Method for increasing organic carbon content of farmland soil based on earthworms and biomass charcoal

Abstract

The invention discloses a method for increasing the organic carbon content of farmland soil based on earthworms and biomass charcoal, and belongs to the technical field of farmland soil improvement. The method aims at solving the problems that the organic carbon improvement effect of farmland soil is poor, the soil structure is prone to damage, and an improvement scheme lacks standardization, and comprises the specific steps that when soil is not frozen after harvest in autumn, land parcels to be treated are subjected to in-situ earth cutting and impurity removal according to layers and stored respectively; laying a gauze at the bottom of the excavated pit, arranging a baffle on the side wall, and performing in-situ backfilling according to layers; the biomass charcoal is applied to the surface of the soil, ploughing and mixing are conducted, earthworms are put in, and then soybeans are planted every year. Through the synergistic effect of the earthworms and the biomass charcoal and in combination with matched planting measures, the soil organic carbon content is accurately increased, the soil structure is optimized, a farmland ecological virtuous cycle is constructed, and the scheme is standardized and easy to popularize in a large scale.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil ecology, and more particularly to a method for improving the organic carbon content of farmland soil based on earthworms and biochar. BACKGROUND

[0002] In the agricultural ecosystem, the application of biochar to farmland is conducive to increasing soil organic carbon storage, promoting soil structure formation, and improving farmland soil quality, and is a prerequisite for realizing the ecological service functions of soil animals and microorganisms. However, previous studies on the influence of biochar on farmland soil organic carbon often ignored the role of soil animals.

[0003] As the most important large soil animals in terrestrial ecosystems, earthworms play an important role in the decomposition and transformation of soil organic carbon. On the one hand, earthworms can affect the properties of biochar through activities such as ingestion, peristalsis, and excretion; on the other hand, earthworms can stimulate the mineralization of soil organic carbon by regulating soil microbial activity and community structure, thereby changing the carbon sequestration potential of biochar.

[0004] Therefore, how to combine farmland animals with biochar to improve field soil quality is a problem that needs to be solved by those skilled in the art. SUMMARY

[0005] Therefore, the present application provides a method for improving the organic carbon content of farmland soil based on earthworms and biochar, which has an unexpected effect when biochar and earthworms are used together.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: A method for improving the organic carbon content of farmland soil based on earthworms and biochar, comprising the following steps: After harvesting in autumn and before the soil freezes, dig the soil in situ in the land to be treated, and store the in-situ soil after layering and removing impurities; Lay a gauze on the bottom of the excavated soil pit, set a baffle on the side wall of the soil pit, and then backfill the soil layers treated in step (1) in situ according to the layers; Uniformly spread biochar on the surface of the backfilled soil, and then mix by plowing to a depth of 0-20 cm; Put earthworms into the soil after plowing in step (3); After the earthworms are put in, soybeans are planted at the end of April every year, and harvested at the end of October. Preferably, the soil layers are divided according to the thicknesses of 0-20 cm, 20-40 cm, 40-60 cm, and 60-80 cm in step (1).

[0007] Preferably, the baffle in step (2) is made of PVC.

[0008] Preferably, the biomass charcoal in step (3) is corn straw biomass charcoal, which is formed by calcining corn straw under anaerobic conditions at 500 DEG C.

[0009] Preferably, the biomass charcoal in step (3) is corn straw biomass charcoal, which is formed by calcining corn straw under anaerobic conditions at 500 DEG C.

[0010] Preferably, the earthworms in step (4) are selected from local dominant species, and the earthworms are uniformly put in when the size and activity are consistent.

[0011] Preferably, the earthworms in step (4) are selected from local dominant species, and the earthworms are uniformly put in when the size and activity are consistent. 2 .

[0012] Preferably, in the soybean planting, chemical fertilizer is used as base fertilizer, the planting row spacing is 30-35 cm, and the plant spacing is 10-12 cm.

[0013] Further, the chemical fertilizer and the application amount are as follows: diammonium phosphate 150 kg / ha, and potassium sulfate 60 kg / ha.

[0014] Preferably, artificial weeding is performed every 2 weeks during the soybean planting process.

[0015] According to the technical scheme, compared with the prior art, the method for improving the organic carbon content of farmland soil based on earthworms and biomass charcoal has the following beneficial effects: The quantitative application of corn straw biomass charcoal can directly supplement stable organic carbon to the soil, and the earthworms are put in, the activities of digging, eating and excretion of the earthworms can accelerate the fusion of the biomass charcoal and the soil, promote the decomposition and transformation of organic matter, reduce the loss of soil organic carbon, and realize the significant and continuous improvement of the soil organic carbon content under the double effects.

[0016] The operation mode of in-situ layered soil digging-backfilling avoids the damage to the original micro-ecology and physicochemical structure of the soil caused by soil layering; the setting of the gauze and the PVC baffle reduces the escape of the earthworms and the risk of soil loss; the activities of the earthworms and the pore structure of the biomass charcoal are coordinated, further improving the soil air permeability, water retention and aggregate structure, and providing a suitable soil environment for the retention of organic carbon.

