Saline-alkali land farmland soil improvement method

Abstract

The invention relates to the technical field of soil improvement, and provides a saline-alkali soil farmland soil improvement method which comprises the following steps: S1, preparing tamarix chinensis-based biochar; s2, culturing the Piriformospora indica by adopting a potato glucose liquid culture medium, so as to obtain a Piriformospora indica microbial inoculum; s3, using a beef extract peptone liquid culture medium to culture the phosphate solubilizing bacteria Pantoea vagans separated from the saline-alkali soil of the Yellow River Delta to obtain a phosphate solubilizing bacteria bacterial agent; s4, mixing the tamarix chinensis-based biochar, a piriformospora indica microbial agent and a phosphate solubilizing bacteria bacterial agent to prepare the biological bacterial fertilizer, wherein the mass ratio of the piriformospora indica microbial agent to the phosphate solubilizing bacteria bacterial agent to the tamarix chinensis-based biochar is (1-2): 1: (1-4); s5, applying a nitrogen-phosphorus-potassium fertilizer to the saline-alkali land farmland soil as a base fertilizer before sowing; s6, the biological bacterial fertilizer is applied to the saline-alkali land farmland soil before sowing or during sowing, and the application amount of the biological bacterial fertilizer is 675-3500 kg / hm < 2 >. By means of the technical scheme, the saline-alkali land farmland soil can be greatly improved, and the tiller number of wheat in the saline land environment is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of soil improvement, and in particular to a method for improving saline-alkali farmland soil. Background Art

[0002] Soil salinization poses a serious threat to agricultural production around the world and is one of the global environmental problems that restricts plant growth and agricultural production. my country’s salinized soils are also abundant and widely distributed, with a total area of ​​9.9×10 7 hm 2 , of which the coastal saline-alkali soil in the Yellow River Delta is 500,000 hm2 2 , is an important reserve land in my country. The efficient use of saline-alkali land in agriculture has important practical significance for improving my country's agricultural production capacity.

[0003] In the related technology, biochar is generally used as a low-cost and effective saline-alkali soil remediation measure, but the application differences of biochar carriers prepared by different raw materials and methods are very obvious. Conventional biochar carriers in the existing technology are still difficult to repair saline-alkali land well, especially in the implementation and promotion of rice-wheat rotation cultivation technology. The wheat planting time is delayed, and the wheat tillering results in conventional saline-alkali farmland are not ideal. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0005] To this end, an object of the present invention is to provide a method for improving saline-alkali farmland soil, which can greatly improve saline-alkali farmland soil and increase the tillering number of wheat in a salt environment by utilizing a new biochar carrier in collaboration with Indian pear-shaped spore Serendipita indica and phosphate-solubilizing bacteria Pantoea vagans.

[0006] In order to achieve the above object, the technical solution of the present invention provides a method for improving saline-alkali farmland soil, comprising the following steps:

[0007] S1, preparing Tamarix-based biochar, washing mature Tamarix branches with water, drying at a constant temperature, crushing and sieving, dry-thermal cracking for 2-4 hours under oxygen-limited conditions, the dry-thermal cracking temperature is 300-400° C., cooling to room temperature with the furnace, leaching and drying to obtain Tamarix-based biochar;

[0008] S2, using potato glucose liquid medium to culture Indian pear-shaped spore Serendipita indica, the culture temperature is 28 ℃, the culture time is 8 days, and then centrifuged at a low temperature of 10 ℃ and a speed of 4500 rpm / min for 10 minutes, and after washing, Indian pear-shaped spore agent is obtained;

[0009] S3, using beef extract peptone liquid medium to culture the phosphate-solubilizing bacteria Pantoea vagans isolated from the saline-alkali land of the Yellow River Delta, the culture temperature is 30°C, the culture time is 36 hours, and then centrifuged at a low temperature of 10°C and a speed of 4500 rpm / min for 10 minutes, and after washing, the phosphate-solubilizing bacteria bacterial agent is obtained;

