Soil is the foundation of agriculture and horticulture, and plays a crucial role in plant growth, carbon capture, and supports diverse ecosystems.

What is soil?

Soil is not just soil, as we like to say at SoilSteam.

In the context of agriculture and gardening, we are actually talking about topsoil. Topsoil refers to the upper part of the Earth's crust that is particularly suitable for plant growth. This layer consists of a mixture of minerals, organic matter, water, and air. Topsoil is crucial for plants to have a place to take root, and it is the roots that absorb water and nutrients from the soil.
Good topsoil has adequate drainage while retaining moisture. It contains essential nutrients and provides favorable conditions for microorganisms beneficial to plant growth. Good topsoil contains a significant amount of organic matter, which is decomposed plant material and other organic waste. This helps improve soil structure and provides necessary nutrients to plants. Good soil structure creates pores where water and air become available to plant roots.
Agriculture and gardening rely on the quality of topsoil to cultivate healthy and thriving crops. Good topsoil is a valuable resource for society, and the conservation and sustainable management of topsoil are essential to maintain productivity in food production and preserve healthy ecosystems.

What soil types do we have?

There are several soil types, and they vary based on factors such as climate, geography, and geological conditions. We have the following soil types:

  1. Clay Soil: This type of soil consists of very small particles. Clay soil retains water well, but drainage can be a problem if it becomes compacted. It is also challenging to work with when wet, and one must ensure it is dry enough before starting soil cultivation or driving on it.
  2. Silt Soil: Silt soil has particles smaller than sand but larger than clay. It drains better than clay and retains water better than sandy soil.
  3. Sandy Soil: Sandy soil has coarse particles and good drainage, but it retains water and nutrients poorly.
  4. Peat Soil: Peat soil forms in bogs and marshy areas. It has a high organic content and retains water well.

Most soil types are different combinations of the mentioned soil types. Soil can also be acidic or alkaline depending on the pH level. The various soil types contribute to variations in plant life and agricultural practices around the world.

Carbon Sequestration in Soil

Soil binds more CO2 than all the world's plants and trees combined. Efficient storage of CO2 in soil can be a crucial strategy to reduce greenhouse gas emissions and maintain a balanced carbon cycle in ecosystems. Research and practices promoting sustainable agriculture and forest management play a significant role in this effort.

The soil also harbors over 50% of all the world's organisms. Healthy and fertile soil is, therefore, crucial for food supply, biodiversity, and climate. Research in the field indicates that it is possible to increase carbon sequestration in soil by 1.85 billion tons annually through better utilization and management of the soil. This is more than the entire global transportation sector emits annually. There is also increased focus on preserving the soil in its current state, protecting already vulnerable areas, especially those storing a significant amount of carbon, such as peatlands.

Carbon sequestration in soil, also known as soil carbon sequestration, refers to processes where atmospheric carbon dioxide (CO2) is absorbed and stored in the soil. This plays a crucial role in the fight against climate change as it helps reduce the amount of CO2 in the atmosphere. Here are some ways this can occur:

  1. Plant Growth and Photosynthesis: Plants play a key role in binding CO2 from the air through photosynthesis. During this process, plants absorb CO2 and use solar energy to convert it into organic compounds like carbohydrates. When plants die, the organic material they leave in the soil contributes to carbon sequestration.
  2. Agricultural Practices: Certain agricultural practices can promote carbon sequestration. For example, the use of organic fertilizers and practices like reduced tillage can help preserve organic material in the soil, increase carbon content, and reduce CO2 emissions.
  3. Forestry: Forestry, especially through afforestation and forest management, can contribute to significant carbon binding in the soil. Dead leaves, branches, and other organic material from trees contribute to soil carbon storage.
  4. Conservation of Natural Habitats: Preserving natural ecosystems like marshes, wetlands, and shallow lakes is crucial as they act as significant carbon reservoirs. These habitats can also help reduce methane emissions, another greenhouse gas.
  5. Carbon Sinks: Some soil types naturally have high carbon content, such as peat soil. Conservation and restoration of these carbon sinks are essential to maintaining and increasing soil carbon sequestration.

