CN106929027B

CN106929027B - Soil improvement method

Info

Publication number: CN106929027B
Application number: CN201710060446.7A
Authority: CN
Inventors: 朱明�; 刘涵; 王吉峰
Original assignee: Beijing Kaifeng Thailand Intelligent Technology Research Co Ltd
Current assignee: Beijing Lianlu Ecological Environment Co ltd
Priority date: 2017-01-25
Filing date: 2017-01-25
Publication date: 2020-01-07
Anticipated expiration: 2037-01-25
Also published as: CN106929027A

Abstract

The invention provides a soil improvement method, which comprises the steps of scraping surface soil with the thickness of 1-10cm from the surface soil of an orchard, mixing the surface soil with a soil conditioner, and then paving the mixture back to the surface of the orchard. The method can effectively improve the fertilizer efficiency of the barren soil and can continuously improve the pH value of the acidified soil.

Description

Soil improvement method

Technical Field

The invention belongs to the technical field of soil improvement, and particularly relates to a method for improving soil by using biochar, in particular to a method for improving soil fertilizer efficiency and pH value by using biochar.

Background

With the improvement of the degree of agricultural mechanization, the traditional organic fertilizer is gradually replaced by agricultural fertilizer, resulting in the gradual decline of the soil fertility. How to maintain the balance of soil nutrients, improve the soil structure and physicochemical properties, increase the soil fertility and improve the crop yield is widely concerned. With the continuous cropping time being prolonged, the soil acidification of the orchard is continuous and serious, so that the productivity of the orchard is reduced year by year, diseases are frequent, and the fruit quality is reduced. Therefore, how to improve the soil environment and improve the fertility of the soil is the key point for ensuring the high yield, high quality and sustainable development of the apples.

The biochar is applied to the soil, and the physicochemical property of the soil can be improved to a certain extent. After the fertilizer is applied to the soil containing the biochar, the biochar can adsorb a part of nutrient fertilizer and increase the adsorption and exchange capacity of the soil to the nutrient fertilizer, so that the release of the fertilizer nutrients is delayed, the leaching loss of the soil nutrients is reduced, the utilization rate of the nutrient fertilizer is increased, and the pollution of the fertilizer to the water area environment is reduced. Meanwhile, after the biochar is applied, the water holding capacity of the soil can be effectively improved, soil pores can be increased, the soil volume and weight can be reduced, and the like, so that the soil fertility is improved, and the crop yield is increased. The biochar is suitable for soil improvement mechanism, soil and carbon, is reasonably utilized, and has important practical significance for improving the yield of crops such as grains and solving the grain crisis faced by the current society.

CN105075444A discloses a soil improvement method, which realizes soil improvement of the land to be improved after two years, in the first year, the land to be improved is not planted with crops, but still carries out cultivation measures including rotary tillage, fertilization and irrigation; in the rotary tillage process, a natural soil conditioner is used; in the fertilization process, applying an organic fertilizer; in the second year, the land to be improved is planted with green manure crops and organic fertilizer is applied.

CN102823355B discloses a soil improvement method, comprising the following steps: a. crushing the organic materials, and then performing composting fermentation and decomposition to obtain decomposed organic fertilizer; b. thoroughly mixing the decomposed organic fertilizer and the phosphate fertilizer, uniformly spreading the mixture on the leveled ground surface, and turning into soil, wherein the dosage of the decomposed organic fertilizer is 800-1500 kg/mu, and the dosage of the phosphate fertilizer is 50-100 kg/mu.