[0010] S4, mixing the Tamarix-based biochar, the Indian pear-shaped spore agent, and the phosphate-solubilizing bacteria agent to obtain a biological fertilizer, wherein the mass ratio of the Indian pear-shaped spore agent, the phosphate-solubilizing bacteria agent, and the Tamarix-based biochar is (1-2):1:(1-4);

[0011] S5: Apply nitrogen, phosphorus and potassium fertilizers as base fertilizer to the saline-alkali farmland soil before sowing, with the nitrogen fertilizer application rate of 105kg / hm2. 2 , the amount of phosphate fertilizer applied is 90kg / hm 2 , the amount of potassium fertilizer applied is 90kg / hm 2 ;

[0012] S6, applying the biological fertilizer to the saline-alkali farmland soil before or during sowing, wherein the application amount of the biological fertilizer is 675-3500 kg / hm 2 .

[0013] Preferably, in step S6, the biological fertilizer is used alone, and the application amount is 2500-3500kg / hm 2 .

[0014] Preferably, in step S6, the biofertilizer is mixed with crop seeds, wherein the amount of biofertilizer applied is 500-800 kg / hm 2 Preferably, step S1 of preparing Tamarix-based biochar specifically comprises the following steps:

[0015] S11, taking the stems of Tamarix chinensis from the coastal wetland of the Yellow River Delta, cleaning the dust on the surface, rinsing them with deionized water for 5 times, and drying them in an oven at a constant temperature of 80-105° C. for 24 h;

[0016] S12, putting the dried Tamarix into a grinder and crushing it, and passing it through a 2 mm sieve for later use;

[0017] S13, placing the Tamarix chinensis powder in a muffle furnace for dry thermal cracking at 300-400° C. for 2 h, and cooling to room temperature along with the furnace;

[0018] S14, loading the material obtained in step S13 into a column, eluting with deionized water for 1 min and then drying at 70° C. to obtain Tamarix-based biochar.

[0019] Preferably, in step S13, pyrolysis is performed at 400° C. for 2 h.

[0020] Preferably, in step S6, the biological fertilizer is applied to the soil layer of saline-alkali farmland to a depth of <20 cm.

[0021] The method for improving saline-alkali farmland soil proposed by the present invention has the following beneficial technical effects:

[0022] (1) The method for improving saline-alkali farmland soil proposed in the present invention utilizes Tamarix chinensis, an abundant plant resource in the Yellow River Delta, to prepare biochar in collaboration with Indian pear-shaped spore Serendipita indica and phosphate-solubilizing bacteria Pantoea vagans. The method can strengthen mycorrhizae, integrate mycorrhizae with mycelial microorganisms, and jointly develop the soil organic nutrient pool. Through the mycorrhizal pathway, the utilization efficiency of soil nutrients can be effectively improved.

[0023] (2) The method for improving saline-alkali farmland soil proposed in the present invention has a significant effect on improving saline-alkali farmland soil fertility and wheat yield. The amount of base fertilizer used is half of the conventional amount, thereby reducing the amount of chemical fertilizer used.

[0024] (3) The method for improving saline-alkali farmland soil proposed in the present invention can increase wheat yield by more than 100%.

[0025] (4) The method for improving saline-alkali farmland soil proposed in the present invention comprises biochar, Indian pear-shaped spores and phosphate-solubilizing bacteria, which have a synergistic effect and can effectively improve the soil microenvironment, specifically enrich the rhizosphere microbial population Morierellomycota (Mycetomycota) with phosphate-solubilizing ability and the population Clostridia (Clostridia) with nitrogen-fixing ability in saline-alkali land, promote the transportation and translocation of plant nutrients, increase the tillering number of wheat in saline-alkali land, and ultimately achieve the effect of high yield and quality improvement of saline-alkali land wheat.