Why is soil microorganisms important for plants?

Soil is not just an inert material that anchors plants; it is a living ecosystem consisting of various organisms that collaborate and influence each other. These organisms, known as soil microorganisms, or microbiota, are crucial for the growth and well-being of plants.

Microorganisms in the soil are vital for plants because they contribute to the release of nutrients essential for plant growth and survival. Microorganisms include bacteria, fungi, protozoa, arthropods, and nematodes. These organisms decompose organic matter in the soil, breaking it down into simpler compounds that plants can absorb through their roots. Microorganisms also play a role in maintaining biodiversity in the soil, which is crucial for a healthy ecosystem. Additionally, they can protect plants from pests and diseases by competing with or attacking harmful organisms.

Soil microorganisms can be categorized into four main groups:

  1. Bacteria
  2. Fungi
  3. Protozoa
  4. Multicellular Animals

Bacteria and fungi are the most numerous and diverse microorganisms in the soil. They break down organic material like plant residues, dead animals, and excrement, releasing nutrients that plants can absorb. Bacteria and fungi can also form symbiotic relationships with plant roots, assisting them in accessing water and minerals while protecting them from diseases and pests.

Protozoa are single-celled organisms that consume bacteria and other organic material in the soil, releasing nutrients to make them available for plants. Biodiversity is crucial for a healthy ecosystem, and all microorganisms play a role in maintaining fertile soil. Protozoa can be grouped into three main categories: flagellates, ciliates, and amoebas. They have different ways of moving and capturing food and serve as a food source for others in the food chain.

Multicellular animals in the soil include earthworms, nematodes, arthropods, and insects. These small animals also play essential roles in decomposition and the food chain. Earthworms, in particular, are beneficial for the soil, creating burrows that enhance air circulation and water infiltration. They also consume organic material and produce nutrient-rich soil known as worm castings. Nematodes are roundworms that can eat bacteria, fungi, protozoa, and plant roots. Some nematodes can be harmful to plants, while others are beneficial, controlling pests or releasing nutrients.

  • Microorganisms in the soil affect soil structure, water retention, and air access in the soil, all of which are crucial for plant growth conditions.
  • Microorganisms also contribute to various chemical reactions in the soil, influencing pH, oxygen levels, and nutrient availability.
  • Microorganisms in the soil can protect plants from pests and diseases by competing with or attacking harmful organisms.
  • Microorganisms live in symbiosis with living plants, with some forming mutualistic relationships with plant roots, such as mycorrhizal fungi. These fungi help plants absorb water and minerals and receive carbohydrates from the plants in return.
  • Soil microorganisms are part of an ecosystem consisting of various species interacting with each other. Biodiversity is crucial for a healthy and sustainable ecosystem.

In conclusion, soil microorganisms contribute to making the soil more fertile, healthy, and sustainable for plants. By taking care of soil microorganisms, we can also take care of our plants. Some measures that can promote soil microorganisms include:

  • Adding organic materials such as compost, manure, or cover crops
  • Avoiding plowing and intensive soil cultivation
  • Using organic fertilizers instead of synthetic ones (mineral fertilizers)
  • Crop rotation
  • Keeping the soil moist but not waterlogged

In many cases, these practices may not align with efficient industrial agriculture, which is also a reason why a significant portion of agricultural soil is degraded.

How do plants absorb nutrients

Plants are remarkable organisms that can produce their own food using sunlight, water, and carbon dioxide through photosynthesis. However, to grow and develop, they also need other nutrients that they must absorb from their surroundings. These nutrients consist of various substances that plants take up from the soil, air, and water.

Photosynthesis: Energy from sunlight and CO2 uptake

Photosynthesis is the process in which plants use energy from sunlight to convert carbon dioxide (CO2) and water into carbohydrates (sugar) and oxygen. This occurs in specific parts of plant cells called chloroplasts, aided by the green pigment chlorophyll. Sugar is a vital energy source for plants, which they can use to build other organic molecules such as proteins, fats, and starch. Oxygen is a byproduct released into the air.

