CN111548223A - Biodegradable light-weight base soil and preparation method thereof - Google Patents

Abstract

The invention discloses biodegradable light base soil and a preparation method thereof, and relates to the field of preparation of nutrient soil. The invention discloses biodegradable lightweight base soil which is composed of base soil, plant fiber, diatomite, zeolite, attapulgite, vermiculite and porous composite material. The biodegradable light barrier soil provided by the invention has the characteristics of plastic molding, light weight, difficult scattering of soil and no environmental pollution, can be used for planting various plants, has excellent water retention and air permeability, meets the reusable requirements of the three-dimensional greening industry, and can also meet the degradable use requirements of mechanical dry soil planting and desertification plant planting.

Description

Biodegradable light-weight base soil and preparation method thereof

Technical Field

The invention belongs to the field of preparation of nutrient soil, and particularly relates to biodegradable lightweight plastic nutrient soil.

Background

The nutrient soil is bed soil which is specially prepared for satisfying the growth and development of seedlings, contains various mineral nutrients, is loose and ventilated, has strong water and fertilizer retention capacity and does not have diseases and insect pests. In order to meet the requirements of flower nursery stock on growth and development, according to different requirements of various varieties on soil, the culture soil which is specially and manually prepared and contains abundant nutrients, has good drainage and air permeability, can preserve moisture and fertilizer, does not crack when being dry, does not stick when being wet and does not crust after being watered is used. Along with global warming and pollution aggravation, the environmental protection consciousness of modern people is enhanced, and then the high-speed development of garden greening and flower seedling industries is driven, how to ensure that the culture soil is not lost and scattered and can be solidified, the water retention capacity of the soil is enhanced, and meanwhile, the ventilation and air permeability of the culture soil are kept, so that the development direction of people is formed.

In recent years, in large and medium-sized cities, greening is performed on high-rise floors such as roofs, artificial slopes, and high-rise wall surfaces in order to promote greening and protect the environment. At present, a common method is to fill nutrient soil in a plastic tray or wrap the plastic tray with non-woven fabrics, and then the whole plant is put on a roof and an artificial slope together with a bag.

The population aging of China is gradually accelerated, the population in rural areas is gradually reduced, the mechanization and scale of agricultural activities are continuously promoted, and the automatic rice transplanter and the rice seedling throwing technology are widely adopted. At present, the seedlings wrapped with culture soil are usually taken out of the plastic mold and placed into an automatic transplanter for planting, but the culture soil of the root system part of the plant is not good in fixing effect and is easy to disperse when collision is received, so that the planting efficiency of the planter is not high. The existing arbor planting base plate technology is the main research direction of the vegetation recovery, the technology can realize the early survival and the subsequent sustainable growth of arbor planting under the condition of not carrying out artificial normalized watering and fertilizing, the survival of single trees is ensured by water-retaining nutrient soil in the base plate, and the groundwater in rock cracks is fully drawn after the root system of the trees enters wet roots at the bottom of the base plate, so that the later-period sustainable growth of the trees is realized. However, the base plate nutrient soil of the technology is easy to disperse during collision in the transplanting process, and the planting efficiency is affected.

The Chinese patent CN105367216B discloses a plastic fiber culture soil and a preparation method thereof, the culture soil can be shaped in a plastic way, the property of easy scattering of soil is changed, and the culture soil has good water holding rate. However, the culture soil contains bi-component hot-melt bonding composite fibers, although the bi-component hot-melt bonding composite fibers can be recycled, the bi-component hot-melt bonding composite fibers belong to non-degradable plastics, the waste materials are easy to cause pollution in the environment, and the environment-friendly culture soil does not accord with the green environmental protection concept advocated at present. The existing biochar cotton is a soilless nutrition pot made of biochar, turf, pearl cotton, imported slow release fertilizer, high molecular polymer and the like, can directly replace basic soil and a container of a potted plant, has the advantages of cleanness, sanitation, high survival rate, convenient management, easy replacement and the like, but has poor water retention effect, can normally plant plants only under the condition of manual normalized watering and fertilizing, is not suitable for planting green plants in a water-deficient environment, contains non-degradable substances in the components, and easily causes pollution in the environment due to abandonment.

