Zerodig or “No-dig” commercial horticulture

 

It’s time to put the biologists back in charge of growing our food

 

At one level, “no-dig” horticulture is about growing crops and producing healthy food in an environmentally sustainable way using methods that maximise returns to labour to create commercially viable farms. To achieve this, no-dig puts biology – especially soil and plant ecology – at the heart of the farming system. An understanding and appreciation of the soil food web, ecological inter-connections, the role of biodiversity in mitigating pest damage to crops and how plants feed themselves is vital for no-dig success.

At another level no-dig farming is about so much more. A no-dig farm has adopted exactly the right balance of ecological, social and economic principles to be sustainable environmentally, socially and commercially. By building up stable organic matter in the soil, no-dig farming is a carbon sink – sequestering carbon dioxide from the atmosphere and locking it up in the soil. This – on a large scale – can help to mitigate the effects of climate change. 

Food that is grown following ecological rather than chemical principles is more nutritious and healthier for us. By replacing capital with smart systems that use labour efficiently and creatively a host of new rewarding jobs are created. Participation and engagement by and with local communities can be extremely high and diverse.

The Ecological Principles

Good healthy soil is vibrant and full of life. It works as an ecosystem now often referred to as the “soil food web.” The soil food web consists of a wide variety of micro-organisms that can unlock and make available all the nutrients that plants need to grow and stay healthy. 

The soil micro-organisms of the soil food web include bacteria, fungi, protozoa, nematodes, micro-arthropods, earthworms, etc. A teaspoon of healthy soil contains more micro-organisms than people on the planet. Literally thousands of species of bacteria and fungi are working non-stop producing enzymes, other proteins and all the nutrients that plants need. Bacterial and fungal predators start the process of making these nutrients available to plants. 

Most importantly the soil food web makes nutrients available to the plant when it needs it and in a form it can use. Developing the soil food web as a source of plant nutrients eliminates the leaching of nutrients into water supplies from artificial fertilisers and animal waste. Our understanding of the soil food web is just beginning. 

However, we now know plants coexist and trade with the soil food web to grow and remain healthy. Up to 60% of the energy from photosynthesis is exuded into the soil to feed the micro-organisms of the soil food web. In return the plants receive soluble forms of the nutrients they need for growth and enzymes for protection against disease and pathogens. The richer and more diverse the soil food web the better plants will grow and the more they will be protected. It’s the soil biology that unlocks the nutrients that plants need.

When the soil food web includes a strong fungal network, plant growth goes into overdrive. Plant roots will connect with fungal hyphae, called mycorrhiza, which can amplify the reach of the plant roots at least 100 times, perhaps up to 1,000 times. This means the plant is more drought-tolerant and can access plant nutrients from a much wider area. Fungi also synthesise many complex biological molecules that are important for both plants and our health.

Nurturing and understanding the soil food web underpins no-dig practice. Under no-dig conditions, the soil is undisturbed so the soil food web thrives. Its organisms can work and multiply. Disturbing the soil has a negative impact on the mycorrhizal networks within the soil food web fungi.

By feeding the soil food web with live compost and organic mulches we can accelerate the development of the soil food web. At the same time, we reduce the habitat for pathogens and pests such as slugs; and develop a soil that discourages the establishment of early succession plants such as weeds. The types and mix of composts and organic mulches we use influence the composition of the soil food web.

Altering the balance, particularly between bacteria and fungi, will influence which plants grow, and how they grow. Altering the balance of the soil food web towards later stages of plant succession creates a habitat unattractive to weeds.

Plant succession reflects soil biology

As the soil food web develops, the organic matter of the soil will increase as will the pool of carbon that remains in the soil. This means that your horticultural system is absorbing and retaining more carbon dioxide (CO2) than is being emitted. You are sequestering CO2 from the atmosphere and the stock of carbon in the soil is increasing. At scale this can mitigate the effects of global warming by taking greenhouse gases out of the atmosphere.

Before agricultural soils were tilled and advent of the now almost ubiquitous use of chemical fertilisers, pesticides and fungicides most of these soils contained 8-10% organic matter. Today we are down to an average of 2-3%. 

UK agricultural soils currently hold about 10 billion tonnes of carbon; down from 18-23 billion tonnes of carbon before agriculture. Current farming practices ensure the losses continue – In England and Wales soils are losing 5.3 million tonnes of carbon per year (equivalent to annual CO2 emissions of 19.5 million tonnes per year). Changing farming practices to put this carbon back into the soil reduces net CO2 emissions.

The French government “4 per 1,000” initiative calculates that putting back the carbon that has been lost by agriculture at a rate of 0.4% per year we can stop the annual increase of CO2 in the atmosphere.

