A method for planting garden greening plants based on carbonization modification of agricultural and forestry wastes

Abstract

The application discloses a kind of based on agroforestry waste carbonization modification garden greening plant planting method, it is related to garden greening planting technical field, comprising the following steps: step one, raw material classification pretreatment: selecting agroforestry waste, it is divided into three groups according to lignocellulose composition: high lignin group, medium lignin group and high silicon hemicellulose group;Step two, oxygen-limited gradient pyrolysis carbonization: the mixed feed obtained in step one is loaded into pyrolysis carbonization device, and temperature treatment is carried out under inert atmosphere or oxygen-limited atmosphere, and the discharge is obtained, to obtain crude biochar;Meanwhile, when using, by carbonization material is divided into coarse grain grade (8-20mm), medium grain grade (2-8mm) and fine powder grade (<2mm) according to particle size, and is respectively used for bottom drainage cushion layer, rhizosphere contact layer, backfill layer and surface cover layer, four layers each play its own role, fundamentally solve the function conflict problem caused by single particle size, single layer laying in prior art, significantly improve seedling survival rate and growth.

Description

Technical Field

[0001] This invention relates to the field of landscaping planting technology, specifically a method for planting landscaping plants based on the carbonization modification of agricultural and forestry waste. Background Technology

[0002] With the acceleration of urbanization, the planting of landscaping plants faces prominent problems such as soil compaction, poor drainage, poor water and fertilizer retention capacity, and low survival rates. Existing technologies have attempted to apply biochar or carbonized wood to planting substrates, for example, by simply mixing biochar into backfill soil or laying it as a salt barrier layer at the bottom of tree pits. However, these methods generally have the following shortcomings: 1. Most existing technologies involve mixing biochar into the soil or laying it in a single layer using a single particle size and method, failing to utilize and construct it in layers according to the physical characteristics of different particle sizes of biochar (such as the skeletal drainage function of coarse particles, the adsorption and slow release function of medium particles, and the moisture retention and covering function of fine powder). This leads to conflicts between the functions of drainage, aeration, water retention, and slow release of nutrients in the tree pit, making it impossible to synergistically optimize the rhizosphere environment. For example, simply mixing in biochar can improve porosity in the short term, but long-term use can easily cause the char powder to settle and block drainage channels, or the water-retaining layer and drainage layer to become confused, weakening the overall effect.

[0003] 2. Existing technologies often mix various agricultural and forestry wastes (such as branches, sawdust, and straw) and carbonize them uniformly, ignoring the significant differences in their lignin, hemicellulose, and ash composition. This results in unstable pore structures, low specific surface areas, and a lack of surface functional groups in the carbonized products. Furthermore, the lack of effective surface modification methods (such as acid-base pore expansion, nutrient loading, and bio-inoculation) means that the carbonized material is used only as an inert filler, failing to fully realize its potential as an adsorbent carrier, slow-release fertilizer carrier, and microbial carrier. Summary of the Invention

[0004] To address the shortcomings mentioned in the background art, the present invention aims to provide a method for planting garden greening plants based on the carbonization modification of agricultural and forestry waste.

[0005] The objective of this invention can be achieved through the following technical solutions: A method for planting landscaping plants based on carbonization modification of agricultural and forestry waste includes the following steps: Step 1: Raw material classification and pretreatment: Select agricultural and forestry waste and divide it into three groups according to its lignocellulose composition: high lignin group, medium lignin group and high silica hemicellulose group; The three groups of raw materials were dried to a moisture content of ≤15wt%, weighed in a mass ratio of (2-4):(1-3):(1-2), and mixed evenly to obtain a mixed feed. Step 2, oxygen-limited gradient pyrolysis carbonization: The mixed feed obtained in Step 1 is loaded into the pyrolysis carbonization device and heated under an inert atmosphere or an oxygen-limited atmosphere. The feed is then discharged to obtain crude biochar. Step 3: Grading and screening of carbonized material: The coarse biochar obtained in Step 2 is mechanically crushed and screened into three grades: coarse grade with a particle size of 8-20 mm; medium grade with a particle size of 2-8 mm; and fine powder grade with a particle size of <2 mm. Step 4: Surface modification treatment: Take the medium-particle and fine-powder grades from the three grades obtained in Step 3 and perform modification treatment; Step 5: Layered Construction and Planting of Tree Pit: Excavate the tree pit according to the design specifications, and construct the planting pit layer by layer from bottom to top: ① Bottom drainage layer: Lay coarse-grained or a mixture of coarse-grained and 5-20mm graded crushed stone, with a thickness of 8-18cm. When the groundwater level is high or there is water accumulation on the site, blind pipes or drainage gravel ditches should be installed at the bottom or side of the subbase. ② Rhizosphere contact layer: Mix medium-sized modified carbonized material with garden soil and decomposed organic fertilizer in a volume ratio of (15-35): (60-75): (5-15) to form a root zone matrix. Backfill the root zone matrix to the bottom of the planting hole and construct a planting mound or planting bed that is 10-25cm higher than the top surface of the bedding layer. Place the seedlings in the mound, so that the root collar of the seedlings is slightly higher than the surrounding ground surface by 2-5cm. ③ Backfill layer: Mix the fine-powder modified carbonized material with the original excavated soil in a volume ratio of: fine-powder modified carbonized material: original soil = (5-15): (85-95), and backfill in layers. Each backfill layer should be 15-20cm thick and lightly compacted to a relative compaction degree of 70-85%. Backfill to 3-8cm above the top of the soil ball. ④ Surface coating layer: A mixture of fine-powdered modified carbonized material and organic mulch is laid on the surface of the tree pit, with a covering thickness of 3-6cm, leaving a 5-10cm bare ring from the base of the trunk. Step Six: Root establishment and post-planting care.

