Better Farming February 2017

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Thank a Farmer.

Better Farming

February 2017

CROPS:

YIELD

MATTER$

that to SOM by multiplying by a factor of 1.8. To look at

it another way, the 3.0 to 5.0 per cent SOM is 1.7 to 2.7

per cent organic carbon.

Soil organic matter is derived from plants growing in

the soil itself. SOM content is not static; it is constantly

changing over time. We often refer to three components

of SOM as (1) the active or living, which is all of the

micro-organisms; (2) the dead, which is recently-added

crop residue or biosolids, manures and composts; and

(3) the very dead or humus, which is the long-term

stable component of SOM.

Other references suggest SOM has only two compo-

nents: (1) the active, which includes both the living and

the dead that change forms easily by action of soil

microbes; and (2) the passive or humus that resists

changes and contains a higher lignin content.

SOM and the resulting soil health effects offer many

benefits and societal services which are worth noting –

just from the biological component alone:

• Nutrient cycling,

• Disease and pest management,

• Decomposition residues,

• Soil structure,

• Detoxification – degrading of chemistry,

• Growth promotion,

• Carbon sequestration, and

• Nitrous oxide consumption.

Submitting a representative soil sample to an

accredited lab and requesting a SOM test will

provide you with a result expressed as a percentage.