Background: Soil formation, or pedogenesis, is the combined effect of physical, chemical, biological and anthropogenic processes working on soil parent material. Soil is said to be formed when organic matter has accumulated and colloids are washed downward, leaving deposits of clay, humus, iron oxide, carbonate, and gypsum, producing a distinct layer called the B horizon. This is a somewhat arbitrary definition as mixtures of sand, silt, clay and humus will support biological and agricultural activity before that time. These constituents are moved from one level to another by water and animal activity. As a result, layers (horizons) form in the soil profile. The alteration and movement of materials within a soil causes the formation of distinctive soil horizons. However, more recent definitions of soil embrace soils without any organic matter, such as those regoliths that formed on Mars and analogous conditions in planet Earth deserts.An example of the development of a soil would begin with the weathering of lava flow bedrock, which would produce the purely mineral-based parent material from which the soil texture forms. Soil development would proceed most rapidly from bare rock of recent flows in a warm climate, under heavy and frequent rainfall. Under such conditions, plants (in a first stage nitrogen-fixing lichens and cyanobacteria then epilithic higher plants) become established very quickly on basaltic lava, even though there is very little organic material. The plants are supported by the porous rock as it is filled with nutrient-bearing water that carries minerals dissolved from the rocks. Crevasses and pockets, local topography of the rocks, would hold fine materials and harbour plant roots. The developing plant roots are associated with mineral-weathering mycorrhizal fungi that assist in breaking up the porous lava, and by these means organic matter and a finer mineral soil accumulate with time. Such initial stages of soil development have been described on volcanoes, inselbergs, and glacial moraines.

Situation: Ben and Jerry studied agricultural sciences. Ben was specialized in pedology and pedogenesis, while Jerry specialized in entomology and phytopathology.

Question: Which person learned more about soil formation?
Answer: Ben

Situation: Ben and Jerry studied agricultural sciences. Ben was specialized in pedology and pedogenesis, while Jerry specialized in entomology and phytopathology.

Question: Which person learned less about soil formation?
Answer: Jerry

Situation: Ben and Jerry studied agricultural sciences. Ben was specialized in pedology and pedogenesis, while Jerry specialized in entomology and phytopathology.

Question: Which person learned less about the accumulation of organic matter?
Answer: Jerry

Situation: Ben and Jerry studied agricultural sciences. Ben was specialized in pedology and pedogenesis, while Jerry specialized in entomology and phytopathology.

Question: Which person learned more about the accumulation of organic matter?
Answer: Ben

Situation: Ben and Jerry studied agricultural sciences. Ben was specialized in pedology and pedogenesis, while Jerry specialized in entomology and phytopathology.

Question: Which person learned more about deposits of clay?
Answer: Ben

Situation: Ben and Jerry studied agricultural sciences. Ben was specialized in pedology and pedogenesis, while Jerry specialized in entomology and phytopathology.

Question: Which person learned less about deposits of clay?
Answer: Jerry

Situation: Ben and Jerry studied agricultural sciences. Ben was specialized in pedology and pedogenesis, while Jerry specialized in entomology and phytopathology.

Question: Which person learned less about deposits of humus?
Answer: Jerry

Situation: Ben and Jerry studied agricultural sciences. Ben was specialized in pedology and pedogenesis, while Jerry specialized in entomology and phytopathology.

Question: Which person learned more about deposits of humus?
Answer: Ben

Situation: Ben and Jerry studied agricultural sciences. Ben was specialized in pedology and pedogenesis, while Jerry specialized in entomology and phytopathology.

Question: Which person learned more about deposits of iron oxide?
Answer: Ben

Situation: Ben and Jerry studied agricultural sciences. Ben was specialized in pedology and pedogenesis, while Jerry specialized in entomology and phytopathology.

Question: Which person learned less about deposits of iron oxide?
Answer: Jerry