CN111374020A

CN111374020A - Dredger fill afforestation process method

Info

Publication number: CN111374020A
Application number: CN202010276094.0A
Authority: CN
Inventors: 梁晶; 张青青; 蔡永立; 伍海兵; 陈平; 何小丽; 徐冰
Original assignee: Shanghai Academy of Landscape Architecture Science and Planning
Current assignee: Shanghai Academy of Landscape Architecture Science and Planning
Priority date: 2020-04-09
Filing date: 2020-04-09
Publication date: 2020-07-07

Abstract

The invention provides a dredger fill afforestation method, in particular to a dredger fill afforestation process method. In order to solve the technical problem of greening and forestation by using dredger fill, the invention mainly drains accumulated water by ditching the dredger fill, the dug dredger fill is accumulated at two sides of a drainage ditch, the ground is lifted, then planting holes are dug in the dredger fill between the drainage ditches, agricultural organic wastes such as cotton straws and corn straws or landscaping organic wastes such as dead branches and weeds are paved at the bottom and the periphery of a tree hole for salt separation, the dug dredger fill is improved by adopting desulfurized gypsum, an organic medium, polymeric ferric sulfate and an acidic organic fertilizer, the physicochemical property of the dredger fill is improved, and the tree hole is backfilled for planting greening plants. The method does not need to add soil, accelerates the solidification of the dredger fill by changing the terrain and draining water, quickly improves the dredger fill for forestation, and can improve the survival rate of trees.

Description

Dredger fill afforestation process method

Technical Field

The invention provides a dredger fill afforestation method, in particular to a dredger fill afforestation process method.

Background

The dredger fill is formed by hydraulic flushing mud and sand, it is one of the common artificial fill in the coastal zone of China, mainly because of the regulation or dredging of the river channel, or because of the industrial and agricultural production needs to fill up or fill up some districts near the river, the mud and sand dug out of the dredger with the high-pressure slurry pump, through the mud conveying pipe, discharge to needing to fill up the district and mud and sand accumulation area, the former is planned, purposefully to fill up, the latter is purposeless to pile up, form the large piece of dredger fill layer after depositing and draining, its ingredient is clay and silt, under the hydraulic sorting action, the soil granule has obvious coarse and fine settlement, the drift soil formed is in the non-uniform distribution in the direction of length and breadth. The dredger fill soil body has higher natural water content which is about 65.6 percent; greater porosity, 56.4%; the soil body is seriously hardened, basically impermeable, airtight and quite hardened, and the specific gravity is 2.72; the high compressibility, the plastic limit of 25.3 percent and the liquid limit of 45.0 percent, large deformation under the action of load and long consolidation time. Therefore, the dredger fill is not processed, is difficult to be directly applied as a building foundation, and even cannot meet the basic requirements of personnel and equipment construction operation at all.

Meanwhile, the salt content of the dredger fill soil body is extremely high and exceeds 12 g/kg, the pH value of the soil body also reaches 8.3-9.0, and the dredger fill soil body is severe saline-alkali soil; the organic matter content is low, and the average content is 4.13 g/kg; the soil texture is mainly silty clay, the content of silty sand grains is more and mainly ranges from 60% to 70%, and the content of sand grains and the content of sticky grains are lower. The indexes all meet the technical requirements of the main control index of 'green planting soil' CJ/T340-2016, so that the use of dredger fill for planting green plants is more difficult.

However, as the urban land resources are less and less along with the gradual expansion of cities, but the requirements of urban ecological civilized construction are higher and higher, the dredger fill must become a backup for land development and utilization, and the dredger fill greening afforestation process method has important significance for recycling the dredger fill land.

At present, the existing dredger fill improvement method 'salt drainage under concealed pipes and backfill of foreign soil' wastes time and labor, and 'water-saving type comprehensive physical-chemical-ecological improvement of saline-alkali beach lands and vegetation construction technology' needs irrigation and desalination as the basis and needs improvement of the foreign soil. Both improvements are carried out after the curing of the dredger fill, and no mention is made of the curing of the dredger fill.

Disclosure of Invention

The invention provides a dredger fill afforestation process method, which comprises the following steps:

(1) digging a plurality of drainage ditches in parallel on the dredger fill, digging a plurality of tree holes (the tree holes are 40cm deep and 60cm wide) between adjacent drainage ditches, paving organic wastes (the organic wastes comprise one or more of cotton straws, corn straws, sugar-removed straws of sugarcanes, rice straws, wheat straws, soybean straws and dead branches) at the bottoms and the side walls of the tree holes, and backfilling the improved dredger fill after planting nursery stocks;

organic wastes (one or more of cotton straws, corn straws, sugar-removed straws of sugarcanes, rice straws, wheat straws, soybean straws and dead branches) with the thickness of 5-10cm are paved at the bottom and around the planting hole to serve as isolation layers, on one hand, cellulose in the organic wastes (the cotton straws) has strong adsorbability, and the high-salt-content underground water can be prevented from rising into the improved soil by virtue of capillary action; on the other hand, the cellulose in the organic waste (cotton straw) increases the bearing capacity of the dredger fill and accelerates the consolidation of the dredger fill. Furthermore, pine needles with the thickness of 4-5cm are paved on the surface of the tree pit as a covering layer after the seedlings are planted, so that the soil loss is reduced, the soil nutrient is increased, and the soil salinity is reduced.

