Method for improving soil health by using nitrogen-fixing blue-green algae
By applying Nostoc commune to the soil surface and controlling light exposure, the structural damage and nutrient imbalance caused by fertilizer use in the soil were resolved, resulting in a systematic improvement in soil health, reduced reliance on fertilizers, and enhanced soil self-repair capabilities.
Patent Information
- Application Number
- CN202511899343.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-16
- Publication Date
- 2026-02-13
AI Technical Summary
In existing agricultural technologies, the excessive use of chemical fertilizers has led to damage to the physical structure of soil, a decline in organic matter, reduced biological activity, and nutrient imbalance. There is a lack of low-cost bioremediation methods to reduce reliance on chemical fertilizers and restore soil ecological functions.
Nitrogen-fixing cyanobacteria (Nostoc) were applied to the soil surface, with controlled light intensity of 1000 Lux for 12 hours and an addition rate of 10 g/m2. The mixture was cultured until the optical density reached 0.9-1.0 and then centrifuged. The mixture was then cultured in BG11 medium, and the soil field water holding capacity was maintained at 20%-30%.
It significantly improves soil aggregate stability and average weight diameter, increases soil organic carbon and total nitrogen content, enhances soil microbial diversity and biological activity, reduces reliance on chemical fertilizers, and improves maize growth.
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Figure CN121511706A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of soil improvement, and particularly relates to a method for improving soil health by using nitrogen-fixing cyanobacteria. BACKGROUND
[0002] Soil health is the cornerstone of agricultural production and ecological environment protection. With the widespread use of chemical fertilizers and pesticides, soil fertility is declining and soil degradation is becoming increasingly serious. At the same time, resource waste and increased agricultural non-point source pollution have become a major problem facing the industry.
[0003] Increasing soil organic matter is considered one of the important means to improve soil health. Traditional methods of increasing soil organic matter mainly include applying mature organic fertilizer, straw returning and planting green manure, but these methods have their own limitations, such as the source of mature organic fertilizer is not extensive enough; large-scale agricultural mechanical operation of straw returning is not widely promoted, and small-scale mechanical straw returning is costly; planting green manure will indirectly increase the input cost of farmers.
[0004] Nitrogen-fixing cyanobacteria is a type of microorganism that can fix nitrogen in the air and improve soil nitrogen content and soil fertility through nitrogen fixation. Among nitrogen-fixing cyanobacteria, Nostoc is the dominant species in black soil, and its composition varies with soil region, playing a multiple key role in soil ecology and agricultural productivity.
[0005] 20th century science, especially in the fields of chemistry and physics, has achieved great success, with its core method being "reductionism" - breaking down complex systems into individual components for study. This idea was transplanted to agriculture, leading to soil being viewed as a "container" that holds various chemical substances. As a result, increasing yield was simplified to "supplementing the missing chemical elements" (such as nitrogen, phosphorus, and potassium) to the container, while ignoring the essence of soil as a living, complex ecosystem of physical structure, chemical properties, and biological communities interacting with each other. In traditional agriculture, livestock breeding was closely integrated with crop cultivation, forming a "manure returning" material cycle. Industrialization led to the separation of breeding and cultivation, making organic fertilizer sources scarce and costly to collect and apply. Chemical fertilizers, as a perfect substitute for their standardization, easy transportation, and easy application, quickly filled the gap, but also cut off the valuable source of soil organic matter and microorganisms. Frequent compaction by large agricultural machinery, while improving tillage efficiency, also severely compacted the soil, damaging its aggregate structure. When the soil's physical structure deteriorates, its water retention, aeration, and root extension capacity decline, and in order to maintain yield, water and fertilizer inputs must be further increased, forming another vicious cycle, causing the soil to degenerate from a separate ecosystem to a fragile, passive container.
[0006] Therefore, there is an urgent need for a low-cost, easy-to-apply biological remediation technology that can improve soil structure, improve nutrient levels, and activate microbial communities from a system level, thereby reducing dependence on chemical fertilizers and restoring soil ecological functions. SUMMARY
[0007] The embodiments of the present application provide a method for improving soil health by using nitrogen-fixing cyanobacteria, which solves the various health problems in the soil in the prior art, reduces energy input such as chemical fertilizers, and improves the degree of soil health.