Plants absorb carbon dioxide from the air through small openings in the leaves, called stomata. These openings can open and close depending on light conditions, temperature, and humidity. When the stomata are open, plants can also lose water through evaporation. Therefore, plants must balance between taking in enough carbon dioxide and avoiding excessive water loss.

Other essential elements must be absorbed by plants from the soil through their roots, and these are called mineral nutrients.

Nutrients in Soil

Nutrients are crucial for the biological processes of plants. Carbon, oxygen, and hydrogen are obtained from air and water, while mineral nutrients must be extracted from the soil through the roots. Nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur are macronutrients, whereas iron, manganese, zinc, copper, boron, molybdenum, and chlorine are micronutrients.

Nutrients are elements that plants need to carry out various biological processes. Some of these elements are obtained by plants from the air and water, such as carbon (C), oxygen (O), and hydrogen (H). These elements are used to create carbohydrates like glucose and starch, which serve as the energy source and storage material for plants.

Other elements must be absorbed by plants from the soil through their roots, and these are called mineral nutrients or minerals. Plants absorb mineral nutrients through their roots, which have small extensions called root hairs. Root hairs increase the surface area of the roots, making it easier to absorb water and ions from the soil.

For plants to absorb minerals, they must be in ion form, meaning atoms or molecules with an electric charge. These ions must be soluble in the water surrounding soil particles, and this depends on the soil's pH value. Some ions are more soluble in acidic soil, while others are more soluble in alkaline soil.

Plants require different amounts of these minerals depending on their function in the plant. Some minerals are needed in large quantities, such as nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S). These are called macronutrients. Other minerals are needed in smaller quantities, such as iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), molybdenum (Mo), and chlorine (Cl). These are called micronutrients. Plants use these nutrients to build larger molecules, such as proteins, DNA, RNA, and chlorophyll. They can also be essential for the regulation of specific enzyme functions, osmoregulation, or as signaling molecules.

How do plants absorb minerals from the soil?

Plants absorb nutrients as ions through their roots. Ion exchange is an essential process where plants release hydrogen ions when taking up cations and exchange anions with bicarbonate ions. This requires transport mechanisms across the cell membrane in root hairs, either through passive or active transport. Once ions are taken up by the root hairs, they are transported through the root tissue to the vascular tissue and further up the plant.

Ions can be either positive (cations) or negative (anions), depending on whether they have lost or gained electrons. Plants take up both cations and anions through the roots but must maintain a balance between them to avoid altering the pH value in the cells. When a plant takes up a cation, it must simultaneously release a hydrogen ion (H+) into the soil, and when it takes up an anion, it must exchange it with a bicarbonate (HCO3-) from the soil. This process is called ion exchange and is a way to maintain the electrical balance in the cells. When a cation is taken up in the root, and the plant releases a hydrogen ion, it will acidify the soil, while the uptake of anions involves an exchange with bicarbonate, which has an alkaline effect on the soil, causing the pH to rise in the soil around the root.

Minerals taken up as positive ions (cations) include ammonium (NH4+), potassium (K+), calcium (Ca2+), zinc (Zn2+), iron (Fe2+).

Minerals taken up as negative ions (anions) include nitrate (NO3-), phosphate (PO4^3-), and sulfate (SO4^2-).

For plants to absorb these ions, they must also have a transport mechanism across the cell membrane into the root hairs. This can occur in two ways: passive transport or active transport. Passive transport means that ions move from an area of high concentration to an area of low concentration without the use of energy. This can happen through diffusion or with the help of specific transport proteins in the membrane. Active transport means that ions move against the concentration gradient using energy in the form of ATP. This also occurs with the assistance of specific transport proteins in the membrane acting as pumps.

Once the ions have entered the root hairs, they are transported further through the root tissue to the vascular tissue (xylem) and then upward in the plant.

