By Justin Petrosino, Darke Ag and Natural Resources Extension educator
The other day I noticed here in the office a little drip of water coming from the ceiling. The cause was ice thawing on the flat roof. Water melting from underneath that frozen layer of snow and ice was percolating its way into my office.
The water from above that snow and ice layer is running off to the gutter and out into the parking lot.
Out in our fields much of the ground underneath that layer of snow and ice is thawed. It is taking up a portion of that snowmelt just like our porous roof here in the office. However some snowmelt on top of that frozen snow pack is running off. With the heavy infiltration of water some of those fields have become saturated and we are seeing runoff. We are no more than a few days into the thaw and reports of manure moving off the field and into the creek are already coming in. A recent check has also revealed that stream flows are up.
Monday the Chickasaw Creek was flowing around 2 cubic feet per second, a check today shows that flow is up to 46 cubic feet per second. Needless to say we are at a high potential for manure runoff.
Since Grand Lake hit the news last year we are under the spotlight. The Soil & Water Conservation District office in Darke County has already received calls from concerned citizens about winter applications. Other SWCD offices in the state are reporting manure complaints are at an all time high. To top it all off there is already a dairy runoff event up on 49 in the Wabash watershed in the news. The consensus is non-farm citizens are watching, whether we like it or not.
Under this new scrutiny we need to be more diligent in making sure our applications don’t make the news. A way to avoid this is to use some manure best management practices (BMP).
For BMPs under conditions that give us a high runoff potential we can at look the Natural Resources Conservation Service Conservation Practice Standard Waste Utilization – 633. If you have never read it before you might want to become familiar with it: http://www.ohleap.org/FactSheets/1004/OH633_Waste_Util_June2003.pdf.
A good, if mildly revised, portion of this document has essentially become the law of the land for the Grand Lake Watershed. There is a good chance that once it has been in play in Grand Lake for some time we may see it or some form of it become law statewide for everyone.
With high phosphorus loss potential, whether it be application to frozen, snow covered ground, application prior to a period of heavy rain, or to a phosphorus rich soil, observing setbacks can help limit runoff. Just as a review some of the most common setback distances are 100 feet to ponds, streams ditches, and surface inlets to tile. For a good reference on setback distance take a look at the table on page 5 of the 633 practice. Some distances can be decreased if a perennial vegetative strip is in place to protect the
sensitive area. The strip acts as a barrier to slow water, which allows suspended particles to drop. Heavy runoff events like a major storm can overwhelm the strip and runoff may still occur. So watching the weather before an application can be crucial.
Two other variables can impact setback distance. If the application occurs to frozen or snow covered soils the setbacks to sensitive areas are increased to 200 feet unless a vegetative strip is used. Setbacks can be essentially eliminated for some sensitive areas if manure is injected or incorporated within 24 hours. However if a heavy rainfall event occurs within those 24 hours there is a good chance runoff will occur.
Another good BMP is to apply manure to a field with a green crop (cover or cash) or high levels of residue. The crops and residue can reduce rainfall impact and slow water flow, reducing the erosive power of the water. In season application of manure as a side dress or to wheat after green-up is an option.
Glen Arnold up in Putnam County has some great research on the AgCrops Web site related to this. He also has an ongoing experiment with draglining manure onto wheat and so far the results are promising. To view some of his research take a look at:
As you scroll through research on corn and wheat Glen will have a few articles on manure listed. If you haven’t read 633 before take a few minutes and glance through it. There are some very good common sense practices listed and as government documents
go it isn’t a terrible read. There is good information on calculating application rates. It also has the Robert Mullen, Extension Soil Fertility Specialist, stamp of approval. So remember watch your setbacks and mind your standpipes. They are a direct route to your tile outlet and to a creek.
Additional points to consider from Jon Rausch, Union County AgNR & State
Manure Specialist are that Best Professional Judgment (BPJ) would suggest that the required setback/buffer identified in 633 may not be sufficient in areas of concentrated flow. In some cases runoff can overwhelm these setbacks, thus more may be necessary.
These are recommendations that require individual/personal knowledge of the situation and farmers should focus on what is necessary to keep manure/nutrients out of the water not just following the recommendations or the rule. I think we are often too prescriptive in possible solutions and less focused on the desired outcome — improved water quality.
If we focus on keeping manure out of the water, less concern could be placed on how that is accomplished, with a little BPJ.