sources + losses

I'm still confused on the losses and sources of phosphorus, sulfur, and potassium. can someone help me with this?

Sophia, have a look at the nutrient cycles in the class notes. You will notice that the arrows are colour coded. Red = losses, blue = inputs, black = transformations.

Phosphorous: Additions (sources):

- Fertilizers (Excess amounts must be applied to over come the phosphorus fixing capacity) - Decaying organic matter - Deposition from eroded rocks by wind and water (dust & precipitation)

Losses: - Plant removal - Uptake by plants via mycorryzal networks - Leaching (But rarely happens because inorganic (plant available) phosphorus gets fixed. By Ca in alkaline soils and by Fe and Al in acidic soils. It gets fixed into an insoluble and immobile form. - Erosion of phosphorous carrying particles

Sulfur:

Additions (sources): - Decaying organic matter - Minerals - Coal burns into the atmosphere then is added to the soil by acid rain or by direct absorption from the atmosphere by plants

Losses: - Leaching of sulfates in solution - Volitilzation of S(2-) to sulfur gasses - Erosion - Plant Removal

Potassium:

Additions (sources): - Fertilizers - Decaying organic matter - Minerals

Losses: - Leaching (translocation down through profile and exit into ground water) - Runoff (to rivers from irrigation or rain) - Erosion

Hope this helps! :-)