Disclosure of Invention

The invention provides biodegradable light barrier soil, which mainly aims at being plastic-molded, light, difficult to scatter and free of environmental pollution, can be used for planting various plants, and has excellent water retention and air permeability so as to meet the reusable requirements of the three-dimensional greening industry and the degradable use requirements of mechanical dry soil planting and desertification plant planting.

In order to realize the purpose of the invention, the invention provides biodegradable lightweight rampart, which comprises 15-30 parts of base soil, 20-40 parts of plant fiber, 10-20 parts of diatomite, 5-10 parts of zeolite, 10-20 parts of attapulgite, 5-10 parts of vermiculite and 5-10 parts of porous composite material by weight, and the preparation method comprises the following steps: the base soil, the plant fiber, the diatomite, the zeolite, the attapulgite, the vermiculite and the porous composite material are stirred and mixed uniformly, then low-temperature sterilization treatment is carried out, and the biodegradable lightweight rampart soil with the required shape is prepared by heating and pressurizing at the temperature of 120-.

Furthermore, the plant fiber is prepared by drying and crushing crop straws, sawdust, algae, bamboo sawdust or leaves and other plants, and the length of the plant fiber is 3-6 mm.

Further, the particle size of the diatomite and the zeolite is 2-4 mm; the particle size of the attapulgite and the vermiculite is 1-3 mm.

Further, the particle size of the porous composite material is 1-3 mm.

Further, the porous composite material is composed of PHB, aliphatic polycarbonate, plant cellulose and polycaprolactone, and the preparation method comprises the following steps:

(1) surface-modified plant cellulose: soaking plant cellulose in 2mol/L NaOH solution and silane impregnant at 50-70 deg.C for 2-3 hr, filtering, and drying to obtain surface modified cellulose;

(2) cellulose/polycaprolactone blend: uniformly mixing the surface modified cellulose and polycaprolactone, and reacting at 80-100 ℃ for 1-2h under the pressure of 5-8MPa to obtain a cross-linked cellulose/polycaprolactone mixture;

(3) porous composite material: first, CO is introduced₂Injecting the mixture into an extruder through a metering pump at a gas injection port on the extruder barrel, exhausting air in the inner cavity of the extruder, and continuously introducing CO₂And then uniformly mixing the cellulose/polycaprolactone mixture, the aliphatic polycarbonate and the PHB, then sending the mixture into an inner cavity of an extruder for mixing for 3-5min, and carrying out extrusion granulation to obtain the porous composite material.

Further, the preparation method of the plant cellulose comprises the following steps: drying plant straw in the sun, pulverizing, hydrolyzing in 50% sulfuric acid solution for 30min, neutralizing with NaOH solution, washing with distilled water to neutrality, and drying to obtain the desired plant cellulose.

Further, in the step (1), the mass ratio of the NaOH solution to the silane impregnant is 1 (2-3).

Further, in the step (2), the mass ratio of the surface-modified cellulose to the polycaprolactone is 1: (3-7).

Further, in the step (3), the mass ratio of the cellulose/polycaprolactone mixture to the aliphatic polycarbonate to the PHB is 2: (0.5-1): (3-6).

Further, in the step (3), the temperature of the inner cavity of the extruder is set to be 80-100 ℃, and the melt pressure at the head of the extruder is 6-10 MPa.

The invention achieves the following beneficial effects:

1. the porous composite material of the invention modifies the plant cellulose, so that the surface modified cellulose and the polycaprolactone can be crosslinked at high temperature and high pressure to prepare the cellulose/polycaprolactone mixture with a three-dimensional network structure. The polycaprolactone has good mechanical property and thermal stability, and also has excellent toughness and compatibility, so that the thermal stability of the porous composite material can be improved, the toughness of cellulose can be improved, and the compatibility with PHB and a soil-barrier matrix can be enhanced.

