What provides organic matter to the soil and adds to its fertility​

Humus improves soil fertility by acting as a reservoir for nutrients, increasing the water holding capacity of the soil, improving soil structure and friability, and providing a source of energy for living soil organisms.

i am a little confused myself with what goes with the letters and what goes with the numbers but ill do my best to you

the cordillera states and grand canyon are along the southwest u.s. and northern mexican pacific.

the great plains and southwest desert are also the prairie and home to many earthquakes too .

the coastal plains have poor soil and many factories started in the south.

is this what u needed? if not i can see what i can do