A key element of soil health is the soil microbiome, a diverse community of microorganisms, including bacteria, fungi, archaea, viruses, and protozoa. Understanding and managing the soil microbiome is essential for improving soil health and agricultural productivity.
Soil health in detail
When discussing soil health, one considers the various characteristics and interactions that occur in the soil to make it more profitable for agriculture:
Physical properties:
– Soil structure: The arrangement of soil particles into aggregates, which affects aeration, water infiltration, and root growth – passive of change.
– Soil texture: The proportion of sand, silt, and clay particles – impossible to change.
– Water holding capacity: The ability of soil to retain water for plant use – depending on the structure and texture.
Chemical properties:
- pH: Influences nutrient availability and microbial activity.
- Nutrient content: Levels of essential nutrients for plant growth and development; it can be classified into two categories:
- Macro-nutrients: These include nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulphur (S). They are required in large quantities for plant growth.
- Micro-nutrients: Elements such as iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), boron (B), and chlorine (Cl) are needed in smaller amounts but are equally essential for plant development.
- Organic matter: Decomposed plant and animal residues that provide nutrients and improve soil structure.
Biological properties (Microbiome):
– Microbial biomass: The total mass of microorganisms in the soil.
– Microbial diversity: The variety of microbial species present.
– Microbial activity: Soil microbes’ metabolic processes include decomposition and nutrient cycling.
The microbiome plays several crucial roles in maintaining and enhancing soil health. These roles can be broadly categorised into nutrient cycling, plant growth promotion, disease suppression, and environmental stress tolerance.
Soil microbiome and its role in agriculture
The agricultural microbiome comprises a wide variety of microorganisms, such as bacteria, fungi, archaea, viruses, and protozoa, that live in the soil, on plant surfaces, and inside plant tissues. These microorganisms play essential roles in nutrient cycling, maintaining plant health, and promoting soil fertility. Here’s an in-depth look at these functions:
Nutrient cycling: Microorganisms decompose organic matter, fix atmospheric nitrogen, solubilise phosphorus, and mobilise other nutrients, enhancing their availability to plants.
Disease suppression: certain soil microbes can inhibit plant pathogens through competition, predation, or the production of antimicrobial compounds.
Soil structure improvement: fungi, especially mycorrhizae, help bind soil particles into stable aggregates, improving soil structure and water retention.
Plant growth promotion: Some bacteria and fungi produce growth-promoting hormones or solubilised nutrients for better uptake, directly enhancing plant growth.
Stress tolerance: certain microbes help plants withstand abiotic stresses like drought, salinity, and heavy metals.
All these actors have an essential role in the agricultural industry. That’s why good practices such as crop rotation, cover crops, reduced tillage, or organic amendments, combined with solutions that enhance the microbiome, will create a more fertile and healthy soil environment.
New generation biofertilizers: key players in soil health
Biofertilizers play a significant role in enhancing soil health and the microbiome, contributing to sustainable agricultural practices. They are composed of living microorganisms that, when applied to seeds, plant surfaces, or soil, colonise the rhizosphere or the plant’s interior and promote growth by increasing the supply or availability of primary nutrients to the host plant.
How do biofertilisers work?
Biofertilizers promote plant growth by increasing the availability and supply of essential nutrients. They play a crucial role in sustainable agriculture, offering numerous benefits for soil health, crop productivity, and environmental conservation. These solutions boast the following key features:
Enhancing soil fertility:
– Nitrogen fixation: Biofertilizers such as Rhizobium, Azospirillum, and Azotobacter fix atmospheric nitrogen into a form that plants can absorb and utilise, reducing the need for traditional nitrogen fertilisers.
– Phosphate solubilisation: Microorganisms like Pseudomonas and Bacillus species convert insoluble phosphates in the soil into soluble forms that plants can absorb, improving phosphorus availability.
– Potassium mobilization: Certain bacteria (e.g., Bacillus spp.) and fungi (e.g., Aspergillus niger) help in the mobilisation of potassium, making it more accessible to plants.
Improving soil structure and health:
– Organic matter decomposition: Biofertilizers contribute to the breakdown of organic matter, enhancing soil structure and increasing the soil’s water-holding capacity.
– Humus formation: The decomposition process leads to the formation of humus, which improves soil texture and fertility.
Enhancing soil microbiome diversity:
– Microbial balance: Introducing beneficial microorganisms through biofertilizers can enhance the diversity and balance of soil microbial communities, which is crucial for nutrient cycling.
Biofertilizers also compete with less favorable microorganisms in the rhizosphere, thereby enhancing the plant’s growth environment
Promoting plant growth and health:
– Growth hormones production: Biofertilizers can produce growth-promoting substances like auxins, gibberellins, and cytokinins, which stimulate plant growth and development.
– Enhanced stress tolerance: By improving nutrient uptake and soil health, biofertilizers help plants better withstand abiotic stresses such as drought and salinity.
In short, promoting soil health through a focus on the soil microbiome not only enhances agricultural productivity but also contributes to broader environmental goals such as carbon sequestration, water quality improvement, and biodiversity conservation.
Benefits of biofertilizers:
There are several biofertilizers with different functions. The most well-known biofertilizers and their functions are as follows:
– Rhizobium: Symbiotic nitrogen fixer for legumes.
– Azospirillum and Azotobacter: Free-living nitrogen fixers.
– Phosphate solubilising bacteria (PSB): Enhance phosphorus availability.
– Mycorrhizae: Symbiotic fungi that enhance nutrient and water uptake.
– Trichoderma: Fungi that improve nutrient uptake.
In addition, biofertilizers offer several benefits for sustainable agriculture, including environmental sustainability, as they have the potential to reduce reliance on traditional fertilisers and help minimise environmental impact. They are cost-effective, providing farmers with lower input costs due to reduced traditional fertiliser usage. Furthermore, biofertilizers improve soil health by enhancing soil structure, fertility, and microbial activity, contributing to long-term soil health and productivity.
Biofertilizers are vital for promoting soil health and a balanced microbiome for sustainable agriculture. Their role in nutrient cycling, enhancing soil structure, and supporting plant health makes them an integral part of eco-friendly farming practices.
Challenges and future directions
Understanding complexity: The soil microbiome is highly complex and varies with soil type, climate, and management practices.
– Tailoring practices: Developing location-specific recommendations based on soil health assessments.
– Technology integration: Using advanced tools like metagenomics to study and manage the soil microbiome.
Encouraging soil health through a focus on the soil microbiome not only enhances agricultural productivity but also contributes to broader environmental goals such as carbon sequestration, water quality improvement, and biodiversity conservation.
Additionally, focusing on soil health benefits broader environmental goals such as carbon sequestration, water quality improvement, and biodiversity conservation. In summary, biofertilizers are crucial in promoting soil health and maintaining a balanced soil microbiome. Their impact on nutrient cycling, soil structure, and plant health makes them essential for eco-friendly farming practices.
Looking ahead, addressing challenges like understanding soil microbiome complexity, tailoring practices to specific locations, and integrating advanced technologies will further enhance sustainable agriculture.
