Manure in a drought year
Thinking of applying manure this fall? There are some unique challenges this year, courtesy Mother Nature's stinginess with rainfall through this last growing season.
"The extended period of dry weather has caused low water flow in many Iowa streams," says Angela Rieck-Hinz, coordinator of the Iowa Manure Management Action Group and Iowa Satate University Extension program specialist. "Low flow coupled with high temperatures has put a strain on aquatic life in many Iowa streams and can cause the streams to be highly vulnerable to any nutrients that may reach it."
These conditions put as premium on knowing your surroundings and making sure your application equipment's in good shape and set up correctly. First, check your soils. The drought may have caused cracking in your soils, but that doesn't mean you need to automatically till before you put down manure.
"Tillage prior to manure or fall fertilizer application may actually shatter soils such that no structure will remain and intense rainfall may cause surface crusting that reduces water infiltration and could cause runoff of nutrients," Rieck-Hinz says.
Once you know you have a wide enough weather window to apply manure, it's important to calibrate your equipment so you're putting down the right amount, staying within state and federal rules on manure application and putting it down as efficiently as you can. This requires finding out your total equipment weight, manure density and spray pattern. Then, complete a worksheet like the one by Iowa State University Extension ag engineer Kapil Arora to determine your application rate.
Once you've got your application rate nailed down and changing in-field speed doesn't do enough to adjust that rate on the fly, consider a flow control module, Arora says.
"Flow controls should be considered to achieve maximum nutrient efficiency from liquid manure," he says. "However, the distribution of liquids uniformly across the tool bar should be considered when applying liquid manure."