[0017] The soybean planting not only guarantees the normal growth and yield of soybeans, but also improves the soil nutrient condition by means of the nitrogen fixation of soybeans, and the soybean root system and residues can return to the soil as a supplement of carbon source, forming a closed loop of soil improvement-crop planting-carbon source supplement, and taking into account the soil fertilization and crop production. BRIEF DESCRIPTION OF DRAWINGS

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the experimental setup for Example 1; Figure 2 The soil organic carbon content in the third year of the experiment in Example 1. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 The experimental site was located at the Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences. The specific process is as follows: I. Preparation of in-situ soil: After the autumn harvest and before the soil freezes, the soil for the in-situ soil column is excavated in layers (each layer is 20 cm thick, for a total of 4 layers). Visible soil animals, gravel, plant residues and other impurities are removed and the soil is placed in bags of different colors to distinguish them. II. Establishment of in-situ soil column: Use stainless steel shovels, spades and other tools to dig a pit, and put a PVC material frame (1.0 m long, 1.0 m wide and 0.8 m deep) into the pit without bottom or top cover. Leave part of the PVC frame 20 cm above the ground and seal the bottom with a mesh to prevent earthworms from escaping, isolate soil animals and maintain water circulation. 3. Transfer of in-situ soil: Fill the soil in the original layers into the soil frame in sequence. IV. Preparation of biochar: It is made by calcining corn stalks at 500℃ under anaerobic conditions; V. Selection and capture of earthworm species: Select the local dominant species Eisenia nordenskioldi. Earthworms are obtained in the weedy area near the original soil pillar area. Try to select earthworms of similar size and vitality. 6. Spread the prepared biochar evenly on the soil surface inside the soil column (3400 kg C / ha), and mix it thoroughly with the 0-20 cm soil by tilling; 7. Release the pre-cultured earthworms into the tilled soil, with 280 earthworms inoculated into each soil column; 8. Plant 3 rows of soybeans ("Jinong 46") in each soil column, with a plant spacing of 10-12 cm between each row, resulting in a soybean density of approximately 21 plants / m². 2 Chemical fertilizers are applied as base fertilizers and are applied once a year when soybeans are sown, with an application rate of 150 kg / ha of diammonium phosphate and 60 kg / ha of potassium sulfate. 9. No pesticides or herbicides are added during the soybean growing season; weeding is done manually every two weeks. Soybeans are harvested in early October each year and planted in late April.

[0022] The survival rate of earthworms is investigated by electric shock before each year's sowing in order to replenish and maintain a relatively constant earthworm population. Soil sampling and analysis: Soil samples were collected annually before soybean harvest, followed by testing, data analysis, and result evaluation. Soil organic carbon content was determined using the potassium dichromate oxidation method with external heating. 0.5 g of soil sample was weighed and placed in a 150 mL Erlenmeyer flask, and 5 mL of 0.8 mol / L potassium dichromate and 5 mL of concentrated sulfuric acid were added. The sample was heated on a 180℃ hot plate for 5 min, cooled, diluted with distilled water, and titrated with 0.2 mol / L ferrous sulfate using o-phenanthroline as an indicator.

[0023] The group that did not introduce earthworms (the rest of the operation was the same as in Example 1) served as the control.

[0024] After three years of continuous treatment, the organic carbon content in the soil was measured, and the results were as follows: Figure 2 As shown, Figure 2 This indicates that the organic carbon content in Example 1, which introduced earthworms, was significantly increased compared to the example without earthworms.

[0025] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for increasing the organic carbon content of farmland soil based on earthworms and biochar, characterized in that, Includes the following steps: After the autumn harvest and before the soil freezes, excavate the soil in situ in the plot to be treated, remove impurities from the soil in situ in layers, and store them separately. Lay the mesh at the bottom of the excavated pit, set up baffles on the side walls of the pit, and then backfill the soil layers treated in step (1) in situ. Spread biochar evenly on the surface of the backfill soil, then till and mix it in, with a tilling depth of 0-20cm. Place the earthworms into the soil after tilling in step (3); After releasing earthworms, soybeans are planted at the end of April each year and harvested at the end of October.

2. The method for increasing the organic carbon content of farmland soil based on earthworms and biochar according to claim 1, characterized in that, In step (1), the soil layers are divided according to the thickness of 0-20cm, 20-40cm, 40-60cm, and 60-80cm.

3. The method for increasing the organic carbon content of farmland soil based on earthworms and biochar according to claim 1, characterized in that, The baffle mentioned in step (2) is made of PVC.

4. The method for increasing the organic carbon content of farmland soil based on earthworms and biochar according to claim 1, characterized in that, The biochar mentioned in step (3) is corn stalk biochar, which is made by calcining corn stalks at 500°C under anaerobic conditions.

5. A method for increasing the organic carbon content of farmland soil based on earthworms and biochar according to claim 1, characterized in that, The biochar dosage in step (3) is 3400 kg C / ha.

6. A method for increasing the organic carbon content of farmland soil based on earthworms and biochar according to claim 1, characterized in that, In step (4), the earthworm species should be local dominant species, and earthworms of the same size and with similar vitality should be evenly released when releasing them.

7. A method for increasing the organic carbon content of farmland soil based on earthworms and biochar according to claim 1, characterized in that, The earthworm release quantity in step (4) is 280 earthworms / m². 2 .

8. A method for increasing the organic carbon content of farmland soil based on earthworms and biochar according to claim 1, characterized in that, In soybean cultivation, chemical fertilizers are applied as base fertilizer, with a row spacing of 30-35cm and a plant spacing of 10-12cm.

9. A method for increasing the organic carbon content of farmland soil based on earthworms and biochar according to claim 8, characterized in that, The fertilizers and their application rates are: 150 kg / ha of diammonium phosphate and 60 kg / ha of potassium sulfate.

10. A method for increasing the organic carbon content of farmland soil based on earthworms and biochar according to claim 1, characterized in that, Weeding is done manually every two weeks during soybean cultivation.

Images