For most local farmers, wheat has been harvested, straw has been placed in the barn, and silage harvest is quickly approaching.  The Mercer Soil & Water Conservation District reminds producers to use best management practices on their land especially when dealing with liquid manure application during dry conditions.  As your holding ponds are emptied and liquid manure is land applied, consider the effects to water quality.
For liquid wastes, application rates should be adjusted to the most limiting factor to avoid ponding, surface runoff, tile discharge, and satisfy the nutrient needs of the field.  The total application should be adjusted for field conditions and soil moisture.  Application rates should never exceed 13,000 gallons/acre.  Soils may require some tillage to improve infiltration, retention of liquid manure, and prevent runoff.
Fields that are tiled require additional precautions. When liquid wastes are applied to fields with subsurface tile, the liquid can follow soil cracks and worm holes directly to the tile creating a surface water pollution hazard from direct tile discharge.  Prior to manure application, use a tillage tool that can disrupt/close preferential flow paths (worm holes, cracks, root channels) in the soil, or till the soil 3-5 inches deep to a condition that will absorb the liquid wastes.
This tillage allows the surface soil to act as a sponge to soak up the liquid manure and keep it out of preferential flow channels. This is especially important if shallow tile are present.  Any pre-application tillage should leave as much residue as possible on the soil surface.  The adsorption of liquid manure by the soil in the root zone will minimize manure/nutrient runoff potential. For perennial crops (hay or pasture), or continuous no till fields where tillage is not an option, all tile outlets from the application area should be plugged prior to application. 
If injection is used, inject only deep enough to cover the manure with soil. Till the soil at least 3 inches below the depth of injection prior to application of manure.  In addition to tillage prior to liquid waste application, install tile plugs that mechanically stop tile flow prior to application, or have on site if needed to stop tile flow. Use caution not to back tile water where it may impair the functioning of an offsite subsurface drainage system.  All broken tile or blow holes must be repaired prior to application.
Attention is usually focused on winter manure application; however, farmers and applicators need to guard water quality throughout the year by following the current USDA/NRCS Practice Standard #633 when manure application is planned.  There are suggested guidelines (#633) in place that if implemented will greatly reduce or eliminate the potential for nutrients to enter into watercourses, road ditches, streams and rivers. Anyone applying manure should be aware of all catch basins, watercourses, concentrated field flow areas, grassed waterways, riser pipes, tile inlets, culvert pipes and tile blowouts in the application area.
Minimum Setback Distances for the Surface Application of Manure:
  • 100 ft. from Residences/Private Wells down slope from the application area
  • 100 ft. setback from Ponds and Lakes with a minimum of 35 ft. of permanent vegetative buffer
  • 35ft. Vegetative Barrier OR 100’ in Non-Vegetative setback from Streams, Ditches, and Surface Inlets 
  • 35 ft. from Grassed Waterways
  • 35 ft. from Field Surface Drains
  • 300 ft. from Public Wells
  • 300 ft. upslope from Developed Springs
  • 300 ft. from Public Surface Drinking Water Intake
Minimum Setback Distances for Surface Incorporation of Manure within 24 Hours OR Direct Injection:
  • 100 ft. from Residences/Private Wells down slope from the application area
  • 35 ft. Vegetative Barrier from Ponds or Lakes
  • No Required  Setbacks from Streams, Ditches, and Surface Inlets 
  • No Required Setbacks from Grassed Waterways
  • No Required Setbacks from Field Surface Drains
  • 100 ft. from Public Wells
  • 300 ft. upslope from Developed Springs
  • 300 ft. from Public Surface Drinking Water Intake
For more information about manure application criteria or other manure management issues, contact the SWCD office at 419-586-3289.