A Day with Blackberry Farm, Producing Organic Heirloom Vegetables Without Tilling
Blackberry Farm is a 4,200-acre luxury hotel resort located in Walland, Tennessee, near the Great Smoky Mountains National Park. Blackberry Farm wasbuilt in 1939 and has evolved into the luxury resort in Blount County that it is today. My interest in Blackberry Farm began about a year ago in September, 2016. I was asked by Blount County Soil Conservation District's Conservation Director, Erich Henry to join him to work with Michael Washburn, Garden Manager at Blackberry Farm. In 2015, Michael became the garden manager. The garden consists of approximately 3 acres. The garden produces heirloom vegetables that are served at the resort's two kitchens. There is close correlation and team chemistry between the gardeners and the chefs.
I could tell when I first met Michael Washburn that he was a trained agronomist. He also had experience in restaurants, so again you could see a close correlation of producing and preparing the food. The garden produces food organically. They are not organic certified, but they grow food without chemicals and work on improving their most important natural resource, their soil. Some areas and especially one of the lower fields that had been regularly tilled in the past, were of particular interest. Here soil structure was still lacking. Michael had already followed some great conservation practices. They were making their own compost and applying it regularly. Michael had done research on biochar and constructed an outdoor stove to burn wood and collect the char. You can see the black char in the rows of vegetables. Compost is an active carbon source that feed soil biology. Biochar is a stable carbon source. Many of the chemical properties of soil from humus can be improved by adding bio-char. For background, go to Terra preta on Wikipedia, Terra preta is Portuguese for black soils. Michael is emulating Terra preta by adding bio-char.
While soil practices of the past had lacked ample organic matter inputs, the main problem seemed to be frequent tilling of the soil. Tillage, especially a rototiller, destroys soil aggregates. This exacerbates decomposition of soil carbon (soil organic matter) by adding oxygen to the soil. In addition, it exposes the choice food for soil microbes, glomalin, a sugar-protein important to helping glue soil aggregates together. When bacteria populations explode due to the oxygen, they can easily consume the glomalin (active carbon). This can cause soil structure to degrade, which results in a harder soil that infiltrates less water. When soil is no longer covered with plant material, rainfall hits the exposed soil surface at roughly 30 miles per hour and the soil begins to erode. The soil also seals (soil particles fills the void spaces) and runoff and erosion continues as long the soil is left unprotected. As soil productivity decreases, so does soil functions such as water infiltration and nutrient cycling. As soil organic matter decreases, so does soil productivity, structure support for plants, and the soil's ability to filter and buffer.
We discussed some soil health principles and talked about multi species cover crops. This was not new to them so we were able to quickly devise a good combination based on observed soil conditions. I recommended a winter cover cocktail mix to Michael, consisting of cereal rye, buckwheat, oats, crimson clover, Daikon radishes, turnips, wheat, Austrian Winter Peas, Phacilia and others. The grasses with their fibrous roots will aid in erosion protection and add carbon to the soil. The brassicas will penetrate deeply into soil bringing up nutrients. The legumes fix nitrogen for the plants. The green plants growing continuously provide carbon through photosynthesis. The plant roots leak approximately 30% of their sugars produced by photosynthesis into the soil. This is like asking soil biology to come to a smorgasbord. Also by diversifying the mix, the quality and quantity of soil biology increase. This equates to better functioning soil. Michael's objective was to improve soil structure and water infiltration. He also wanted to improve nutrient cycling. Increasing soil carbon and improving the soil food web will help him in both areas as well as making his soil more productive. As Michael adds biochar and uses cover crops, and quits tilling, soil carbon will increase and buffer the soil from pH decreases. The biochar additions also have a liming effect, therefore pH is buffered and will increase. This reduces the need for lime.
I visited the farm again September 14, 2017. Wow, what a difference in a year. Michael had grown many combinations of covers. Various hoes, including a wheel hoe were the only tools being used to control weeds. Better yet, some “weeds” were allowed to stay while others were simply pulled by hand. It was a great compromise of no-till and hand labor to handle the weeds. Most of the cover crops had been knocked down with the use of a weed eater. Cover cropping with rye and wheat chokes out early germinating weeds. The hoes and weed eater can handle the rest.
What was astonishing is the change in soil structure in one year. Last year, the soil in a particular area that had been regularly tilled was lacking in soil structure. This year, there were numerous granular oval-like aggregates ranging from very small to decent size aggregates. Aggregates provide pore space or voids between soil particles. It is like putting marbles into a jar. Water flows between marbles unimpeded to the bottom of a jar. The same thing happens into soil. Tillage destroys soil aggregates and structure causing soil fill into void spaces which slows down infiltration. There were also many earthworm casts (manure) dried that adds nutrients and also helps aggregate the soil. Proper soil management adds nutrients to the soil by enhancing soil biology.
The soil also had a healthy earthy smell which comes from an organic compound called geosmin. Geosmin is produced by colony-growing bacteria that grow like fungi. This group of colony-growing bacteria is called Actinomycetes. Actinomycetes and arbuscular mycorrhiza are very important in helping small hyphae, root-like structures increase nutrient and water transfer to the roots. The symbiotic relationship helps the soil to function better. As roots leak organic acids and reach into small soil aggregates and the subsoil, minerals are released and brought upward by roots. Nutrients are cycled with less need from other amendments. However, adding compost continues to add carbon and feed the soil biology which in turn allows roots to uptake nutrients to the soil surface, improving soil productivity.
Blackberry Farm has made major strides to increase soil health with the use of various no-till and cover crop practices. Blackberry Farm incorporates numerous farming strategies that promote ecological diversity and balance. Their main goal is to provide produce of the highest taste and nutritional value. This is achieved by establishing healthy soil. Gardeners and larger farmers can learn from their example. I am amazed in the changes in one year. I cannot wait to see changes next year from their management.