soil organic carbon and water-stable aggregates, the present invention provides a soil conditioner, its preparation method and application. The soil conditioner provided by the present invention increases the content of soil organic matter in black soil, increases the content of large water-stable aggregates in the soil, and achieves the effect of carbon increase and soil improvement.

[0006] The present invention provides a soil conditioner, which is made of the following components in parts by weight: 160 to 200 parts of volcanic ash-modified biochar, 50 to 70 parts of straw fermentate, and 50 to 70 parts of livestock and poultry manure; the volcanic ash-modified biochar is obtained by carbonizing a mixture of volcanic slag and crop straw in a mass ratio of 1:4 to 5 at 450°C to 650°C.

[0007] The present invention carbonizes and modifies crop straw with volcanic slag to prepare volcanic ash-modified biochar with white granular minerals filled and attached between the pores on the surface of the biochar. Through the physical protection of volcanic ash minerals, the types and quantities of microorganisms in contact with the biochar are reduced, the mineralization and decomposition rate of the biochar itself is lowered, the stability of the biochar is improved, and the exogenous carbon in the soil is increased; at the same time, it promotes the formation of large soil aggregates, plays a role in protecting soil organic carbon, and reduces the decomposition of the soil background carbon. When mixed with straw fermentate and livestock and poultry manure, it synergistically promotes the improvement of soil physical and chemical properties.

[0008] Further, the soil conditioner is made of the following components in parts by weight: 200 parts of volcanic ash-modified biochar, 50 parts of straw fermentate, and 50 parts of livestock and poultry manure.

[0009] Further, the mass ratio of the mixture of volcanic slag and crop straw is 1:4.

[0010] Further, the straw fermentate is obtained by fermenting crop straw with a fermentation bacterium agent into humus.

[0011] Further, the fermentation bacterium agent contains Bacillus subtilis, Geobacillus stearothermophilus, Bacillus amyloliquefaciens, Bacillus megaterium, Candida tropicalis, Saccharomyces cerevisiae, Streptomyces microflavus and Streptomyces albogriseolus.

[0012] The present invention also provides a preparation method of a soil conditioner, which includes the following steps:

[0013] Weigh 160 to 200 parts of volcanic ash-modified biochar, 50 to 70 parts of straw fermentate, and 50 to 70 parts of livestock and poultry manure in parts by weight, mix them evenly and dry them at 22°C to 28°C to obtain the soil conditioner;

[0014] The preparation process of the volcanic ash modified biochar is as follows: Mix crop straw and volcanic slag in a mass ratio of 1:4 - 5, and then carry out a carbonization reaction at 450°C - 650°C to obtain the volcanic ash modified biochar;

[0015] The preparation process of the straw fermentate is as follows: Ferment crop straw particles with a fermentation inoculant to obtain the straw fermentate.

[0016] Further, the crop straw is corn straw or rice straw.

[0017] Further, the carbonization reaction conditions include a first carbonization temperature and a second carbonization temperature. During the carbonization process, first heat up to the first carbonization temperature for carbonization reaction, then heat up to the second carbonization temperature and continue the carbonization reaction. The first carbonization temperature is 350°C - 500°C, the second carbonization temperature is 450°C - 650°C, and the first carbonization temperature is less than the second carbonization temperature.

[0018] Further, the heating rate for heating up to the first carbonization temperature and the second carbonization temperature is both 20°C / min - 25°C / min.

[0019] Further, the fermentation inoculant includes Bacillus subtilis, Geobacillus stearothermophilus, Bacillus amyloliquefaciens, Bacillus megaterium, Candida tropicalis, Saccharomyces cerevisiae, Streptomyces microflavus, and Streptomyces albogriseolus.

[0020] Further, 0.65 kg - 0.85 kg of the fermentation inoculant is added per ton of the crop straw particles.

[0021] Further, the fermentation inoculant is first mixed into rice bran and then added to the crop straw particles. The mass ratio of the fermentation inoculant to rice bran is 1 kg:3 kg - 5 kg.

[0022] Further, the crop straw particles are corn straw particles or rice straw particles.