Plants collaborate with bacteria and fungi to acquire more minerals

The collaboration between plants and microorganisms is an example of mutualism, a form of symbiosis where both parties benefit from each other. This demonstrates that plants have developed complex strategies to adapt to different environments and increase their chances of survival and reproduction.

Despite the fact that the air consists of 78% nitrogen, this nutrient is not necessarily easily accessible for plants. Plants cannot convert nitrogen gas from the air into nitrogen compounds that they can utilize. However, plants can form partnerships with bacteria and fungi living in or on their roots. These microorganisms assist the plant in breaking down organic matter in the soil, making it available for the plant. They can also fix nitrogen from the air and convert it into a plant-accessible form.

An example of such collaboration is between legumes and nitrogen-fixing bacteria. Legumes belong to the pea family and include plants like peas, beans, clover, and lupines. These plants have nodules on their roots that house bacteria of the genus Rhizobium. These bacteria can convert nitrogen gas (N2) from the air into ammonium (NH4+), which plants can absorb. In exchange, microorganisms receive sugar and other organic compounds from the plant.

This enables legumes to grow in nitrogen-deficient soil while also enriching the soil with nitrogen for other plants.

Another adaptation to obtain nutrients is to enter into a mutualistic relationship with fungi. When a fungus grows near a plant, its thin hyphae can wrap around or grow into plant roots, forming what we call mycorrhiza. The fungus helps the plant absorb more water and minerals from the soil, especially phosphorus. In return, the fungus receives carbohydrates produced by the plant through photosynthesis. Mycorrhiza is common in many plants, especially trees.

What is the difference between synthetic fertilizer and organic fertilizer?

Organic fertilizer is a collective term for organic materials used to provide nutrients to plants. Organic fertilizer can include compost, manure, green manure, or other organic waste. It contains both macronutrients and micronutrients that are essential for the growth and development of plants. However, these nutrients are not always readily available to plants in the form they exist in organic fertilizer. Synthetic fertilizer, on the other hand, is a chemically manufactured plant nutrient containing inorganic compounds that provide a quick and precise supply of nutrients to plants.

Synthetic fertilizer is a chemically produced plant nutrient containing inorganic compounds such as nitrogen (N), phosphorus (P), potassium (K), and other essential nutrients for plant growth. Organic fertilizer is an organic plant nutrient derived from sources like manure, compost, or other organically decomposed materials. In principle, plants can only absorb nutrients in the form of inorganic compounds like nitrate (NO3-), ammonium (NH4+), and phosphate (PO4^3-). Synthetic fertilizer makes nutrients directly available to plants, ensuring maximum utilization of the plant's growth potential. Organic fertilizer needs to be converted into inorganic compounds by microorganisms in the soil before plants can absorb them.

The advantage of synthetic fertilizer is its ability to provide a rapid and precise nutrient supply to plants, potentially increasing yields and improving the quality of food production. However, the downside is that it may lead to leaching or immobilization of nutrients in the soil, contaminating waterways and harming ecosystems. Synthetic fertilizer can also contribute to the emission of greenhouse gases such as N2O and CO2, as well as reduce biodiversity and organic carbon storage in the soil.

The advantage of organic fertilizer is its contribution to maintaining healthy soil biodiversity, improving soil structure, water retention, disease resistance, and nutrient balance. Organic fertilizer can also reduce greenhouse gas emissions by sequestering carbon in the soil and decreasing the use of fossil fuels in synthetic fertilizer production. The disadvantage of organic fertilizer is that it provides a more uncertain and variable nutrient supply to plants, potentially reducing yields and the quality of food production. Organic fertilizer may also contain undesirable substances such as heavy metals, pathogens, or weed seeds.

What is needed for the plants to absorb nutrients from natural fertilizer?

For natural fertilizer to release nutrients in a plant-available form, organic material must undergo decomposition. This process is called mineralization and is carried out by microorganisms and other soil-dwelling organisms. Microorganisms use oxygen and water to convert organic carbon into carbon dioxide, simultaneously releasing minerals such as ammonium, nitrate, phosphate, and potassium. Plants can then absorb these minerals through their roots or leaves.

