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shahidullah soil microorganisms ppt.pptx
- 2. Islamic Emirate of Afghanistan Ministry of Higher Education Nangarhar University Agriculture Master Program in Agronomy Introduction to Soil microorganisms Prepared by: Shahidullah Ihsan, M.S.C student of Agronomy Department Instructor Lecture: Professor, Ph.D Asmatullah Durani Date: 23/12/2024
- 3. Definition of Soil microorganisms : Soil microorganisms are microscopic organisms living in the soil , and they are vital to soil health, nutrient cycling, and ecosystem stability . They include bacteria , fungi ,algae , protozoa ,actinomycetes and viruses . Below are detailed insights into their roles ,diversity ,interaction and importance. Soil microorganisms are the backbone of healthy soil ecosystems ,playing essential roles in agriculture , environmental sustainability and ecosystem services . Their conservation and proper management are critical for long term soil productivity and environmental health.
- 4. Types of Soil Microorganisms 1 Bacteria: Single celled organisms most abundant microorganisms in soil . Most abundant microorganisms,billions in just a teaspoon of soil , 0.5 to 5 micrometers in size .
- 5. Roles of Bacteria in soil Decomposers: Break down organic matter into simpler substances. Nitrogen fixation : Convert atmospheric nitrogen into ( Rhizobium, Azotobacter) Nutrient cycling : Aid in the sulfur and phosphorus cycles . Bioremediation : Degrade toxic components and pollutants.
- 6. 2 Fungi :Fungi is Eukaryotic organisms , Larger the bacteria ,includes both unicellular (yeasts) and multicellular forms(molds,mushrooms) Roles : Decomposition : Break down resistant materials like lignin and cellulose Symbiotic Relationships : Mycorrhizal fungi enhance plant root nutrient uptake . Pathogenicity : Some fungi cause plant diseases (Fusarium, Pythium) Antibiotic production: Fungi like penicillium produce antibiotic.
- 7. 3 - Actinomycetes: Appearance : Filamentous , resembling fungi under a microscope. Roles: Decomposers : Break down complex organic substance. Soil Aroma : Responsile for the earthy smell of soil ( produces geosmin). Antibiotics : Produce substances like streptomycin and tetracycline.
- 8. 4 - Protozoa : Size : larger than bacteria . Feed on organic matter and microorganisms. Roles: Control bacterial populations through predation. Release nutrients like nitrogen into the soil ,benefiting plant roots .
- 9. 5 - Algae: Photosynthetic: Produce oxygen and organic matter in soil. Roles: Improve soil structure by binding particles . Enhance soil fertility , especially in flooded conditions . 6 - Viruses : Nature : Infect soil microorganisms like bacteria (Bacteriophages ) and fungi. Roles: Regulate microbial populations . Facilitate horizontal gene transfer among microbes.
- 10. 2 -Roles of soil microorganisms A Nutrient cycling Microorganisms convert complex organic and inorganic materials into plant available nutrients: 1 - Nitrogen cycle: A Fixation :Conversion of atmospheric nigrogen ton ammonia(Rhizobium,Azotobacter). B Nitrification : Ammonia to nitrate by nitrosomonas and nitrobacter. D denitrification : nitrates to nitrogen gas ( Pseudomonas , clostridium). 2 Phosphorus cycle:solubilize and mineralize phosphorus , making it available to plants (Bacillus , aspergillus)
- 11. 3 - Carbon cycle :Decompose organic matter ,releasing Co2 and storing carbon in stable forms. Improving soil Structure 1 - Excrete extracellular polysaccharides that bind soil particles ,enhancing aggregation. 2 Promote aeration ,water retention and resistance to erosion. Disease suppression 1 Produce antifungal and antibacterial compounds(Bacillus subtilis,Trichoderma) 2- Outcompete pathogens for nutrients and space. Biodegradation 1- Break down pollutants like pesticides ,hydrocarbons and heavy metals ,reducing soil contamination
- 12. Factors affecting soil microorganisms Environmental factors 1- pH: Most microorganisms thrive in a PH range of 6-7. Acidic or alkaline condition reduce activity. 2 Tempreture : Optimal ativity occurs between 20-30属c. 3- Moisture : Microbial activity is highest in moist soils but declines in dry or waterlogged conditions. 4- Oxygen : Aerobic microbos dominate in well aerated soil ,while anaerobic ones thrive in noorly aerated conditions.
- 13. Soil properties: 1 Organic matter : Provides energy and nutrients for microbial Populations. 2 Texture : Loamy soil support higher microbial diversity compared to sandy or clay soils. 3 Nutrient Levels : Availability of nitrogen , phosphorus and other nutrients influences microbial growth.
- 14. Application in Agriculture and environment Biofertilizers Microbial inoculants improve soil fertility (Rhizobium for nitrogen fixation ,phosphate solubilizing bacteria ). Biopesticides Suppress plant pathogens and pests naturally(Bacillus thuringiensis for insect control) Composting Accelerate organic waste decomposition , converting it into nutrient rich compost. Soil Remediation Microbes degrade pollutants and restore soil health( Pseudomonas for oil spill cleanup).
- 15. Importance of soil microbial diversity 1 A diverse microbial community ensures resilience against environmental changes and disturbances. 2 Enhances soil multifunctionality ,including productivity , disease resistance and carbon sequestration . 3- Loss of microbial diversity due to overuse of fertilizers ,pesticides and deforestation can degrade soil health.
- 16. Challenges in maintaining microbial health 1 Overuse of synthetic fertilizers and pesticides harms beneficial microbes . 2 Soil erosion and compaction reduce microbial habitats. 3 Climate change alters microbial activity through temperature and moisture shifts. Sustainable practices to enhance soil microbial activity 1- Add organic amendments like compost and manure. 2 Minimize tillage to preserve microbial habitats. 3- Avoid overuse of chemicals and use biocontrol agents instead. 4 Rotate crops and include cover crops to maintain soil diversity.
- 17. 5- Ensure adequate soil aeration and moisture.
- 18. 惠悴 拱盒潮