[0006] Furthermore, the agricultural and forestry waste mentioned in step one originates from fruit tree pruning, street tree pruning, forest tree pruning, wood processing sawdust, shavings, wheat straw, rice straw, corn straw, or a combination thereof; the drying method is selected from one of natural sun drying, airflow drying, or chamber drying.

[0007] Furthermore, the inert atmosphere mentioned in step two is nitrogen or carbon dioxide, and the oxygen-limiting atmosphere maintains the oxygen concentration at 0.5-5 vol% by controlling the inlet flow rate; the first stage of the two-stage heating has an end temperature of 220-280℃ and is held for 30-50 min, the second stage has an end temperature of 460-580℃ and is held for 90-150 min; the outlet temperature of the volatile matter throughout the pyrolysis process is controlled at ≤120℃; In step two, the volatiles produced by pyrolysis are condensed and separated to recover the wood vinegar. After the recovered wood vinegar is allowed to stand and separate into layers, the middle clear liquid is taken and reused as a raw material for foliar fertilizer dilution. The heating process described in step two is a two-stage process. In the first stage, the temperature is raised from room temperature to 200-300℃ at a rate of 5-15℃ / min and held for 20-60min. In the second stage, the temperature is raised to 420-620℃ at a rate of 3-10℃ / min and held for 60-180min. After the pyrolysis is completed, the temperature is cooled to ≤60℃ under an inert atmosphere.

[0008] Furthermore, the surface modification treatment in step four is selected from one or more combinations of the following three methods; Method 1: Acid-base pore-expanding activation: The carbon powder is immersed in an activation solution, which is selected from one of the following: 0.5-3.0 mol / L H3PO4 aqueous solution, 0.5-2.5 mol / L KOH aqueous solution, or 0.2-1.0 mol / L ZnCl2 aqueous solution, with a liquid-to-solid mass ratio of (3-8):1. The immersion time is 2-8 h, then the powder is removed, dried at 80-105℃, calcined twice at 350-500℃ for 30-90 min, washed until neutral, and then dried again to obtain activated modified carbonized material. Method 2: Nutrient Loading The carbon powder is brought into contact with a loading liquid containing potassium humate, seaweed extract or amino acid water-soluble fertilizer, with a total dissolved organic matter concentration of 10-80 g / L and a liquid-to-solid mass ratio of (2-6):1. The mixture is soaked for 1-6 hours, and then dried at 60-90℃ to obtain nutrient-loaded modified carbonized material. Method 3: Biological inoculation: The charcoal powder and the fungal agent suspension are mixed evenly. The fungal agent suspension contains one or more of the following: arbuscular mycorrhizal fungi, PGPR root-promoting bacteria, or Trichoderma, with an effective viable count ≥1×10⁻⁶. 7 CFU / g carbon, after mixing, is allowed to stand at 25-35℃ in the dark for 12-48h to obtain bio-inoculated modified carbonized material; The surface modification treatment described in step four includes the combination of method one (acid-base pore-expansion activation) and method two (nutrient loading) in the following order: First, medium-sized or fine-sized carbon powder is impregnated in 0.8-2.0 mol / L H3PO4 solution at a liquid-to-solid mass ratio of (4-6):1 for 3-6 hours. After drying at below 105℃, it is calcined again at 380-450℃ for 40-70 minutes. After cooling, it is washed with deionized water until the pH of the washing solution is 6.5-8.0. After drying again, activated carbon is obtained. Then, the activated carbon is impregnated in a loading solution containing 15-40 g / L potassium humate for 2-4 hours and dried at 60-80℃ to obtain modified carbonized material with both high specific surface area and nutrient slow-release function.

[0009] Furthermore, in step five, the diameter of the tree pit is the diameter of the seedling root ball plus 40-80cm, and the depth of the tree pit H = the height of the root ball h plus (20-40)cm. In the bottom drainage cushion layer of step five, the volume ratio of the coarse-grained grade to the graded crushed stone is (3-7):(7-3), the porosity of the coarse-grained grade is ≥55%, and the net distance between the top surface of the cushion layer and the groundwater level is ≥30cm. When the depth of the groundwater level is <50cm, a perforated drainage pipe is pre-embedded in the cushion layer and connected to the collection well or municipal storm drain.

[0010] Furthermore, in step five, the ② rhizosphere contact layer, the decomposed organic fertilizer is selected from one or more of decomposed cow and sheep manure, decomposed garden compost, or earthworm castings, with an organic matter content ≥30wt%, the total porosity of the rhizosphere matrix ≥50%, the aeration porosity ≥18%, and the pH is 6.5-8.0.

