Here & Now

UW-Madison Expert Analyzes Liquid Manure Irrigation Safety

ZAC SCHULTZ:

SHIFTING GEARS NOW TO AGRICULTURAL NEWS, WITH SPRING HERE FARMERS AROUND THE STATE ARE GETTING BACK INTO THEIR FIELDS. AND THAT INCLUDES SPREADING MANURE. OVER THE PAST FEW YEARS MORE LARGE DAIRY OPERATORS HAVE STARTED SPRAYING LIQUID MANURE USING IRRIGATION SYSTEMS. SUPPORTERS SAY IT CAN REDUCE RUNOFF BY ALLOWING THEM TO SPRAY THROUGHOUT THE GROWING SEASON. AND THAT IT REDUCES WEAR AND TEAR ON ROADS BY REDUCING THE NUMBER OF TRIPS A MANURE TANKER NEEDS TO MAKE. BUT OPPONENTS WORRY ABOUT SENDING POSSIBLE PATHOGENS INTO THE AIR INFECTING NEARBY RESIDENTS. FOR THE PAST FEW YEARS A SPECIAL WORK GROUP HAS BEEN LOOKING INTO MANURE IRRIGATION TO STUDY IF IT IS SAFE AND WHAT BEST PRACTICES SHOULD BE PUT IN PLACE. JOINING US NOW TO TALK ABOUT THE REPORT IS THE CHAIR OF THE WORK GROUP, UW PROFESSOR KEN GENSKOW. THANK YOU FOR JOINING US.

KEN GENSKOW:

THANK YOU FOR HAVING ME.

ZAC SCHULTZ:

HOW COMMON IS MANURE IRRIGATION?

KEN GENSKOW:

IT’S VERY COMMON IN SOME OTHER STATES. NEBRASKA USES IT FREQUENTLY. NORTH CAROLINA HAS BEEN USING IT THERE IN RELATION TO SWINE MANURE. NEBRASKA’S MORE TRADITIONAL DAIRY. IN WISCONSIN IT HAS BEEN USED FOR QUITE SOME TIME, BUT THE CENTER PIVOTS, THOSE LARGE APPLICATION EQUIPMENT PIECES THAT PEOPLE ARE CONCERNED ABOUT, THERE HAVE NOT BEEN A LOT OF THOSE SO FAR. SO FAR I THINK THERE’S EIGHT OR TEN THAT ARE EITHER ACTIVELY DOING THAT OR CONSIDERING IT. IT’S REALLY OVER THE PAST FIVE YEARS OR SO THAT THEY’VE BEEN USING THAT TECHNOLOGY MORE. THERE’S ANOTHER TECHNOLOGY, THE TRAVELING GUN SYSTEM, AND THAT’S BEEN IN USE FOR A LONGER PERIOD OF TIME. WE DON’T KNOW EXACTLY HOW WIDESPREAD THAT IS. IT’S USED FAIRLY COMMONLY ACCORDING TO THOSE WE’VE TALKED TO.

ZAC SCHULTZ:

THE BIGGEST CONCERN ABOUT THIS SEEMS TO BE THE IDEA OF DRIFT - THAT MANURE GETS SPRAYED INTO THE AIR, BECOMES PART OF THE WIND MOVING AND IT CAN CARRY MUCH FURTHER THAN THE ACTUAL DROPLETS THAT CARRY ONTO A FIELD AND THAT IT CAN GET SOMEONE SICK. WHAT HAVE YOU LEARNED ABOUT DRIFT IN THIS STUDY?

KEN GENSKOW:

OUR STUDY WAS REALLY LOOKING AT COMPILING INFORMATION ABOUT A NUMBER OF CONCERNS. SO DRIFT WAS ONE OF THEM. ODOR WAS ANOTHER. WATER QUALITY IMPACTS, THE OTHER ISSUES THAT YOU MENTIONED. A LOT OF WHAT WE LEARNED FROM DRIFT HAD BEEN ALREADY RESEARCHED FOR THER DRIFT PURPOSES. FOR REGULAR WATER IRRIGATION PURPOSES AND FOR OTHER CHEMICALS THAT ARE APPLIED THROUGH THOSE KINDS OF SYSTEMS, ESPECIALLY PESTICIDES, OTHER KINDS OF NUTRIENTS AND AG CHEMICALS. SO WE LOOKED AT WHAT DO WE KNOW ABOUT DRIFT BASED ON THOSE STUDIES AND HOW MIGHT THAT APPLY TO MANURE APPLICATIONS AND THE DRIFT IMPACT THERE. MANURE THAT WOULD BE PUT THROUGH AN IRRIGATION SYSTEM IS VERY MUCH LIKE WATER. IT’S A VERY LOW SOLIDS CONTENT LIQUID. AND ONE THING THAT WE LEARNED, FOR EXAMPLE, WAS TO MINIMIZE DRIFT WE WOULD WANT TO MAXIMIZE THE DROPLET SIZE OF THE MANURE THAT COMES OUT OF WHATEVER SYSTEM IS BEING USED. AND THERE ARE NOZZLES DESIGNED TO HAVE MORE COURSE OR VERY COURSE KINDS OF LARGE DROPLETS TO MINIMIZE DRIFT.

