Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

Crop production typically entails applications of nitrogen, phosphorus, and potassium through chemical fertilizer or livestock manure. Regardless of the nutrient source, more nutrients must be applied than the crop can take up. This is because one portion of nutrients is said to be plant available nutrients while the other portion is not plant available. The plant available portion can be applied to crops and harvested. Nutrients that are not plant available are either not in the proper chemical form for crop uptake, or leave the area they were applied via leaching or runoff (henceforth, runoff). Excess nutrients (nutrients applied to the crop but not harvested) can potentially leave the field, enter surface waters, and pollute waters through eutrophication. (Download PDF)    (Export to EndNotes)