[0011] Furthermore, in step five, ④, the volume ratio of fine-powder modified carbonized material to organic mulch is (1-3):(7-9), the apparent dry bulk density of the mulch is 0.15-0.35 g / cm³, and a 5-10 cm wide breathable weed-proof film or gravel is laid within the exposed area to prevent the mulch from adhering to the tree trunk and causing trunk rot.

[0012] Furthermore, in step six, the root establishment and post-planting maintenance involve constructing an irrigation weir after backfilling, thoroughly watering the roots once, with the amount of water determined so that the soil volumetric water content at a depth of 15-30cm in the root zone reaches 80-95% of the field capacity; during the maintenance period of 7-21 days after planting, apply liquid organic fertilizer or water-soluble fertilizer 1-3 times, with the total amount of fertilizer applied not exceeding 70% of the amount of fertilizer applied in conventional field planting; thereafter, the surface covering layer is replenished every 4-8 months with a 1-2cm thick layer of fine powder carbonized material, depending on the amount of loss. After thoroughly watering the roots, check the water accumulation in the planting hole 24 hours later. If the water depth is >3cm and does not recede within 12 hours, add a vertical drainage gravel column to the side wall of the planting hole, connecting to the blind pipe of the bedding layer or a new water collection ditch, or add a water pipe at the bottom of the planting hole to drain the water to the surrounding drainage system.

[0013] Furthermore, it can be applied to one or more of the following scenarios: Tree planting in urban road green belts, park green spaces, tree pits in gaps in hard paving, tree planting in rooftop or elevated greening areas where the load-bearing capacity is permissible, and green space renovation in saline-alkali areas. Furthermore, when applied to saline-alkali areas, a 5-10cm thick medium-fine sand transition layer or geotextile filter layer is added above the bottom drainage cushion layer in step five. After the surface modification treatment in step four, iron or magnesium salt impregnation modification is further carried out and heat treatment at 150-300℃, so that iron or magnesium is loaded on the carbon surface in the form of hydrated oxides for anion adsorption enhancement treatment.

[0014] The beneficial effects of this invention are: 1. This invention classifies carbonized material into coarse-grained (8-20mm), medium-grained (2-8mm), and fine-powdered (<2mm) grades according to particle size, and uses them respectively for bottom drainage layer, root contact layer, backfill layer, and surface covering layer. This solves the functional conflict problem caused by single particle size and single-layer laying in the prior art, and significantly improves the survival rate and growth of seedlings.

[0015] 2. This invention categorizes agricultural and forestry waste into high-lignin, medium-lignin, and high-silica hemicellulose groups based on their lignocellulose composition, and then performs compound pyrolysis on these groups. This results in carbonized products possessing a high-strength skeleton, abundant mesopores, and a suitable amount of ash. Furthermore, the medium-particle and fine-powder grades undergo modification treatments such as acid-base pore-expansion activation, nutrient loading, or biological inoculation. This transforms the carbonized material from an inert filler into a functional medium that actively regulates rhizosphere water, fertilizer, and air, overcoming the limitation of single-function carbonized materials in existing technologies. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1 This is a cross-sectional view of the layered structure of the tree pit in this invention.

[0018] Figure 2 This is a flowchart of the overall process of planting method of the present invention.

[0019] Figure 3 This is a schematic diagram of the carbonization material preparation and surface modification steps of the present invention.

[0020] Figure 4 This is a dynamic line graph of the root zone volumetric water content of the present invention.

[0021] In the diagram: 1. Bottom drainage cushion layer; 2. Medium-fine sand transition layer / geotechnical filter layer; 3. Root contact layer; 4. Backfill layer; 5. Top cover layer. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] A method for planting landscaping plants based on the carbonization modification of agricultural and forestry waste, such as Figures 1 to 3 As shown.

[0024] Example 1: Activation + nutrient loading combined modification for planting trees in urban roadside green belts. Common landscaping trees with a diameter at breast height (DBH) of 5-8cm, such as purple-leaf plum (or crabapple / osmanthus), were selected, with a root ball diameter of approximately 30-35cm. Tree pit specifications: 80×80cm in diameter and 65cm in depth.

[0025] Step 1: Raw material sorting and pretreatment Apple tree branches (high lignin group) from spring pruning, poplar sawdust (medium lignin group) from a wood processing plant, and wheat straw (high silica hemicellulose group) were selected as raw materials. The initial moisture contents of each raw material were: branches 42wt%, sawdust 35wt%, and straw 55wt%. After natural sun drying for 3 days, they were transferred to a box dryer and dried with hot air at 60℃ until the moisture content of each material was ≤15wt%. The dried branches were crushed to a particle size of 10-40mm using a jaw crusher; the sawdust was passed through a vibrating screen, and the 2-10mm particle size fraction was collected; the wheat straw was chopped to a length of 20-60mm using a chaff cutter. The three groups of raw materials were weighed according to the mass ratio of branches: sawdust: straw = 3:2:1 after drying, and stirred in a twin-shaft paddle mixer for 8 minutes to obtain a uniformly mixed feed.

