Cover crop varieties provide nutrients at different times throughout growing season

IRON RIDGE – “If you were running a big company you would not want every employee to have the same skill sets,” crop consultant Byron Blank said.  “In the field, every plant requires different things from the soil. Each plant pulls out different nutrients from the soil.”

Blank addressed a group of farmers on the benefits of diversity in cover crop mixes during the Dodge County Land and Water Conservation Department Field Day last week at K & S Farms, Iron Ridge.

Blank explained that some plants provide nutrients early in the season while others contribute later on, thus the decaying cover crop constantly feeds the new crop  nutrients throughout the growing season.

“Anything in a cover crop has a purpose,” he said. “Legumes provide nitrogen for next year’s crop. That’s good if you are planting corn but if you are planting soybeans you will want legumes in your cover mix.”

The test strips on the Miller farm included a variety of mixes, with Blank explaining the benefits of each species. The covers were established following the winter wheat harvest in mid-summer. Before that, the field had been planted in alfalfa.

One colorful strip featured 12 varieties including a some clover, sunflowers, tillage radish, and sorghum sudan. Some of those species such as the sorghum sudan will decompose quickly with the first frost. Others will take a little longer while some survive the winter and need to be killed off the following spring.

Kevin Miller shared his experience no-tilling into a cover mixture that included airy vetch. 

"The vetch was tall but planting into it worked good. I set the planter at 3 inches and it cut into the mat real well,” Miller said.

Miller suggests that in a dry spring it might be best to terminate the crop earlier so it will be easier for the planter to penetrate the mat.

He also cautioned that hairy vetch has tough long stems and that could wrap around the row cleaners in a planter if the plant is not partially decomposed before planting into it.

Blank described different plants that are a part of cover crop mixes, noting that each farm is different and a mix that works on one farm may not be the best choice for another.

He stressed that it is important for farmers to consider the goals of growing nutrients, loosening soil and preventing weeds.

“Consider your planter set-up and how much of a mat it can cut through in spring,” he said. “What crop do you want to plant into it? What nutrients do you need according to your soil tests?”

As fertilizer and fuel prices continue to rise, Blank stressed the importance of soil testing and providing only what is needed and can be utilized.

“We have turned this field into a solar panel," said Blank, pointing to the field planted with a 12-way mix including flowering plants like sunflowers. "The plants in this field are pulling energy from the sun and storing it in the plant so it will be available next year.”

Soil moisture conditions can also impact the nutrient output of plants,

“If you only put in cereal rye as a cover, it was so dry this spring that the nutrients didn’t release as quickly because it took longer for the plants to decompose," Blank said. "By having a mixture of species in the cover, some decompose earlier so they are available early and the nutrients from the rye were available later.”

The Healthy Soils- Healthy Water group from Dodge County will evaluate the nutrients on farms utilizing a variety of cover crops to calculate the dollar value of the fertilizer savings from the cover. The group also provides funding for farmers who would like to try cover crops.