[0023] The present invention also provides the application of the soil conditioner in improving the physical and chemical properties of black soil. The soil conditioner is used to increase the content of organic matter in black soil and increase the content of water-stable macroaggregates in the soil.

[0024] Further, the soil conditioner is used to increase the yield of crops planted on black soil.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] The soil conditioner provided by the present invention increases the content of soil organic matter in black soil, increases the content of water-stable macroaggregates in the soil, and achieves the effect of carbon addition and soil improvement. The volcanic ash-modified biochar in the soil conditioner significantly improves the physical and chemical properties of the soil compared with the use of ordinary biochar, manifested as a significant increase in the content of soil organic carbon, water-stable macroaggregates and soil porosity, and a significant decrease in soil bulk density.

[0027] In the present invention, by setting the carbonization temperature at 450°C to 650°C, the carbonization is complete, and at the same time, the biological functional groups are enriched, thereby improving the adsorption capacity of the biochar and increasing the yield of corn planting. Brief Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0029] [[ID=eleven]] Figure 1 It is the SEM appearance diagram of the volcanic ash-modified biochar prepared in Example 1 of the present invention; in the figure, A is the 1000-fold imaging of ordinary biochar under the scanning electron microscope; B is the 1000-fold imaging of the volcanic ash-modified biochar under the scanning electron microscope.

[0030] Figure 2 It is the SEM appearance diagram of the volcanic ash-modified biochar prepared in Example 4 of the present invention.

[0031] Figure 3 It is the SEM appearance diagram of the volcanic ash-modified biochar prepared in Comparative Example 8.

[0032] Figure 4 It is the FTIR spectrum of the functional group analysis of the volcanic ash-modified biochar with different substances prepared in Example 4.

[0033] Figure 5 It is the FTIR spectrum of the functional group analysis of the volcanic ash-modified biochar with different substances prepared in Comparative Example 8.

[0034] Figure 6 It is the appearance diagram of the biochar with different carbonization temperatures in Example 4 and Comparative Example 11;

[0035] In the figure, A is the appearance of the biochar obtained by carbonization at 450°C in Example 4;

[0036] B is the appearance of the biochar obtained by carbonization at 350°C in Comparative Example 11. Detailed Embodiments

[0037] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the protection scope of the present invention is not limited by the specific embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified. The materials, reagents, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.

[0038] Example 1: A soil conditioner and its preparation method.

[0039] The soil conditioner provided in this example is composed of the following raw materials in parts by mass: 200 parts of volcanic ash modified biochar, 50 parts of straw ferment, and 50 parts of livestock and poultry manure. The above raw materials are fully mixed and dried in an environment with a room temperature of 25°C until the water content is less than 10%, and a dry soil conditioner is obtained.

[0040] Preparation of volcanic ash modified biochar: Select 60-mesh corn straw as the raw material for preparing biochar, and select 80-mesh volcanic slag as the mineral modification material for biochar. After mixing corn straw and volcanic slag in a mass ratio of 1:4, put them into a carbonization reactor, and set the heating program as follows: the initial temperature is 65°C, the heating rate is 25°C / min, heat up to the first carbonization temperature: 500°C, and maintain this temperature for 1.5 hours, then heat up to the second carbonization temperature: 650°C at a heating rate of 25°C / min, and maintain for 2 hours. After cooling to room temperature, it is reserved for use. The volcanic slag used in this example was collected from the Changbai Mountain area in Jilin Province, and its physical and chemical indexes are shown in Table 1.

[0041] Table 1 Physical and chemical indexes of volcanic slag in this example

[0042]

[0043]

[0044] Preparation of straw ferment: Select corn straw, crush it to a fineness of 0.5 mm to obtain corn straw particles, place them in a fermentation tank, pour 4 times the mass of water of the straw into the fermentation tank, add a fermentation agent and ferment for 18 hours, and the straw becomes humus, that is, the straw ferment is obtained.

[0045] Add 0.75 kg of fermentation agent per ton of straw. When adding the fermentation agent, it needs to be mixed into rice bran and then added, and it is mixed in a ratio of 1 kg of fermentation agent to 4 kg of rice bran.