[0026] (5) The present invention proposes a method for improving saline-alkali farmland soil, in which biochar, Indian pear-shaped spores and phosphate-solubilizing bacteria have a synergistic effect. The symbiotic mycorrhiza formed by Indian pear-shaped spores and plants can greatly expand the absorption range of plant roots, enhance the efficiency of water and nutrient absorption, and promote the absorption of soil nutrients transformed by a large number of effective microorganisms by plants. The synergistic effect of mycorrhizal secretions and hyphae microorganisms enhances the nutrient cycle of plants, jointly develops the soil organic nutrient pool, and effectively improves the utilization efficiency of soil nutrients through the mycorrhizal pathway.

[0027] (6) The method for improving saline-alkali farmland soil proposed in the present invention can specifically enrich the rhizosphere microbial population Morierellomycota (Hyphomycetes) with phosphate solubilization ability and the population Clostridia (Clostridia) with nitrogen fixation ability in saline-alkali land, significantly increase the wheat ear weight and tiller number, and increase the yield by 149.64% compared with the blank control, by 55.69% compared with the use of Indian pear-shaped spore alone, and by 50.29% compared with the use of biochar alone.

[0028] (7) The method for improving saline-alkali farmland soil proposed in the present invention has a significant improvement effect on saline-alkali farmland soil. The total nitrogen, total potassium and organic matter content increased by 19.67%, 3.4% and 84.38% respectively. Other metal ions in the soil, such as magnesium, calcium, iron, manganese, copper, zinc, etc., were also significantly improved.

[0029] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0031] Figure 1 A physical picture of Tamarix-based biochar is shown;

[0032] Figure 2 A comparison of the effects of different Tamarix-based biochars on the available phosphorus components in saline-alkali soils is shown;

[0033] Figure 3 A comparison chart of the content of various forms of phosphorus components in different Tamarix-based biochars is shown;

[0034] Figure 4 Fourier transform infrared spectra of different Tamarix-based biochars are shown;

[0035] Figure 5 X-ray diffraction patterns of different Tamarix-based biochars are shown;

[0036] Figure 6 SEM images of different Tamarix-based biochars are shown;

[0037] Figure 7 A picture of a culture of Serendipita indica is shown;

[0038] Figure 8 A picture of a culture of Pantoea vagans is shown;

[0039] Fig. 9 A comparison of the abundance of rhizosphere microbial bacterial populations is shown;

[0040] Fig.10 A comparison of the abundance of rhizosphere microbial fungal populations is shown. DETAILED DESCRIPTION

[0041] The present invention discloses a method for improving saline-alkali farmland soil. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0042] The present invention will be further described below in conjunction with embodiments:

[0043] Example 1

[0044] Preparation of Tamarix-based Biochar

[0045] 1) Pretreatment of Tamarix chinensis

[0046] The stems of Tamarix chinensis were sampled from the coastal wetlands of the Yellow River Delta. After cleaning the surface dust, they were rinsed with deionized water for 5 times and dried in an oven at a constant temperature of 80-105°C for 24 hours. The dried Tamarix chinensis was put into a grinder and crushed through a 2 mm sieve for later use.

[0047] 2) Preparation of Tamarix-based biochar

[0048] The Tamarix powder obtained in step 1) was placed in a muffle furnace for dry thermal cracking, and pyrolyzed at 300°C, 400°C, 500°C, 600°C and 700°C for 2h to obtain Tamarix-based biochars under corresponding conditions, which were recorded as BC300, BC400, BC500, BC600 and BC700, respectively.

[0049] 3) Washing: The biochar obtained in step 2) is loaded into a column, washed with deionized water for 1 min, and dried at 70° C. to obtain the Tamarix-based biochar. Figure 1 shown.

[0050] The effects of different Tamarix-based biochars on increasing available phosphorus in saline-alkali soil were tested, specifically:

[0051] 1) Experimental Sample Soil Samples Soil was obtained from the coastal saline soil of the Yellow River Delta, with a soil pH of 8.1-8.3, an initial salinity of 0.34%, a total phosphorus of 2.52 g / kg, an available phosphorus of 21.8 mg / kg, and ammonia nitrogen of 3.01 mg / kg. After sieving, impurities were removed and set aside.