[0008] The embodiments of the present application provide a method for improving soil health by using nitrogen-fixing cyanobacteria, which solves the various health problems in the soil in the prior art, reduces energy input such as chemical fertilizers, and improves the degree of soil health.
[0009] Further, the nitrogen-fixing cyanobacteria is Nostoc, and the addition amount is 10 g / m 2 .
[0010] Further, the nitrogen-fixing cyanobacteria is Nostoc, and the addition amount is 10 g / m 2 .
[0011] Further, the culture uses a BG11 culture medium, which contains sodium nitrate 1.5 g, sodium bicarbonate 20 mg, citric acid 6 mg, ethylenediaminetetraacetic acid disodium 1 mg, potassium phosphate dibasic 40 mg, ferric ammonium citrate 6 mg, magnesium sulfate 75 mg, calcium chloride 36 mg, copper sulfate 0.08 mg, sodium molybdate 0.39 mg, boric acid 2.86 mg, manganese chloride 1.81 mg, zinc sulfate 0.22 mg, cobalt nitrate 0.049 mg, and distilled water 1 L.
[0012] Further, the Nostoc is centrifuged after culture, at a speed of 2000 r / min for 10 minutes.
[0013] Further, the soil field moisture content is maintained at 20%-30% after application.
[0014] The one or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: By using the technical means of applying active nitrogen-fixing cyanobacteria, the problems of physical structure damage, organic matter decline, biological activity reduction, and nutrient imbalance caused by excessive use of chemical fertilizers in the prior art are effectively solved, thereby achieving the technical effects of significantly improving soil aggregate stability and average weight diameter, increasing soil organic carbon and total nitrogen content, enhancing soil microbial diversity and biological activity, and reducing dependence on chemical fertilizers in agricultural production. BRIEF DESCRIPTION OF DRAWINGS
[0015] Figure 1 The physical index changes of the experimental and control groups of this invention are shown. Figure 2 The chemical index changes of the experimental and control groups of this invention are shown. Figure 3 The biological indicator changes of the experimental group and the control group of this invention are shown. Figure 4 The soil health comprehensive score (a) of the control group of the present invention and the weight of each indicator (b) are shown. Figure 5 This is a photograph of the soil used in the planting experiment of this invention. Figure 6 This is a comparison diagram of maize photosynthesis in the soil of the experimental group and the control group of this invention. Figure 7 This is a comparison diagram of the diameter length of maize planted in the soil of the experimental group and the control group of the present invention. Figure 8 This is a comparison chart of the weight of 100 corn kernels in the soil of the experimental group and the control group of this invention. Figure 9 This is a comparison chart showing the correlation between the strains of this invention and soil organic matter. Detailed Implementation
[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0017] Example 1: A method for improving soil health using nitrogen-fixing cyanobacteria, the specific steps of which include: Filamentous nitrogen-fixing cyanobacteria (Nostoc), Nostoc sp.) was placed in BG11 medium and cultured until OD. 750 =0.9-1.0, the BG11 culture medium comprises the following components: sodium nitrate 1.5 g, sodium bicarbonate 20 mg, citric acid 6 mg, disodium ethylenediaminetetraacetate 1 mg, dipotassium hydrogen phosphate 40 mg, ferric ammonium citrate 6 mg, magnesium sulfate 75 mg, calcium chloride 36 mg, copper sulfate 0.08 g, sodium molybdate 0.39 g, boric acid 2.86 g, manganese chloride 1.81 g, zinc sulfate 0.22 g, cobalt nitrate 0.049 g, and distilled water 1 L; The Nostoc commune used was screened from the correlation experiment between soil organic matter (SOM) and various bacterial species in black soil. It can effectively increase the organic matter in the soil. The screening results are as follows:Figure 9 ; The cultured filamentous nitrogen-fixing cyanobacteria were centrifuged at 2000 r / min for 10 min, and 10 g / m 2 was uniformly spread on the surface of healthy soil, the light intensity was 1000 Lux, and the light time was 12 h.