Natural fertilizer is organic material containing nutrients that plants need to grow and thrive. Examples of natural fertilizer include compost, manure, poultry litter, seaweed, or other organic waste. The advantage of natural fertilizer is that it also helps improve soil structure, enhance soil microbial life, and retain moisture.

For plants to absorb nutrients from natural fertilizer, organic material must undergo decomposition. This process involves various microorganisms, bacteria, fungi, and earthworms that convert organic material into simpler compounds or ions that plants can take up through their roots.

The decomposition of natural fertilizer depends on several factors such as temperature, moisture, air supply, and pH. Generally, decomposition occurs more rapidly when it is warm, moist, oxygen-rich, at a neutral pH, and when there is a rich and diverse microbial life in the soil.

Natural fertilizer contains varying amounts of macronutrients (nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur) and micronutrients (iron, zinc, copper, manganese, boron, and molybdenum). The dominant nutrients in natural fertilizer depend on its composition. For instance, manure may have more nitrogen than compost, while seaweed may contain more potassium than poultry litter.

Natural fertilizer is a valuable resource for sustainable and environmentally friendly agriculture. By using natural fertilizer, organic matter and nutrients are recycled in the natural cycle. Natural fertilizer not only provides nutrients to plants but also benefits the soil and all life within it.

However, natural fertilizer has some drawbacks and challenges. It may contain weed seeds, pathogens, or pests that can spread to plants. Natural fertilizer can also lead to odor issues or contamination of groundwater or surface water.

Mineralization can be influenced by the type and amount of natural fertilizer used. Some types of natural fertilizer have high nitrogen or other nutrient content, while others have low nutrient content or a high carbon content. The carbon-to-nitrogen ratio (C/N ratio) in natural fertilizer affects the rate of mineralization. A lower C/N ratio leads to faster nutrient release. For example, manure has a low C/N ratio (10-20), while straw has a high C/N ratio (80-100). If the natural fertilizer has a high C/N ratio, microorganisms may use more nitrogen than they release, potentially reducing the nitrogen available to plants. Therefore, excessive use of carbon-rich materials like straw as natural fertilizer should be avoided.

Natural fertilizer has numerous benefits for soil fertility and plant health. It increases organic matter content in the soil, enhancing soil structure, water retention, and air exchange. Natural fertilizer also stimulates microbial activity in the soil, improving nutrient cycling, disease prevention, and biological nitrogen fixation. Biological nitrogen fixation is a process where certain bacteria living in symbiosis with legumes can capture nitrogen from the air, making it available to plants. This reduces the need for artificial nitrogen supplementation.

What are nitrogen-fixing bacteria?

Nitrogen, essential for all life, constitutes the elemental basis of important molecules such as proteins, DNA, and chlorophyll. Atmospheric nitrogen, mainly in the form of nitrogen gas, is unreactive and inaccessible to most organisms. Therefore, nitrogen fixation is necessary, a process carried out by specific bacteria. Some nitrogen-fixing bacteria are free-living in soil and water, while others live in symbiosis with plants. Nitrogen fixation contributes to increased biologically available nitrogen in ecosystems, with a significant impact on plant growth and productivity.

Nitrogen is an essential element for all life on Earth, forming part of crucial molecules such as proteins, DNA, and chlorophyll. However, the majority of nitrogen in the atmosphere is in the form of nitrogen gas (N2), which is unreactive and cannot be directly utilized by most organisms. Hence, there is a need for a process called nitrogen fixation, which converts nitrogen gas into more biologically available forms such as ammonium (NH4+) and nitrate (NO3-).

Nitrogen fixation is a characteristic found in only a few bacteria. These bacteria can use a special enzyme called nitrogenase, which catalyzes the reaction between nitrogen gas and hydrogen to form ammonia. This reaction requires a significant amount of energy, which the bacteria obtain from various sources depending on their habitat and lifestyle.

