Lori J. Wilson
The reduction of phosphorous containing compounds from animal manures is a highly desirable goal from the standpoint of environmental protection. Excess phosphorous from farms can enter a watershed and accumulate in larger bodies of water. Phosphorous from farmland runoff is associated with widespread contamination and expanding eutrophication of freshwaters. In this project, we measured the total phosphorous in geological and agricultural samples from EKU’s Meadowbrook Farm using EPA method 365.2. Phosphorous can be classified into four groups: dissolved in water, sorbed to surfaces of clay minerals or Fe and Al oxides, primary phosphate minerals and in organic substances and living organisms. Dissolved phosphate, commonly referred to as orthophosphate, reacts with ammonium molybdate and antimony potassium tartrate react in an acid medium to form an antimony-phospho-molybdate complex. This complex is reduced to an intensely blue-colored complex by ascorbic acid. The color is proportional to the phosphorus concentration. Only orthophosphate forms a blue color in this test. Polyphosphates, and some organic phosphorus compounds, are converted to the orthophosphate form by sulfuric acid hydrolysis. Organic phosphorus compounds are converted to the orthophosphate form by persulfate digestion. We describe the results of our adaptation of the EPA method to measure total phosphorous of samples of water from farm runoff and animal manures from EKU’s Meadowbrook Farm.