Composite soil conditioner, preparation method thereof and limestone mine waste land soil improvement method

Abstract

The invention relates to a composite soil conditioner, a preparation method thereof and a limestone mine waste land soil improvement method, and belongs to the technical field of ecological restoration. The composite soil conditioner comprises humus, modified diatomite, rice husk charcoal, a microbial inoculum, sepiolite and a binder, wherein the microbial inoculum comprises alkali-resistant nitrogen-fixing bacteria and phosphate solubilizing bacteria. According to the composite soil conditioner and the soil improvement method, the soil fertility, the air permeability and the water retention capacity of limestone mine waste land can be improved, the survival rate and the coverage rate of pioneer plants are remarkably increased, a stable pioneer vegetation community can be built, and water and soil loss is effectively reduced; the ecological restoration period of the limestone mine waste land is remarkably shortened on the premise of saving resources and cost input, and the method has the advantages of being wide in adaptability, outstanding in environmental friendliness and good in improvement effect.

Claims

1. A composite soil conditioner, characterized in that: The invention comprises the following components in parts by weight: 20 to 30 parts of humus, 40 to 50 parts of modified diatomaceous earth, 10 to 18 parts of rice husk charcoal, 5 to 10 parts of bacterial agent, 3 to 5 parts of sepiolite, and 0.05 to 6 parts of binder; The bacterial agent includes alkali-resistant nitrogen-fixing bacteria and phosphate-solubilizing bacteria; The mass ratio of the alkali-resistant nitrogen-fixing bacteria to the phosphate-solubilizing bacteria is 1-3:0.5-2; The initial viable bacterial concentration of the alkali-resistant nitrogen-fixing bacteria is 0.5 to 2×10 8 CFU / g; The initial live bacterial concentration of the phosphate-solubilizing bacteria is 2 to 6×10 7 CFU / g.

2. The composite soil conditioner according to claim 1, characterized in that The particle size of the modified diatomaceous earth is 0.5 to 1 mm, and the specific surface area of ​​the modified diatomaceous earth is greater than 50 m 2 / g.

3. The composite soil conditioner according to claim 2, characterized in that The pore diameter of the rice husk charcoal is 2-50 μm, and the porosity of the rice husk charcoal is greater than 80%.

4. The composite soil conditioner according to claim 3, characterized in that The binder includes one or more of sodium carboxymethyl starch, sodium carboxymethyl cellulose, polyacrylamide and sodium humate.

5. The method for preparing the composite soil conditioner according to any one of claims 1 to 4, characterized in that: The steps include: (1) mixing rice husk charcoal and bacterial agent, vacuum impregnating for 1 to 4 hours to obtain a premix, and mixing the premix, humus, modified diatomaceous earth, sepiolite, and a binder to obtain a mixture; (2) Granulate the mixture, dry it for 20 to 29 minutes, and sieve it to obtain a composite soil conditioner.

6. The preparation method according to claim 5, characterized in that The pressure of the vacuum impregnation in step (1) is -0.3 to -0.05 MPa.

7. The preparation method according to claim 6, characterized in that The granulation method in step (2) is twin-screw extrusion granulation; The drying method is fluidized bed drying, and the drying temperature is 50-80°C; The screening method is vibration screening, the sieve aperture is 60-100 mesh, the vibration frequency is 600-800 rpm, the screening temperature is ≤40°C, and the screening time is 20-30 min; The particle size of the composite soil improver is 2 to 4 mm, and the porosity of the composite soil improver is ≥40%.

8. A soil improvement method for limestone mine wasteland, characterized in that: The steps include: (a) Applying composite soil conditioner to the abandoned limestone mine land, and then covering it with foreign soil after rotary tillage; (b) digging a planting trench on the imported soil, inoculating the planting trench with a fungal agent, sowing pioneer herbaceous plants in the planting trench, and sowing pioneer woody plants along the edge of the planting trench; The composite soil conditioner is the composite soil conditioner according to any one of claims 1 to 4.

9. The soil improvement method according to claim 8, characterized in that: The application amount of the composite soil conditioner in step (a) is 2-4 kg / m 2 ; The depth of the rotary tillage is 25 to 35 cm, and the number of rotary tillage is 1 to 3 times; The covering thickness of the imported soil is 20 to 25 cm; The imported soil includes improved slag soil and garden waste compost; The mass ratio of the improved slag soil to the garden waste compost is 6-7:3-4.

10. The soil improvement method according to claim 9, characterized in that: The planting ditch described in step (b) is a U-shaped planting ditch, the width of the planting ditch is 30 to 45 cm, the depth of the planting ditch is 10 to 15 cm, and the spacing between the planting ditch is 20 to 30 cm; The fungal agent is an arbuscular mycorrhizal fungal agent, the propagule concentration of the fungal agent is 20,000 to 30,000 / g, and the inoculation amount of the fungal agent is 150 to 300 kg / ha; The pioneer herb is alfalfa and / or castor; The sowing rate of alfalfa is 14-16g / m 2 ; The sowing amount of castor oil plant is 150 to 200 seeds per mu; The pioneer woody plants are one or more of Robinia pseudoacacia, Broussonetia chinensis and Amorpha fruticosa; The sowing spacing of the pioneer woody plants is 1.5 to 2 meters.