Keeping manure out of tile lines
Farmers spread manure over fields to take advantage of the nutrients. However, there should be precautions to prevent it from leaching into tile drains through preferential flow paths, which are tunnels and cracks in the soil.
Matt Ruark is an associate professor of nutrient management at the University of Wisconsin. He says there are various ways to apply manure, but its consistency can make a difference in where it goes.
" If your manure is 5% solids or more, that’s going to be enough solid material to help maybe clog up some of those flow paths in the soil. But if you’re using separated liquid manure, you don’t have that solid content, you’re going to see often less than 2% solids," says Ruark. "There you’re going to have a situation where you’re going to have a little more risk of the manure moving through preferential pathways, and then you want to think about how then you’re applying that manure."
The greater the application rate, the greater volume of water that is added to the soil, which increases the risk of manure getting into the tile drains. This also means that the right soil moisture at the time of application is an important factor.
"So, if your soil is saturated, that also means that all of those pores are connected with water," says Ruark. "That means that manure can easily move with the water down the tile drains. But, if your soil is too dry and you apply, your soil may have developed some cracking in it, then those pores may have opened up a little bit more, and then would be more likely to move especially if followed by a rainfall event."
Ruark advises waiting on manure application if rain is expected within a couple of days.