[0052] 2) Weigh 200 g of the soil sample from step 1) and put it into a conical flask. The soil salinity simulates moderate to severe saline-alkali soil and is adjusted with sodium chloride. The final salinity of the soil is a salt concentration gradient of 0.5%, 0.8%, 1.1%, 1.4% and 1.7%, respectively. The soil moisture content is maintained at 20%.

[0053] 3) An orthogonal experimental design was used to add 1% of Tamarix-based biochar BC300, BC400, BC500, BC600 and BC700 to the culture bottles in step 2), and each treatment was repeated 4 times.

[0054] 4) Each treatment group was placed in an artificial climate chamber at 28°C, with a light / dark cycle of 12 / 12, and a treatment time of 48 days. During this period, the soil was taken out and weighed, and water was added according to the difference. After the experiment, the soil available phosphorus content was measured, and variance analysis was performed using a single dependent variable and multiple factors.

[0055] Test results such as Figure 2 As shown by Figure 2 It can be seen that the BC400 biochar based on Tamarix has the best effect on improving soil available phosphorus, followed by BC300 biochar. As the salinity increases, the effect of improving soil available phosphorus decreases significantly. Combined with the phosphorus content of each component of Tamarix-based biochar, it can be seen that the increase in soil available phosphorus content is due to the fact that the added Tamarix-based biochar itself contains a high amount of soluble phosphorus. If the pyrolysis temperature is too high, the soluble phosphorus content of Tamarix-based biochar will be greatly reduced. The two-way ANOVA showed that the preparation temperature of biochar had a significant effect on soil available phosphorus (F=13.97, p<0.05), while salinity had no effect on soil available phosphorus (F=1.09, p=0.37). It can be seen that Tamarix-based biochar can significantly improve the effectiveness of phosphorus in saline soil. Taking the above factors into consideration, BC400 has the best effect on improving available phosphorus in saline-alkali land, followed by BC300.

[0056] After grinding different Tamarix-based biochar samples, the samples were analyzed and characterized. The basic physical and chemical indicators are shown in Table 1.

[0057] Table 1 Basic physical and chemical indicators of Tamarix chinensis biochar prepared under different temperature conditions

[0058]

[0059]

[0060] As can be seen from Table 1, the pH values ​​of biochars prepared under all conditions are alkaline. When the temperature exceeds 400°C, the pH of Tamarix-based biochar shows a downward trend with increasing temperature. As the temperature increases, the yield of Tamarix-based biochar decreases rapidly, and its nutrient elements such as nitrogen, phosphorus, potassium, total carbon, organic matter and salt content increase. However, when the temperature reaches 600°C, the content of each index shows a downward trend.

[0061] Comparison of the contents of various forms of phosphorus components in different Tamarix-based biochars Figure 3 As shown in the figure, the soluble phosphorus content of Tamarix chinensis biochar prepared at different temperatures is significantly different. As the preparation temperature increases, the soluble phosphorus content decreases significantly; the Fe / Al bound phosphorus content shows the same trend; the Ca bound phosphorus content accounts for the highest proportion of the total phosphorus content, and as the preparation temperature increases, the Ca bound phosphorus content increases, and the change in the inert phosphorus content does not show an obvious trend. It can be seen that the preparation temperature can significantly affect the soluble phosphorus content of Tamarix chinensis biochar. BC400 and BC300 have higher effective phosphorus content.