2. The porous composite material is prepared by blending PHB, aliphatic polycarbonate and a mixture of grafted starch/polycaprolactone, and the PHB and the cellulose/polycaprolactone are cross-linked and blended, so that the thermoplasticity of the porous composite material is further improved, and the porous composite material is processed into finished products in various shapes; the aliphatic polycarbonate and the polycaprolactone with good compatibility enable the components of the porous composite material to have good compatibility, enable the porous composite material to have good compatibility with the earth-building matrix, and are beneficial to the plastic stability of the porous composite material, so that various service performances in earth building are effectively realized.

3. The invention adopts a physical foaming agent CO₂The PHB, the aliphatic polycarbonate and the mixture of the grafted starch/polycaprolactone are foamed in an extruder, the production process is easy to control, and because the components of the porous composite material generate a blend with a network structure in the extruder, the blend is subjected to a physical foaming agent CO₂The porous composite material with large aperture and high porosity is prepared under the action of the (A), so that the porous composite material has light weight per unit volume, and when the porous composite material is combined with the soil-blocking matrix, the weight per unit volume of the soil-blocking matrix is reduced, and the porosity is increased.

4. The plant fiber is from discarded crops, resources are reasonably utilized, the price is low, the length of the plant fiber is set to be 3-6mm, the plant fiber with the size is effectively matched with the granularity of the porous composite material to be subjected to hot melt adhesion, so that a three-dimensional network structure is formed between the plant fiber and the porous composite material, and the plant fiber has good water retention and air permeability.

5. The diatomite has the characteristics of light weight, porosity and strong permeability, and the particle size of the diatomite is combined with other components in the base soil, so that the base soil has better water retention performance, and the porosity of the internal structure of the base soil is optimal; the zeolite is an aqueous alkali metal or alkali metal aluminosilicate mineral, has the characteristics of adsorptivity, ion exchange property and the like, and can provide a required nutrient medium for plants; the attapulgite enables the subsoil to have excellent adsorbability, plays a role in deinsectization and sterilization and provides essential trace elements for plant growth; the vermiculite has light weight, good ventilation, water retention and water permeability, has high cation replacement amount, and can provide required nutrition for plants and maintain good water retention rate.

6. The melting temperature and the decomposition temperature of the components of the porous composite material are not greatly different, and the thermal decomposition temperature of the aliphatic polycarbonate is lower, so that the processing temperature requirement is strict during the plastic soil-blocking heating treatment, and the temperature is generally controlled to be between 120 ℃ and 140 ℃, thereby being beneficial to the better bonding effect between the porous composite material and the components of the soil-blocking, and the porous composite material can not generate thermal decomposition; the porous composite material can be completely decomposed by environmental microorganisms, is combined with various components of the base soil, is naturally degraded in a certain time and under certain conditions, and cannot burden the natural environment.

7. The porous composite material can be fused with a soil-barrier matrix, and is prepared by blending the porous composite material with modified cellulose by mainly utilizing the processability and forming characteristics of PHB, polycaprolactone and aliphatic polycarbonate. Due to the existence of the modified cellulose and the porous structure of the foaming treatment, the composite material has excellent water retention; the porous structure of the invention can be uniformly combined with each component of the soil, is not easy to form balls, and forms good plant growth pores.

8. The base soil has good water holding performance, no water-retaining agent needs to be added, the cost is saved, the environmental burden is reduced, and the original curing structure of the base soil is ensured.

9. The base soil can be solidified and molded, so that the problems of soil scattering and water washing loss are solved, and basic nutrient substances in the base soil required by plants are guaranteed; the soil-building agent has the characteristics of light soil-building weight, good construction curing property, good water retention property and the like, can realize ecological environment restoration such as three-dimensional greening, high-rise greening engineering, desertification and the like, and does not pollute the environment; after the small seedlings are wrapped by the base soil, the drought soil can be mechanically planted in the soil without recovery, and the drought soil can be degraded by microorganisms in the soil, so that the environment is not polluted, and the greening and environment-friendly effects are realized.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The following examples are provided to observe and calculate the physical properties of the biodegradable lightweight base soil according to the present invention, such as porosity, water retention, plant growth conditions, base soil stability, pH value, and soil particle composition.

