Jim Hoorman
Ohio State University
Preferential flow of manure through tile lines to surface water can be a problem in Ohio. Water and liquid manure moves downward through the soil following a path of least resististance. Deep cracks, root channels, earthworm burrows, and loamy soils promote preferential flow of manure. Since most liquid manure is 95-98% water, anything that promotes good drainage can result in preferential flow of liquid manure to subsurface drain tiles.
According to the Ohio Department of Natural Resources, between 1997 and 2002, there were 356 fish kills (560,000 fish) in Ohio with agriculture accounting for 22.5% of them. In the past three decades in Ohio, the number of fish kill cases actually decreased 37% (from 2,330 to 1,473/decade) but the number of agriculture related fish kills has increased by 72 percent (from 180 to 311 per decade). Manure in surface water is the number one cause of fish kills in Ohio. Water quality tests from streams where manure spills occurred showed ammonia levels 47 times higher downstream (44.73 mg/L) of a manure spill compared to upstream (0.94 mg/L) tests. The EPA Upper Limit for ammonia is 13 mg/L.
An investigation of 98 manure violations in Ohio show that the typical operation was a mid-size or large livestock operation with liquid manure. An analysis of these reports indicate that, for those caused by preferential flow, the majority occurred with manure applied on cropland without tillage or incorporation (surface application) with less than 6% slope and took place in autumn and during wet/rainy weather. Farm operators accounted for 71 manure violations and custom applicators 26 violations (one unknown), several with mutiple violations. Over 76 percent of the violations occurred with surface manure applications (irrigation, tanker, dragline) and 24 percent with injected liquid manure (dragline/toolbar or tanker/toolbar). Verification of eight cases by the local Soil and Water Conservation Districts revealed that approximately twice as much liquid manure was applied as was reported to investigators. Excess rain or saturated soils, lack of manure storage management, over-application, operator error, equipment failures, dry cracked soils, broken tile lines and earthworm burrows were major reason identified. Although drainage outlet tiles can be plugged, approximately 50% fail due to improper use or installation resulting in manure in surface water.
Better manure management and education, lower manure rates, regular tile line inspections, equipment calibration and maintenance, and equipment that spreads the manure more evenly in the soil could prevent manure in tile lines and surface water contamination. It is estimated that 75% of the fish kills could have been avoided with better management, primarily avoiding application when rain is expected or the available water capacity of the soil is high; ensuring that adequate storage is available; and following the application rate recommendation in a manure management plan written for the farm. Application equipment that is easy to calibrate and is designed to spread large volumes evenly and at low pressure, could also reduce incidents. More research and education is needed in these areas.
Discussion:
Tom Zimmerman (ATI) questioned a reference that most of the problems are from larger farms. How are large and small defined? Hoorman replied that the terminology is somewhat subjective but, in general, larger farms refer to those swine and dairy farms large enough to use a liquid manure handling systems. Such systems result in the highly liquid manure (less than 5% solids) that can flow to drain tiles.
Ted Short (OSU) asked if neighbors targeting larger operations could result in more reports of spills by these farms. Hoorman agreed and suggested that what has been reported is the tip of the iceberg for all sizes.
Short asked about the consequences to the applicator for causing a fish kill. Hoorman replied that it depends on the number of fish killed, but ODNR fines can range from $15 to $65,000. Compared to Indiana, Ohio’s enforcement is relatively lax. For example, in Indiana a manure spill that does not kill any fish could result in a $5,000 to $10,000 fine. In Ohio a $25 litter fine would be imposed.
Zimmerman referred to a photograph of a demonstration held in Apple Creek in September 2003 where smoke forced through a tile line came to the surface indicating pathways for preferential flow. Why were there pathways on tilled soil? Hoorman replied that the tilling was expected to disrupt the macropores that develop on no-till. The fact that the smoke surfaced may have been the result of the loamy soil; however, additional research is needed to assess the effect of tillage.
Short noted that although many small farms apply solid manure, there is a large laying facility in Ohio that composts and dries the manure before application. Hoorman noted that most poultry spills are from egg wash liquids. As long as application of solid poultry manure is about 2-3 tons/acre, there should not be a problem unless there is a very heavy rain.
Maurice Watson (OSU) suggested that there may be an inconsistency between ammonia and TKN concentrations as represented. Hoorman will check. Watson noted that standard procedures have been developed for manure analysis.
Jeff LeJeune (OSU) asked what percentage of farms surface apply liquid manure. Hoorman replied that more information is needed. Jon Rausch (OSU) noted swine and dairy facilities in Ohio are being surveyed and questions about application methods are included.
Summary by Jim Hoorman
Discussion notes by Mary Wicks
The OCAMM (Ohio Composting and Manure Management) Program is funded by OARDC/OSU.