[0026] Step 2: Oxygen-limited gradient pyrolysis carbonization The mixed feedstock was loaded into an externally heated rotary pyrolysis carbonization unit (effective volume 0.5 m³). First, the unit was purged with nitrogen for 15 minutes to remove air. Then, a mixture of nitrogen and air was introduced, with the intake flow rate controlled by a rotor flow meter to maintain the oxygen concentration in the reactor at 2.0-3.0 vol%. Heating was initiated, employing a two-stage heating process: the first stage increased the temperature from room temperature to 250°C at a rate of 10°C / min, holding for 40 minutes to remove free water and pre-crack some volatiles; the second stage increased the temperature from 250°C to 500°C at a rate of 5°C / min, holding for 120 minutes. Throughout the pyrolysis process, the volatile matter outlet temperature was controlled to ≤120°C by a condenser. The condensate was collected in a stainless steel storage tank and allowed to stand for 48 hours. After standing, the condensate separated into an upper layer of tar, a middle layer of wood vinegar solution, and a lower layer of sediment. The middle layer solution was used as a raw material for foliar fertilizer dilution. After pyrolysis, heating was stopped, and nitrogen was continuously introduced to cool the condensate to 50°C. The resulting crude biochar was then discharged. The carbon yield obtained in this embodiment is approximately 30 wt% (based on the mass of the dried feed), which is consistent with the representative data at a final temperature of 500℃ in Table 1.

[0027] Table 1: Representative range values ​​of typical straw + sawdust + branch compound pyrolysis at three temperature levels ; Wherein, char yield = (mass of dried char / mass of dried feed) × 100.

[0028] Step 3: Grading and screening of carbonized materials After being lightly broken up by a hammer crusher, the crude biochar was passed through standard sieves of 20mm, 8mm and 2mm in sequence to obtain three grades: coarse grade (8-20mm) with a yield of about 29wt%, medium grade (2-8mm) with a yield of about 43wt%, and fine powder grade (<2mm) with a yield of about 24wt% (see Table 1). The grades were collected in sealed bags for later use.

[0029] Step 4: Surface Modification Treatment Medium-particle size and fine powder size were subjected to combined modification using "Method 1 + Method 2" in the following order: (1) Acid-base pore-expansion activation: Medium-sized and fine-sized carbon powders were immersed in a 1.5 mol / L H3PO4 aqueous solution at a liquid-to-solid mass ratio of 5:1 for 4 hours at room temperature. After removal, they were dried in a 90℃ hot air drying oven for 6 hours, and then transferred to a muffle furnace for a second calcination at 420℃ for 50 minutes. After cooling, they were washed with deionized water until the pH of the washing solution was 6.5-8.0, and then dried again at 80℃ to obtain activated carbon. The specific surface area of ​​the medium-sized carbon powder increased from about 186 m² / g to 387 m² / g after activation (see Table 1), and the total pore volume increased from 0.11 cm³ / g to 0.22 cm³ / g. (2) Nutrient loading: The activated carbon was immersed in a loading solution containing 25 g / L potassium humate at a liquid-to-solid mass ratio of 3:1 for 3 h at room temperature. After immersion, it was dried at 70 °C for 8 h to obtain modified carbonized material with both high specific surface area and slow-release nutrient function. The apparent nutrient equivalent after loading was approximately N 0.9%, P2O 50.5%, and K2O 2.2% (see Table 1), with a CEC of 38 cmol(+) / kg and a stable pH of around 7.9, suitable for a weakly acidic to neutral rhizosphere environment. The coarse-grained grade was not modified in step four and was directly disposed of separately with the modified medium-grained and fine-grained grades according to functional requirements. The relevant physicochemical test results are shown in Table 2.

[0030] Table 2: Physicochemical Test Results ; The increase in conductivity after H3PO4 activation is normal (due to residual P salt and soluble ash dissolution), and the conductivity decreases after washing to neutral.

[0031] Note: The nutrient phase (N-P2O5-K2O) data in the table are apparent equivalent values ​​calculated based on the feed concentration, not the values ​​obtained from the digestion analysis of all elements; all other physicochemical indicators are measured values ​​according to industry standards. Unmodified charcoal and H3PO4-activated modified charcoal served as control groups. In this experiment, 2–8 mm medium-sized particles were uniformly used for physicochemical characterization to compare the modification effect with the medium-sized modified charcoal used in this invention at the same particle size scale. All three were derived from the same batch of coarse charcoal through grading and sieving, with consistent sieving yields (see the yield data of this invention group in the table), so the control group is not listed again. In the actual planting comparison experiment (Table 3), the control group was applied by directly mixing the above-mentioned charcoal powder into the rhizosphere backfill soil at a volume ratio of 8%, without grading and stratification.

[0032] After loading, the specific surface area decreased slightly to about 352 m² / g, but remained at a high level, indicating that the nutrient load did not seriously clog the pores.