Alternatively put, a 15% increase in the world’s terrestrial carbon stock would remove all the carbon pollution emitted since the industrial revolution. A 2% maintained increase in soil organic matter across the world’s farmlands would remove all the carbon emitted from the burning of fossil fuels over the last 100 years. 

It is agriculture that produces the food we eat. How agriculture is practised has an impact on food quality and our health as expressed by Lady Eve Balfour in 1943:

“If the nation’s health depends on the way its food is grown, then agriculture must be looked upon as one of the health services, in fact, the primary health service.” 

Improving the nutritional quality of our food goes hand-in-hand with the ecological principles behind “no-dig”. Our food system is currently in disjunction with our evolutionary bodies. Our cultural adaptation is taking place faster than our evolutionary adaptation. The paradoxical consequence is that, although we have lower mortality and higher life expectancy than ever before, we also, at the same time, have higher morbidity. This mismatch uses up an increasing share of our healthcare budgets. Such nutrient deficiency is sometimes called the “hidden hunger” – although we are satiated we are not well fed.

As Hippocrates put it in 400 B.C.:

“Let food be thy medicine, and medicine by thy food”

Largely as a result of modern agriculture and increased levels of food processing, both the nutrient density and richness of much of the food we eat has declined, sometimes dramatically, over the last 100 years. The result is that we are feeding our gut biome with an ever-simplified mix of nutrients, often laced with a cocktail of chemical residues. In the same way that the microbiome in the soil breaks down compounds to make nutrients available to plants; our gut biome is the front line breaking down the compounds in the food we eat to make the nutrients available that our body needs. 

In the same way that plants have evolved to have a symbiotic relationship with the soil biome; we have evolved to have a symbiotic relationship with our gut biome. A healthy gut biome needs the diversity of the 80 or so primary compounds and 1000s of complex compounds from animal and plant foods that we have evolved with and, as hunter-gatherers, ate. Today’s diet, for most of us, is far removed from that evolutionary starting point.

Primary nutritional compounds consist of water, fibre, fat, carbohydrates, vitamins, proteins and minerals. Secondary compounds, sometimes referred to as “phytonutrients”, consist of a diverse range of phenols, turpenes, alkaloids, and sulphur containing compounds. As a result of co-evolution with herbivores, plants have almost certainly evolved possibly over 100,000 of these secondary compounds. Many of these secondary compounds are no longer available in the food produced by modern agriculture.

Because it is based on establishing a healthy and diverse soil micro-biology, “no-dig” raises the nutrient density and nutrient diversity in the plants that are grown. 

The Commercial Principles

Building on these ecological principles to create a highly productive and commercially successful horticultural enterprise starts with careful planning and organisation.

*The supply and availability of organic matter is what drives the soil food web. This comes from plant residues, live compost and organic mulches. Compost and organic mulches can either be brought into the enterprise and/or made onsite. Initially, these may almost certainly need to be brought in but over time woody biomass – ideally in the form of ramial woodchips – can increasingly be made onsite. For a completely closed system you probably need an area three to five times the size of your cropping area to support the plants you wish to grow with the organic matter they need.

Compost needs to be “alive” so that it can act as an inoculant to supply a wide range of especially bacteria and fungi but also nematodes and protozoa to the soil. In order to multiply and thrive these building blocks of the soil food web need to be fed with organic matter and plant sugars.

Compost bought in bulk may have a high level of organic matter but contain little life. This should be checked using a microscope and where life is absent the bought in compost should be mixed – inoculated – with home-grown compost that is teeming with life. The micro-organisms will soon spread throughout the mix.

Not always, but often compost will often tend to be richer in bacteria than fungi. Adding a small amount of ramial wood fibre to the compost mix will raise the level of fungi.

How big the growing area should be is up to you. But bear in mind that one person cannot look after much more than 1,200 m2 of beds plus some tunnel space for propagation – even that is a stretch. Allowing for growing, composting, storage, packing, etc. areas; my view is that one hectare (10,000 m2) is more than plenty of space for a “no-dig” horticultural enterprise. Small is both beautiful and good – and especially to start with.

The horticultural enterprise should be small enough to manage without the use, and expense, of machinery. To this one could add three to five hectares for a completely closed system providing enough biomass onsite to feed the soil food web, build soil health and lock down some carbon.

There are probably as many designs as people and blending the production of biomass with cropping areas in an agro-forestry format can also be a good option. You might also want to experiment with cover crops and rotations. The possibilities are simply endless.