CN104641753A discloses a soil improving machine and a soil improving method, the soil improving machine includes a frame, a surface soil processing assembly and a deep soil processing assembly arranged on the frame, the surface soil processing assembly includes a surface soil cutting assembly, a surface soil lifting machine and a surface soil conveyer, the surface soil conveyer conveys soil backwards; the deep soil treatment component comprises a deep soil cutting component, a deep soil lifter and a deep soil conveyor, and the deep soil conveyor conveys soil backwards; a deep soil paving plate arranged on the frame and behind the deep soil cutting assembly; a surface soil spreading plate arranged on the frame and behind the deep soil spreading plate; the distance between the bottom of the deep soil cutting assembly and the ground surface is greater than the distance between the bottom of the surface soil cutting assembly and the ground surface, and the distance between the bottom of the surface soil paving plate and the ground bottom is greater than the distance between the deep soil paving plate and the ground bottom. The invention digs out the surface soil and the deep soil in turn, buries the surface soil deeply and the deep soil on the surface soil, and achieves the purpose of changing the soil layer.

CN103718689A discloses a tobacco field soil improvement method, which mainly comprises the steps of adopting deep ploughing and deep soil loosening, alternate crop rotation planting, returning straws to the field, irrigating and improving, reasonably applying fertilizers, developing protective farming, adjusting soil pH value and other measures suitable for tobacco growth, preparing good tobacco growth soil, and achieving the purpose of improving the quality and benefit of tobacco leaves.

CN 106116934a discloses a method for improving acid soil, comprising the following steps: step 1: preparing biomass charcoal and preparing fine-grain mushroom residue by using agricultural and forestry residues; step 2: fully and uniformly mixing the prepared biomass charcoal, mushroom residues and acid soil to obtain a soil mixture; and step 3: and performing biochemical culture on the soil mixture.

CN103828507A discloses a method for improving soil polluted by a snow-melting agent, which comprises uniformly mixing mushroom bran and sepiolite, and paving on the surface of the soil polluted by the snow-melting agent. The soil improved by the method has good air permeability and strong water holding capacity, enhances the soil fertility and adjusts the composition of soluble salt. The modified soil is suitable for the growth of plants, and plays a good role in promoting the growth of green plants.

CN104789226A discloses a biochar-based microbial soil conditioner, which comprises the following components: 80-85 parts by weight of charcoal, 10-13 parts by weight of composite microbial flora and 1-2 parts by weight of oxidized starch adhesive, wherein the strains in the composite microbial flora comprise: photosynthetic bacteria, actinomycetes, lactic acid bacteria, yeast, bacillus subtilis and bacillus thuringiensis.

The influence of local soil improvement combined with short stock intensive cultivation on the updating effect of an old apple orchard, Liangbo Wen and the like, a summary of academic annual meeting treatises in 2014 of Chinese horticulture academy 2014, and the influence of local soil improvement combined with intercropping grass growing, high spindle-shaped shaping trimming and other management measures on the pH value of the soil of the apple orchard after improvement, the soil nutrient condition, the tree growth and the fruit quality and the change of the soil microbial community composition before and after improvement are discussed, so that the method has important guiding significance on the updating and reconstruction of the old apple orchard and the overcoming of continuous cropping obstacles.

However, in the above prior art, the problem of compatibility of biochar with soil is not generally recognized, and the effect of improving the pH of soil is not generally accompanied. There is a need in the art for a soil improvement method that has good compatibility with soil, strong nitrogen fixation and fertility enhancement capability, and can improve the pH of soil.

Disclosure of Invention

In order to solve the problems, the inventor fully researches the soil improvement requirement and the performance of the biochar through intensive research and a large number of experiments, particularly the deterioration reason of the continuous cropping apple orchard soil and the characteristics of the straw carbon, and provides the following technical scheme.

In one aspect of the invention, there is provided a method of soil improvement, the method comprising: scraping surface soil with the thickness of 1-10cm, preferably 3-8cm, from the surface soil of the orchard, mixing the surface soil with a soil conditioner, and then paving the mixture back to the surface of the orchard.

Preferably, the orchard is an old orchard with more than 10 years of continuous cropping. More preferably, the orchard is an old orchard with more than 20 years of continuous cropping.

Further, the content of the soil conditioner is 0.5 to 3.0%, preferably 1.0 to 2.0%, based on the total weight of the surface soil and the soil conditioner.

