Loam is a type of soil that is primarily made up of sand, silt, and a tiny quantity of clay. Sand, silt, and clay make up roughly 40-40-20% of its mineral content by weight, respectively. However, these ratios can vary to some extent, leading to many varieties of loam soils, including clay loam, sandy clay loam, silty clay loam, and loam.
In comparison to sandy soils, loam soils often have higher levels of nutrients, moisture, and humus. They also have greater air and water infiltration and drainage than silt and clay-rich soils and are simpler to till than clay soils. In truth, many gardeners adopt the primary definition of loam found in most dictionaries, which refers to soils containing humus without mentioning particle size or texture. Each variety of loam soil has a few distinctive qualities, with some draining liquids more effectively than others. Important aspects of the soil’s texture include its capacity to hold water and nutrients. Most plant species can be grown in loam soil.
The ratio of soil solids (a mix of sand, silt, and clay) to pore spaces and water in normal loam soil is about 50%. The size and shape of the mineral particles, as well as the activity of microorganisms, will determine the distribution and size of the pore spaces. Because clay particles are so minute and can compact so well, soil that is primarily made of clay typically has extremely few pore spaces. Because sand granules are more amorphous and do not compact as easily, sandy soils tend to have substantially bigger pore spaces. Depending on the surface conditions, atmospheric gases (most notably oxygen and carbon dioxide) can migrate passively through the soil profile and occupy pore spaces as well.
Micropores (0.06 mm and smaller) and macropores (0.06 mm and larger) are terms used to describe pore spaces. In contrast to micropores, which are the first to fill up with water in damp field soil and do not allow much air movement into or out of the pores, macropores tend to enable air and percolating water to travel through them extremely easily.
Convection can facilitate gas exchange inside the soil or between the soil and the atmosphere above. When soil has extensive, interconnected pore networks or channels, aeration—the flow of oxygen and other gases—happens most easily near the soil’s surface. Barometric pressure variations, temperature differences, and wind gusts all have an impact on the pace of aeration. The diffusion of gases into and out of soil depends on factors such as temperature, relative humidity, surface texture, and the continuity of soil pores.
Bearing Capacity of Loam Soil
Because loam contains the right proportions of clay, sand, and silt, it is the best soil type for construction. It strikes the perfect balance between all of their best attributes to support a foundation. Loam typically responds effectively to the presence of water and does not radically change, grow, or contract. Alluvial, loam, sandy loam, and sandy clay loam have safe bearing capacities of between 80 to 270kN/m2 respectively.
