Riccardo G, Italy - I.C. "Falcone-Cascino" : THE SOIL

 The soil is a mixture of substances in the three states solid, liquid and aeriform.

Solid particles of mineral origin are the main part of the soil. The soil contains roughly one half of mineral particles, one quarter of water and one quarter of air, and only a small percentage of organic matter. Solid particles are classified according to their size :

 -The small particles, indistinguishable to the naked eye and impalpable like flour, are clays and (slightly larger) silt; 

-The largest particles, but with dimensions less than 2 mm, are called sand: they are those that form the beaches; 

-Particles with a diameter greater than 2 mm are called gravel if they have sharp edges, or pebbles if the edge is rounded.

The combination of the different categories of solid particles of mineral origin is called soil texture

The different mineral particles give their names to the most common types of soil:

-clayey soil contains more than 20-30% of clays; 

-the loamy soil contains about 50% of silt; 

-the sandy soil contains more than 70-80% of sand; 

-the gravelly soil contains about 50% gravel and pebbles.

Since the different types of particles can be combined in many different ways, there are also intermediate types of soil (for example clayey-loamy soil, or loamy-sandy soil). Based on the texture of the soil they have available, farmers decide what to grow, how much to irrigate, which agricultural machinery to use.




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