For the method of the present invention, water is preferably applied 1 time every 5 days, at a field capacity, for 30 days.

Preferably, the soil conditioner comprises biochar, which is biochar derived from straw.

Preferably, the soil amendment comprises a compatilizer.

The soil conditioner also preferably comprises a calcium magnesium phosphate fertilizer.

Preferably, the ratio of the calcium magnesium phosphate fertilizer to the biochar is 1:5-1: 100.

The orchard may be an apple orchard.

Particularly preferably, the soil conditioner comprises biochar and a compatilizer, wherein the weight ratio of the biochar to the compatilizer is 200:1-50:1, and the compatilizer is a compound shown in the following formula (I):

preferably, the biochar is biochar derived from straw, more preferably, the biochar is biochar derived from cotton straw.

The compatilizer contains strong-adsorbability group hydroxyl and ammonium ions, and can be strongly adsorbed on the clay surface and the biochar surface by means of hydrogen bond acting force and positive and negative charge acting force, so that the combination of the clay surface and the biochar is enhanced, and the soil improvement effect is improved. In addition, researches show that the compatilizer also has intercalation effect, can enter soil clay crystal layers to perform intercalation adsorption, and can drain water molecules between the bentonite crystal layers because of containing positive ions and hydroxyl groups capable of forming hydrogen bonds and Van der Waals attractive force with the surface of the bentonite, thereby effectively inhibiting the lattice expansion of the improved soil.

The compatibilizer can be synthesized simply by the following method: weighing triethanolamine, adding into a reaction vessel, introducing nitrogen, heating to the required temperature of 50-80 ℃, adding bromopropylene, keeping the temperature for condensation reflux reaction for 1-6 hours, cooling the reaction system to room temperature, recrystallizing with a mixed solvent of ethyl acetate and absolute ethyl alcohol (volume ratio of 1:3-3: 1) to obtain white powder, and vacuum drying to obtain the finished product of the compatilizer.

The nitrogen atoms in the compatilizer can also be chelated with the polluted heavy metal ions in the soil, so that the heavy metal ions are fixed and prevented from migrating into crops.

Preferably, the soil conditioner further comprises a calcium magnesium phosphate fertilizer. The ratio of the calcium magnesium phosphate fertilizer to the biochar is 1:5-1: 100. The effective phosphorus content (P) of the calcium magnesium phosphate fertilizer₂O₅) Preferably greater than 16.0%.

In the invention, the biochar can also play a role in synergism on the calcium magnesium phosphate fertilizer, can promote the release of water-soluble phosphorus of the calcium magnesium phosphate fertilizer, improves the phosphorus supply capacity of the calcium magnesium phosphate fertilizer, and better meets the requirement of crops on phosphorus absorption.

The biochar is preferably biochar derived from cotton straw. The biochar can be prepared by the following method, which comprises the following steps: (1) cutting cotton stalks into sections, the average length of the sections being 0.5cm to 2cm, preferably 0.5cm to 1.0cm, most preferably 0.8 cm; (2) soaking cotton stalk segments in NH₄Soaking in Cl solution at 50-80 deg.C for 1-5 hr; (3) taking out the soaked cotton straw sections in the step (2), and draining; (4) placing the drained cotton straw sections in a container, introducing steam (also used as steam) with the temperature of 150-; (5) then cooled to room temperature and washed thoroughly with hydrochloric acid solutionWashing the carbonized product, washing with distilled water until the pH of the washing solution is 6-7, and drying to obtain the biochar.

Preferably, the water vapour is free of oxygen.

The water vapour preferably comprises 10-50% by volume of water vapour of nitrogen.

In the process of the invention, the NH₄The Cl solution is an aqueous solution, and the concentration of the Cl solution is 0.1-0.5 mol/L.

Preferably, the temperature of the water vapor is 350 ℃.

The cotton straw and NH₄The mass ratio of the Cl solution is preferably 1:2 to 1: 5.

