Forage Density Determination

Field cover is an important consideration for application of man
ure. Vegetation works to reduce overland flow, help water infiltrate into the soil, reduce surface compaction, and take up nutrients. Application to bare or sparsely vegetated fields (<50% cover) will have a much greater risk of runoff than dense fields. Only established, dense (>75% cover) grass or cover/relay crops grown for harvest are effective at reducing the runoff potential from fields. Fields with sparse vegetation (<50% cover) should not be applied to during the wet season.
  • Grass Forage Density
  • Cover Crop Forage Density

Grass Field Forage Density

The following pictures show differing forage densities. You can determine your forage density visually, or by grid evaluation. To conduct a grid evaluation, frame out a representative 1 foot by 1 foot block of your field. Determine how much (%) of the area is not covered by forage (i.e., bare ground) and subtract from 100%. Repeat in at least three other locations to get an average for the field.

Forage density less than 50% is not permitted for application due to the elevated potential for runoff.


100% Density


90% Density


80% Density


70% Density


60% Density


<50% Density



Saturated (no application)

Cover Crop Forage Density

Manure can be applied to a cover crop field in the spring if it is agronomic and that crop is going to be harvested. Cover crops that will be killed or tilled under may not be applied to as it is not agronomic. 

Cover is dense enough to evaluate spring application on a cover crop that will be harvested.

Cover is not dense enough for manure application. Application would not be permitted on these fields prior to March 15, at which time injection is recommended prior to corn planting.


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