[0046] The fermentation inoculant is a special straw fermentation inoculant commercially available from Chengdu Tianxing Agricultural Science and Technology Co., Ltd. The strains it contains are: Bacillus subtilis, Geobacillus stearothermophilus, Bacillus amyloliquefaciens, Bacillus megaterium, Candida tropicalis, Saccharomyces cerevisiae, Streptomyces microflavus, and Streptomyces albogriseolus. The straw after fermentation is non-toxic and harmless.

[0047] Preparation of livestock and poultry manure: Select commercially available fermented livestock and poultry manure, which is commercially available fermented sheep manure, with organic matter ≥ 30%, N-P2O5-K2O ≥ 4%, pH 6.5, and process it to a fineness of 20 mesh for standby.

[0048] Example 2: A soil conditioner and its preparation method.

[0049] The soil conditioner provided in this example is composed of the following raw materials in parts by mass: 180 parts of volcanic ash-modified biochar, 60 parts of straw fermented product, and 60 parts of livestock and poultry manure. Mix the above raw materials thoroughly and dry them in an environment at room temperature of 25 °C to obtain the dried soil conditioner.

[0050] The preparation steps of the volcanic ash-modified biochar, straw fermented product, and soil conditioner are the same as those in Example 1.

[0051] Example 3: A soil conditioner and its preparation method.

[0052] The soil conditioner provided in this example is composed of the following raw materials in parts by mass: 160 parts of volcanic ash-modified biochar, 70 parts of straw fermented product, and 70 parts of livestock and poultry manure. Mix the above raw materials thoroughly and dry them in an environment at room temperature of 25 °C to obtain the dried soil conditioner.

[0053] The preparation steps of the volcanic ash-modified biochar, straw fermented product, and soil conditioner are the same as those in Example 1.

[0054] Example 4: A soil conditioner and its preparation method.

[0055] Prepare the soil conditioner according to the raw materials in Example 1, the difference is:

[0056] Preparation of volcanic ash-modified biochar: Select 60-mesh corn straw as the raw material for preparing biochar, and select 80-mesh volcanic slag as the mineral modification material for biochar. After mixing the corn straw and volcanic slag in a mass ratio of 1:4, put them into a carbonization reactor, and set the heating program as follows: initial temperature 65 °C, heating rate 25 °C / min, rise to the first carbonization temperature: 400 °C, and maintain this temperature for 1.5 hours, then rise to the second carbonization temperature: 450 °C at a heating rate of 25 °C / min, maintain for 2 hours, and cool to room temperature for standby.

[0057] Example 5: A soil conditioner and its preparation method.

[0058] Prepare a soil conditioner according to the raw materials in Example 4, with the difference that:

[0059] During the preparation of the volcanic ash modified biochar, 60-mesh rice straw is selected as the raw material for preparing the biochar.

[0060] Comparative Example 1: A soil conditioner and its preparation method.

[0061] The soil conditioner provided by Comparative Example 1 is composed of the following raw materials in parts by mass: 140 parts of mineral modified biochar, 80 parts of straw fermented product, and 80 parts of livestock and poultry manure. The remaining steps are the same as those in Example 1.

[0062] Comparative Example 2: A soil conditioner and its preparation method.

[0063] The soil conditioner provided by Comparative Example 2 is composed of the following raw materials in parts by mass: 120 parts of mineral modified biochar, 90 parts of straw fermented product, and 90 parts of livestock and poultry manure. The remaining steps are the same as those in Example 1.

[0064] Comparative Example 3: A soil conditioner and its preparation method.

[0065] The preparation process of the soil conditioner provided by Comparative Example 3 is the same as that in Example 1. The difference is that: the soil conditioner is composed of the following raw materials in parts by mass: 180 parts of ordinary biochar, 60 parts of straw fermented product, and 60 parts of livestock and poultry manure.

[0066] The preparation steps of the ordinary biochar are as follows: Select 60-mesh corn straw as the raw material for preparing the biochar, put it into a carbonization reactor, and set the heating program as: initial temperature 65°C, heating rate 25°C / min, raise the temperature to the first carbonization temperature: 500°C, and maintain this temperature for 1.5 hours, then raise the temperature to the second carbonization temperature at a heating rate of 25°C / min: 650°C, maintain for 2 hours, and cool to room temperature for standby.