Optionally and preferably, before the step (1), the method further comprises the step of pretreating the cotton stalks, wherein the pretreatment comprises removing cotton leaves and cotton hulls on the cotton stalks.

The container may be a charring container. The charring vessel is preferably a tube furnace or a tunnel heating vessel.

It is particularly preferred that the water vapor in step (4) contains 5 to 10% by volume of NH based on the volume of the water vapor₃。

Compared with the charcoal prepared by adopting dry distillation (thermal decomposition) or inert gas such as nitrogen as carrier gas for decomposition, the charcoal prepared by the method has rich pore structure due to the high-temperature water vapor with high permeability, relatively low carbonization temperature and short time, and can retain and obtain higher content of organic matters compared with the prior art, so that the biomass charcoal has higher fertilizer efficiency when being used as a soil improvement component.

The pyrolysis and carbonization of the cotton straws means that the cotton straws are pyrolyzed under a certain temperature condition, macromolecular organic matters in the raw materials are heated and then decomposed by controlling the carbonization condition, and finally, solid products, namely biochar and/or other products with high added values are generated. The biochar obtained by the anaerobic high-temperature pyrolysis of the cotton straw has high biochemical decomposition resistance, and can greatly improve the stability of a soil carbon reservoir compared with the condition of directly returning to the field. Therefore, the carbonization of cotton stalks is considered as heavyRequired CO₂Reduce emissions and increase revenue generating ways.

The method can also obtain higher charcoal yield, and the yield of the biochar is 50-70%, preferably 60%. In contrast, in the method of thermal decomposition using nitrogen as a carrier gas, the char yield or char yield was about 40%.

In the existing general biochar preparation, zinc chloride is added as a chemical activating agent. However, the inventor finds that the existing biochar is basically prepared by the activated carbon for adsorption, and if the biomass carbon prepared by the method is used for soil improvement or restoration, undesirable zinc ions can be introduced into soil, and the zinc ions can enter planted crops to further bring harm to human bodies. For this reason, the present inventors have made studies to use NH₄Cl is used as an activating agent, has slightly lower activating effect than zinc chloride, does not bring harm to soil, and residual ammonium can also bring fertility synergy to soil. By NH₄Cl as an activator has not been reported in the prior art.

Compared with the simple steam carbonization, the invention has the advantages that the existence of the nitrogen can improve the heat value of the carbonization medium and the heating efficiency, thereby improving the carbonization efficiency, simultaneously saving the consumption of the steam, and in addition, the required steam partial pressure can be adjusted by adding the nitrogen, so that the process operation is more flexible.

The inventor of the invention also finds that if cotton straws are crushed to be carbonized according to a conventional operation method, the cellulose texture of the cotton straws can be influenced, and further the form and the structure of the prepared biochar can be influenced in the carbonization process. Biochar for soil improvement has different requirements in properties and morphology from activated carbon for other uses such as adsorbents, and studies have found that biochar for soil improvement is not expected to be fully carbonized and may be more effective as a product of incomplete carbonization, in which case both the porosity of the biochar can be delivered to a point and the bionutrients of the biomass such as incompletely carbonized organic matter such as cellulose and the like can be retained. If the cotton straws are crushed and then carbonized, the cotton straws are easily carbonized completely, and the process energy consumption and the cost are increased. When the method of the invention is adopted to carbonize the sectional cotton straws, the carbonization is gradually more sufficient from the center to the outside of the straws, namely, the outer layer of carbon protects the incomplete carbonization product inside, and the advantages of the carbon and the biological nutrient components can be fully combined. Sufficient soil nutrients can be retained even if the obtained product is pulverized. It will be appreciated by those skilled in the art that without the chopping treatment, the impregnation and charring would not be effective, which would be a significant process upset. Studies have shown that segments having an average length of 0.5cm to 2cm, preferably 0.5 to 1.0cm, are most advantageous, above or below which it is difficult to obtain the desired activation or charring effect.

