USDA Agricultural Research Service scientists have determined how channel sediments in creeks and rivers capture and release manure phosphorus – and as a result have discovered strategies to reduce phosphorus loads from manure spills. Scientists collected sediments from two drainage ditches in a specific watershed and added the sediments to an artificial water channel – using swine manure minimally diluted with water as a “worst-case manure spill.” They then cleaned it up after 24-hours. The simulation first resulted in an average dissolved phosphorus concentration of 5.57-milligrams per liter. They then dropped to around point-two-milligrams per liter after another 24-hours. However – they exceeded the Environmental Protection Agency’s standards for rivers, stream and drainage ditches in the watershed.
After cleanup – scientists also realized the sediments released phosphorus back into the water at rates that increased phosphorus loads to levels exceeding EPA’s maximum acceptable levels by at least 67-percent. Through another study – scientists found amending the sediments with 1.6-milligrams of alum-calcium carbonate per gram of sediment subdued phosphorus release in sandy sediments by 92-percent and by 72-percent in clay loam and loamy sand sediments. Phosphorus release was subdued 100-percent with higher amendment levels in all three soil types.
Source: NAFB News Service