[0067] Comparative Example 4: A soil conditioner and its preparation method.

[0068] The soil conditioner provided by Comparative Example 4 is composed of the following raw materials in parts by mass: 150 parts of ordinary biochar, 75 parts of straw fermented product, and 75 parts of livestock and poultry manure. The remaining steps are the same as those in Comparative Example 3.

[0069] Comparative Example 5: A soil conditioner and its preparation method.

[0070] The soil conditioner provided by Comparative Example 5 is composed of the following raw materials in parts by mass: 100 parts of ordinary biochar, 100 parts of straw fermented product, and 100 parts of livestock and poultry manure. The remaining steps are the same as those in Comparative Example 3.

[0071] Comparative Example 6: A soil conditioner and its preparation method.

[0072] The soil conditioner provided by Comparative Example 6 is composed of the following raw materials in parts by mass: 200 parts of ordinary biochar, 50 parts of straw fermented product, and 50 parts of livestock and poultry manure. The remaining steps are the same as those in Comparative Example 3.

[0073] Comparative Example 7: A soil conditioner and its preparation method.

[0074] The soil conditioner provided by Comparative Example 7 is composed of the following raw materials in parts by mass: 250 parts of modified biochar, 25 parts of straw fermented product, and 25 parts of livestock and poultry manure. The remaining steps are the same as those in Comparative Example 3.

[0075] Comparative Example 8: A soil conditioner and its preparation method.

[0076] A soil conditioner is prepared according to the raw materials in Example 4, with the difference that:

[0077] The heating program is set as follows: the initial temperature is 65°C, the heating rate is 25°C / min, it is heated to the first carbonization temperature: 500°C, and this temperature is maintained for 1.5 hours, then it is heated to the second carbonization temperature: 700°C at a heating rate of 25°C / min and maintained for 2 hours, and after cooling to room temperature, it is reserved for use.

[0078] Comparative Example 9: A soil conditioner and its preparation method.

[0079] A soil conditioner is prepared according to the raw materials in Example 4, with the difference that:

[0080] The heating program is set as follows: the initial temperature is 65°C, the heating rate is 25°C / min, it is heated to 350°C and the carbonization reaction is maintained for 3.5 hours, and after cooling to room temperature, it is reserved for use.

[0081] Comparative Example 10: A soil conditioner and its preparation method.

[0082] A soil conditioner is prepared according to the raw materials in Comparative Example 8, with the difference that:

[0083] During the preparation process of the volcanic ash modified biochar, 60-mesh rice straw is selected as the raw material for preparing the biochar.

[0084] Comparative Example 11: A soil conditioner and its preparation method.

[0085] The specific steps are the same as those in Example 1, with the difference that:

[0086] During the preparation process of the volcanic ash modified biochar, the carbonization conditions are as follows: the initial temperature is 60°C, the heating rate is 20°C / min, it is heated to 300°C, and this temperature is maintained for 1.5 h, then it is heated to 350°C at the same heating rate and maintained for 2 h, and after cooling to room temperature, the volcanic ash modified biochar is obtained.

[0087] Comparing the appearance diagrams of the volcanic ash-modified biochar obtained in Comparative Example 4 and Comparative Example 11, it can be seen from Figure 6 that the carbonization at the final carbonization temperature of 350 °C is incomplete.