[0062] Fourier transform infrared spectra of different Tamarix-based biochars Figure 4 As shown in Figure 2, it can be seen that the biochars prepared at different temperatures all contain rich functional groups. All biochars have a wave number of 3405 cm -1 There are strong absorption peaks at the wave number of 2922cm for BC300 and BC400, which is the characteristic absorption peak of -OH. As the preparation temperature increases, the absorption peak gradually decreases. -1 and 2852cm -1 The absorption peak near the aliphatic -CH 2 When the temperature increases to above 500℃, the characteristic peak of this area basically disappears, indicating that the alkyl and aliphatic compounds have been transformed. -1 The absorption peak that appears near the carbonyl or carboxyl group is the C=O absorption peak. The surface of BC300 biochar contains such oxygen-containing functional groups. However, as the preparation temperature increases, the C=O absorption peak weakens. When the temperature is increased to above 400°C, the characteristic absorption peak of this functional group disappears completely. This indicates that as the biochar preparation temperature increases, C=O breaks and generates CO and CO at high temperatures. 2 In addition, BC300 and BC400 biochars have more absorption peaks, such as 1315 cm -1 The peak of (C=S) is no longer detectable in BC500, BC600 and BC700. 1600-1450cm -1 and 1113cm -1The spectral bands respond to the absorption peaks of benzene rings and CO, which are characteristic absorption peaks of Tamarix lignin, cellulose and hemicellulose. As the charcoal burning temperature increases, the absorption peaks of functional groups become larger and then slightly decrease; the absorption peaks of aromatic groups, such as C=C, shift to the direction of lower wavenumbers, and the peak value also weakens. In the temperature range of 300-400℃, the peak value increases slightly, indicating that the higher the temperature, the higher the degree of aromatization, and the more stable the biochar; after exceeding 400℃, the number of aromatic absorption peaks decreases sharply. At 700℃, only CH absorption peaks exist, and the peak value is also weak, indicating that part of its structure is also undergoing cracking. From the FT-IR spectrum, it can be seen that as the pyrolysis temperature increases, cellulose and hemicellulose undergo dehydration and decarboxylation reactions, and aliphatic carbon transforms into graphite crystals. At the same time, due to the decarboxylation of cellulose and lignin, the aromatic C=C and CO groups are reduced.

[0063] X-ray diffraction patterns of different Tamarix-based biochars Figure 5 As shown in the figure, after pyrolysis, as the temperature increases from 300℃ to 600℃, the number of diffraction peaks of Tamarix biochar increases. The diffraction patterns of BC400, BC500 and BC600 are basically similar. When the temperature exceeds 600℃, the number of diffraction peaks decreases sharply and the intensity weakens. A typical characteristic diffraction peak of amorphous carbon material appears near 2θ=25.5°, which belongs to the (002) crystal plane of graphite microcrystals. This is caused by the interlayer spacing of aromatic domains and is called π band. The peak height shows that the amorphous carbon content of BC400, BC500 and BC600 is significantly higher than that of BC300 and BC700. As the treatment temperature increases, the peak intensity of BC700 near 2θ=45° increases, indicating that the amorphous carbon structure is sp 2 The configuration of hybrid carbon changes, and the carbon connection performance is stronger, and graphitization occurs. The diffraction patterns all show mineralized crystals of Ca. The content gradient of each ion in the tamarisk branch is SO 4 2- >K + >Ca 2+ >Cl - , and SO 4 2- The content of CaCO is the highest in all organs of Tamarix chinensis, which is probably due to CaCO 3 and CaSO 4 .

[0064] SEM images of different Tamarix-based biochars, such as Figure 6 As shown, it can be seen that the biochar prepared at low temperature (see Figure 6 The surface of the biochar is smooth when the temperature is raised to above 400℃, and the surface of the biochar is uneven, indicating that there are gaps in the biochar. The higher the temperature, the lower the surface integrity. Figure 5From the XRD results in the figure, we can see that the higher the temperature, the more intense the internal reaction of the biochar, which causes the surface morphology to change. Since Tamarix is ​​a salt-secreting plant, mineral crystal particles are found on the surface of the biochar prepared by it. Combined with the determination of biochar salt content and XRD diffraction pattern, its mineral crystal components are likely to be mineral crystals of Ca and Na.