However, when drawing up your design bear in mind the following seven principles:

• minimise walking and carrying distances by positioning your growing and biomass production areas around a central zone where deliveries are made, harvested material is brought, tools are stored, etc.
• think about water and how you are going to irrigate your growing crops
• think about wind and the need for shelter either building in agro-forestry into the design and/or bushy perennial crops
• aesthetics, you’ll be selling the farm and its story as much as the produce. Think about first impressions for visitors, sweet smelling herbs and bees, etc…
• maximise benefits from the soil food web by getting some compost going as soon as possible you’ll need it to inoculate and get your growing area off to a flying start. Generally speaking, the older the compost the richer its biological diversity 
• plan to start building your packing and harvesting area at least six months before your first harvest as a lot can go wrong here and you’ll probably need some sort of permit from someone.
• plan to start establishing your plant propagation tunnels or greenhouse at least six months before your fist-planting out date. Really effective plant propagation will be key to the success of your “no-dig” horticultural enterprise. Transplanting as much as possible also maximises the time that your growing area is covered with growing plants and your soil food web being fed with the plant sugars of photosynthesis. You should aim to keep growing crops in the ground as much as possible – including over winter. Aim to replant almost at the same time as you harvest.

Beds should be narrow – The Zerodig system uses 75 centimetres – probably not more than 1.2 metres and paths between beds at 45 centimetres. A 45 centimetre wide path is about the right width for a wheel-barrow and comfortable to work from.

Tilling is not required to establish the beds. The area should be mowed and clean of large perennials with stones removed. On top of this lay down sheets of cardboard – a 75 cm wide roll of industrial cardboard is a good way of doing this quickly. Next dig out the paths and place the earth from the paths on top of the cardboard with any plants face down with their roots exposed. The paths should be dug to a depth of about 15 centimetres leaving you with a trench about 30 centimetres deep – roughly one spade.

The paths should then be filled with wood chips – ideally ramial wood fibre – to at least 10 centimetres above the level of the beds. As you can imagine you need a considerable quantity of wood chips to start with. The wood chip paths will provide a reservoir for the development of fungi and help maintain their mycorrhizal networks. Inter-cropping with perennial crops will also further enhance mycorrhizal development.

Bed and path preparation is best done in the autumn and is hard work but only needs to be done once. Once your beds are established your focus should be on three things: (1) propagating healthy plants to transplant; (2) nurturing the soil food web – you can have a lot of fun using a microscope with 400x magnification to do this; and (3) harvesting, marketing and selling.

You do not want to spend time weeding and tilling. You also do not want lots of mud!

By minimising – preferably eliminating – the time spent weeding and tilling you can concentrate on growing, harvesting, marketing and selling. Successful growing requires a well thought through crop plan telling you what to grow when. Before doing your crop plan you first need to understand what your customers would like to buy.

Critical to the success of your enterprise is a rock-solid marketing and sales strategy. The ideal sales strategy is to grow pre-sold produce. This requires an in-depth understanding of the local market and marketing well in advance of the growing season. Marketing is not just about the benefits of healthy fresh vegetables but also about the story of how and where they are produced. The “no-dig”, soil food web, bio-diversity, carbon sequestration, nutrient density for better flavour and health story will resonate with many customers. That’s even before we’ve started to discuss the social dimension to the story!

Bear in mind the following marketing and sales principles:

• Spend as much time as possible on thinking through your marketing plan – at least as much time as digging out those paths! Talk about your ideas with prospective customers, get their feedback and refine your ideas again and again – at least three times.
• Be as specific as possible – when a customer expresses interest in bags of “mixed salad leaves” – think about what exactly this means.
• Expect to spend considerable time getting the word out – talking about your farm, what’s going to be available and when; and – most importantly – asking prospective customers which vegetables they like to buy and what price they would be prepared to pay
• Develop your brand and the story to justify a price premium
• Try and develop a wide variety of customers with a mix of retail – individuals and households – and wholesale – restaurants, other growers, distributors, etc.
• Build in lots of margin for error – especially at the beginning – if you are growing pre-sold produce you must be able to deliver on your promise.
• Repeat business is the best business. Repeat business will only happen with exemplary service, dependability and clean well presented fresh vegetables
• Make it as easy as possible to get paid
• Do not develop your crop plan until you have a well developed marketing and sales strategy

How you value your time is critical to your planning. For example, if you are aiming for a return to labour or revenue target of £20,000 per year on 1,200 m2 you will need to be planning for a net income of £17 per m2 of bed per year. A return to labour of £40,000 per year requires a more productive and intensive plan of £34 per m2 of bed per year.