1. And (3) measuring the porosity of the light barrier soil: the pore structure of the soil is a containing space for water and air in the soil and also a living space for plant roots, and is an important index of the growth condition of plants.

The soil porosity is the percentage of the soil void volume in the soil volume, and the formula is as follows: the soil porosity (%) (1-volume weight/specific gravity) is 100%, and the volume weight refers to the ratio of the weight of naturally dry soil to the weight of water with the same volume in a unit volume (including a void volume); the specific gravity is a ratio of the weight of solid soil particles (soil particle bodies excluding voids) per unit volume to the weight of water of the same volume.

2. Measurement of Water holding Property: and soaking the rampart blocks in water for 30min to make the rampart blocks fully absorb water, taking out until no free water flows out, weighing, and weighing after 5 hours. And (3) putting the soil sample in an oven at 105 +/-2 ℃ and drying to constant weight, so that the contained water (including hygroscopic water) is completely evaporated, and the water content of the soil is calculated. The concrete steps refer to the operation of the soil moisture determination method according to GB 7172-.

3. And (3) observing the growth condition of the plants: in each of examples and comparative examples, the growth of seedlings was observed 30 days after cucumber sowing.

The seedlings of the planted cucumber are strong in diameter and difficult to pull up, leaves are flourishing and emerald green, and the mark is good; the cucumber seedlings are strong and difficult to pull up and fall, and the leaves are in a common state and are marked as good; the cucumber seedlings are small and easy to pull up and pour, and the leaf state is general and is marked as general; others are noted as poor.

4. The pH value is measured: and (3) crushing a small amount of rampart soil blocks, uniformly stirring the crushed rampart soil blocks in distilled water, fully dissolving the crushed rampart soil blocks, soaking the pH test paper in the distilled water, observing the color change of the pH test paper, and comparing the color change of the pH test paper with the corresponding number of a standard color comparison card when the color of the pH test paper is basically stable and unchanged, so as to accurately read out the teaching characters of the pH value of the soil.

5. And (3) observing the stability of the plant growth soil: and (5) observing the integrity of the root block of the seedling when the seedling is picked up 30 days after the cucumber is planted.

Easy extraction, no scattering of the earth building blocks, and marked as 4; easy extraction, the part of the rampart is scattered and is marked as 3; difficult extraction, the stacking blocks are scattered and marked as 2; the soil blocks could not be extracted and scattered completely like gravel, and are marked as 1.

6. Determination of soil particle composition: the soil is composed of granules with different grain sizes, and the relative content of the granules in each grain size, namely the granules, has profound influence on the water, heat, fertilizer and gas conditions of the soil. Soil particle analysis is to determine the particle composition of soil and to determine the texture type of soil. The test uses a method for measuring texture by hand, and the test is carried out according to the national standard GB7845-1987 determination and classification standard of forest soil particle composition (mechanical composition) (table below).

TABLE 1 soil particle grading Standard

The porous composite material consists of biodegradable polymer, polycaprolactone, starch and cellulose, and the preparation method comprises the following steps:

1) drying plant straw in the sun, pulverizing, hydrolyzing in 50% sulfuric acid solution for 30min, neutralizing with NaOH solution, washing with distilled water to neutrality, and drying to obtain plant cellulose.

2) Surface-modified plant cellulose: soaking the plant cellulose in 2mol/L NaOH solution and silane impregnant for 2-3h at 50-70 ℃, filtering and drying to obtain surface modified cellulose; wherein the mass ratio of the NaOH solution to the silane impregnant is 1 (2-3).

3) Cellulose/polycaprolactone blend: uniformly mixing the surface modified cellulose and polycaprolactone, and reacting at 80-100 ℃ for 1-2h under the pressure of 5-8MPa to obtain a cross-linked cellulose/polycaprolactone mixture; wherein the mass ratio of the surface modified cellulose to the polycaprolactone is 1: (3-7).

