Clay is the most porous sediment but is the least permeable. Clay usually acts as an aquitard, impeding the flow of water. Gravel and sand are both porous and permeable, making them good aquifer materials. Gravel has the highest permeability.

The cell membrane is selectively permeable and able to regulate what enters and exits the cell, thus facilitating the transport of materials needed for survival.

The cell membrane is selectively permeable, meaning it only lets certain things in and out of the cell. A cell is a living thing and needs just the right balance of nutrients and water, called homeostasis. The selective permeability of the membrane allows the cell to stay in homeostasis.

The plasma membrane is virtually impermeable against larger, uncharged polar molecules and all charged molecules including ions.

Permeability in this context refers to how easily a molecule can pass through the cell membrane between the internal cytoplasm and external interstital fluid.

clay is more permeable than sand. Sand is more permeable than sandstone. -is most accurate about permeability. This answer has been confirmed as correct and helpful.

Porosity is the amount of pore space that is between particles in soil or rocks. Surprisingly, clay can have high porosity too because clay has a greater surface area than sand, therefore, more water can remain in the soil.

Good examples of aquifers are glacial till or sandy soils which have both high porosity and high permeability. Aquifers allows us to recover groundwater by pumping quickly and easily. Aquifers are replenished when surface water infiltrates through the ground and refills the pore spaces in the aquifer.

gravel

Porosity varies depending on particle size and aggregation. It is greater in clayey and organic soils than in sandy soils. A large number of small particles in a volume of soil produces a large number of soil pores. Fewer large particles can occupy the same volume of soil so there are fewer pores and less porosity.

The amount of porosity in a soil depends on the minerals that make up the soil and the amount of sorting that occurs within the soil structure. For example, a sandy soil will have larger porosity than silty sand, because the silt will fill in the gaps between the sand particles.

Clayey soils

Both sand and clay deposits (and sandstone and mudstone) are quite porous (30% to 50% for sand and 40% to 70% for silt and clay), but while sand can be quite permeable, clay and mudstone are not.

Soil particles vary greatly in size, and soil scientists classify soil particles into sand, silt, and clay. Starting with the finest, clay particles are smaller than 0.002 mm in diameter. Silt particles are from 0.002 to 0.05 mm in diameter.

Silt has a slightly larger particle size when compared with clay, which gives it a greater ability to drain. It is still a poorly permeable soil type and will take 200 days to drain 40 inches of liquid.

How to Make Soil More Porous

1. Spread a 4-inch layer of compost or dried manure with a shovel over the soil before planting.
2. Add a layer of mulch after you plant crops or flowers.
3. Sow cover crop seeds in the fall after you harvest your warm-season crops.

Sand is one of the cheapest things you can add to your garden soil that will help to break up the soil. The small particle size of the sand will get in between soil clods and break them up, increase drainage, and help to aerate the soil for good root development.

Sandy soil drains more readily than other types of soil. Sand drains so quickly that extremely sandy soil needs to be watered more often because sand will not retain water long enough for plant roots to have good access to the moisture before it drains away. Sand is useful for drainage.

Increasing the protection the soil is afforded by crop residues and plants; adding organic matter to the soil through crop rotations, manures, or crop residues; and carefully managing fertilizers, pesticides, tillage equipment, and other elements of the farming system can improve soil quality.

Sprinkle 1 1/2 pounds of 5-10-10 fertilizer over every 50 square feet of soil. Turn the fertilizer into the top 6 inches of soil so plant roots can easily absorb the nutrients after you replant. Alternatively, apply a suitable fertilizer at the correct rate for the specific plants you grow.

Soil depletion occurs when the components which contribute to fertility are removed and not replaced, and the conditions which support soil’s fertility are not maintained. This leads to poor crop yields. The depletion of soil has affected the state of plant life and crops in agriculture in many countries.

Good choices for the compost include peat moss, well rotted manure and even lawn trimmings. You should try to build a good 3-4″ of organic compost on top of your garden plot. Go over the area again with your rototiller to work the compost into the soil.