[0033] Step 5: Layered construction of tree pits and planting The planting locations were determined according to the urban road greening design drawings. The diameter of the root ball for the purple-leaf plum is approximately 35cm, and the height is approximately 40cm. The planting pit adopts a square design with a side length of 80cm (i.e., the diameter is increased by 22.5cm on each side, conforming to the range of "root ball diameter plus 40-80cm") and a depth of 65cm (i.e., h+25cm). A four-layer structure is constructed from the bottom to the top of the pit.

[0034] ① Bottom drainage cushion layer: A mixture of coarse-grained (8-20mm) and 5-20mm graded crushed stone at a volume ratio of 1:1 is laid at the bottom of the tree pit, with a thickness of 12cm. The groundwater level at this site is about 1.2m deep, which meets the requirement of maintaining a net distance of ≥30cm between the top surface of the cushion layer and the groundwater level. Therefore, no blind pipes are installed. Only a layer of 200g / m² geotextile is laid on the bottom surface of the cushion layer to prevent soil particles from seeping down and clogging it.

[0035] ② Rhizosphere Contact Layer (Planting Layer): Medium-grained modified carbonized material is mixed evenly with excavated garden soil and well-rotted garden compost (organic matter content ≥35wt%) at a volume ratio of 25:65:10 to form the rhizosphere matrix. The measured total porosity of this matrix is ​​52%, with aeration porosity (>0.06mm) of 22% and a pH of 7.8, meeting the requirements of total porosity ≥50% and aeration porosity ≥18%. The rhizosphere matrix is ​​backfilled to the bottom of the planting hole. A planting mound approximately 18cm high is constructed above the top surface of the substrate, ensuring the top of the planting mound is approximately 18cm higher than the top surface of the substrate. The root ball of the purple-leaf plum seedling is placed in the center of the planting mound, and after adjusting its orientation, the root collar of the seedling is slightly higher than the surrounding designed ground surface by approximately 3cm.

[0036] ③ Backfill layer: Mix the fine-powder modified carbonized material with the original excavated soil at a volume ratio of 10:90, and backfill in layers around the root ball. Each backfill layer should be about 18cm thick, and lightly compacted manually with a wooden pestle to control the relative compaction at about 75%. Stop backfilling 5cm above the top of the root ball to avoid burying the root collar due to excessive thickness.

[0037] ④ Surface Covering Layer: Above the backfill layer, mix fine-powder modified carbonized material with bark organic mulch at a volume ratio of 1:4, and cover evenly to a thickness of 4cm. Leave an exposed ring of about 7cm from the base of the trunk. Inside the ring, lay a breathable weed-control film about 8cm wide. Leave a 2cm gap between the inner edge of the weed-control film and the trunk, and press the outer edge 2cm under the covering layer to prevent the mulch from sticking to the trunk and causing trunk rot.

[0038] Step Six: Root Establishment and Post-Planting Care After backfilling, construct a circular irrigation weir approximately 5cm high around the outer edge of the surface covering layer. Water thoroughly once, using about 25L per plant, ensuring the soil moisture content at a depth of 15-30cm in the root zone reaches 85-90% of field capacity. Check the planting hole for water accumulation 24 hours after planting; there should be no waterlogging.

[0039] During the post-planting maintenance period, liquid humic acid organic fertilizer (diluted 300 times) was applied twice, on the 7th and 15th days, approximately 2L per plant each time. The total pure nutrient content of the two applications was about 50% of that of conventional ground planting fertilizer. Survival rate, plant height, new shoot growth, and rhizosphere soil physical properties were regularly observed on the 7th, 15th, 30th, 60th, and 90th days after planting. The results are shown in Tables 3, 4, and 5.

[0040] Table 3: Survival rate and growth after planting ; As shown in Table 3, the experimental group using this embodiment (activated + potassium humate-loaded modified charcoal) achieved a 90% survival rate after 90 days, which was 20 percentage points higher than the traditional planting group (70%) and 10 percentage points higher than the unmodified charcoal mixed soil group (80%). The plant height increased by 24 cm after 90 days, twice that of the traditional planting group. The average length of new shoots in the same year was 23 cm, and the number of new shoots was 6 per plant, both significantly better than the control group. The leaf color score was 4.1 (dark green), indicating good nutrient supply and root vitality.

[0041] Table 4: Physical properties of rhizosphere soil (sampled 30 days after planting) ; Bulk density / porosity was measured using the ring cutter method: a 100cm³ ring cutter was used to collect samples from three points near each plant for mixing, and the samples were dried at 105℃ to constant weight. Table 4 shows that at a depth of 15-25 cm in the rhizosphere, the soil bulk density in this embodiment decreased to 1.22 g / cm³, the total porosity was 52%, the aeration porosity was 22%, and the field water holding capacity was 32%, which were improved by 12.9%, 26.8%, 83.3%, and 33.3% respectively compared with the traditional planting group. This indicates that the graded carbonized modified material combined with the stratified construction significantly optimized the physical structure of the rhizosphere soil.

[0042] Table 5: Dynamics of root zone volumetric water content (TDR / oven drying method – first 30 days after planting) ; Note: At each time point, 3 plants were randomly selected from each treatment group, and 3 points were measured on each plant. The average value was taken.

