One of the highlights (for dirt nerds like me, anyways!) at this year's New York State Cut Flower Growers Conference was a presentation on soil health in high tunnels. Cornell University researcher Judson Reid shared data collected from farms and the surprising trends he found.
As farmers and growers, it is our tendency to worry often about "feeding the soil." We know that our plants take nutrients away every season, and that we need to replace those nutrients. However, along with all of that nitrogen we're adding come other elements: phosphorus and calcium can be a problem for us.
In greenhouse high tunnel production, where the soil is not left to the sleep with the weather during the winter, certain elements build up over time. Phosphorus and calcium levels can grow exponentially. For New York growers, calcium is also naturally occurring in much of our well water supplies. We are certainly watering with calcium every time we turn the irrigation system on here at our own place. And, as calcium goes up in the soil, nitrogen become less available to our plants. Eeek!
(Potassium and Manganese fall into a different category in high tunnel soil health. They actually slow in appreciation. Responsible farmers should look into supplementing their high tunnel soil with more of them, if needed.)
At almost every farm that the Cornell researchers visited, there was too much calcium and phosphorus and decreasing potassium and manganese in high tunnel soil samples.
What can you do?
First- spend $50 to have your high tunnel (and field) soil tested. Find out what is going on. It is worth it.
Second- if possible, irrigate with collected rain water or find out how to improve your calcium-rich water (if that is a problem for you).
Third- Use low phosphorus and low calcium pre-plant nitrogen sources like Alfalfa meal, blood meal, composted plant material, feather meal, and soybean meal. Chilean Nitrate, blood meal, Nature's Source 3-1-1, Pure Protein Dry, Verdanta PL-2, Ferti-Nitro Plus, Wisegeranic are in-season low nitrogen and low calcium options. Avoid using fish emulsion, bone meal, and composted animal manure in high tunnels.
Fourth- Avoid using gypsum to improve the tilth of high tunnel soil-- it is high in calcium.
Adding a high tunnel to your farm? Start off right with these tips from Judson:
Choose a location that:
- has little or no shade
- is near a water source or frost-proof hydrant
- has drive-up access for deliveries, if possible
- has a North-South orientation
- is visible from the road (to help people find your farm)
- HAS GOOD DRAINAGE (all of that run-off from the plastic will need to go somewhere and you don't want it running down and puddling around you crops!)
*And lastly- remember that in New York State, high tunnels are considered farming equipment, not taxable property. They are 'temporary greenhouses' and cannot be assessed for tax purposes.
For more information on high tunnel research and for assistance with high tunnel grant programs, contact your local extension office. Have a comment or question to share? Please use the comment window below. We'll do our best to help. We don't have a high tunnel ourselves yet, but we hope that all these things we're learning will help us figure out how to do it right when the time comes! Happy holidays.