Planting green into cover crops

Posted on Posted in News, Newsletters

Four PPF members test conservation practices 

By Barry Bubolz, USDA-Natural Resources Conservation Service Area Great Lakes Restoration Initiative coordinator 

Some farmers have heard of the term “planting green.” However, many are unaware of the planting method and some have predetermined that it’s “crazy and can’t work this far north!”   

Planting green refers to no-till planting into green and actively growing cover crops. This contrasts with past no-till practices, when no-till planting occurs into dead residues from the past year or cover crops that have been previously terminated for several weeks. 

Fortunately, farmers in Door and Kewaunee counties have four USDA Natural Resources Conservation Service Demonstration Farms funded through the Great Lakes Restoration Initiative that took the challenge this past year to plant green and share what they learned.  

The four farms, like many others in the region, have grown in their comfort level of utilizing cover crops and have seen the benefits over the past several years. Benefits associated with cover crops are well documented in their ability to decrease erosion, scavenge residual nutrients, increase infiltration and increase organic matter levels. However, when planting green, the benefits become much greater. 

Augustian Farms and Deer Run Dairy both planted winter cereal rye as a cover crop in fall 2018, following the harvest of corn silageAugustian Farms even planted rye after fourth crop alfalfa that was fallterminated with plans to plant corn this past spring.   

Not shocking to anyone, this spring turned out to be anything but normal. Cool temperatures and ample moisture caused some fields to not be planted and many to be delayed and then planted into less than desirable seedbeds. Several days of dry weather in a row this spring to allow for tillage and then planting was very uncommon, however, both farms were able to plant green into their winter rye cover crops, which continued to grow under spring conditions. Winter rye that grew during the wet spring continued to take up water from the soil and provided a firm foundation due to the increased soil structure, allowing for corn planting.   

The winter cereal rye on both farms was terminated after planting. Termination after planting is a major key to success in planting greenCorn planters running through cover crops that have started to die off (starting to turn yellow) tend to wrap and plug up. When planting into the green vegetation of a growing cover crop, the planter can more easily cut and slide throughIn addition, the growing winter rye helped to remove excess moisture from the seed bed and allowed the planter to achieve to even stands of corn.  

Deer Run Dairy corn that was planted green showing a nice evenly growing stand on July 8.

Additional biomass achieved from planting green was dramatically increased due to the delayed termination of the winter rye. Several Augustian Farms field biomass samples were taken by Nick Guillette of Ag Source Labs and analazied for biomass. The results were dramatic, with samples showing 7,000 to 9,000 pounds of dry matter per acre. This did not account for the belowground root biomass that wasn’t measured!  

This mat of rye residue remained between the rows as we entered September, however it is being greatly reduced by the thriving soil ecoystem utlizing this material to build soil structure, increase organic matter, feed beneficial soil micobes and cycle nutrients. 

As you may have guessed by now, planting green does require changing some management techniques and practices. Aside from patience and not being the very first to plant in the spring, a big change is nitrogen management.  

Winter rye, as shown, can produce large amounts of biomass. As rye matures, the carbon to nitrogen ratio (C:N) increases. A wellbalanced soil allowing for microbes to release Nitrogen (N) and other nutrients is optimal at a C:N ratio of 24:1. Depending on the maturity of the cover crops when terminated, the residue may have a C:N ratio that is much higher, resulting in a “tie up” of nitrogen. To achieve optimal corn yields, we know that nitrogen is crucial at the early stages of growth, therefore when planting green into cover crops more of your nitrogen budget is needed early on to overcome any N that is being tied up by the additional carbon in the system from  cover crops. Utilizing resources such as Pre-Plant Nitrogen and Pre-Side Dress Nitrogen tests can enable producers to determine nitrogen needs, as well as working with your agronomist or conservation professional. 

With continued rain at corn silage harvest, farmers once again faced muddy fields, resulting in costly compaction. Like last year, fields that utilized cover crops and notill planting had greater soil structure and better harvesting conditions. With the reductions in field work, time, fuel and improved harvesting conditions, more farmers are seeing economic advantages of implementing a soil health system.   

A late corn silage harvest will cause cover crop planting to be delayed this fall. Winter rye is the best choice for late planted cover crops. Rye will germinate at temperatures as low as 33 degrees and will be the first to start growing the following spring.   

While this year has been hard and challenging, we have learned much on the Demo Farms. Planting green into living cover crops can be successful and will be a management tool that should be used to build soils and protect water quality in northeastern Wisconsin.   

If you are interested in finding out more about soil health, cover crops and the financial and technical assistance NRCS provides to farmers, visit wi.nrcs.usda.gov and make an appointment at your local USDA Service Center