[0065] In summary, BC400 has better performance. Therefore, BC400 is the preferred Tamarix-based biochar for improving saline-alkali farmland soil.

[0066] Example 2

[0067] Cultivation and acquisition of Indian pear-shaped spore, Indian pear-shaped spore Serendipita indica, purchased from the Institute of Microbiology, Chinese Academy of Sciences (strain number: cgmcc3.17686)

[0068] The culture was carried out in a potato glucose liquid medium at a temperature of 28°C for 8 days, and then centrifuged at 4500 rpm / min at a low temperature of 10°C for 10 minutes. After washing, the Indian pear-shaped spore agent was obtained. Figure 7 shown.

[0069] Example 3

[0070] Cultivation and acquisition of phosphate-solubilizing bacteria Pantoea vagans was isolated and obtained from the saline-alkali land of the Yellow River Delta by the laboratory. It is the strain disclosed in CN 108841751 A, a salt-alkali tolerant phosphate-solubilizing bacterial strain and its application.

[0071] Beef extract peptone liquid medium was used for cultivation, the culture temperature was 30°C, the culture time was 36 hours, and the culture was centrifuged at a low temperature of 10°C for 10 minutes at a speed of 4500 rpm / min. After washing, the phosphate-solubilizing bacteria cell inoculum was obtained. Figure 8 shown.

[0072] Example 4

[0073] Jimai 22 was used as the test plant, and the seeds were sterilized and planted in an outdoor plot of the greenhouse in the Yellow River Delta (soil salt content 0.24%).

[0074] Before sowing, nitrogen, phosphorus and potassium fertilizers were applied to the soil of saline-alkali farmland as base fertilizer, among which the nitrogen fertilizer application rate was 105kg / hm 2 , the amount of phosphate fertilizer applied is 90kg / hm 2 , the amount of potassium fertilizer applied is 90kg / hm 2 , the amount of base fertilizer is half of the conventional amount.

[0075] The biofertilizer is obtained by mixing the Tamarix-based biochar, the Indian piriform spore agent, and the phosphate-solubilizing bacteria agent. The mass ratio of the Indian piriform spore agent, the phosphate-solubilizing bacteria agent, and the Tamarix-based biochar is 2:1:4, and the Tamarix-based biochar here is BC400.

[0076] Apply the above-mentioned biofertilizer to the soil at 3500kg / hm2 before sowing. 2 .

[0077] It is recorded as bacterial fertilizer treatment group 1 and represented by "bacterial fertilizer 1".

[0078] Example 5

[0079] Jimai 22 was used as the test plant, and the seeds were sterilized and planted in an outdoor plot of the greenhouse in the Yellow River Delta (soil salt content 0.24%).

[0080] Before sowing, nitrogen, phosphorus and potassium fertilizers were applied to the soil of saline-alkali farmland as base fertilizer, among which the nitrogen fertilizer application rate was 105kg / hm 2 , the amount of phosphate fertilizer applied is 90kg / hm 2 , the amount of potassium fertilizer applied is 90kg / hm 2 , the amount of base fertilizer is half of the conventional amount.

[0081] The biofertilizer is obtained by mixing the Tamarix-based biochar, the Indian piriform spore agent, and the phosphate-solubilizing bacteria agent. The mass ratio of the Indian piriform spore agent, the phosphate-solubilizing bacteria agent, and the Tamarix-based biochar is 2:1:2, and the Tamarix-based biochar here is BC400.

[0082] Apply the above-mentioned biofertilizer to the soil at 2500kg / hm2 before sowing. 2 .

[0083] It is recorded as bacterial fertilizer treatment group 2 and represented by "bacterial fertilizer 2".

[0084] Example 6

[0085] Jimai 22 was used as the test plant, and the seeds were sterilized and planted in an outdoor plot of the greenhouse in the Yellow River Delta (soil salt content 0.24%).