ZAC SCHULTZ:

ANOTHER BIG QUESTION WAS THE PATHOGEN RISK. MANURE CAN CONTAIN PATHOGENS THAT COULD MAKE PEOPLE SICK IF THEY CAME INTO CONTACT WITH IT. WHAT IS THE LIKELIHOOD OF SOMEONE 500 TO 1,000 FEET AWAY FROM THIS PRACTICE GETTING HIT AND THEN BECOMING SICK?

KEN GENSKOW:

IT’S A DIFFICULT QUESTION TO ANSWER. WHAT WE DID — AND I’LL JUST SAY TO CLARIFY, THE WORK GROUP INCLUDED 18 PEOPLE. IT WAS A DIVERSE SET OF PERSPECTIVES LOOKING AT THIS ISSUE. IT INCLUDED REPRESENTATIVES FROM THE DEPARTMENT OF HEALTH SERVICES, THE STATE AGENCY FROM DEPARTMENT OF NATURAL RESOURCES, AS WELL AS LOCAL PUBLIC HEALTH OFFICIALS. AND WE WERE LOOKING AT A VARIETY OF THINGS. SEPARATE FROM THAT, THERE WAS A STUDY THAT INCLUDED SOME OF THE WORKER MEMBERS LOOKING SPECIFICALLY AT PATHOGEN DRIFT AND WHAT THE HEALTH RISK MIGHT BE ASSOCIATED WITH THAT. THEY WERE ABLE TO DO MEASUREMENTS AND QUANTIFY RISK AT DIFFERENT LEVELS. BUT IT’S HARD TO SAY WHAT ANY SINGLE INDIVIDUAL WOULD EXPERIENCE. WHAT THEY FOUND WAS THAT AT 500 FEET OR LOWER, IN THE MOST — WELL, DEPENDING ON HOW CONSERVATIVE SOME OF THEIR ASSUMPTIONS WERE, THE RISK WOULD BE LESS THAN THAT THAT’S ACCEPTABLE FOR PUBLIC DRINKING WATER SYSTEMS, FOR EXAMPLE.

ZAC SCHULTZ:

THERE ARE A NUMBER OF RECOMMENDATIONS IN THIS REPORT. THERE’S A LOT OF IDEAS THAT ARE SIMILAR TO WHAT IS ALREADY BEING ENFORCED BY THE DNR IN SOME AREAS. DO YOU EXPECT STATE LEGISLATORS TO GET INVOLVED OR PERHAPS AT THE COUNTY LEVEL TO PUT SOME OF THIS INTO ORDINANCES OR LAW?

KEN GENSKOW:

MOST OF THE CONVERSATIONS HAVE HAPPENED AT THE LOCAL LEVEL SO FAR. THE LEVEL OF TOWN GOVERNMENT OR COUNTY GOVERNMENT. AND I THINK THAT’S WHERE MOST OF THE ACTION WILL CONTINUE TO HAPPEN. WE WROTE THIS REPORT WITH THE INTENTION OF THOSE AUDIENCES BEING ABLE TO USE THIS INFORMATION IN THOSE LOCAL CONVERSATION. THOSE INTERESTED IN IT, THOSE CONCERNED ABOUT IT. SO I THINK THAT’S WHERE MOST OF THE ACTIVITY WILL HAPPEN. A NUMBER OF TOWNS AND COUNTIES HAVE ALREADY TAKEN ACTION ON THAT.

ZAC SCHULTZ:

THANK YOU FOR YOUR TIME. THAT’S ALL WE HAVE. LOOK FORWARD TO IT.

KEN GENSKOW:

THANK YOU.