Some nitrogen-fixing bacteria are free-living in soil and water, where they derive energy from organic material or light. Examples of such bacteria include Azotobacter, Klebsiella, Clostridium, cyanobacteria, and purple bacteria. Other nitrogen-fixing bacteria live in symbiosis with plants, obtaining energy from the plants' photosynthesis and, in return, providing the plants with access to fixed nitrogen. Examples of such bacteria include Rhizobium, which forms nodules on the roots of leguminous plants (such as peas, clover, and beans), Frankia, which forms nodules on the roots of certain trees, and cyanobacteria that live in the water fern Azolla or in lichens with fungi.

Nitrogen-fixing bacteria play a crucial role in the nitrogen cycle, the biochemical cycle that involves the recycling and utilization of nitrogen through metabolic processes in all living organisms. Nitrogen fixation contributes to increasing the amount of biologically available nitrogen in ecosystems, which can have a significant impact on plant growth and productivity.

What kind of environment do nitrogen-fixing bacteria need?

Nitrogen-fixing bacteria can be influenced by various environmental factors such as temperature, pH, salt content, humidity, and nutrient availability. Some of these factors can be detrimental to the bacteria, either by inhibiting their growth or their ability to fix nitrogen.

Nitrogen fixation is an energy-demanding process that requires an optimal temperature for the enzymes catalyzing the reaction. If the temperature becomes too high, the enzymes may become denatured and lose their function. High temperature can also increase water evaporation from the soil and reduce oxygen availability for the bacteria.

Nitrogen-fixing bacteria have varying temperature tolerances, depending on their habitat. Some bacteria are mesophiles, meaning they thrive best at moderate temperatures between 20 and 40 degrees Celsius. Other bacteria are thermophiles, meaning they tolerate high temperatures up to 80 degrees Celsius or more. There are also some extremophilic bacteria that can live at temperatures above 100 degrees Celsius, but these are rare and are often found in geothermal springs or volcanic areas. In general, nitrogen fixation will be reduced or halted at too high or too low temperatures because the enzyme nitrogenase is destroyed or inactivated.

Nitrogen fixation requires a neutral or slightly alkaline environment to function effectively. Low pH can inhibit enzyme activity and damage the cell membranes of the bacteria. Low pH can also increase the concentration of heavy metals and other toxic substances in the soil that may be harmful to the bacteria.

Nitrate is a form of nitrogen that is readily available to plants but can also inhibit nitrogen fixation. If there is too much nitrate in the soil, the bacteria will reduce their activity or stop altogether, as they do not need to produce ammonia. High nitrate concentration can result from excessive use of synthetic fertilizers or pollution from industrial or agricultural sources.

When the temperature is too low or too high, or when there is a lack of water or nutrients, some nitrogen-fixing bacteria can form spores. Spores are a kind of dormant form that allows the bacteria to survive unfavorable conditions. The spores have a thick shell that protects them from drying out, heat, and cold. When conditions improve, the spores can germinate and become active bacterial cells again. Spore formation is a form of dormancy, not death. Examples of spore-forming bacteria include Bacillus and Clostridium.

How are nitrogen-fixing bacteria affected by soil steaming?

Nitrogen-fixing bacteria, crucial for converting nitrogen gas into biologically available ammonium in the soil, are impacted by high temperatures. To minimize this effect, limited and targeted steaming, addition of organic material after steaming, and planting leguminous plants to restore nitrogen balance in the soil are recommended. It is important to weigh the advantages and disadvantages of steaming in relation to other control methods and take measures to promote the regrowth of nitrogen-fixing bacteria, ensuring sustainable resource use in the circular bioeconomy.

What happens to the beneficial bacteria that fix nitrogen in the soil when exposed to high temperatures? Nitrogen fixation is a process where certain bacteria convert nitrogen gas (N2) from the air into ammonium (NH4+), a more biologically available form of nitrogen. Nitrogen is a crucial element for all living organisms as it is a component of proteins, DNA, and chlorophyll. Plants need nitrogen to grow and produce biomass, but most plants cannot directly utilize nitrogen gas. Therefore, they rely on nitrogen-fixing bacteria that live freely in the soil or in symbiosis with leguminous plants such as peas, beans, and clover.

