Which of the following is an effect of organic matter on soil?
a.
improved soil structure
b.
decreased water retention
c.
increased nutrient loss
d.
all of the above

a.  improved soil structure

Organic matter is a material that is obtained from the dead and decaying biological wastes of the living or pre-living organisms. It is a large pool of carbon based products. The organic matter improves the quality of the soil. The humus is the main ingredient produced by the decaying process of the organic matter. It provides density to the soil and increases it's nutrition and water retention capacity. It improves the texture of the soil as the soil particles are more aggregated. Therefore, it improves the soil structure.

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allowed for the prediction of the properties of missing elements.