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Organic Matter - A TerraSoil Overview

TerraSoil

03 Aug 2024

The Vital Role of Organic Matter in Fertile Soils

Understanding Organic Matter

Organic matter refers to the complex mixture of carbon-containing compounds derived from the decomposition of plant, animal, and microbial residues. It encompasses a diverse array of materials, including dead plant roots, crop residues, manure, compost, and soil organisms such as bacteria, fungi, and earthworms.

Formation of Organic Matter

Organic matter is formed through the biological and chemical breakdown of organic materials by soil microorganisms and macroorganisms. Processes such as decomposition, mineralization, and humification transform complex organic compounds into simpler substances, releasing nutrients and organic molecules that become part of the soil organic matter pool.

Organic Matter Examples

Organic Matter Type	Composition	Physical Characteristics	Origin	Macro/Micronutrient Profile (% by weight)	Micronutrient Profile (mg/kg)	Typical pH
Humus	Decomposed plant and animal residues	Dark-colored, amorphous	Microbial decomposition	N: 1-5%, P: 0.2-0.5%, K: 0.5-1%, Ca: 2-4%, Mg: 0.5-1%	Fe: 500-800, Na: 200-300, Cu: 5-10, Se: 0.1-0.5, Si: 100-200	6-7
Plant Residues	Stems, leaves, roots, and crop residues	Variable texture, fibrous	Plant decomposition	N: 0.5-1.5%, P: 0.1-0.3%, K: 1-2%	Fe: 100-300, Na: 50-100, Cu: 2-5, Se: 0.1-0.3, Si: 50-100	6-7
Animal Manure	Animal excreta and bedding materials	Rich in nutrients, odoriferous	Animal metabolism	N: 0.5-2.5%, P: 0.2-0.8%, K: 0.5-2%	Fe: 1000-2000, Na: 500-1000, Cu: 10-30, Se: 0.5-2, Si: 200-300	7-8
Compost	Decomposed organic matter from plant and food waste	Nutrient-rich, crumbly	Controlled decomposition	N: 1-3%, P: 0.5-1%, K: 1-2%, Ca: 3-5%, Mg: 0.5-1%	Fe: 400-800, Na: 100-300, Cu: 5-15, Se: 0.2-1, Si: 100-200	6-8
Peat	Partially decomposed plant material	Brown to dark brown, fibrous, water-retentive	Accumulation in waterlogged environments	N: 1-3%, P: 0.1-0.3%, K: 0.1-0.3%	Fe: 100-300, Na: 50-100, Cu: 2-5, Se: 0.1-0.3, Si: 50-100	4-5
Biochar	Charred organic material (e.g., wood, crop waste)	Porous, charcoal-like, lightweight	Pyrolysis of organic material	Low in nutrients, mainly a soil conditioner	Fe: 50-100, Na: 10-50, Cu: 1-3, Se: <0.1, Si: 20-50	7-9
Vermicompost	Decomposed organic matter processed by earthworms	Fine texture, nutrient-rich, dark-colored	Earthworm digestion and decomposition	N: 2-4%, P: 1-2%, K: 1-3%, Ca: 3-5%, Mg: 0.5-1%	Fe: 500-1000, Na: 100-300, Cu: 5-10, Se: 0.5-1, Si: 100-200	6-8
Green Manure	Freshly cut or uprooted green plants	Moist, fibrous, rapidly decomposing	Plant growth and incorporation into soil	N: 1-4%, P: 0.1-0.3%, K: 0.5-1%	Fe: 200-500, Na: 50-150, Cu: 2-5, Se: 0.1-0.3, Si: 50-150	6-7
Leaf Mold	Decayed leaves	Light, crumbly, dark brown	Fungal decomposition of leaf litter	N: 0.5-1.5%, P: 0.1-0.3%, K: 0.5-1%	Fe: 100-300, Na: 30-70, Cu: 2-4, Se: <0.1, Si: 50-100	5-6
Mulch	Organic materials like straw, wood chips, and bark	Coarse texture, varied color	Plant materials applied to soil surface	Variable nutrient content, mainly a soil conditioner	Fe: 50-150, Na: 10-50, Cu: 1-3, Se: <0.1, Si: 20-50	6-8
Wood Chips	Chipped wood from trees and shrubs	Coarse, fibrous, slow to decompose	Mechanical processing of woody materials	Low in nutrients, mainly a soil conditioner	Fe: 50-150, Na: 10-30, Cu: 1-3, Se: <0.1, Si: 20-50	6-7
Sawdust	Fine wood particles from sawing processes	Light, fluffy, variable decomposition rate	Woodworking and milling byproduct	N: 0.1-0.3%, P: 0.01-0.02%, K: 0.1-0.2%	Fe: 20-50, Na: 5-20, Cu: 0.5-1.5, Se: <0.1, Si: 10-30	6-7
Crop Residue	Leftover plant material from harvesting	Fibrous, varied texture, nutrient-rich	Harvesting and agricultural processes	N: 0.5-1.5%, P: 0.1-0.3%, K: 1-2%	Fe: 100-300, Na: 30-70, Cu: 2-5, Se: 0.1-0.3, Si: 50-100	6-7
Mushroom Compost	Spent substrate from mushroom farming	Dark, crumbly, nutrient-rich	Mushroom cultivation waste	N: 1-2%, P: 0.3-0.5%, K: 1-2%	Fe: 500-1000, Na: 100-200, Cu: 5-10, Se: 0.1-0.3, Si: 100-200	6-8