[0088] The principle of the synergistic treatment of the modified biochar, straw ferment and livestock manure in the present invention: Biochar is composed of elemental carbon and organic carbon such as graphite, containing more than 60% carbon element. Since biochar has a high and stable carbon content itself, it can effectively protect soil organic carbon and reduce mineralization loss, thus achieving carbon sequestration. On the one hand, due to the porous structure and large surface area of biochar, it can increase soil water retention and aeration, improve soil structure, and the high and stable carbon content of biochar itself can sequester carbon. On the other hand, biochar can provide a good microbial habitat, promote the growth and reproduction of beneficial microorganisms, and increase the decomposition rate of soil organic matter. Although biochar has many advantages mentioned above, however, if biochar is directly used for soil improvement, there are still technical defects. For example, biochar is mainly composed of carbon element and has simple nutrient components, and its effect of repairing and improving soil is affected by factors such as environment, soil and climate, and sometimes the effect is not obvious. Therefore, it is modified with volcanic ash because volcanic ash is rich in dozens of minerals and trace elements such as silicon, aluminum, calcium, sodium, magnesium, titanium, manganese, iron, nickel, cobalt and molybdenum. It is a substance that naturally has strong cation exchange capacity and adsorption performance, is beneficial to loosening the soil and promoting plant growth, and has the advantages of low cost and ecological friendliness. Its characteristics are: non-toxic, non-radioactive, and does not contain heavy metals, etc. Based on its rich mineral elements, the performance of carbon sequestration and soil fertility improvement of biochar can be improved after modification. At the same time, after biochar is applied to the soil, it often produces a priming effect (PE) that accelerates the mineralization and decomposition of soil organic carbon (SOC). The PE of biochar-induced SOC mineralization shows two directions, positive and negative. Positive PE will promote the degradation of SOC and biochar itself, resulting in a decrease in SOC content and exacerbating soil infertility. Negative PE will inhibit SOC mineralization, on the one hand increasing soil fertility, and on the other hand reducing greenhouse gas emissions (playing a role in carbon sequestration and soil fertility improvement). Therefore, in addition to modifying biochar, it is also necessary to supplement organic matter, such as straw ferment and livestock manure, so that the organic matter can enter the pores of biochar or adsorb on the outer surface of biochar. This process greatly reduces the decomposition of soil organic carbon; the encapsulation of organic carbon in biochar pores will exclude the addition of microorganisms and other biological groups and their extracellular enzymes, thus providing physical protection for natural organic carbon and preventing it from being mineralized; at the same time, it also promotes the formation of soil aggregates, improves stability, promotes the increase of organic matter, and plays a role in carbon sequestration and soil fertility improvement through the addition of straw ferment and livestock manure.

[0089] The soil conditioners prepared in the above examples and comparative examples were respectively used for treating black soil, and a plot experiment was carried out to study the effects of different soil conditioners on the physical and chemical structure of the soil and crop yields. The land without any treatment was used as a blank control group. The specific methods and results are as follows:

[0090] I. Test methods

[0091] A plot experiment was set up in the experimental field of Shenyang Agricultural University in Shenyang, Liaoning Province. Nine plots were divided in the corn planting plot with consistent soil physical and chemical properties. The plot area was 18 square meters. All experimental groups adopted the same field management method and fertilization treatment. After maturity, the soil organic carbon content, water-stable macro-aggregate content, soil bulk density and crop yields were measured. The volcanic ash-modified biochar-based carbon sequestration and fertility improvement soil conditioners prepared in Examples 1 to 5 and the biochar-based carbon sequestration and fertility improvement soil conditioners prepared in Comparative Examples 1 to 7 were respectively applied once in each plot in the form of basal application.

[0092] 1. Differences between volcanic ash-modified biochar and ordinary biochar

[0093] The volcanic ash-modified biochar prepared in Example 1 and the ordinary biochar obtained in Comparative Example 3 were scanned by electron microscopy; at the same time, the volcanic ash-modified biochar prepared in Example 4 at a carbonization temperature of 450 °C and the volcanic ash-modified biochar prepared in Comparative Example 8 at a carbonization temperature of 700 °C were scanned by electron microscopy to observe the structural changes of the above biochars.

[0094] 2. Effects of carbonization temperature on the biological functional groups of biochar

[0095] The biological functional groups on the surface of the volcanic ash-modified biochar obtained by carbonization modification at 450 °C in Example 4 and the volcanic ash-modified biochar obtained by carbonization modification at 700 °C in Comparative Example 8 were analyzed by FTIR test.

[0096] The specific method is as follows:

[0097] Method: Take a biochar sample, directly press it into a tablet and place it on the sample stage. Use an infrared light source to irradiate the sample to make it absorb infrared radiation. Measure the energy and frequency of the absorbed light through a spectrometer to obtain the spectral image of the sample.

[0098] 3. Effects of mineral modification on the yield and carbon retention of biochar

[0099] Taking Examples 4 to 5, Comparative Example 8 and Comparative Example 10 as examples, the yields and carbon retention amounts of the volcanic ash-modified biochars prepared with corn and rice as raw materials at a final carbonization temperature of 450 °C and 700 °C were studied.

