Soil Organic Matter

Soil is composed of : (a ) packing material , ( b ) water , and ( c ) the air. The packing material can be: (a ) mineral material , and ( b ) organic matter . A mineral composed of particles of sand, dust and clay . Third particle sorting soil texture. Mineral soil organic matter ranges from 5 % of the total weight of the soil. Although mineral soil organic matter content slightly ( +5 % ) but significant role in determining the Soil Fertility .

Definition of Organic

Organic matter is a diverse group of complex organic compounds - compounds that are or have undergone a process of decomposition , either in the form of humus results humifikasi inorganic compound or compounds , including the results of mineralization and heterotrophic microbial and ototrofik involved and be in it.

Soil Organic Material Resources, Soil organic matter can be derived from :
1. primary sources, namely: organic net plant ( flora ) that can be:
a. leaves
b. the twigs and branches
c. stem
d. fruits
e. roots.

2. secondary sources , namely: organic networks fauna , which can be: filth and microfauna .
3. Other sources from outside , namely : the provision of organic fertilizer in the form of :
a. manure
b. green manure
c. bokasi fertilizer ( compost )
d. biological fertilizer .

Biochemical Composition of Organic Materials
According to Waksman (1948 ) in Brady ( 1990 ) that the biomass of organic matter derived from biomass forage , consisting of: ( 1 ) water ( 75 % ) and ( 2 ) dry biomass ( 25 % ) .

Biochemical composition of organic matter from the dry biomass , consisting of:
1. carbohydrates ( 60 % )
2. lignin ( 25 % )
3. protein ( 10 % )
4. fats , waxes and tannins ( 5 % ).

The dry biomass carbohydrate compiler, consisting of:
1. sugar and starch ( 1 % -s/d- 5 % )
2. hemicellulose ( 10 % -s/d- 30 %
3. cellulose ( 20 % -s/d- 50 % ).

Based on the categories of nutrient elements composing the dry biomass, consisting of:
1. Carbon ( C = 44 % )
2. Oxygen ( O = 40 % )
3. Hydrogen ( H = 8 % )
4. Mineral ( 8 % ).


Decomposition of organic material
The process of decomposition of organic matter through three reactions, namely:
1. enzymatic reactions or enzymatic oxidation, namely: the oxidation reactions occurring hydrocarbon compounds through enzymatic reactions produce the final product in the form of carbon dioxide (CO2 ), water (H2O ), steam and hot.
2. specific reaction or immobilized form of mineralization and nutrient elements essential connection in the form of nutrient nitrogen ( N ), phosphorus ( P ), and sulfur ( S ).
3. the formation of a new compound, or derivative compounds are very resistant form of soil humus.

Based on the category of the final product , the process of decomposition of organic matter are classified into two, namely:
1. the process of mineralization, and
2. humifikasi process.

Mineralization process occurs mainly on organic - compounds from compounds that are not resistant, such as cellulose, sugar, and protein. Ions produced at the final mineralization or nutrient available to plants.

Humifikasi process occurs on organic material from the compound - resistant compounds, such as lignin, resins, oils and fats. The final process humifikasi humus produced more resistant to decomposition processes.

Massage facilities compilers decomposition of various materials from the soil organic matter terdekomposisi fastest terdekomposisi up with the latest, is as follows:
1. sugars, starch, and protein medium
2. crude protein ( protein complex leih )
3. hemicellulose
4. cellulose
5. fats, oils and waxes, as well as
6. lignin.

Humus
Humus can be defined as the original complex network of organic compounds plants ( flora ) and or fauna that has been modified or synthesized by microbes, which are relatively resistant to weathering, brown, amorphous ( without form / nonkristalin ) and colloidal nature.

Humus Characteristics
Some features of soil humus as follows:
1. are colloidal ( size less than 1 micrometer ), because the small size makes humus colloid has a surface area greater association weights, so high above the clay absorbent cottonwool. KTK organic colloidal size 150 s / d 300 me/100 g higher than KTK clay, ie 8 s / d 100 me/100g. Humus exerts on the water absorbent cottonwool 80% s / d 90 % and is significantly higher than the clay that only 15 % s / d 20 %. Humus has carboxyl and phenolic functional group abundance.
2. the cohesion and low plasticity, thereby reducing soil clamminess and helps granulation soil aggregates.
3. Composed of lignin, poliuronida, and crude protein.
4. dark brown, which can cause earthy dark.

Role Against Soil Organic Matter
Organic matter can influence the changes in soil properties following :
1. physical properties of the soil
2. the chemical properties of the soil
3. the nature of the soil biology.

The role of organic matter on changes in soil physical properties, including:
1. stimulant of granulation land
2. improve the soil structure becomes more crumb
3. reduce soil plasticity and cohesion
4. improve the soil hold water until no excess drainage, soil moisture and temperature stabilized
5. influence earthy brown to black
6. neutralize the rain damaged the details
7. inhibit erosion, and
8. reduces leaching ( washing / leaching).

The role of organic matter on changes in soil chemical properties , including:
1. increase the nutrient available from the mineralization process degradable organic matter
2. produce humus soil that acts as a colloidal mineral residue from the compound and the compound decomposes in the process humifikasi confidential
3. increase the cation exchange capacity ( KTK ) 30 times larger land rather than inorganic colloids
4. positive unload land through chelation of mineral oxides and Al and Fe cations are reactive , thus decreasing soil P fixation
5. improve the availability and efficiency through improved fertilization and P by acid - leaching the organic acid decomposition of organic material.

The role of organic matter on changes in soil biological properties, including:
1. increasing the diversity of organisms that can survive in soil ( makrobia and microbial soil )
2. increase the population of soil organisms ( makrobia and microbial soil )

Good diversity of population increase mupun closely related to the function of organic matter for soil organisms , namely as :
1.  organic matter as a source of energy for soil organisms, especially soil organisms heterotropik
2. organic matter as a nutrient source for soil organisms.