Seaweed	Marine algae	Moist, fibrous, high in micronutrients	Harvested from coastal areas	N: 0.5-1.5%, P: 0.1-0.3%, K: 1-3%, Mg: 1-3%, Ca: 1-2%	Fe: 100-500, Na: 3000-10000, Cu: 1-5, Se: 0.1-0.5, Si: 50-150	6-8
Fish Emulsion	Processed fish parts and oil	Liquid, nutrient-rich, strong odor	Byproduct of fish processing	N: 5-9%, P: 1-2%, K: 0.2-0.5%	Fe: 200-500, Na: 500-1000, Cu: 10-30, Se: 1-2, Si: 50-100	5-7
Bat Guano	Accumulated bat feces	Granular, nutrient-rich, high in nitrogen	Cave deposits from bat colonies	N: 5-10%, P: 3-8%, K: 1-3%	Fe: 200-600, Na: 100-300, Cu: 10-20, Se: 1-3, Si: 50-100	6-8
Coconut Coir	Fibers from coconut husks	Lightweight, fibrous, good water retention	Byproduct of coconut processing	Low in nutrients, mainly a soil conditioner	Fe: 50-100, Na: 100-300, Cu: 1-3, Se: <0.1, Si: 20-50	5-7
Rice Hulls	Outer coverings of rice grains	Lightweight, fibrous, silica-rich	Byproduct of rice processing	Low in nutrients, mainly a soil conditioner	Fe: 50-100, Na: 20-50, Cu: 1-3, Se: <0.1, Si: 1000-2000	6-7
Alfalfa Meal	Ground alfalfa plant material	Fine, granular, nutrient-rich	Harvested and processed alfalfa plants	N: 2-5%, P: 0.5-1%, K: 1-2%	Fe: 200-500, Na: 50-100, Cu: 5-10, Se: 0.5-1, Si: 50-100	6-7
Sheep Manure	Sheep excreta and bedding materials	Fine, less odoriferous than other manures	Animal metabolism	N: 1-2%, P: 0.3-0.6%, K: 0.5-1%	Fe: 500-1000, Na: 200-500, Cu: 10-20, Se: 0.5-1, Si: 100-200	7-8
Poultry Litter	Chicken and turkey manure with bedding materials	High nitrogen content, variable texture	Poultry farming waste	N: 3-4%, P: 1-2%, K: 2-3%	Fe: 1000-2000, Na: 500-1000, Cu: 20-40, Se: 1-3, Si: 200-300	6-8
Blood Meal	Dried, powdered blood from slaughterhouses	High nitrogen content, fast-acting	Byproduct of meat processing	N: 12-15%, P: 0.5-1%, K: 0.3-0.5%	Fe: 1000-3000, Na: 200-500, Cu: 50-100, Se: 2-5, Si: 50-100	6-7
Kelp Meal	Dried and ground kelp	High in trace minerals, fine texture	Harvested from oceanic environments	N: 1-2%, P: 0.1-0.2%, K: 2-3%, Ca: 1-2%, Mg: 1-2%	Fe: 200-600, Na: 2000-5000, Cu: 5-10, Se: 0.5-2, Si: 50-100	6-8
Palm Fiber	Fibers from the outer husk of palm fruits	Coarse, fibrous, good drainage properties	Byproduct of palm oil processing	Low in nutrients, mainly a soil conditioner	Fe: 50-100, Na: 50-100, Cu: 1-3, Se: <0.1, Si: 20-50	6-7
Hair	Human or animal hair clippings	Slow-release nitrogen, fine strands	Barber shops and pet grooming waste	N: 12-15%, P: 0.1-0.2%, K: 0.1-0.2%	Fe: 50-100, Na: 20-50, Cu: 1-3, Se: <0.1, Si: 10-30	6-7
Paper Mulch	Shredded or layered paper products	Lightweight, biodegradable, moisture-retentive	Recycled paper waste	Low in nutrients, mainly a soil conditioner	Fe: 20-50, Na: 10-30, Cu: 0.5-1.5, Se: <0.1, Si: 10-30	6-8
Worm Castings	Excreta from earthworms	Fine, crumbly, nutrient-rich	Worm farming and vermicomposting	N: 1-2%, P: 1-2%, K: 1-2%	Fe: 1000-2000, Na: 100-300, Cu: 10-20, Se: 0.5-1, Si: 100-200	6-8
Insect Frass	Insect excreta, dead insect material, eggs, and bedding material	Fibrous, varied texture, nutrient-rich with high levels of chitin	Insect farming waste	N: 2-4%, P: 1-2%, K: 1-2%	Fe: 500-1000, Na: 100-300, Cu: 10-20, Se: 1-2, Si: 100-200	6-8
Bark Mulch	Shredded or chipped tree bark	Coarse texture, slow decomposition	Timber processing waste	Low in nutrients, mainly a soil conditioner	Fe: 50-150, Na: 20-50, Cu: 1-3, Se: <0.1, Si: 20-50	5-6
Pine Needles	Fallen pine leaves	Acidic, fibrous, slow decomposition	Coniferous forest floor material	Low in nutrients, mainly a soil conditioner	Fe: 50-100, Na: 20-50, Cu: 1-3, Se: <0.1, Si: 20-50	3.5-4.5
Duckweed	Floating aquatic plant	High protein content, fast-growing	Cultivated or wild-harvested from water bodies	N: 4-6%, P: 1-2%, K: 1-2%	Fe: 200-600, Na: 100-300, Cu: 5-10, Se: 0.5-1, Si: 50-100	6-7
Soybean Meal	Ground soybean cake after oil extraction	Granular, high nitrogen content	Byproduct of soybean processing	N: 7-8%, P: 0.5-1%, K: 1-2%	Fe: 200-500, Na: 50-100, Cu: 5-10, Se: 0.5-1, Si: 50-100	6-7

