Season Extension of Hay-Mulched Potatoes Using High Tunnels
We have completed the first half of the project. The high tunnel for the first half was ordered in July and delivered in late August. We erected it in September after preparing the site, and planted certified organic ‘Red Thumb’ seed potatoes while the soil temperature was still about 65 degrees F. We hayed over the seed potatoes, leaving out the drip tape as we chose instead to add moisture with portable sprinklers as needed. (The soil and hay received several downpours before the high tunnel plastic was put on). We installed soil thermometers and have kept weekly soil temperature readings and charted the changes in the seed potatoes.
We also harvested our comparison potatoes, the same fingerling variety from the same soil area, on the day we planted in the high tunnel. A few pounds of these potatoes were refrigerated at 41 degrees F to be available for comparison analysis of nutrients etc.
We had expected the seed to sprout in October; it did not. The weather after planting turned unseasonably cold and soul temperature, even under the thermal blanket of hay, quickly fell to 49 degrees F and stayed there throughout October and November. Outdoor soil temps in the adjacent plots went down to 28 degrees F over the same period. We put plastic on the high tunnel earlier than planned in the hope that higher daytime air temps (average daily high of 88 degrees F) inside the tunnel would heat the surface soil. The hay proved to be an excellent thermal blanket, keeping the soil at 1 inch depths at 49 degrees F. As of January 24, inside soil temps have declined to 10 degrees F – perfect for storing potatoes, but not for growing them. We do not expect any plant growth until the ground begins to warm in the spring. It will be interesting to see if they hay makes the soil in the enclosed high tunnel warm more slowly than that outside!
What we have learned is that we are prone to under-estimating the difference in climate between the cloudy Great Lakes bioregion and our previous land in SE Ohio. The soil got colder much, much more quickly than we anticipated, albeit partly due to the unusual weather. We do have a plan for repeating this portion of the experiment next fall using earlier planting dates, as described in the work plan, below.
WORK PLAN FOR 2008
We have our second high tunnel ready to be ordered, and we will build it as soon as we receive the second grant payment. We have already ordered the necessary seed and have developed the site. The late winter work plan is:
February – construct second high tunnel, and enclose, put down soil warming green plastic mulch, and track temperatures.
Feb/March – plant and hay over when soil temps reach 60 degrees F and track plant growth and record harvest dates/yields.
We will repeat the first phase of the project in fall 2008. Our high tunnels are mobile, so we will move one to an adjacent plot and plant half on August 1 and half on September 1 to increase the possibility that we will have producing plants when we attempt to make the plants go dormant in late fall. We should be able to report out on the redone portion of the experiment in February of 2009, thus meeting the final report requirement, since we think we will have important additional data and insights.
We had a field day in August 2007 as part of the Mohican Valley Farm Fest which we helped found in 2006. Unfortunately we were rained out. Our future plans include a scheduled Ohio Ecological Food & Farm Association (OEFFA) field day in 2008, and we will be presenting results of our nutritional analyses at the 2009 OEFFA annual conference. We also hope to have an article in Farming Magazine in 2008 and one of us, John, will write about the project in his weekly column in the Ag section of the Wooster Daily Record. We expect that Dr. Kleinhenz will invite us to present at a 2009 OARDC high tunnels workshop.