Garden with Insight v1.0 Help: Soil daily structure/chemistry group
Albedo at soil surface today: The proportion of solar
radiation reflected from the soil surface, which affects soil evaporation
and plant transpiration. Albedo calculation starts with the bare-soil
albedo (a parameter) and is increased by vegetative cover and by snow
(over 5 mm).
Soil cover index today: An index based on the amount of vegetative cover (living and dead) on
the soil surface today. Inversely proportional to the amount of cover. Important in runoff, water erosion, soil temperature, and evaporation.
pH by layer: This pH model is very simple: pH starts from the soil type, is reduced by the auto
application of N fertilizer and N fixation, and is increased by liming,
automatically (at the end of the year) or using the bag. Actual pH variation is much more complex.
Aluminum saturation by layer: The percent of cation exchange
sites occupied by aluminum cations (Al+++). High aluminum saturation can inhibit plant growth.
Base-forming cations by layer: The number of cation exchange
sites occupied by bases (basic cations including Ca++, Mg++, K+ and Na+) expressed in moles of
positive charge held (adsorbed) per
unit soil mass. This amount is changed only by fertilization and liming in this version.
Free calcium carbonate by layer: Calcium carbonate that is not bound up in mineral solids as
percent by weight. This is entered as a parameter and never changed; it affects the equilibrium between mineral phases (active and stable) of phosphorus.
Cation exchange capacity by layer: The capacity of
the clay and humus in the soil to hold exchangeable cations, expressed
in moles of positive charge held (adsorbed) per unit soil mass. CEC is changed only by fertilization in this version.
Porosity by layer: Porosity, or percent pore space, is the percent of the total soil volume
not taken up by soil solids -- sand, silt, clay, rocks and organic matter and therefore available to be
taken up by water and air. Important in all soil water calculations.
Bulk density by layer: Bulk density is the weight of
the soil per unit volume -- the soil's density. It is increased by soil
compaction and rainfall, and decreased by mixing and aerating the soil (though too much mixing
can cause compaction). It affects many soil processes.
Bulk density settled by layer: Settled bulk density is the weight of the soil per unit volume when the soil is undisturbed. This is used as a
reference point for changes to bulk density due to rainfall and tillage, and depends partly on soil texture
and the amount of organic matter.
Bulk density oven-dry by layer: Oven-dry bulk density is the weight of the soil per unit volume
after the soil being tested has been baked in an oven. This makes sure all the water weight has
been removed. This is input as a parameter and used as a reference
point for calculations.
Clay content by layer: Percent of the small particulate matter in the soil (not organic matter or
rocks) taken by clay particles (by weight). Soils with large amounts of clay appear shiny and cohesive
when moistened and rubbed between your fingers.
Sand content by layer: Percent of the small particulate matter in the soil (not organic matter or
rocks) taken by sand particles (by weight). Soils with large amounts of sand crumble and fall apart when
moistened and rubbed between your fingers.
Silt content by layer: Percent of the small particulate matter in the soil (not organic matter or
rocks) taken by silt particles, which are intermediate between sand particles and clay particles in size.
Rock content by layer: The percent of the soil in each layer taken up (by weight) by rocks, that
is, particles larger than two millimeters in diameter.