[0043] See Table 5 and Figure 4 Data shows that within 30 days after planting, the volumetric water content of the root zone (15cm) in this embodiment gradually decreased from 29.3% after the initial watering to 19.8%, while the traditional planting group saw a sharp drop from 29.2% to 14.4% during the same period. This indicates that the synergistic water retention effect of the modified carbonized material covering layer and the rhizosphere matrix effectively extended the effective water supply period and reduced the risk of drought stress.

[0044] Example 2: Application in Saline-Alkali Areas This embodiment, based on Embodiment 1, targets a slightly to moderately saline-alkali area in North China (soil salinity approximately 0.3-0.5%, groundwater mineralization 2-5 g / L, Cl... - and SO4 2- (The main salt ions) are used for planting trees in parks and green spaces.

[0045] Steps one through four are the same as in Example 1, but after step four, the medium-particle and fine-powder modified carbon materials are further subjected to anion adsorption enhancement treatment: the modified carbon loaded with potassium humate in step four is immersed in a 0.5 mol / L FeCl3 aqueous solution at a liquid-to-solid mass ratio of 4:1, and immersed at room temperature with shaking for 2 hours. After removal, it is pre-dried at 80°C for 4 hours, and then transferred to a muffle furnace for heat treatment at 200°C for 1 hour to enhance the Fe... 3+ A hydrated iron oxide coating is formed on the carbon surface, and after cooling, anion adsorption-enhanced modified carbon is obtained. 3+ Forming a hydrated iron oxide coating on the carbon surface can enhance its resistance to Cl. - and SO4 2- Its specific adsorption and electrostatic adsorption capabilities.

[0046] In step five, an 8cm thick medium-fine sand transition layer (particle size 0.25-1mm) is added above the bottom drainage cushion layer. 200g / m² geotextile is laid above and below the medium-fine sand layer, forming a composite salt-barrier structure of "cushion layer—filter layer—rhizosphere layer". During the rainy season or irrigation leaching, the medium-fine sand transition layer prevents fine particles from the upper soil layer from entering the cushion layer pores, while allowing salt to infiltrate with the water and be discharged through the cushion layer; FeCl3 modified carbon retains anions in the upward-flowing salt. The remaining layered construction and maintenance measures are the same as in Example 1.

[0047] Observations 90 days after planting showed that the survival rate of seedlings in the experimental group in the saline-alkali area was about 25 percentage points higher than that of traditional planting (original soil + organic fertilizer) in the same site. The Cl⁻ content in the rhizosphere soil decreased by about 38%, and the SO₄²⁻ content decreased by about 31%. No obvious salt damage chlorosis symptoms were observed.

[0048] Example 3: Bio-inoculation Modification Example This embodiment demonstrates the independent application effect of surface modification method three (bioinoculation), using crabapple seedlings with a diameter at breast height of 6 cm as test seedlings, which were planted in a park green space.

[0049] Steps one through three are the same as in Example 1. Step four involves taking medium-sized and fine-grained charcoal powder and mixing it with PGPR root-promoting bacterial suspension, with an effective viable bacteria count of 2 × 10⁻⁶. 7 The CFU / g char was calculated, and sterile water was added to adjust the liquid-to-solid mass ratio to 3:1. After stirring evenly, the mixture was allowed to stand at 30°C in the dark for 24 hours. During this period, the bacteria adsorbed and colonized within the char pores, forming a bio-inoculated modified charcoal material.

[0050] The tree pit was constructed in the same layered manner as in Example 1, except that the medium-sized modified charcoal in the rhizosphere contact layer was replaced with bio-inoculated modified charcoal, while all other conditions remained unchanged. Sampling was conducted 30 days after planting. The total number of culturable bacteria in the rhizosphere soil of the bio-inoculated group was 1.2 orders of magnitude higher than that of the unmodified charcoal-mixed soil group. Root scanning showed an increase of approximately 35% in total root length and approximately 12% in average root diameter, indicating that the synergistic effect of PGPR and biochar significantly promoted early root expansion.

[0051] Example 4: Economically Simplified Example To verify the applicability of a single nutrient loading method in a low-cost scenario, this embodiment only modifies the medium-particle and fine-powder grades using the second method, omitting the acid-base activation step, and directly impregnating them with a 20g / L potassium humate loading solution for 4 hours and drying them at 70℃. The tree pit construction, planting, and maintenance are the same as in Example 1.

[0052] The results showed that the survival rate of the single nutrient load group was 85% after 90 days, and the plant height increased by 20cm. Although this was slightly lower than that of the activation + load combination group (90%, 24cm), it was significantly higher than that of the traditional planting group (70%, 12cm). Moreover, the process cost was reduced by about 30%, making it suitable for cost-sensitive general park green spaces or road green belt projects.

[0053] The above embodiments demonstrate that the present invention, through the integration of technologies such as "gradual carbonization of agricultural and forestry waste, three-stage particle size screening, differentiated surface modification, functional layered construction of tree pits, and precise post-planting maintenance," can systematically solve problems such as poor soil structure, low survival rate, and extensive water and fertilizer management in urban landscaping tree planting. It is especially suitable for complex urban site conditions such as limited drainage, poor soil, or slightly saline-alkali soil.