Nitrogen-fixing bacteria are sensitive to high temperatures because the enzyme catalyzing the reaction between nitrogen gas and hydrogen (nitrogenase) is destroyed at temperatures above 50 °C. This means that soil steaming can reduce the number and activity of nitrogen-fixing bacteria in the soil, which can have negative consequences for plant nitrogen availability. Therefore, it is crucial to consider the pros and cons of soil steaming compared to other methods for controlling unwanted organisms in the soil, such as the use of chemicals, mechanical cultivation, or biological control.

There are measures that can be taken to minimize the impact of soil steaming on nitrogen-fixing bacteria. Firstly, one can limit the extent and duration of steaming to what is necessary to achieve the desired effect on weeds, diseases, and pests. Secondly, organic material or compost can be added to the soil after steaming to increase the carbon and nitrogen content and stimulate the growth of microorganisms. Thirdly, leguminous plants or other plants that have symbiosis with nitrogen-fixing bacteria can be sown or planted after steaming to restore the balance between nitrogen forms in the soil.

Soil steaming is an effective method for reducing unwanted organisms in the soil, but it also affects beneficial nitrogen-fixing bacteria. It is therefore essential to consider this impact when choosing and using this method and to take measures to promote the regrowth of nitrogen-fixing bacteria after steaming. In this way, sustainable use and conservation of natural resources can be achieved in the circular bioeconomy.

Can nitrogen-fixing bacteria reestablish themselves after the soil has been steamed?

Nitrogen-fixing bacteria are crucial for soil fertility and ecosystems, but they are also vulnerable to steaming as a method to sterilize the soil. Whether they can reestablish themselves after steaming depends on several factors, such as the type of bacteria, soil characteristics, environmental conditions, and the intensity and frequency of steaming. It is, therefore, challenging to provide a general answer to this question, but it is possible to say that some bacteria have better chances than others to survive and recover their function after steaming.

The question of whether nitrogen-fixing bacteria can reestablish themselves after steaming depends on several factors. There is no straightforward answer to this question, but some general considerations can be made.

Firstly, it is essential to distinguish between free-living and symbiotic nitrogen-fixing bacteria. Free-living bacteria are more susceptible to steaming as they live directly in the soil that is heated. Symbiotic bacteria live in nodules on the roots of leguminous plants, which can protect them from the heat.

Some nitrogen-fixing bacteria are more resistant to heat and can survive in spore forms that tolerate high temperatures. These can resume their activity when conditions become favorable again. Other types of nitrogen-fixing bacteria are more sensitive to heat and may be entirely eliminated or replaced by other microorganisms after steaming.

Secondly, it is crucial to consider soil characteristics and environmental conditions. Some soil types have more organic matter and porosity, providing better insulation and survival for bacteria during steaming. Soil moisture, pH, and temperature can also affect bacterial growth and activity after steaming.

Thirdly, it is important to evaluate the intensity and frequency of steaming. The higher the temperature and the longer the soil is exposed to steaming, the more bacteria will be killed. The same applies if steaming is repeated often or over large areas.

After steaming the soil, it is essential to take measures to promote the recolonization of nitrogen-fixing bacteria. This may involve adding organic material such as compost or manure, providing nutrients and substrate for microorganisms. It may also involve sowing or planting legumes or other plants that have symbiosis with nitrogen-fixing bacteria.

It may also be advisable to avoid the use of synthetic fertilizers or pesticides that can inhibit or harm nitrogen-fixing bacteria.

In summary, nitrogen-fixing bacteria can reestablish themselves after the soil has been steamed, but it requires time and efforts to restore the microbial balance and function of the soil. The smaller the portion of the soil that is steamed, the faster the reestablishment will occur.

Table of contents