[0100]

[0101] In the formula: Y is the yield, C is the carbon retention. M is the total mass of biomass and minerals before co-pyrolysis; Cbc is the carbon content in the solid residue after co-pyrolysis, %; Mbc is the carbon content of the biomass material, %; Mbm is the mass of the biomass material, g; Ma is the mass of the added mineral, and Ca is the carbon content of the added mineral, %.

[0102] 4. Treating soil with different soil conditioners and planting crops

[0103] The crop selected for planting in the present invention is corn, and the corn variety is Dongdan 1775. Eleven treatment plots with an area of 40 m 2 are divided. One of the treatment plots is not added with a soil conditioner as a blank control group, and the remaining 10 treatment plots are experimental groups. Sowing is carried out on May 1st, and the soil conditioners obtained in Examples 1 to 4 and Comparative Examples 1 to 8 are respectively applied to each experimental group in a one-time basal application method, with an application rate of 20 tons / ha. Conventional field management (refer to GB / T8321 Guidelines for the Rational Use of Pesticides and NY / T496 Guidelines for the Rational Use of Fertilizers), and harvesting is carried out on October 6th. At the same time, 5 points are selected in a plum blossom shape in each treatment plot, and soil from the 1 cm deep plough layer is taken, mixed, and an appropriate amount of soil is retained for testing by the quartering method. At the same time, soil is taken back with a core sampler to measure the water content and calculate the soil bulk density, and other indicators are measured according to conventional methods.

[0104] All the ears are harvested from each treatment plot. After counting the number of ears, the fresh ear weight Y1 (kg) is weighed. According to the average ear weight method, 20 ears are taken as standard samples to measure the fresh ear kernel ratio (%) and moisture content (%). And the actual area of the harvesting sample point is accurately measured. (The area of the sampling point × the average weight of 20 ears = (ear weight / number of ears) × 20. Select 20 ears of corn from the total number of ears, and the weight is the average weight of 20 ears. These 20 ears of corn are threshed to measure the moisture content of the kernels). Kernel moisture content M (%): Use a nationally recognized and calibrated seed moisture meter to measure the moisture content of the kernels, and repeat the measurement 10 times at each point to obtain the average value (M). The samples are retained for future reference or re-calibrated after natural air drying.

[0105] Calculation formula:

[0106] Fresh ear weight per mu Y (kg / mu) = (Y1 / S) × 666.7; in the formula, Y1 represents the total fresh ear weight, unit: kg; S represents the area, unit: m 2 .

[0107] Kernel ratio L (%) = X2 / X1; in the formula, X2 represents the fresh kernel weight of 20 samples, unit: g; X1 represents the fresh ear weight of 20 samples, unit: g.

[0108] Measured yield (kg / mu) = Fresh ear weight (kg / mu) × Seed setting rate (%) × [1 - Grain moisture content (%)] ÷ (1 - 14%).

[0109] II. Experimental Results

[0110] 1. Differences between volcanic ash modified biochar and ordinary biochar

[0111] The results are as Figure 1 shown. Volcanic ash modified biochar ( Figure 1 B) is the biochar modified by volcanic ash mineral powder. Volcanic ash mineral components will fill the pores (white granular minerals adhere to the surface of the biochar). Therefore, through the physical protection of volcanic ash minerals, the types and quantities of microorganisms in contact with the biochar are reduced, the mineralization and decomposition rate of the biochar itself is decreased, the stability of the biochar is improved, and the exogenous carbon in the soil is increased. At the same time, it promotes the formation of soil macro-aggregates, plays a role in protecting soil organic carbon, and reduces the decomposition of soil background carbon. Therefore, the stability of the volcanic ash modified biochar in the present invention is significantly improved, thereby realizing the efficient regulation of soil physical and chemical indexes. Ordinary biochar ( Figure 1 A) has uneven pore distribution, a high proportion of micropores but insufficient medium / large pores, which restricts the diffusion of macromolecular pollutants or microorganisms; it has low mechanical strength, and some biochars are easy to break (such as rice husk charcoal), and the pores collapse after long-term use; at the same time, functional groups are easy to lose, especially the oxygen-containing functional groups of low-temperature charcoal may be oxidized and degraded in the environment, resulting in unstable performance. Generally speaking, ordinary biochar generally has a low content of mineral nutrients, limited nutrients that can be directly provided to crops, and the biochar is light in weight, brittle and easy to break, occupies a large space, and has high costs for transportation and storage.