4) Porous composite material: first, CO is introduced₂Injecting the mixture into an extruder through a metering pump at a gas injection port on the extruder barrel, exhausting air in the inner cavity of the extruder, and continuously introducing CO₂And then uniformly mixing the cellulose/polycaprolactone mixture, the aliphatic polycarbonate and the PHB, then sending the mixture into an inner cavity of an extruder for mixing for 3-5min, setting the temperature of the inner cavity of the extruder to be 80-100 ℃, setting the melt pressure at the head of the extruder to be 6-10MPa, and carrying out extrusion granulation to obtain the porous composite material a1 fused with the base material of the base soil. Wherein the mass ratio of the cellulose/polycaprolactone mixture to the aliphatic polycarbonate to the PHB is 2: (0.5-1): (3-6).

In the porous composite material of the subsequent embodiment or the comparative example of the present invention, the mass ratio of the NaOH solution to the silane impregnant in step 2) is 1: 2; the mass ratio of the surface modified cellulose to the polycaprolactone in the step 3) is 1: 5; in the step 4), the mass ratio of the cellulose/polycaprolactone mixture to the aliphatic polycarbonate to the PHB is 2: 1: 5.

the base soil in the biodegradable lightweight base soil component of the present invention may be loess as in the following examples and comparative examples, or may be sterilized garden soil.

Example 1: preparation of biodegradable lightweight base soil A1

(1) Drying and crushing straws in the sun to prepare plant fiber powder with the length of 4mm, then mixing 30 parts of the plant fiber powder, 20 parts of loess, 15 parts of diatomite, 5 parts of zeolite, 15 parts of attapulgite, 8 parts of vermiculite and 7 parts of the porous composite material, and stirring uniformly.

(2) And (2) performing low-temperature sterilization treatment on the base material mixed and configured in the step (1), heating at 160-170 ℃ for 5min, and performing film pressing molding on the plastic base soil by using a pressing device to obtain a plastic base soil block A1. And then the porosity, water retention, plant growth condition, soil-setting stability, pH value and soil particle composition of the plastic soil-setting block are detected according to the test method, and the detected result is shown in table 2.

Example 2: preparation of biodegradable lightweight base soil A2

The preparation method of A2 is the same as A1 in example 1, the specific steps refer to example 1, and the soil-blocking base material in A2 comprises 40 parts of plant fiber powder, 15 parts of loess, 10 parts of diatomite, 5 parts of zeolite, 15 parts of attapulgite, 8 parts of vermiculite and 7 parts of porous composite material. The results are shown in Table 2.

Example 3: preparation of biodegradable lightweight base soil A3

The preparation method of A3 is the same as A1 in example 1, the specific steps refer to example 1, and the soil-blocking base material in A3 comprises 20 parts of plant fiber powder, 30 parts of loess, 15 parts of diatomite, 5 parts of zeolite, 15 parts of attapulgite, 110 parts of vermiculite and 7 parts of porous composite material. The results are shown in Table 2.

Example 4: preparation of biodegradable lightweight base soil A4

The preparation method of A4 is the same as A1 in example 1, the specific steps refer to example 1, and it is noted that the plant fiber powder is straw sun-dried powder with the length of 3 mm. The results are shown in Table 2.

Example 5: preparation of biodegradable lightweight base soil A5

The preparation method of A5 is the same as A1 in example 1, the specific steps refer to example 1, and it is noted that the plant fiber powder is straw sun-dried powder with the length of 6 mm. The results are shown in Table 2.

Comparative example 1: preparation of culture soil B1

The preparation method of B1 is the same as A1 in example 1, the concrete steps refer to example 1, and it is noted that the plant fiber powder is straw sun-dried powder with the length of 2 mm. The results are shown in Table 2.

Comparative example 2: preparation of culture soil B2

The preparation method of B2 is the same as A1 in example 1, the concrete steps refer to example 1, and it is noted that the plant fiber powder is straw sun-dried powder with the length of 7 mm. The results are shown in Table 2.