(2) Excavating transverse ditches at intervals (preferably excavating transverse ditches at intervals of 6-6.5 meters) in a direction perpendicular to a river channel or a main canal, and discharging accumulated water and salt in the dredger fill; the cross ditch can be the trapezoidal, also can be the U type to prevent that the escape canal collapses, the size is: the width of the surface is 50cm, the width of the bottom is 30cm, and the depth is 60 cm; the bottom of the ditch has a slope of 3-5 per mill, which is convenient for draining water into an external water system, and the reclamation of greening and afforestation by dredger fill can be completed.

The improved dredger fill is a mixture of air-dried dredger fill, desulfurized gypsum, an organic medium, polymeric ferric sulfate and an acidic organic fertilizer. The air-dried dredger fill can be accumulated on two sides of the drainage ditch by using dredger fill dug out of the drainage ditch and is naturally air-dried. The method is used for improving the granular structure of the dredger fill, reducing the pH value and the total salt content of the dredger fill, and improving the organic matter content of the dredger fill.

The mass ratio of the air-dried dredger fill to the desulfurized gypsum to the organic medium to the polymeric ferric sulfate to the acidic organic fertilizer is 12-18: 2-4: 3-8:0.5-1:0.8-1.5.

The addition of the desulfurized gypsum and the polymeric ferric sulfate improves the structure of the dredger fill, reduces the pH and the total salt of the dredger fill, can reduce the pH to about 8.3 (namely 8.11-8.34) approximately, and can reduce the total salt content to below 3 g/kg). The desulfurized gypsum is white powder, the purity is 90-95%, the water content is 10-15%, and the average particle size is 50 μm. The polymeric ferric sulfate is yellow powder with the particle size of 20 μm.

The particle size of the organic medium is 1-20mm, the pH is 6.5-7.5, and the EC is 0.5-10.0mS cm^-1The organic matter content is more than 35 percent.

The acidic organic fertilizer is composed of one or more of cow dung, sheep dung and the like, the pH value is 5.5-6.5, the content of organic matters is more than or equal to 45%, and the content of total nutrients of nitrogen, phosphorus and potassium is more than or equal to 5%.

The addition of the organic medium and the acidic organic fertilizer improves the fertility of the dredger fill on the basis of reducing the alkalinity of the dredger fill. Can be improved to 12 g/kg or more.

The improved dredger fill is characterized in that any one or two of alginic acid, ammonium polyphosphate, urea activated humic acid, gamma-glutamic acid and soybean phospholipid are also added into the improved dredger fill, and the addition amount of the alginic acid, the ammonium polyphosphate or the urea activated humic acid, the gamma-glutamic acid and the soybean phospholipid is 1-5% of the quality of the dredger fill.

Any one of alginic acid, ammonium polyphosphate, urea activated humic acid, gamma-glutamic acid, soybean lecithin that this application added has the solid salt effect of chelation to the salt solution in the salt moisture that the straw of lower floor adsorbs, makes the salinity be difficult to move to the soil with the help of the straw and plants the top layer, has promoted the survival rate of nursery stock. After the improved dredger fill on the upper layer is chelated and enriched with salt and alkali, a solution state is formed in soil with a large amount of moisture and humidity, and particularly, ammonium polyphosphate is easy to form a solution, so that soluble nutrients which are easy to absorb can be provided for plants, and the growth of nursery stock plants is promoted.

The nursery stock comprises any one of larch, Chinese tallow tree, chinaberry, camphor, poplar and privet.

Annual grasses are planted on the dredger fill, and the grasses comprise any one of radix notoginseng, alfalfa, hemerocallis fulva, iris tectorum and euonymus petiolatus.

Spraying the defluorinated phosphogypsum once every season after planting the grass, wherein the spraying amount of the phosphogypsum is 10-15 kg/mu.

Furthermore, after arbor planting, additional sowing of green manure is performed according to soil improvement conditions.

The invention has the advantages that the drainage ditch can quickly drain the moisture of the dredger fill, and the straws such as cotton straws, corn straws and the like laid around the tree pits can increase the bearing capacity of the dredger fill and accelerate the solidification speed of the dredger fill; meanwhile, soil is not needed to be removed, the dug dredger fill of the drainage ditch is piled up to be high, the planting ground is lifted, salt can be discharged by means of height difference water spraying under the scouring of rainwater, and the improvement effect is long. Compared with the existing dredger fill improvement method, the process method can accelerate the consolidation of the dredger fill, save the investment of manpower and material resources when improving the soil, save the cost and the subsequent investment, and improve the survival rate of plants.