From SEM analysis of the biochar, it can be seen that the carbonized product obtained by the method of the invention retains a certain cellulose form. In addition, the biochar produced had a high surface area as can be seen from its irregular and rough morphology. During the carbonization process, the evaporation of ammonium chloride leaves abundant pores in the biochar.

The biochar is rich in organic carbon, so that the content of the organic carbon in the soil can be increased, the biochar can be kept stable for a long time and is not easily decomposed by microorganisms in a short time after being applied to the soil, most of the organic carbon can be stored, and the nitrogen nutrition consumed by carbon mineralization can be reduced, so that the content of the organic carbon and the total nitrogen in the soil can be obviously increased compared with straw returning, application of pig manure and common carbonized products.

In said step (4), the pressure is preferably 0.1 to 0.5 MPa.

For the purposes of the present invention, draining is essentially the same as draining in the art, meaning that most of the water is drained without affecting subsequent operations.

In a preferred embodiment, the BET specific surface area (S) of the biochar of the invention_BET) 200-1800m²/g, preferably 1400-1800m²/g。

More preferably, the biochar surface of the present invention is enriched in oxygen-containing functional groups. The oxygen-containing functional groups are rich, so that the adsorption capacity and the exchange activity of the biochar can be obviously improved, the cation exchange capacity of soil is increased, the slow release of nutrient substances is promoted, the leaching of nutrients is reduced, and the nutrient utilization rate is improved.

It was found that when NH is introduced into the water vapor₃When the activated carbon is used, the activated carbon can generate nitrogen-containing functional groups through reaction with carbonyl or hydroxyl on the surface of the activated carbon at high temperature, so that the prepared activated carbon can provide good nitrogen elements for soil. The reaction process can be shown by the following equation:

-OH+NH₃→-NH₂+H₂O

by the method, the nitrogen content of the prepared biochar is higher than that of water vapor, and NH is not introduced into the biochar₃The time is 15-30 percent higher.

Apple orchard soil is strongly acidic, with average pH values typically between 4.5 and 5.5, and some years of continuous cropping orchards such as Shandong Xixia some orchards have very strong soils, even below pH 4.5, and have a tendency to decline year by year. The acidification of orchard soil is intensified, which leads to the annual decline of orchard productivity, frequent diseases and the decline of fruit flavor and quality. In the biochar production of the present invention, NH is introduced into water vapor₃The biomass charcoal is strong in alkalinity, and the alkalinity has a slow release effect, namely, the long-term sustainability, so that the pH value of a strong-acid orchard is greatly improved.

Detailed description of the preferred embodiments

As understood by those skilled in the art, the specific surface area of the biochar can be determined according to the standard BET method, and nutrient determination can be performed by methods conventional in soil agrochemical analysis. The pH value of the soil is determined by a composite electrode method according to the ratio of water to soil being 1:3.0, the exchangeable acid is leached by 1.0mol/L potassium chloride solution, and the pH value is determined by an alkali titration method.

Example 1

The cotton straw is taken from Shanghai county of Jinan City, mature cotton straw collected from cotton in the year is taken, leaves and shells are removed without removing side branches, and the cotton straw is stored in a laboratory for ventilation and cool standby. Will be provided withCutting cotton stalk into segments with average length of 0.8cm, soaking the segments in NH₄Soaking in Cl solution at 60 ℃ for 3h, taking out the soaked cotton straws, draining, putting the drained cotton straws in a tubular heater (from the Creutzfeldt-Jakob mechanical company), introducing water vapor with the temperature of 350 ℃ and the pressure of 0.3MPa, heating for 5h, cooling to room temperature, taking out, fully washing the product with 35% hydrochloric acid solution, washing with distilled water until the pH of the washing solution is between 6 and 7, and drying to obtain the biochar. The biochar and the compatilizer shown in the formula (I) are uniformly mixed according to the weight ratio of 150:1 to prepare the soil conditioner.