Benefits of Organic Matter in Soil

Nutrient Recycling: Organic matter serves as a reservoir of essential nutrients. As the Microbes and Fungi decompose the material, it releases plant available forms of: nitrogen; phosphorus; potassium; and all other required micronutrients thereby replenishing soil fertility.
Soil Structure Improvement: Organic matter enhances soil aggregation, porosity, and water infiltration, promoting root growth, and providing a favorable environment for soil organisms.
Water Retention: Organic matter improves soil water-holding capacity, reducing water runoff, erosion, and drought stress on plants.
Microbial Activity: Organic matter stimulates microbial biomass and activity, supporting nutrient cycling, disease suppression, and plant growth promotion.

Negatives of Organic Matter in Soil

Nitrogen Tie-Up: Fresh organic matter can temporarily immobilize soil nitrogen as soil microbes decompose organic residues, potentially leading to nitrogen deficiency in plants.
Carbon Dioxide Emissions: Decomposition of organic matter releases carbon dioxide (CO2) into the atmosphere, contributing to greenhouse gas emissions and climate change.
Disease Potential: Certain types of organic matter, such as raw manure or diseased plant residues, may harbor pathogens and pests that can spread to crops.

Optimum Level of Organic Matter in Soil

The optimum level of organic matter in soil varies depending on factors such as soil type, climate, land use, and management practices. Generally though, soils with 3-5% organic matter content are considered fertile for supporting healthy plant growth and soil ecosystem function. Most soils are approximately 2% organic matter whereas some soils such as Chernozem can even have 17% organic matter.

Benefits of Adding Organic Matter to Soil

Incorporating organic matter into soil through practices such as cover cropping, mulching, composting, and green manuring can provide numerous benefits including:

Enhancing soil fertility and nutrient availability
Improving soil structure and water retention
Promoting beneficial soil microbial communities
Mitigating soil erosion and compaction
Supporting sustainable agriculture and ecosystem resilience

Dangers of Using Organic Matter and Appropriate PPE

Handling organic matter, particularly fresh manure or compost, can pose health risks due to exposure to pathogens, allergens, and bioaerosols. Appropriate personal protective equipment (PPE), including gloves, masks, and protective clothing, should be worn when handling organic matter to minimize health hazards and ensure safety.

Sustainability of Using Organic Matter

The sustainable use of organic matter in agriculture relies on responsible management practices that balance soil health, environmental stewardship, and agricultural productivity. By integrating organic matter management strategies into farming systems, such as conservation tillage, crop rotation, and agroforestry, farmers can enhance soil fertility, mitigate climate change, and promote food security in a sustainable manner.

Conclusion

Organic matter, the lifeblood of fertile soils, embodies the timeless wisdom of nature's cycles and rhythms. What initially appears to be the simple decomposition of plant and animal residues proves to have a profound impact on soil fertility and ecosystem health. Controlling Organic matter levels remains as the cornerstone of sustainable agriculture. Let us honor the nurturing embrace of organic matter and cultivate a future where soil fertility flourishes in harmony with the natural world.

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