[0112] 2. Influence of carbonization temperature on the biological functional groups of biochar

[0113] Figure 2 Figure shows the morphological characteristics of the volcanic ash modified biochar prepared in Example 4 at a carbonization temperature of 450 °C, Figure 3 and Figure shows the morphological characteristics of the volcanic ash modified biochar prepared in Comparative Example 8 at a carbonization temperature of 700 °C. From Figures 2 - 3 this, it can be seen that carbonization is incomplete below 450 degrees Celsius, and after exceeding 650 °C, that is, after carbonization at 700 °C, the structure of the biochar is severely broken.

[0114] The FTIR spectra of the volcanic ash modified biochars with different substances prepared in Example 4 are as Figure 4 shown, and the FTIR spectra of the volcanic ash modified biochars with different substances prepared in Comparative Example 8 are as Figure 5 shown. From Figures 4 - 5It can be seen that the surface functional group analysis of the modified biochar at two temperatures of 450°C and 700°C shows that compared with the pyrolysis conditions at 700°C, functional groups such as alcohol hydroxyl (-OH), carbonyl (C=O), carboxyl (-COOH), and ether bond (C-O-C) are more abundant under the pyrolysis conditions at 450°C. Abundant biological functional groups can endow biochar with better adsorption capacity.

[0115] 3. Influence of Mineral Modification on the Yield of Biochar

[0116] Table 2 Basic Physicochemical Properties of Biochar and Modified Biochar

[0117] Biochar Yield Carbon retention % Corn at 450°C 62.37 53.68 Corn at 700°C 57.88 47.68 Modified corn at 450°C 69.00 67.94 Modified corn at 700°C 60.16 52.69 Rice at 450°C 63.46 51.68 Rice at 700°C 56.24 49.28 Modified rice at 450°C 85.41 61.63 Modified rice at 700°C 62.02 56.12

[0118] As can be seen from Table 2, for corn straw and rice straw, mineral modification increases the yield of biochar. In the temperature range of 450°C to 700°C, the yield is increased compared with unmodified biochar. Among them, at 450°C, the yield of modified biochar is the highest, with an increase of 10.6% for corn and even 34.6% for rice. At 700°C, the increase for corn is 3.9% and for rice is 10.3%. And after modification of the same raw material, the yield at 450°C is higher than that at 700°C, which may be because at higher temperatures, there will be varying degrees of decomposition loss of carbon.

[0119] The carbon retention rates of different biomass chars modified by volcanic ash are shown in Table 2. As can be seen from Table 2, the carbon retention rates of different biomass chars modified by volcanic ash have all increased. At the pyrolysis temperature of 450°C, the carbon retention rates of modified corn biochar and modified rice biochar increased by 26.6% and 19.3% respectively compared with unmodified biochar; at the pyrolysis temperature of 700°C, the two increased by 9.9% and 13.9% respectively compared with unmodified biochar. It shows that under the pyrolysis temperature condition of 450°C, the carbon retention rate of modified biochar is higher. It also shows that the influence of volcanic ash modification on carbon sequestration of biochar is not specific to a certain biomass.

[0120] 4. Influence of Treatments with Different Soil Conditioners on Soil Physicochemical Indexes and Crop Yields

[0121] Table 3 Influence of Treatments with Different Soil Conditioners on Soil Physicochemical Indexes and Crop Yields

[0122]

[0123] Note: Different letters indicate significant differences (F = 0.05), and the same letter indicates no significant difference between different groups.

