Organic Matter and Humus
Posted: Friday, January 14, 2011
by Robert Wright
UsaveHydroponics
Soil Matrix :
Organic matter. 5% Mineral. 45 % Water. 25% and Air. 25%
2. Organic matter – Any material produced originally by living organisms (plant and animal) that is returned to the soil and goes through the decomposition process.
A. Most originate from plants on the surface and from decaying foots...
C. Nutrient cycle – By- products from growing roots and plant residues feed soil organisms. In turn, soil organisms support plants health as they decompose organic matter, cycle nutrients, enhance soil structure and control the populations of soil organisms. Note: the rate of addition of organic matter must equal to the rate of decomposition to sustain the nutrient cycle.
D. At any given time, it consists of a range of material from the intact original tissues of plants and animals to the substantially decompose mixture of materials known as humus.
1. Humus--. 40-60% of the organic matter is humus. It is probably the most widely distributed organic carbon-containing material in both land and water environments.
A. Humus is the extremely well decomposed- part of the organic matter and has characteristics very different from other organic matter
B. Humus cannot be decomposed readily because of its intimate interactions with soil mineral phases and is chemically too complex to be used by most organisms.
C. Interaction with metals – Humic substances have the ability to interact with metal ions, oxides, hydroxides, mineral and organic compounds, including toxic pollutants, to form water- soluble and water- insoluble complexes. As a result humus can reduce toxicity and pollutants.
D. Composition of humus-- Humus consists of fulvic acids, humic acids, and humin. The term acid is used to describe humus because it behaves like a weak acid. The relative amount of fulvic vs Humic acids in the humus in soil vary with soil types and management practices.
1. Fulvic acids are produced in the earlier stages of humus formation and are the water soluble portion of the humus in all pH conditions. Color is light yellow to yellow brown.
2. Humic acids are water soluble in pH conditions of 2 or less. Color is dark brown to black.
3. Humin is that portion not soluble in water. Color is black.
Forest Soils Grasslands
High fulvic acids High humic acids
(OM on top of soil) (OM below the soil)
B. Importance of Humus:
1. Acts as a buffer to reduce fluctuation in soil acidity and nutrient availability.
2. Humus substances can dissolve, mobility and transport metals and organics in soils and water.
3. Some substances function as natural plant hormones and can improve.
- Seed germanation
- root initiation
- Uptake of plant nutrients Serve as source of nitrogen, potassium and sulfur.
- Provides long life nitrogen (60-80 days longer)
- Improve nutrient uptake (particularly potassium and calcium)
- Salinity (sodium) management-buffers plants from excess sodium
- Catalyst for increasing soil carbon levels
- Complex humic substances can reduce toxicity and pollutants.
- Humus enhances soil water holding capabilities.
10 By providing better plant nutrition reduces disease, insect and frost impact.
Author: Robert R. Wright
This Article has been viewed 224 times. (Not updated in real-time.)
No comments yet.We want your comments! If you can read this, you don't have javascript enabled, so you can't use this comment system. Please enable javascript.