Drawings

FIG. 1 is a flow chart of a dredger fill afforestation process.

FIG. 2 is a schematic sectional view of a drainage ditch and a tree pit.

FIG. 3 is a view showing arrangement of lateral grooves.

Detailed Description

Example 1

Selecting 3.5 mu of dredger fill in Shanghai for demonstration, excavating transverse ditches on the dredger fill every 6m by using a small excavator, wherein the ditches are arranged perpendicular to the peripheral conventional river channel, and discharging accumulated water and salt in the dredger fill; the transverse groove is of a ladder shape, and the size is as follows: the width of the surface is 50cm, the width of the bottom is 30cm, and the depth is 60 cm; the groove bottom has a gradient of 3 per mill. And accumulating dredger fill dug out of the drainage ditch at two sides of the drainage ditch, and naturally drying. And digging holes with the depth of 40cm and the width of 60cm in the soil between the drainage ditches. Cotton straws with the thickness of 5cm are paved at the bottom and the side wall of the hole to be used as isolation layers. And after the dredger fill dug out in the drainage ditch and the planting hole is naturally air-dried, 3kg of flue gas desulfurization gypsum, 750g of polyferric sulfate, a half-square organic medium and 35kg of acidic organic fertilizer are applied to each cubic dredger fill for mixing and backfilling. Wherein the organic medium has a particle size<80% of 15mm, maximum particle diameter of 20mm, pH of 7.23, and EC of 2.54 mS · cm^-147.8 percent of organic matter, 5.79 percent of pH of acid organic fertilizer and 50.1 percent of organic matter, then planting 3-year-old larch according to the spacing of 2 × 2 plants, planting about 120 plants, paving 5 cm-thick pine needles on the surface of a tree pit as a covering layer, additionally sowing green manure according to the soil improvement condition after the larch is planted, wherein the survival rate of the larch reaches 88 percent after 2 years of planting, and the volume weight of the soil is 1.38 Mg/m³The pH value is 8.24, the salt content is 2.76 g/kg, and the organic matter content of the soil is 15.2 g/kg.

Example 2

On the basis of example 1, sesbania sessiliflora 12g/m was dusted in the forest²And spraying the defluorinated phosphogypsum once every season, wherein the spraying amount of the phosphogypsum is 12 kg/mu. The survival rate of the larch reaches 92 percent after 2 years of planting, and the volume weight is 1.26 Mg/m³The pH value of the soil is 8.11, the salt content is 2.53g/kg, and the soil organic matterThe content was 16.3 g/kg.

Example 3

On the basis of the embodiment 1, alginic acid with the weight ratio of 3.5 is added into the tree pit planting soil, the survival rate of the larch reaches 95 percent after 2 years of planting, and the volume weight is 1.23Mg/m³The pH value of the soil is 8.05, the salt content is 2.48g/kg, and the organic matter content of the soil is 16.5 g/kg.

Example 4

The specific implementation scheme is as in example 1, but the modified dredger fill is a mixture of air-dried dredger fill and desulfurized gypsum, organic medium, polymeric ferric sulfate, acidic organic fertilizer, ammonium polyphosphate and urea-activated humic acid, and the mass ratio of the air-dried dredger fill to desulfurized gypsum, organic medium, polymeric ferric sulfate and acidic organic fertilizer is 16: 2.4: 6.5: 0.75: 1.2, the mass of the humic acid activated by ammonium polyphosphate and urea is 1.6 percent of the total mass of the air-dried dredger fill, the desulfurized gypsum, the organic medium, the polymeric ferric sulfate and the acidic organic fertilizer mixture. The particle size of the organic medium is 15-20mm, the pH is 6.5-7.5, and the EC is 8.5-10.0mS cm^-1The organic content is 44.8%. The acidic organic fertilizer is prepared from cow dung, pH 5.5-6.5, organic matter content 48.2% and total nitrogen, phosphorus and potassium nutrients 7.3%. The planted seedlings are cinnamomum camphora (cinnamomum camphora seedlings of about 10 cm). The plant planted on the dredger fill is iris. The survival rate of the cinnamomum camphora reaches 92.3 percent after 2 years of planting, and the volume weight of the soil is 2.03 Mg/m³The pH value is 7.15, the salt content is 2.18g/kg, and the organic matter content of the soil is 17.25 g/kg.