[0124] The results are shown in Table 3. The dosage ratios of volcanic ash modified biochar, straw fermentate, and livestock manure in the soil conditioners in Examples 1 to 4 were 160 parts to 200 parts: 50 parts to 70 parts: 50 parts to 70 parts. Compared with the dosage ratios of volcanic ash modified biochar, straw fermentate, and livestock manure in Comparative Example 1 and Comparative Example 2, which were 120 parts to 140 parts: 80 parts to 90 parts: 80 parts to 90 parts, the proportion of volcanic ash modified biochar in the soil conditioners of Examples 1 to 3 of the present invention was 53.3% to 66.7%, higher than that in Comparative Example 1 to Comparative Example 2. It was found that when the proportion of volcanic ash modified biochar in the soil conditioner was 53.3% to 66.7%, the physical and chemical properties of the soil were significantly improved, the soil organic carbon content, the content of water-stable macroaggregates, and the soil porosity were significantly increased, and the soil bulk density was significantly reduced.

[0125] When Examples 1 to 3 of the present invention were compared with Comparative Examples 3 to 6, it was found that using volcanic ash modified biochar significantly improved the physical and chemical properties of the soil compared with using ordinary biochar, manifested as a significant increase in the soil organic carbon content, the content of water-stable macroaggregates, and the soil porosity, and a significant reduction in the soil bulk density.

[0126] At the same time, it was found that the soil conditioner prepared by the present invention significantly increased the crop yield after treating the soil.

[0127] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concept.

[0128] Obviously, those skilled in the art can make various changes and deformations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and deformations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and deformations.

Claims

1. A soil conditioner, characterized in that, It is made from the following components in parts by weight: 160 to 200 parts of volcanic ash modified biochar, 50 to 70 parts of straw fermentate, 50 to 70 parts of livestock and poultry manure; The volcanic ash modified biochar is obtained by carbonizing a mixture of volcanic slag and crop straw in a mass ratio of 1:4 to 5 at 450°C to 650°C.

2. The preparation method of the soil conditioner according to claim 1, characterized in that, It includes the following steps: Weigh 160 to 200 parts of volcanic ash modified biochar, 50 to 70 parts of straw fermentate, and 50 to 70 parts of livestock and poultry manure in parts by weight, mix them evenly and dry at 22°C to 28°C to obtain a soil conditioner; The preparation process of the volcanic ash modified biochar is: mix crop straw and volcanic slag in a mass ratio of 1:4 to 5, and carry out a carbonization reaction at 450°C to 650°C to obtain volcanic ash modified biochar; The preparation process of the straw fermentate is: ferment crop straw particles with a fermentation bacterium agent to obtain straw fermentate.

3. The preparation method of the soil conditioner according to claim 2, characterized in that, The carbonization reaction conditions include a first carbonization temperature and a second carbonization temperature. During the carbonization process, first heat up to the first carbonization temperature for carbonization reaction, then heat up to the second carbonization temperature and continue the carbonization reaction. The first carbonization temperature is 350°C to 500°C, the second carbonization temperature is 450°C to 650°C, and the first carbonization temperature is lower than the second carbonization temperature.

4. The preparation method of the soil conditioner according to claim 3, wherein The heating rate for heating up to the first carbonization temperature and heating up to the second carbonization temperature is both 20°C / min to 25°C / min.

5. The preparation method of the soil conditioner according to claim 2, wherein The fermentation bacterium agent includes Bacillus subtilis, Geobacillus stearothermophilus, Bacillus amyloliquefaciens, Bacillus megaterium, Candida tropicalis, Saccharomyces cerevisiae, Streptomyces microflavus, and Streptomyces albogriseolus.

6. The preparation method of the soil conditioner according to claim 2, characterized in that, 0.65 kg to 0.85 kg of the fermentation bacterium agent is added per ton of the crop straw particles.

7. The preparation method of the soil conditioner according to claim 2, wherein Before adding the fermentation bacterium agent, it is first mixed into rice bran and then added to the crop straw particles. The mass ratio of the fermentation bacterium agent to rice bran is 1 kg:3 kg to 5 kg.

8. Use of the soil conditioner according to claim 1 in improving the physical and chemical properties of black soil, characterized in that, The soil conditioner is used to increase the content of soil organic matter in black soil and increase the content of water-stable macro-aggregates in the soil.

9. Use of the soil conditioner according to claim 8 in improving the physical and chemical properties of black soil, characterized in that, The soil conditioner is used to increase the yield of crops planted on black soil.

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