Taking lettuce as an example one m2 of no-dig should yield three crops of lettuce per year. Assuming nine plants per m2 should give 27 plants. Allowing for losses of around 20% leaves you 20 plants each one of which needs to give you a net income of £1.70 to hit a labour target of £40,000 per year. This drops to 0.85 per plant if your target is £20,000 per year or you might decide to drop down to two crops of lettuce per year.

Hopefully, from this simple example you can see how your revenue target has a significant impact on your crop planning and the amount of work involved. You can also see that as soon as you start to buy in inputs and use machinery – such as in conventional agriculture – your costs will start to increase. As a result the amount of lettuce you need to grow to meet your income target also rises.

The Social Principles

Our society – and rural areas are no exception – is riddled with social challenges. These range from an unequal access to housing, to lack of meaningful employment opportunity, to dominance of “big is best” thinking and one could go on. One could also discuss and disagree endlessly about priorities and possible solutions.

However, within this context “no-dig” horticulture does create small scale, meaningful and rewarding job opportunities. These are in rural areas where often such opportunities are few and far between. No-dig horticulture also has the potential to provide people looking for a career in agriculture but unable to access the land they need with a path to doing so.

In some ways, no-dig farming is very “cutting-edge”. New discoveries are frequent and our understanding of soil biology is improving on a daily basis. Over the last 20 years, research from around the world has completely transformed our thinking about soil. This in turn will – eventually – transform agriculture and the way we produce food. No-dig is part of that change.

A substance called “glomalin” was only discovered in 1996. We now think that glomalin, which is made by soil fungal networks, may account for the storage of one third of stable soil carbon. This single fact has huge implications for agriculture as we know that fungal networks are fragile and easily destroyed by tillage.

Quite simply, it has never been so exciting or so rewarding as to be involved in agriculture as it is today.

Farming is an incredibly social activity. After all it involves the production of food which we all need and enjoy! The impression of a lonely farmer tied to tilling and working the land no longer applies with “no dig”.

“No dig” horticulture is “smart” horticulture that benefits from over 360 million of nature’s R&D programme. No dig finds its solutions in nature that some people are calling “bio-mimicry” – essentially working with nature for our mutual benefit. As we have shown above this means: minimising disturbance, maximising soil cover, maximising continuous living roots and maximising biodiversity.

This approach is a new paradigm – compared to conventional agriculture – and requires a host of new skills. Above all it requires a good level of what I like to call “ecological literacy” – the ability to read an ecosystem and think “I wonder how I could arrange things so that nature did some of the work for me?” No tillage and limited weeding are two of the results. In this way more time is spent thinking, experimenting, planning, harvesting & promoting.

Because the no-dig skills required are broad – they range from scientific and ecological skills; to expertise in practical propagation, growing and harvesting skills; to planning, business and marketing skills – they are best done with plenty of interaction with other practitioners, volunteers, customers and scientists.

For this reason “no dig” horticulture is often about social interaction enjoying working with people, exchanging ideas and developing community relationships. A support network can considerably help with success.

 

References

1) A term first used by Dr. Elaine Ingham (www.soilfoodweb.com) and used in the United States Department of Agriculture (USDA) Soil Biology Primer of which she is the author.

2) Young, R. and others (2017). The hidden cost of UK food. Sustainable Food Trust. http://sustainablefoodtrust.org/wp-content/uploads/2013/04/HCOF-Report-online-version-1.pdf

3) Graves A. R. et al. (2015) The total costs of soil degradation in England and Wales.

4) The 4 per 1000 Initiative. www.4p1000.org

5) The Earth’s current terrestrial carbon stock is estimated at 2,000 gT – 500 gT in plants and 1,500 gT in soils – and global emissions from fossil fuels since the start of the industrial revolution are estimated at 300 gT. We increasingly think that the terrestrial carbon stock has halved over the last 3,000 years as a result of our activity. Good soil management can play a significant role in reducing and mitigating the effect of carbon emissions. Source: UNPCC.

6) There is considerable writing on this. For example, the recent (2017) “Hidden Cost of UK Food” report produced by the Sustainable Food Trust. For a more scientific approach see, for example, “Light Farming: Restoring carbon, organic nitrogen and biodiversity to agricultural soils” by Dr Christine Jones (2018).

7) Ramial woodchips are made from woody material which has a stem diameter of seven centimeters or below. This material has a relatively high amount of minerals, sugars and complex plant compounds stored in the cambium relative to lignin. Ramial woodchips are made in the winter when the trees are dormant and stored nutrients are at their highest. Using ramial woodchips as the primary source of organic matter ensures a rich, healthy and fungal dominant soil biology.

8) “Glomalin” was discovered in 1996 by Sara F. Wright who – at the time – was working for the United States Department of Agriculture (USDA).