Garden with Insight
Garden with Insight v1.0 Help: Soil patch next day functions: calculate how much nutrient was lost in eroded soil
The soil eroded from the soil patch in water and wind erosion, also called the sediment yield, must
have taken some nutrients with it. Here the amount of nutrients lost is calculated for several N and P
compartments. Note that this calcalation is done late in the next-day functions, after the total erosion is
calculated. The basic equation for nutrient loss in erosion is the sediment yield times the concentration of
the nutrient in the soil (by weight) times a variable called the enrichment ratio. The enrichment ratio is an index of how fast the eroding water flows and how hard the rain hits the
soil, based on the amount of rainfall and runoff and the peak runoff rate. Notice that wind and water erosion are both included in these
calculations, but the enrichment ratio depends only on variables that describe water flow. Presumably
wind erosion is normally much smaller than water erosion and so it can be passed over here.
EPIC removes some organic N (active and stable), organic P, labile P,
active mineral P, and organic matter in sediment. We added the
removal of the other N, P and C compartments as well (nitrate, ammonia, fresh organic N, fresh organic
P, stable mineral P, flat residue) because it seemed all the compartments should be affected by erosion.
Whether this addition was necessary or correct remains to be determined.
calculation of runoff and water erosion from rainfall, runoff and water erosion from irrigation, wind erosion
EPIC Organic N Transport by Sediment
EPIC P Transport by Sediment