[0018] Four experimental groups were set, including: experimental group S1: directly adding active Nostoc strain (10 g / m 2 ) in soil; experimental group S2: sterilizing the soil (125°C, 2h) to ensure that there is no interference of other microorganisms in the soil, and adding active Nostoc (10 g / m 2 ); experimental group S3: adding inactivated Nostoc (125°C, 2h) in the soil to detect the influence of dead algae (10 g / m 2 ) on soil health; control group (CK): no Nostoc treatment, only maintaining the natural state of the soil. Each treatment area was regularly watered to maintain the field water holding capacity at 20%-30%.
[0019] The soil samples were collected to detect the following indicators: organic carbon (SOC), total carbon (TC), dissolved organic carbon (DOC), total nitrogen (TN), ammonia nitrogen (NH4-N), nitrate nitrogen (NO3-N), dissolved organic nitrogen (DON), total phosphorus (TP), available phosphorus (AP), pH, soil average weight diameter (MWD), soil aggregate stability greater than 0.25 mm (R 0.25 ), biodiversity (Alpha), and chlorophyll a (Chla).
[0020] The Cornell Soil Health Assessment System (CSHA) was used to standardize the scores of each indicator, and principal component analysis (SPSS software) was used to determine the weight of each indicator to calculate the comprehensive score of soil health:
[0021] Wherein, A is the CSHA score of each single soil indicator, and W is the weight value of the soil indicator The results are shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 The experimental group S1 (active Nostoc + healthy soil) was significantly better than the control group in terms of soil structure, nutrient content, and biological activity, and the comprehensive score of soil health was significantly improved.
[0022] A planting experiment was conducted on the soil of the experimental group and the control group. No fertilizer or other nutrients were used during the sowing process, only water was poured every 5 days, the selected crop was maize Zhengdan 958, and the growth process of maize was recorded until the 90th day. The status of the obtained maize during the growth process is as follows:Figure 5 , using a portable photosynthesis instrument to detect photosynthesis intensity, the results are as follows Figure 6 , relative to the control group, photosynthesis increased by 25%; measure the length of corn stem, the results are as follows Figure 7 , relative to the control group, corn stem length increased by 30%, and the corn fruit was detected, 100 samples were randomly taken and weighed three times to take the average as the hundred kernel weight, the results are as follows Figure 8 , relative to the control group, the hundred kernel weight increased by 50%; Nitrogen-fixing cyanobacteria (Nostoc commune Vauch Nostoc ) have multiple ecological functions such as nitrogen fixation, carbon fixation, and exopolysaccharide (EPS) secretion. Cyanobacteria contain nitrogenase in their cells, which can convert inert nitrogen (N2) in the air into ammonia (NH3), and then into ammonium salt (NH4 + ), providing a direct source of available nitrogen for the soil. They can also fix CO2 through photosynthesis to synthesize organic carbon compounds, increasing soil organic carbon (SOC) and dissolved organic carbon (DOC); improve soil pore structure and aeration; EPS and algal residues provide carbon and energy sources for soil primary microorganisms, promoting microbial diversity and forming a benign microecological cycle.
[0023] Live Nostoc commune and soil primary microbial communities form a mutually beneficial and synergistic effect. Nostoc commune and its secreted exopolysaccharides (EPS) and other sticky substances can cement soil particles, binding small soil particles together and promoting the formation of stable water-stable aggregates, which directly leads to an increase in soil aggregate stability (R 0.25 ) and mean weight diameter (MWD) of greater than 0.25mm. The DOC and mucus they secrete are high-quality nutrients for other soil microorganisms, and they have carbon fixation capabilities, so they have the ability to synergistically improve soil health in physical, chemical, and biological dimensions, rather than simply adding nutrients. Algal residues and formed aggregates provide a habitat for microorganisms, constructing a live algal-microbial mutualistic system that drives efficient nutrient cycling and transformation and strengthens soil biological self-regulation capabilities.
[0024] Exopolysaccharide (EPS) secreted by nostoc is a natural and efficient "soil glue" that can bond dispersed soil particles to form water-stable aggregates, which directly repairs the soil pore structure damaged by mechanical compaction. With the restoration of aggregate structure, the water-holding capacity and aeration of the soil are improved, which makes the crop root system more developed, and the utilization efficiency of water and fertilizer is improved, thereby reducing the dependence on additional water and fertilizer input, breaking the vicious cycle of structure deterioration→increased input→further deterioration; The secreted EPS and dissolved organic carbon (DOC) are high-quality food sources for soil primary microorganisms, which can quickly activate the dormant microbial community. The mycelium and formed aggregates provide a good habitat for microorganisms, triggering a synergistic effect (as shown in the experimental group S1). The symbiosis between living nostoc and soil primary microorganisms forms a more dynamic and diverse soil food web, driving the natural cycle and transformation of nutrients, and reducing the dependence on chemical fertilizers.