Example 5

In the specific implementation scheme as in example 4, after planting grass, spraying the defluorinated phosphogypsum once every season, wherein the spraying amount of the phosphogypsum is 13 kg/mu. The survival rate of the cinnamomum camphora reaches 95.75 percent after 2 years of planting, and the volume weight of the soil is 2.25 Mg/m³The pH value is 8.32, the salt content is 1.17 g/kg, and the organic matter content of the soil is 22.3 g/kg.

Example 6

The concrete implementation scheme is as in example 1, but the modified dredger fill is a mixture of the dredger fill after air drying and desulfurized gypsum, organic medium, polymeric ferric sulfate, acid organic fertilizer, ammonium polyphosphate and urea activated humic acid, and the dredger fill is air-driedThe mass ratio of the dredger fill to the desulfurized gypsum to the organic medium to the polymeric ferric sulfate to the acidic organic fertilizer is 16: 2.4: 6.5: 0.75: 1.2, the mass of the alginic acid and the gamma-glutamic acid is 1.6 percent of the total mass of the air-dried dredger fill, the desulfurized gypsum, the organic medium, the polymeric ferric sulfate and the acidic organic fertilizer mixture. The particle size of the organic medium is 15-20mm, the pH is 6.5-7.5, and the EC is 8.5-10.0mS cm^-1The organic content is 44.8%. The acidic organic fertilizer is prepared from cow dung, pH 5.5-6.5, organic matter content 48.2% and total nitrogen, phosphorus and potassium nutrients 7.3%. The planted nursery stock is chinaberry (about 6cm chinaberry nursery stock). The plants planted on the dredger fill are alfalfa. 3 years later, the survival rate of the chinaberry plants reaches 90.6 percent, and the volume weight of the soil is 2.53Mg/m³The pH value is 7.6, the salt content is 2.23 g/kg, and the organic matter content of the soil is 19.75 g/kg.

Example 7

In the specific implementation scheme as in example 6, after planting grass, spraying the defluorinated phosphogypsum once every season, wherein the spraying amount of the phosphogypsum is 13 kg/mu. The survival rate of the chinaberry plants reaches 96.4 percent after 3 years, and the volume weight of the soil is 2.86Mg/m³The pH value is 8.35, the salt content is 1.33 g/kg, and the organic matter content of the soil is 26.4 g/kg.

Claims

1. A dredger fill afforestation process method is characterized by comprising the following steps:

(1) digging a plurality of drainage ditches in parallel on the dredger fill, digging a plurality of tree pits between adjacent drainage ditches, paving agricultural organic waste or landscaping organic waste at the bottoms and the side walls of the tree pits, and backfilling the improved dredger fill after planting nursery stocks;

(2) and excavating transverse ditches at intervals of a certain distance in a direction perpendicular to the river channel or the main canal, and then completing the dredger fill greening forestation.

2. The method according to claim 1, wherein the modified dredger fill is a mixture of air-dried dredger fill, desulfurized gypsum, organic medium, polymeric ferric sulfate, and acidic organic fertilizer.

3. The dredger fill afforestation process method according to claim 2, wherein the mass ratio of the dredgefill after air drying to the desulfurized gypsum, the organic medium, the polymeric ferric sulfate and the acidic organic fertilizer is 12-18: 2-4: 3-8:0.5-1:0.8-1.5.

4. The method according to claim 3, wherein the particle size of the organic medium is 1-20mm, the pH is 6.5-7.5, and the EC is 0.5-10.0mS cm^-1The organic matter content is more than 35 percent.

5. A dredger fill afforestation process according to claim 4, wherein the acidic organic fertilizer is composed of one or more of cow dung and sheep dung, the pH value is 5.5-6.5, the content of organic matters is not less than 45%, and the content of nitrogen, phosphorus and potassium total nutrients is not less than 5%.

6. A dredger fill afforestation process according to any one of claims 2-5, wherein any one or two of alginic acid, ammonium polyphosphate, urea-activated humic acid, gamma-glutamic acid, and soybean lecithin is further added to the improved dredger fill, and the addition amount of alginic acid, ammonium polyphosphate, or urea-activated humic acid, gamma-glutamic acid, and soybean lecithin is 1-5% of the quality of the dredger fill.

7. The method of claim 6, wherein the nursery stock comprises any one of the plants selected from the group consisting of larch, Chinese tallow tree, chinaberry, camphor, poplar, and privet.

8. The dredger fill afforestation process method according to claim 7, wherein the transverse ditches are trapezoidal or U-shaped; the groove bottom has a gradient of 3-5 per mill.

9. The dredger fill afforestation process according to claim 8, wherein annual grasses are further planted on the dredger fill, and the grasses include any one of sedum notoginseng, alfalfa, hemerocallis fulva, iris tectorum and euonymus petiolatus.

10. The dredger fill afforestation process method according to claim 9, wherein the phosphogypsum after defluorination is sprayed once every season after grass planting, and the spraying amount of the phosphogypsum is 10-15 kg/mu.