Example 2

10kg of surface soil 10kg of which the surface soil is 5cm thick and passes through a 2mm sieve in a Mongolian Yin piece continuous cropping apple orchard in 17 years in Shandong province is uniformly mixed with 200g of the soil conditioner obtained in the example 1 and then is paved back to the original place. 2-shoot 10-20 leaf dwarfing stock apple seedlings (from the Baoji Huashengmai Limited liability company) which are similar in growth vigor and pre-cultured for 7 days by using a base fertilizer nutrient solution are selected to be planted in a barrel, 1 plant is fixedly planted in each barrel, the daily management is well done, the culture period is 12 months, and the base fertilizer is 100g of urea, 200g of calcium superphosphate and 50g of potassium sulfate. The pH value of the surface soil is 4.1, the pH value of the surface soil is 4.75 after 45 days of culture, the pH value of the surface soil is 5.01 after 60 days of culture, and the pH value of the surface soil is 5.10 after 90 days of culture.

Comparative example 1

The procedure of example 2 was repeated except that the soil conditioner did not contain the compatibilizer represented by formula (I). The pH value of the surface soil was 4.1, the pH value of the surface soil after 45 days of culture was 4.45, the pH value of the surface soil after 60 days of culture was 4.51, and the pH value of the surface soil after 90 days of culture was 4.55.

At the final harvest, the overall growth of dwarf stock apple seedlings is shown as follows: the apple seedlings with the compatilizer added into the biochar are better than the apple seedlings without the compatilizer, and the average plant height is 40 percent. In addition, when no compatilizer is added, the biochar and the soil are segregated, particularly after watering, the segregation condition is more serious, so that the biochar and the soil cannot be effectively fused, the pH value of the soil cannot be effectively improved, the nutrition accepted by plants is unbalanced, and the growth condition is poor. When the compatilizer is added, the soil and the biochar have good compatibility, so that the pH value effect of the biochar can be continuously and effectively released.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims appended hereto, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. All citations referred to herein are incorporated herein by reference to the extent that no inconsistency is made.

Claims

1. A soil conditioner comprising biochar and a compatibilizer, wherein the weight ratio of biochar to compatibilizer is 150:1, and the compatibilizer is a compound represented by the following formula (I):

the biochar is biochar derived from cotton straws, and is prepared by the following method, wherein the method comprises the following steps: (1) cutting cotton straws into sections, wherein the average length of the sections is 0.5cm-2 cm; (2) soaking cotton stalk segments in NH₄Soaking in Cl solution at 50-80 deg.C for 1-5 hr; (3) taking out the soaked cotton straw sections in the step (2), and draining; (4) placing the drained cotton straw sections in a container, introducing steam with the temperature of 150-; (5) then cooling to room temperature, fully washing the carbonized product with hydrochloric acid solution, washing with distilled water until the pH value of the washing solution is 6-7, and drying to obtain biochar;

when the conditioner is used for improving soil, surface soil with the thickness of 1-10cm on the surface soil of the orchard is scraped, the surface soil and the soil conditioner are mixed, and then the mixture is paved back to the surface of the orchard.

2. A soil amendment according to claim 1, comprising a calcium magnesium phosphate fertilizer.

3. A soil amendment according to claim 2, wherein the ratio of calcium magnesium phosphate to biochar is from 1:5 to 1: 100.

4. A soil amendment according to claim 1, wherein the biochar is prepared such that the water vapour is free of oxygen.

5. A soil amendment according to claim 1, the preparation of biochar, the NH₄The Cl solution is an aqueous solution, and the concentration of the Cl solution is 0.1-0.5 mol/L.

6. A soil amendment according to claim 1, the temperature of the water vapour in the preparation of the biochar is 350 ℃.

7. A soil amendment according to claim 1, the biochar preparation wherein the cotton stalks are mixed with NH₄The mass ratio of the Cl solution is preferably 1:2 to 1: 5.

8. A soil conditioner according to claim 1, wherein said biochar is produced by, prior to step (1), pretreating the cotton stalks by removing cotton leaves and cotton hulls from the cotton stalks.