Comparative example 3: preparation of culture soil B3

The preparation method of B3 is the same as A1 in example 1, the concrete steps refer to example 1, and the mixture ratio of the culture soil base material in B3 is 0 part of plant fiber powder, 30 parts of loess, 35 parts of diatomite, 5 parts of zeolite, 12 parts of attapulgite, 10 parts of vermiculite and 8 parts of porous composite material. The results are shown in Table 2.

Comparative example 4: preparation of culture soil B4

The preparation method of B4 is the same as A1 in example 1, the concrete steps refer to example 1, and the mixture ratio of the culture soil base material in B4 is 30 parts of plant fiber powder, 20 parts of loess, 15 parts of diatomite, 5 parts of zeolite, 15 parts of attapulgite, 8 parts of vermiculite and 0 part of porous composite material. The results are shown in Table 2.

TABLE 2 TABLE OF TEST RESULTS OF EXAMPLES 1-5 AND COMPARATIVE EXAMPLES 1-4

As can be seen from Table 2, the culture soil has no plastic forming property without adding the biodegradable composite material, and the plant fiber powder has great influence on the void structure of the plastic soil, and the larger the adding amount of the plant fiber powder is, the porosity is correspondingly increased, and the stability of plant growth is reduced. When the length of the plant fiber powder is between 3 and 6mm, the comprehensive performance of the plastic soil is optimal, and the plant fiber powder is most suitable for biological growth.

In the invention, the particle size of the diatomite is 3mm, the particle size of the zeolite is 2-4mm, the particle size of the attapulgite and the vermiculite is 1-3mm, and the particle size of the porous composite fiber is 1-3mm in examples 1-5 and comparative examples 1-4.

The following examples are the effect on the content of components in the base soil material on the plastic base soil.

Example 6: preparation of biodegradable lightweight base soil A6

The preparation method of A6 is the same as A1 in example 1, the specific steps refer to example 1, and the soil-blocking base material in A6 comprises 30 parts of plant fiber powder, 23 parts of loess, 10 parts of diatomite, 5 parts of zeolite, 15 parts of attapulgite, 10 parts of vermiculite and 7 parts of porous composite material. The results are shown in Table 3.

Example 7: preparation of biodegradable lightweight base soil A7

The preparation method of A7 is the same as A1 in example 1, the specific steps refer to example 1, and the soil-blocking base material in A7 comprises 30 parts of plant fiber powder, 18 parts of loess, 20 parts of diatomite, 5 parts of zeolite, 15 parts of attapulgite, 5 parts of vermiculite and 7 parts of porous composite material. The results are shown in Table 3.

Example 8: preparation of biodegradable lightweight base soil A8

The preparation method of A8 is the same as A1 in example 1, the specific steps refer to example 1, and the soil-blocking base material in A8 comprises 30 parts of plant fiber powder, 25 parts of loess, 15 parts of diatomite, 5 parts of zeolite, 10 parts of attapulgite, 8 parts of vermiculite and 7 parts of porous composite material. The results are shown in Table 3.

Example 9: preparation of biodegradable lightweight base soil A9

The preparation method of A9 is the same as A1 in example 1, the specific steps refer to example 1, and the soil-blocking base material in A9 comprises 30 parts of plant fiber powder, 20 parts of loess, 10 parts of diatomite, 5 parts of zeolite, 20 parts of attapulgite, 8 parts of vermiculite and 7 parts of porous composite material. The results are shown in Table 3.

Example 10: preparation of biodegradable lightweight base soil A10

The preparation method of A10 is the same as A1 in example 1, the specific steps refer to example 1, and the soil-blocking base material in A10 comprises 30 parts of plant fiber powder, 15 parts of loess, 15 parts of diatomite, 10 parts of zeolite, 15 parts of attapulgite, 8 parts of vermiculite and 7 parts of porous composite material. The results are shown in Table 3.

Example 11: preparation of biodegradable lightweight base soil A11

The preparation method of A11 is the same as A1 in example 1, the specific steps refer to example 1, and the soil-blocking base material in A11 comprises 30 parts of plant fiber powder, 22 parts of loess, 15 parts of diatomite, 5 parts of zeolite, 15 parts of attapulgite, 8 parts of vermiculite and 5 parts of porous composite material. The results are shown in Table 3.

