Planning, Preparing, and Planting Minnesota Biochar Test Gardens (Part 3)

In two previous blog posts, I gave an overview of what we are seeking to learn through this biochar research project, and how we chose and added biochar to the test gardens.  Early in the planning, we first needed to find three locations to implement the gardens.  Next Extension Master Gardener volunteers needed to be recruited and trained about the project.

As part of this CenUSA Bioenergy project, Master Gardener volunteers completed a specialized training to learn about biochar and the CenUSA grant that supports it.  Each of the three sites in Minnesota has one or two team leaders and approximately 10 other volunteers per site.  Master Gardeners were involved in many facets of the research including planting and maintaining gardens, collecting data measurements and harvesting crops as needed.  They were asked to share their observations at the State or County fairs, horticulture field days or other community events.

How We Selected the Minnesota Biochar Test Garden Sites

All of the sites in Minnesota and Iowa needed to be identical in size because the same number of crops needed to be grown at each site. All of the gardens are 1000 sq ft and each site is divided into three plots of 300 sq ft.  Each site has a control plot with no biochar added, treatment 1 has 150 pounds of biochar and treatment 2 has 300 pounds of biochar.

It was also important to have locations with different types of soil to see how the biochar would react with the crops.  All three sites in Minnesota had to be developed from its original condition, meaning two of them had turf that needed to be removed and one was actually in an area filled with underbrush, small trees and weeds.  Soil tests were also conducted at each site and the gardens were amended with fertilizer based on the recommendations of the soil tests.

Biochar Test Gardens and MN Landscape Arboretum
Biochar Test Gardens at the MN Landscape Arboretum

Each site had its own unique issues with watering.  While we tried to replicate what a typical homeowner would do,the Arboretum site became the most labor intensive.  There was a sprinkler head close by, but the Master Gardener volunteers needed to run hoses and water by hand. The other two sites had irrigation that was scheduled by timers.

1) The Minnesota Landscape Arboretum Test Garden

Selecting the Arboretum as a site for this project was a no-brainer.  The Arboretum gets well over a quarter million visitors per year.  It was a great location to showcase this research project.  A couple of site locations at the Arboretum were considered.  Ultimately, the final decision was made and the biochar test garden is located on the 3-mile drive next to the Dahlia Trial Gardens.

Thankfully, the Arboretum staff removed the sod and tilled the soil to loosen it before we began.  One of our fabulous Master Gardener volunteers also offered to install deer proof fencing…a must have.  My colleague Julie, and I, amended the soil with fertilizer and biochar on May 18th.  It also happened to be a 97 degree day with high humidity to-boot. Ugh! Our soil test recommended that we use a nitrogen-only fertilizer with a ratio of 23-0-0.  The soil at the Arboretum site is loamy clay – not too terrible to work in.  The biochar arrived in 50 pound bags, so we just opened the end of the bags and slowly dragged the biochar over the areas of the garden where we needed it, and then my colleague tilled the biochar and the nitrogen fertilizer into the soil at the same time.

2) The St. Paul Campus Test Garden

The garden at the St. Paul Campus located at the intersections of Gortner and Folwell Avenues, was another great location. It is in close proximity to the Display and Trial Gardens and is visited regularly by students, staff, faculty and visitors.   The actual site was a former low-mow turf trial plot.  The sod was not removed but instead was tilled into the soil, which in hindsight we should have asked that it be removed.  The soil also has a fair amount of clay in it.  Because this site was irrigated regularly and wet when we started, it was challenging to work in.

The soil test in this garden also recommended a nitrogen only fertilizer of 23-0-0, the same as the Arboretum site.  The tiller got its workout that morning when trying to mix in the biochar and the fertilizer in the lumpy wet clay mess.  Deer isn’t a problem at this site, but rabbits are so a short fence was installed.

Biochar Test Gardens in St. Paul, MN

3) Bunker Hills Park in Andover Test Garden

The Andover site was a last minute surprise and a very exciting prospect. We originally had a site selected at UMore Park in Dakota County which is on the south end of the Twin Cities.  A new mining operation expanded in that area and there was uncertainty about whether the biochar research garden could remain in the same location for four years.

All along I had my eyes on the Regional and County Extension office location in the Anoka County Bunker Hills Park in Andover as a potential site for the biochar project.  The reason I was hoping for this site is because it is on the north end of the Twin Cities and in the middle of the Anoka sand plain.  Since biochar is known to have positive benefits in nutrient depleted soils, this sandy site was a good option. When I explained the issues about the Dakota County site to the Anoka County Parks Department staff, they were more than willing to accommodate the needs of the project.  Not only did they bring in a Bobcat and clear out an existing area of small trees and underbrush, they also enhanced their irrigation system to allow us to set a sprinkler that was set-up on a timer.  In addition, they brought in a couple of loads of mulch to help beautify and complete the project.  Since this garden is in a large suburban park, a deer fence needed to be constructed there as well.

Biochar Test Gardens at Andover
Biochar Test Gardens at Andover

The soil test recommended a well-rounded fertilizer with a 10-10-10 ratio. One variable in this garden, that presumably will affect the research, and that isn’t present in the other sites, is that one end of the garden gets shade in the morning hours, but full sun the rest of the day. Because of this, it was anticipated that crops would not get as much heat stress as the rest of the garden and the water would not evaporate as quickly, so there was a good chance those plants would be healthier overall from the other two treatments.

What’s next?

We learned a lot the first year (2012) about the sites themselves, how the biochar interacted with the soils, and how data is best collected.  Next week, we’ll share what we learned from our 2012 data collection and research with the CenUSA Bioenergy project.

by Lynne Davenport-Hagen
University of Minnesota Extension
Master Gardener Program Coordinator-Anoka County
CenUSA Biochar Research & Display Garden Project Coordinator-USDA NIFA Grant

“The CenUSA Bioenergy project is supported by Agriculture and Food Research Initiative Competitive Grant No. 2011-68005-30411 from the National Institute of Food and Agriculture.”