[0086] Before sowing, nitrogen, phosphorus and potassium fertilizers were applied to the soil of saline-alkali farmland as base fertilizer, among which the nitrogen fertilizer application rate was 105kg / hm 2 , the amount of phosphate fertilizer applied is 90kg / hm 2 , the amount of potassium fertilizer applied is 90kg / hm 2 , the amount of base fertilizer is half of the conventional amount.

[0087] The biofertilizer is obtained by mixing the Tamarix-based biochar, the Indian piriform spore agent, and the phosphate-solubilizing bacteria agent. The mass ratio of the Indian piriform spore agent, the phosphate-solubilizing bacteria agent, and the Tamarix-based biochar is 1:1:1, and the Tamarix-based biochar here is BC400.

[0088] At the time of sowing, the above-mentioned biofertilizer was mixed with wheat seeds and applied at a rate of 675 kg / hm2. 2 .

[0089] It is recorded as bacterial fertilizer treatment group 3 and represented by "bacterial fertilizer 3".

[0090] Comparative Example 1

[0091] The difference from Example 4 is that no biological fertilizer is applied, which serves as a blank control group, represented by "CK".

[0092] Comparative Example 2

[0093] The difference from Example 4 is that the application of the biological fertilizer is replaced by the application of the Indian piriform spore agent, which is recorded as the Indian piriform spore implementation group and represented by "Si".

[0094] Comparative Example 3

[0095] The difference from Example 4 is that the application of biological fertilizer is replaced by the application of Tamarix-based biochar, which is recorded as the biochar implementation group and represented by "BC".

[0096] In the same time period, the biological shapes of the wheat from Example 4 to Example 6 and Comparative Examples 1 to Comparative Examples 3 were observed and tested, and the results are shown in Table 2 below.

[0097] Table 2 Effects of different treatments on biological traits of wheat

[0098]

[0099]

[0100] As shown in Table 2, the bacterial fertilizer treatment group had a relatively better effect, showing significant differences in wheat agronomic traits such as plant height, straw dry weight, single ear weight, and tiller number. Among them, Example 4 had the best effect, followed by the biochar group and the group using Indian pear-shaped spore alone. Through the weighted analysis of wheat single ear weight and tiller number, the following conclusions can be drawn: compared with the blank control group, the bacterial fertilizer group increased its yield by 149.64%, 55.69% compared with the group applying Indian pear-shaped spore alone, and 50.29% compared with the group applying biochar alone.

[0101] During the wheat harvest period, rhizosphere soil samples were collected and subjected to 16Sr RNA and ITS high-throughput sequencing to obtain the structure and abundance of rhizosphere soil bacterial and fungal populations; the sequencing results were analyzed based on the Micro-Science Bioinformatics Cloud tool, the website of which is as follows: https: / / www.bioincloud.tech / .

[0102] The sequencing results are as follows Fig. 9 , Fig.10 As shown in the figure, it can be seen that biomass fertilizer can significantly improve the structure and abundance of rhizosphere soil microbial flora, and biochar, Indian pear-shaped spores and phosphate-solubilizing bacteria can effectively recruit rhizosphere auxiliary microorganisms and mycorrhizal auxiliary microorganisms. Fig. 9 As shown in Figure 2, the abundance of Clostridia in the nitrogen-fixing population increased significantly, such as Fig.10 As shown in the figure, the abundance of Hyphomycetes, a population with the ability to solubilize phosphate, increased significantly. It can be seen that the three components of the biomass fertilizer have a synergistic effect, effectively enriching the beneficial microbial population in saline-alkali land, thereby promoting the absorption and transformation of nutrients in the rhizosphere and mycorrhizal soil, and improving the transformation and absorption of mineral nutrients such as N and P by crop wheat, achieving the purpose of promoting wheat yield and quality.

[0103] During the wheat harvest period, rhizosphere soil samples were collected and the soil physical and chemical properties were tested. The test results are shown in Table 3 below.