Example 12: preparation of biodegradable lightweight base soil A12

The preparation method of A12 is the same as A1 in example 1, the specific steps refer to example 1, and the soil-blocking base material in A12 comprises 30 parts of plant fiber powder, 17 parts of loess, 15 parts of diatomite, 5 parts of zeolite, 15 parts of attapulgite, 8 parts of vermiculite and 10 parts of porous composite material. The results are shown in Table 3.

Comparative example 5: the invention patent CN105367216B discloses a plastic fiber culture soil, which is an active fiber block B5 prepared in the embodiment example 1. The obtained activated fiber block B5 was subjected to the test items and methods as described in example 1, and the test results are shown in Table 3.

TABLE 3 TABLE of test results of examples 6 to 12 and comparative example 5

The detection results in table 3 show that the optimal ratio of the plastic barrier soil is 20 parts of plant fiber powder, 30 parts of loess, 15 parts of diatomite, 5 parts of zeolite, 12 parts of attapulgite, 10 parts of vermiculite and 8 parts of porous composite material, and the plastic barrier soil of the ratio has the best comprehensive properties and is the optimal growth soil of cucumber. According to different types of plants, the content of the plastic rampart components can be properly changed to obtain the optimal growth state of the plants.

Example 13: preparation of biodegradable lightweight base soil A13

A13 was prepared in the same manner as A1 in example 1, except that the process was as described in example 1, except that the diatomaceous earth had a particle size of 2 mm. The results are shown in Table 4.

Example 14: preparation of biodegradable lightweight base soil A14

A14 was prepared in the same manner as A1 in example 1, except that the process was as described in example 1, except that the diatomaceous earth had a particle size of 4 mm. The results are shown in Table 4.

Comparative example 6: culture soil B6

The preparation method of B6 is the same as A1 in example 1, the concrete steps refer to example 1, and the particle size of diatomite is 1 mm. The results are shown in Table 4.

Comparative example 7: culture soil B7

The preparation method of B7 is the same as A1 in example 1, the concrete steps refer to example 1, and the particle size of diatomite is 5 mm. The results are shown in Table 4.

TABLE 4 TABLE of test results of examples 13 to 14 and comparative examples 6 to 7

		A1	A13	A14	B6	B7
							Diatomite	Particle size (mm)	3	2	4	1	5
Porosity of	％	63	55	60	50	51
							Water binding capacity	％	35	32	36	27	25
pH value	pH value	6.5	6.6	6.8	6.4	7.0
							Growth status of plants	/	Is very good	Good taste	Good taste	In general	In general
Stability of	/	4	3	3	3	2
							Soil particle grade	/	Powder particle	Powder particle	Powder particle	Sticky particle	Coarse powder particles

The detection results in table 4 show that the particle size of the diatomite has a certain influence on the pore structure and the water retention of the light barrier soil, and the excessively large or small particle size of the diatomite is not beneficial to the stability of the light barrier soil, and the comparative analysis shows that the light barrier soil can better meet the requirement of plant growth when the particle size of the diatomite is controlled to be 2-4 mm.

It is noted that the preparation method of the base soil of the invention can also be as follows: uniformly stirring and mixing the base soil, the plant fiber, the diatomite, the zeolite, the attapulgite, the vermiculite and the porous composite material, performing low-temperature sterilization treatment, adding sufficient water to enable the mixture to be in a fully saturated water absorption state, and heating and pressurizing at the temperature of 120-. The water is added in the processing process, and the formation of a three-dimensional network structure is more easily facilitated through the water evaporation process, so that the porous material has higher porosity and is beneficial to the growth of plants.

In the case of seeding in the subsoil, seeding is generally performed after the subsoil is subjected to heat treatment (i.e., the porous composite material and other ingredients of the subsoil are heated and melted). The base soil can be used for sowing and can also be used for cuttage.

