Putting manure in its place
By Janet Kubat Willette
jkubat@agrinews.com
Date Modified: 02/23/2012 9:21 AM
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DODGE CENTER, Minn. — Proper application of manure means dollars in farmers' pockets.
The nutrients in manure result in yield boosts for crops, but when manure application goes wrong there are often environmental side effects.
The dos and don'ts of manure application were discussed at a Current Issues Facing Feedlot Operators meeting Feb. 9 in Dodge Center. The meeting was repeated in Faribault that evening and will be repeated in Albert Lea from 1 p.m. to 3:30 p.m. Feb. 27.
More than 35 people attended the Dodge Center meeting.
Steve Schmidt from the Minnesota Pollution Control Agency reminded producers that when applying manure in winter, state rules require a 300 feet setback from sensitive features.
Producers who have more than 300 animal units need to sample manure every four years. The soil that receives manure from facilities with more than 300 animal units also needs to be tested at least once every four years for phosphorus.
The manure testing must be done by a laboratory certified by the Minnesota Department of Agriculture or by MPCA approved on-farm sampling. County feedlot officers likely have a list of approved laboratories or can provide advice on on-farm sampling.
Feedlot owners who sell their manure aren't off the hook if something goes wrong.
"As a feedlot owner, you're responsible for your manure and applying it properly," Schmidt said.
It's also important for feedlot owners and custom haulers to keep records of manure applications, he said. It shows the public that producers are applying their manure in an environmentally sound manner. The records can also be used by the producer for planning for future year's applications. It's important to write the records down. He's been to a number of farms where the records are in the farmer's head.
Records are required for feedlots of 100 animal units or more. There are sample records on the Minnesota Pollution Control Agency website.
University of Minnesota regional Extension educator Brad Carlson talked about the benefit of using Instinct nitrogen stabilizer when applying manure and delaying manure application. The closer the manure is applied to the time of planting, the more efficient the use of nitrogen, he said.
Studies have also shown using Instinct may pay for itself. In University of Minnesota studies done in 2010, adding Instinct to fall-applied swine manure increased corn grain yields 10 to 12 bushels per acre.
Tim Radatz from Discovery Farms Minnesota talked about the best time to apply manure. He relied on data from Wisconsin Discovery Farms as Minnesota doesn't have enough data yet.
The best time to apply manure is when it's going to stay in the field when it's spread or applied, Radatz said. Weather and field conditions determine what happens to the manure once it's applied.
Avoid spreading manure on melting snow or when it's raining and the ground is frozen. Also, avoid applying manure when soil is saturated or the soil moisture level is high.
The optimum time for applying manure may vary from year to year and by site. The key is to increase the time period between application and a runoff event, Radatz said. The time gives the nutrients in manure time to bind with soil particles.
"Manure management is not an exact science," he said.
The Wisconsin agriculture department has recently developed a risk index for manure application. The index was developed based on modeling and puts entire eight-digit watersheds in high, medium or low risk categories for manure application. The tool is very new, Radatz said.
The take home for farmers and custom manure applicators is to know the weather forecast, know soil conditions and use those to determine the risk for manure runoff.
If forced to apply during critical periods, apply on fields that are located away from sensitive features and on fields with as low a slope as possible. Stockpiling manure may be another option.