[0025] Controlling light 1000 Lux is not only for photosynthesis, fixing carbon dioxide, increasing organic carbon, under light and nitrogen deficiency conditions, part of the cells will differentiate into heteromorphosis, provide protection for nitrogenase, ensure the effect of nitrogen fixation, increase the total nitrogen content, and no longer carry out photosynthesis, which will not cause the inactivation of nitrogenase due to high oxygen content caused by photosynthesis; Light intensity and cycle are important signals for regulating the metabolic flow of nostoc. After completing its own growth, nostoc will convert excess photosynthetic products into exopolysaccharide (EPS) and secrete DOC and EPS into the surrounding environment. Providing light not only increases the carbon content but also increases the nitrogen content, optimizes the soil physical state, and improves microbial diversity and activity.
[0026] In summary, nitrogen-fixing cyanobacteria (nostoc) is a miniature self-sustaining ecosystem. It itself has multiple roles as a producer (photosynthetic carbon fixation), nitrogen fixer (biological nitrogen fixation), and ecosystem engineer (EPS secretion). When introduced into the soil, it is not just adding a substance to the soil, but implanting a functional miniature ecosystem into the soil. The soil is transformed from a passive, externally input-dependent container to an active, self-synthetic key nutrient (nitrogen, carbon) and self-optimized structure living body. Nostoc uses CO2 in the air and sunlight to directly produce organic matter on the surface of the soil, without relying on large-scale livestock breeding or expensive organic fertilizer transportation. Only by using light energy and air, it reopens the short path cycle of atmospheric carbon and nitrogen to soil organic matter, perfectly filling the gap of organic matter caused by the separation of nutrients; The application solves many problems in physical, chemical and biological aspects caused by the reductionist agricultural thought by a simple operation of "seeding nitrogen-fixing cyanobacteria", which actually rebuilds a micro-ecological core capable of self-maintenance and self-repair in the soil, and makes the soil return to a "healthy and active ecosystem" from a "fragile and passive container".
[0027] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application. The present application can be variously changed and modified by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for improving soil health using nitrogen-fixing cyanobacteria, characterized in that, Nitrogen-fixing cyanobacteria were applied to the soil surface and the light intensity was controlled at 1000 Lux for 12 hours.
2. The method for improving soil health using nitrogen-fixing cyanobacteria as described in claim 1, characterized in that, The nitrogen-fixing cyanobacterium mentioned is Nostoc, and the addition amount is 10 g / m³. 2 .
3. The method for improving soil health using nitrogen-fixing cyanobacteria as described in claim 1, characterized in that, The nitrogen-fixing cyanobacteria are cultured before application until the optical density at a wavelength of 750 nm is 0.9-1.
0.
4. The method for improving soil health using nitrogen-fixing cyanobacteria as described in claim 1, characterized in that, The culture was performed using BG11 medium, which contains 1.5 g sodium nitrate, 20 mg sodium bicarbonate, 6 mg citric acid, 1 mg disodium EDTA, 40 mg dipotassium hydrogen phosphate, 6 mg ferric ammonium citrate, 75 mg magnesium sulfate, 36 mg calcium chloride, 0.08 mg copper sulfate, 0.39 mg sodium molybdate, 2.86 mg boric acid, 1.81 mg manganese chloride, 0.22 mg zinc sulfate, 0.049 mg cobalt nitrate, and 1 L distilled water.
5. The method for improving soil health using nitrogen-fixing cyanobacteria as described in claim 3, characterized in that, After being cultured, Nostoc commune was centrifuged at a speed of 2000 r / min for 10 minutes.
6. The method for improving soil health using nitrogen-fixing cyanobacteria as described in claim 1, characterized in that, After application, maintain soil field water holding capacity at 20%-30%.