The soil-building curing and forming method has the following plants suitable for planting: watermelon, towel gourd, pepper, grape, lily, peony, chrysanthemum, rose, eggplant, kidney bean, balsam pear, sweet osmanthus, rose and the like, and the content of the ingredients of the base soil can be changed according to different nutrients required by plants.

The biodegradable light-weight base soil has the characteristics of solidification forming and biodegradation, has excellent water retention performance and ventilation property, is beneficial to plant growth, can be applied to the fields of three-dimensional greening and environmental restoration, and can also be applied to roof greening, wall greening and desertification control. The light base soil can be recycled and can be biodegraded in the environment, so that the environment is not polluted, and the environment is greened and protected.

The technical features of the embodiments described above can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.

Claims (10)

1. The biodegradable lightweight rampart is characterized by comprising 15-30 parts of foundation soil, 20-40 parts of plant fiber, 10-20 parts of diatomite, 5-10 parts of zeolite, 10-20 parts of attapulgite, 5-10 parts of vermiculite and 5-10 parts of porous composite material in parts by weight, and the preparation method comprises the following steps: the base soil, the plant fiber, the diatomite, the zeolite, the attapulgite, the vermiculite and the porous composite material are stirred and mixed uniformly, then low-temperature sterilization treatment is carried out, and the biodegradable lightweight rampart soil with the required shape is prepared by heating and pressurizing at the temperature of 120-.

2. The biodegradable lightweight rampart soil according to claim 1, wherein the plant fiber is prepared by drying crop straw, wood chips, algae, bamboo chips or leaves in the sun and pulverizing, and the length of the plant fiber is 3-6 mm.

3. The biodegradable lightweight barrier soil according to claim 1, wherein the particle size of said diatomaceous earth and zeolite is 2-4 mm; the particle size of the attapulgite and the vermiculite is 1-3 mm.

4. The biodegradable lightweight earth as claimed in claim 1, wherein the particle size of said porous composite material is 1-3 mm.

5. The biodegradable lightweight rampart according to claim 4, wherein said porous composite material is composed of PHB, aliphatic polycarbonate, plant cellulose and polycaprolactone, and the preparation method comprises the following steps:

(1) surface-modified plant cellulose: soaking plant cellulose in 2mol/L NaOH solution and silane impregnant at 50-70 deg.C for 2-3 hr, filtering, and drying to obtain surface modified cellulose;

(2) cellulose/polycaprolactone blend: uniformly mixing the surface modified cellulose and polycaprolactone, and reacting at 80-100 ℃ for 1-2h under the pressure of 5-8MPa to obtain a cross-linked cellulose/polycaprolactone mixture;

(3) porous composite material: first, CO is introduced₂Injecting the mixture into an extruder through a metering pump at a gas injection port on the extruder barrel, exhausting air in the inner cavity of the extruder, and continuously introducing CO₂And then uniformly mixing the cellulose/polycaprolactone mixture, the aliphatic polycarbonate and the PHB, then sending the mixture into an inner cavity of an extruder for mixing for 3-5min, and carrying out extrusion granulation to obtain the porous composite material.

6. The biodegradable lightweight rampart soil according to claim 5, wherein said plant cellulose is prepared by the following steps: drying plant straw in the sun, pulverizing, hydrolyzing in 50% sulfuric acid solution for 30min, neutralizing with NaOH solution, washing with distilled water to neutrality, and drying to obtain the desired plant cellulose.

7. The biodegradable lightweight rampart as claimed in claim 5, wherein in the step (1), the mass ratio of the NaOH solution to the silane impregnant is 1 (2-3).

8. The biodegradable lightweight rampart soil according to claim 5, wherein in the step (2), the mass ratio of the surface-modified cellulose to the polycaprolactone is 1: (3-7).

9. The biodegradable lightweight rampart according to claim 5, wherein in said step (3), the mass ratio of said cellulose/polycaprolactone mixture, aliphatic polycarbonate and PHB is 2: (0.5-1): (3-6).

10. The biodegradable lightweight rampart as set forth in claim 5, wherein in the step (3), the temperature of the inner cavity of the extruder is set to 80-100 ℃, and the melt pressure at the head of the extruder is 6-10 MPa.