[0054] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0055] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for planting landscaping plants based on the carbonization modification of agricultural and forestry waste, characterized in that, Includes the following steps: Step 1: Raw material classification and pretreatment: Select agricultural and forestry waste and divide it into three groups according to its lignocellulose composition: high lignin group, medium lignin group and high silica hemicellulose group; The three groups of raw materials were dried to a moisture content of ≤15wt%, weighed in a mass ratio of (2-4):(1-3):(1-2), and mixed evenly to obtain a mixed feed. Step 2, oxygen-limited gradient pyrolysis carbonization: The mixed feed obtained in Step 1 is loaded into the pyrolysis carbonization device and heated under an inert atmosphere or an oxygen-limited atmosphere. The feed is then discharged to obtain crude biochar. Step 3: Grading and screening of carbonized material: The coarse biochar obtained in Step 2 is mechanically crushed and screened into three grades: coarse grade with a particle size of 8-20 mm; medium grade with a particle size of 2-8 mm; and fine powder grade with a particle size of <2 mm. Step 4: Surface modification treatment: Take the medium-particle and fine-powder grades from the three grades obtained in Step 3 and perform modification treatment; Step 5: Layered Construction and Planting of Tree Pit: Excavate the tree pit according to the design specifications, and construct the planting pit layer by layer from bottom to top: ① Bottom drainage layer: Lay coarse-grained or a mixture of coarse-grained and 5-20mm graded crushed stone, with a thickness of 8-18cm. When the groundwater level is high or there is water accumulation on the site, blind pipes or drainage gravel ditches should be installed at the bottom or side of the subbase. ② Rhizosphere contact layer: Mix medium-sized modified carbonized material with garden soil and decomposed organic fertilizer in a volume ratio of (15-35): (60-75): (5-15) to form a root zone matrix. Backfill the root zone matrix to the bottom of the planting hole and construct a planting mound or planting bed that is 10-25cm higher than the top surface of the bedding layer. Place the seedlings in the mound, so that the root collar of the seedlings is slightly higher than the surrounding ground surface by 2-5cm. ③ Backfill layer: Mix the fine-powder modified carbonized material with the original excavated soil in a volume ratio of: fine-powder modified carbonized material: original soil = (5-15): (85-95), and backfill in layers. Each backfill layer should be 15-20cm thick and lightly compacted to a relative compaction degree of 70-85%. Backfill to 3-8cm above the top of the soil ball. ④ Surface coating layer: A mixture of fine-powdered modified carbonized material and organic mulch is laid on the surface of the tree pit, with a covering thickness of 3-6cm, leaving a 5-10cm bare ring from the base of the trunk. Step Six: Root establishment and post-planting care.

2. The method for planting landscaping plants based on the carbonization modification of agricultural and forestry waste according to claim 1, characterized in that, The agricultural and forestry waste mentioned in step one comes from fruit tree pruning, street tree pruning, forest tree pruning, wood processing sawdust, shavings, wheat straw, rice straw, corn straw, or a combination thereof; the drying method is selected from one of natural sun drying, air drying, or box drying.

3. The method for planting landscaping plants based on the carbonization modification of agricultural and forestry waste according to claim 1, characterized in that, The inert atmosphere mentioned in step two is nitrogen or carbon dioxide. The oxygen concentration in the oxygen-limiting atmosphere is maintained at 0.5-5 vol% by controlling the inlet flow rate. The first stage of the two-stage heating process has an end temperature of 220-280℃ and a holding time of 30-50 min. The second stage has an end temperature of 460-580℃ and a holding time of 90-150 min. The outlet temperature of the volatile matter throughout the pyrolysis process is controlled at ≤120℃. In step two, the volatiles produced by pyrolysis are condensed and separated to recover the wood vinegar. After the recovered wood vinegar is allowed to stand and separate into layers, the middle clear liquid is taken and reused as a raw material for foliar fertilizer dilution. The heating process described in step two is a two-stage process. In the first stage, the temperature is raised from room temperature to 200-300℃ at a rate of 5-15℃ / min and held for 20-60min. In the second stage, the temperature is raised to 420-620℃ at a rate of 3-10℃ / min and held for 60-180min. After the pyrolysis is completed, the temperature is cooled to ≤60℃ under an inert atmosphere.

