26 articles
Alfisols
Alfisols are a soil order in USDA Soil Taxonomy: moderately leached soils with a clay-enriched subsurface and base saturation of 35% or greater, mostly in temperate regions.
ASTM D698
ASTM D698, commonly called the Standard Proctor test after R. R. Proctor's 1933 method, is an ASTM standard for determining soil compaction curves using standard effort.
Cation-exchange capacity
Cation-exchange capacity (CEC) is a soil science measure of the negatively charged sites on soil and clay surfaces that reversibly hold nutrient cations such as calcium, magnesium, and potassium.
CENTURY model
The CENTURY model, developed at Colorado State University's Natural Resource Ecology Laboratory, simulates carbon, nitrogen, phosphorus, and sulfur dynamics in plant-soil systems on a monthly time step.
Chernozems
Chernozems, from the Russian for black earth (чёрнозем), are a WRB Reference Soil Group of deep steppe soils with a thick, dark, humus-rich surface horizon over lime-accumulating material.
Digital soil mapping
Digital soil mapping (DSM) is a geospatial method that predicts soil properties or classes across a landscape by fitting quantitative relationships between soil observations and environmental data layers.
Erosion susceptibility mapping
Erosion susceptibility mapping is a geospatial modeling method that combines environmental factor layers with machine learning classifiers to classify land into erosion-proneness categories, supporting land-use planning and soil conservation.
Fluvisols
Fluvisols are young soils formed in recent river, lake, and marine deposits in floodplains, deltas, and tidal marshes, classified by stratified sediment and irregular organic matter renewed by periodic flooding, covering about 350 million hectares.
Interrill erosion
Interrill erosion, also called sheet erosion, is the removal of soil in thin layers by raindrop impact and shallow overland flow, the first stage of water erosion on a hillslope.
Lessivage
Lessivage, also called argilluviation, is the transfer of fine clay particles, chiefly under 2 μm, from a soil's eluviated E-horizon to a deeper B-horizon, producing the clay-enriched horizons of Luvisols.
Mollisol
A Mollisol is a soil order in USDA Soil Taxonomy defined by a thick, dark, humus-rich surface horizon, making it among the most fertile and extensively farmed soils in the world.
Mollisols
Mollisols, from the Latin mollis meaning soft, are a USDA soil order with a thick, dark, humus-rich surface horizon, formed mainly under grassland and counted among the world's most productive agricultural soils.
Oxisols
Oxisols, known as Ferralsols in the World Reference Base, are the most highly weathered of the twelve USDA soil orders, forming in hot, humid tropics with low natural fertility.
Pedotransfer functions
Pedotransfer functions are mathematical models, typically regressions or machine learning, that estimate hard-to-measure soil hydraulic properties from routinely available data like texture and bulk density.
Revised Universal Soil Loss Equation
The Revised Universal Soil Loss Equation (RUSLE) is an empirical model estimating annual soil loss from water erosion, released in 1992 as a computerized USLE.
Soil acidification
Soil acidification is the process by which soil pH declines over time, affecting roughly 30 to 40 percent of agricultural land globally, with liming as the main remedy.
Soil augering
Soil augering is a field method of obtaining soil samples from depth by rotating a boring tool into the ground without excavating a pit, used widely in soil mapping.
Soil catena
A soil catena is a sequence of related soils along a hillslope, from hilltop to valley floor, that share parent material and age but differ because of drainage.
Soil incubation experiments
A soil incubation experiment is a laboratory method in which soil is held under controlled temperature and moisture while carbon or nitrogen mineralization is measured.
Soil sealing
Soil sealing is the covering of ground by impermeable materials such as asphalt or concrete, considered a major and nearly irreversible cause of soil degradation in the European Union.
Tensiometer (soil science)
A tensiometer is a field instrument that measures the matric potential of soil water through a water-saturated porous ceramic cup, used chiefly to schedule irrigation in medium to fine textured soils.
Test pit (soil survey)
A test pit, or soil pit, is an excavation dug during a soil survey so the soil profile can be observed in place and sampled by horizon.
Ultisols
Ultisols are one of the twelve orders of USDA Soil Taxonomy, strongly weathered acidic forest soils of humid temperate and tropical regions with base saturation below 35 percent.
Universal Soil Loss Equation
The Universal Soil Loss Equation (USLE) is an empirical model that estimates long-term average annual soil loss from sheet and rill erosion using six factors for rainfall, soil, topography, cover, and support practices.
Wet sieving
Wet sieving is a particle size analysis method that washes a sample through stacked sieves with water, separating particles into size ranges down to about 20 µm.
Wind erosion
Wind erosion (aeolian soil erosion) is the detachment and transport of soil by wind via saltation, surface creep, and suspension. It begins above roughly 6 m/s over dry soils, strips fine particles and organic matter, and is controlled by cover, roughness, and windbreaks.