With record hot and dry weather this year allowing deep, wide cracks to develop in many farm fields, state agriculture and natural resource officials are urging farmers to inspect fields for such cracks and take other precautions when spreading manure to reduce the risk of manure entering drain tiles and winding up in lakes, streams and groundwater.
“We want to alert farmers to the dangers that applying manure to fields with deep cracks poses,” says Andrew Craig, who leads Department of Natural Resources nutrient management efforts. “We encourage farmers to inspect their fields before applying manure and advise they either avoid spreading on such areas or take additional actions if they do spread manure.”
Recommendations include working cracked soil with tillage before applying manure and having an emergency response plan and supplies in place so they can respond quickly if there are any problems are found.
“In past years with similar cracking, manure that’s been applied to the surface or injected has flowed down these cracks and directly into tile drains and groundwater,” says Sara Walling, resource planning and water quality section chief of the Wisconsin Department of Agriculture, Trade and Consumer Protection.
In addition to potentially contaminating groundwater and surface water, farmers lose the nutrient value of the manure because it can move below the crop root zone.
Farmers and the nutrient applicators many of them hire will need to take precautions with any liquid manure they apply to the land, regardless of solids content, says Kevin Erb, UW-Extension conservation professional development and training coordinator. In a normal year, the risk is highest when manure solids content is less than 2.5 percent.
“Given how wide soil cracks are this year, however, taking precautions is strongly recommended with ALL liquid manure applications, regardless of solids content,” Erb says. “Wider and deeper cracks mean we need to be more careful this summer.”
Fields that were not worked this spring – i.e. wheat fields or hayfields being topdressed - need to be looked at very carefully before application, Erb says.
He recommends farmers take the following precautions when applying manure under the current dry conditions:
• Check fields for soil cracks and locate drain tile inlets and outlets before applying manure.
• Avoid applying manure to soil-cracked fields, with or without drain tiles.
• When spreading can’t be avoided, work the soil with tillage equipment to fill in cracks and close off pathways and have spill containment and response materials and equipment ready for quick use. Even if the manure is injected, fields should be pre-worked.
• Review your farm’s conservation plan before working up fields.
During and after application
• Apply manure in smaller, multiple low volume applications on pre-tilled fields to help absorb applied manure.
• Monitor field drainage tile outlets for manure before, during and for several days after manure is applied to fields and after the next rainfall.
• Stop applying manure immediately if manure release from tile outlet is found and contain the spill. Capture what leaves and land apply in an appropriate manner.
• Use tillage implements to work up the ground ahead of the spill or use absorptive materials.
• Notify DNR’s spill hotline: 800-943-0003. Immediate spill reporting is required by state law and DNR staff provide spill response and help to contain the spill.
More information can be found on the UW Extension drain tile best management practices website: www.extension.org/pages/27488/preferential-flow-of-manure-in-tile-drainage and a video showing steps to take before applying manure, and how to respond if an accident does occur, can be found on DNR’s YouTube “Farm News” playlist: http://bit.ly/ROrjZd.