4. The method for planting landscaping plants based on the carbonization modification of agricultural and forestry waste according to claim 1, characterized in that, In step four, the surface modification treatment is selected from one or more of the following three methods in combination; Method 1: Acid-base pore-expanding activation: The carbon powder is immersed in an activation solution, which is selected from one of the following: 0.5-3.0 mol / L H3PO4 aqueous solution, 0.5-2.5 mol / L KOH aqueous solution, or 0.2-1.0 mol / L ZnCl2 aqueous solution, with a liquid-to-solid mass ratio of (3-8):

1. The immersion time is 2-8 h, then the powder is removed, dried at 80-105℃, calcined twice at 350-500℃ for 30-90 min, washed until neutral, and then dried again to obtain activated modified carbonized material. Method 2: Nutrient Loading The carbon powder is brought into contact with a loading liquid containing potassium humate, seaweed extract or amino acid water-soluble fertilizer, with a total dissolved organic matter concentration of 10-80 g / L and a liquid-to-solid mass ratio of (2-6):

1. The mixture is soaked for 1-6 hours, and then dried at 60-90℃ to obtain nutrient-loaded modified carbonized material. Method 3: Biological inoculation: The charcoal powder and the fungal agent suspension are mixed evenly. The fungal agent suspension contains one or more of the following: arbuscular mycorrhizal fungi, PGPR root-promoting bacteria, or Trichoderma, with an effective viable count ≥1×10⁻⁶. 7 CFU / g carbon, after mixing, is allowed to stand at 25-35℃ in the dark for 12-48h to obtain bio-inoculated modified carbonized material; The surface modification treatment described in step four includes the combination of method one (acid-base pore-expansion activation) and method two (nutrient loading) in the following order: First, medium-sized or fine-sized carbon powder is impregnated in 0.8-2.0 mol / L H3PO4 solution at a liquid-to-solid mass ratio of (4-6):1 for 3-6 hours. After drying at below 105℃, it is calcined again at 380-450℃ for 40-70 minutes. After cooling, it is washed with deionized water until the pH of the washing solution is 6.5-8.

0. After drying again, activated carbon is obtained. Then, the activated carbon is impregnated in a loading solution containing 15-40 g / L potassium humate for 2-4 hours and dried at 60-80℃ to obtain modified carbonized material with both high specific surface area and nutrient slow-release function.

5. A method for planting landscaping plants based on carbonization modification of agricultural and forestry waste according to claim 1, characterized in that, In step five, the diameter of the tree pit is the diameter of the seedling root ball plus 40-80cm, and the depth of the tree pit H = the height of the root ball h plus (20-40)cm. In the bottom drainage layer of step five, the volume ratio of coarse-grained stone to graded crushed stone is (3-7):(7-3), the porosity of coarse-grained stone is ≥55%, and the net distance between the top surface of the layer and the groundwater level is ≥30cm. When the depth of the groundwater level is <50cm, a perforated drainage pipe is pre-embedded in the layer and connected to the collection well or municipal storm drain.

6. A method for planting landscaping plants based on carbonization modification of agricultural and forestry waste according to claim 5, characterized in that, In step five, the ② root contact layer contains a well-rotted organic fertilizer selected from one or more of well-rotted cow or sheep manure, well-rotted garden compost, or earthworm castings, with an organic matter content ≥30wt%, a total porosity of the root matrix ≥50%, an aeration porosity ≥18%, and a pH of 6.5-8.

0.

7. A method for planting landscaping plants based on carbonization modification of agricultural and forestry waste according to claim 6, characterized in that, In step five, ④, the volume ratio of fine-powder modified carbonized material to organic mulch is (1-3):(7-9), the apparent dry bulk density of the mulch is 0.15-0.35 g / cm³, and a 5-10 cm wide breathable weed-proof film or gravel is laid in the exposed area to prevent the mulch from sticking to the tree trunk and causing trunk rot.

8. A method for planting landscaping plants based on carbonization modification of agricultural and forestry waste according to claim 1, characterized in that, Step six, which describes root establishment and post-planting care, involves constructing an irrigation weir after backfilling and thoroughly watering the roots once. The amount of water should be such that the soil volumetric water content at a depth of 15-30cm in the root zone reaches 80-95% of the field capacity. During the 7-21 day post-planting care period, apply liquid organic fertilizer or water-soluble fertilizer 1-3 times, with the total amount of fertilizer not exceeding 70% of the amount applied in conventional field planting. Subsequently, the surface covering layer should be replenished every 4-8 months with a 1-2cm thick layer of fine powder carbonized material, depending on the extent of loss. After thoroughly watering the roots, check the water accumulation in the planting hole 24 hours later. If the water depth is >3cm and does not recede within 12 hours, add a vertical drainage gravel column to the side wall of the planting hole, connecting to the blind pipe of the bedding layer or a new water collection ditch, or add a water pipe at the bottom of the planting hole to drain the water to the surrounding drainage system.

9. A method for planting landscaping plants based on carbonization modification of agricultural and forestry waste according to claim 1, characterized in that, Applicable to one or more of the following scenarios: Tree planting in urban road green belts, park green spaces, tree pits in gaps of hard paving, tree planting in areas where the load-bearing capacity of rooftops or elevated green spaces is permissible, and green space renovation in saline-alkali areas.

10. A method for planting landscaping plants based on carbonization modification of agricultural and forestry waste according to claim 9, characterized in that, When applied to saline-alkali areas, a 5-10cm thick medium-fine sand transition layer or geotextile filter layer is added above the bottom drainage cushion layer in step five. After the surface modification treatment in step four, iron or magnesium salt impregnation modification is further carried out and heat treatment at 150-300℃, so that iron or magnesium is loaded on the carbon surface in the form of hydrated oxides for anion adsorption enhancement treatment.

Images