Phosphorus in the humus fraction is partitioned between the active and stable organic pools using the ratio of humus active organic N to stable organic N. The amount of phosphorus in the active and stable organic pools is calculated:
3:2.2.3
3:2.2.4
where is the amount of phosphorus in the active organic pool (kg P/ha), is the amount of phosphorus in the stable organic pool (kg P/ha), is the concentration of humic organic phosphorus in the layer (kg P/ha), is the amount of nitrogen in the active organic pool (kg N/ha), and is the amount of nitrogen in the stable organic pool (kg N/ha).
Mineralization from the humus active organic P pool is calculated:
3:2.2.5
where is the phosphorus mineralized from the humus active organic pool (kg P/ha), is the rate coefficient for mineralization of the humus active organic nutrients, is the nutrient cycling temperature factor for layer , is the nutrient cycling water factor for layer , and is the amount of phosphorus in the active organic pool (kg P/ha).
Phosphorus mineralized from the humus active organic pool is added to the solution P pool in the layer.