[0104] Table 3 Detection of soil physical and chemical properties under different treatments

[0105]

[0106] As shown in Table 3, compared with CK, the soil physical and chemical factors of the bacterial fertilizer group have been significantly improved, such as total nitrogen, total potassium and organic matter increased by 19.67%, 3.4% and 84.38% respectively compared with the CK group, and other metal ion indicators have all been significantly improved compared with CK (p<0.05). From the perspective of soil physical and chemical indicators, the bacterial fertilizer can not only promote the growth of wheat, but also has a significant improvement effect on saline-alkali farmland soil.

[0107] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for improving saline-alkali farmland soil, characterized in that: The following steps are involved: S1, preparing Tamarix-based biochar, washing mature Tamarix branches with water, drying at a constant temperature, crushing and sieving, dry-thermal cracking for 2-4 hours under oxygen-limited conditions, the dry-thermal cracking temperature is 300-400° C., cooling to room temperature with the furnace, leaching and drying to obtain Tamarix-based biochar; S2, using potato glucose liquid medium to culture Indian pear-shaped spore Serendipita indica, the culture temperature is 28 ℃, the culture time is 8 days, and then centrifuged at a low temperature of 10 ℃ and a speed of 4500 rpm / min for 10 minutes, and after washing, Indian pear-shaped spore agent is obtained; S3, using beef extract peptone liquid medium to culture the phosphate-solubilizing bacteria Pantoea vagans isolated from the saline-alkali land of the Yellow River Delta, the culture temperature is 30°C, the culture time is 36 hours, and then centrifuged at a low temperature of 10°C and a speed of 4500 rpm / min for 10 minutes, and after washing, the phosphate-solubilizing bacteria bacterial agent is obtained; S4, mixing the Tamarix-based biochar, the Indian pear-shaped spore agent, and the phosphate-solubilizing bacteria agent to obtain a biological fertilizer, wherein the mass ratio of the Indian pear-shaped spore agent, the phosphate-solubilizing bacteria agent, and the Tamarix-based biochar is (1-2):1:(1-4); S5: Apply nitrogen, phosphorus and potassium fertilizers as base fertilizer to the saline-alkali farmland soil before sowing, with the nitrogen fertilizer application rate of 105kg / hm2. 2 , the amount of phosphate fertilizer applied is 90kg / hm 2 , the amount of potassium fertilizer applied is 90kg / hm 2 ; S6, applying the biological fertilizer to the saline-alkali farmland soil before or during sowing, wherein the application amount of the biological fertilizer is 675-3500 kg / hm 2 .

2. The method for improving saline-alkali farmland soil according to claim 1, characterized in that: In step S6, the biological fertilizer is used alone, and the application amount is 2500-3500kg / hm 2 .

3. The method for improving saline-alkali farmland soil according to claim 1, characterized in that: In step S6, the biofertilizer is mixed with the crop seeds for use, wherein the amount of biofertilizer applied is 675 kg / hm 2 .

4. The method for improving saline-alkali farmland soil according to claim 1, characterized in that: Step S1 prepares Tamarix-based biochar, specifically comprising the following steps: S11, taking the stems of Tamarix chinensis from the coastal wetland of the Yellow River Delta, cleaning the dust on the surface, rinsing them with deionized water for 5 times, and drying them in an oven at a constant temperature of 80-105° C. for 24 h; S12, putting the dried Tamarix into a grinder and crushing it, and passing it through a 2 mm sieve for later use; S13, placing the Tamarix chinensis powder in a muffle furnace for dry thermal cracking at 300-400° C. for 2 h, and cooling to room temperature along with the furnace; S14, loading the material obtained in step S13 into a column, eluting with deionized water for 1 min and then drying at 70° C. to obtain Tamarix-based biochar.

5. The method for improving saline-alkali farmland soil according to claim 4, characterized in that: In step S13, pyrolysis is performed at 400° C. for 2 h.

6. The method for improving saline-alkali farmland soil according to claim 1, characterized in that: In step S6, the biological fertilizer is applied to the soil layer of saline-alkali farmland to a depth of less than 20 cm.

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