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Role of organic
matter in soil
Dr. Nazir Hussain
Organic matter is one of the major
constituents of soil among the other three, solid material,
water and air. The microbial life in the soil which has to
perform many important functions like; conversion of plant
nutrients into available form, conserving the applied
fertilizers and all the chemical changes etc. is only active
in the presence of organic matter.
The major roles of organic
matter are:
1. It is the ultimate source of almost all the plant nutrients
like nitrogen, phosphorus, carbon, Zinc, Copper, Manganese,
chloride, molybdenum, iron and boron.
2. It supports the microbial life and provide their carbon and
nitrogen requirements.
3. It is responsible for increasing the water holding capacity
of the soil and providing water from the soil to plant roots
for longer time.
4. It improves the porosity of the soil by increasing size and
number of soil pores due to granulation (making granules of
soil particles).
5. The water infiltration rate (entry of water into the lower
soil profile) is improved and chances of run-off water ore
reduced. The water passage (hydraulic conductivity) becomes
better.
6. The air passage is increased a lot and root development and
elongation are enhanced. Resistance to root penetration is
decreased.
7. It binds the nutrients and decreases their losses.
8. It is useful in sandy as well as clayey soils. In sandy
soils it increases water holding capacity and decreases
nutrient losses through leaching. In clayey soils it improves
heaviness of the soil by keeping it porous, easily cultivable
and soft for roots which results in enhanced germination and
plant growth.
9. It is helpful to decrease the removal and erosion of soil
by wind velocity and water impact.
10. It is beneficial is reclamation of salt affected soils by
improving physical condition and leaching of salts into the
lover profile.
11. The local drainage of the soils is enhanced by orgasmic
matter.
Sources of orgasmic matter in the soil
1. Returning of crop and plant residues into the soil like
straw and husks etc.
2. Plant roots, leaves dropped on the surface and incorporated
into the soil and green manures.
3. Farm yard manures, poultry manure, compost manure, press
mud, rice and wheat straw and rice husks etc.
Strategies to increase
organic matter in the soil
The higher organic matter in the soil is useful for
getting enhanced yields of cops. Therefore, efforts should be
converged to keep it at the maximum possible higher content by
adopting strategies like returning all the crop residues,
including a green manure crop in the rotation, application of
manures in to the soil.
Dr. Nazir Hussain
Ph.D. (Soil Science) UAF
Soil Salinity Research Institute, District Hafizabad
(Punjab)
drnazir@gjr.wol.net.pk,
dr_nazir@yahoo.com |
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