the upper most layer of soil is composed of the very top layer.
the upper most layer of soil is composed of the very top layer.
what is the upper most layer of soil composed of?
very top layer
topsoil is the upper, outermost layer of soil, usually the top to . it has the highest concentration of organic matter and microorganisms and is where most of the earth's biological soil activity occurs. topsoil is composed of mineral particles, organic matter, water, and air. organic matter varies in quantity on different soils. the strength of soil structure decreases with the presence of organic matter, creating weak bearing capacities. organic matter condenses and settles in different ways under certain conditions, such as roadbeds and foundations. the structure becomes affected once the soil is dewatered. the soil's volume substantially decreases. it decomposes and suffers wind erosion.
topsoil
traditional agricultural practices have generally caused declining soil structure. for example, cultivation causes the mechanical mixing of the soil, compacting and sheering of aggregates and filling of pore spaces - organic matter is also exposed to a greater rate of decay and oxidation. soil structure is essential to soil health and fertility; soil structure decline has a direct effect on soil and surface food chain and biodiversity as a consequence. continued crop cultivation eventually results in significant changes within the soil, such as its nutrient status, ph balance, organic matter content, and physical characteristics. while some of these changes can be beneficial to food and crop production, they can also be harmful towards other necessary systems. for example, studies have shown that tilling has had negative consequences towards soil organic matter (som), the organic component of soil composed of plant and animal decomposition and substances synthesized by soil organisms. som plays an integral role in the preservation of soil structure, but the constant tilling of crops has caused the som to shift and redistribute, causing soil structure to deteriorate and altering soil organism populations (such as with earthworms). yet in many parts of the world, maximizing food production at all costs due to rampant poverty and the lack of food security tends to leave the long term ecological consequences overlooked, despite research and acknowledgment by the academic community.
soil biodiversity