The Future is Biology
30 May 2012
Rob Richmond looks at current organic farming practice and argues that it needs to concentrate on biology rather than chemistry (in the form of soil nitrogen availability) if we are to ensure that organic farming really can be a true alternative to non-organic techniques.
In March I attended the Soil Association conference entitled ‘Facing the Future’. It was interesting to hear the Soil Association’s goals and ambitions for the future. Andrew Leu’s comment – “…by changing the ways of small farmers in poorer countries from ‘farming organically by default to farming organically by design’, has resulted in yields being more than doubled…” – got me thinking about the current position in the UK.
Based on my research and experience of talking to my fellow farmers, I came to the conclusion that farming organically by design in the UK often means growing a legume rich ley to provide soil fertility (nitrogen) for the rest of the rotation. Sadly, this represents a biological system, which is locked in narrow minded, chemical thinking (the conventional NPK approach).
In order to grow high yields in an organic system, we must concentrate on managing soil biology. This involves feeding it, and providing it with a suitable environment in which to grow and work efficiently – in much the same way as we do with above ground livestock. In practice this means that organic farmers in the UK need to look closely at their existing systems and experiment closely with adding extra diversity to the cover crops they are using in the fertility building stage of their rotations.
Feeding the soil biology requires two types of ‘feedstuffs’ – those with a low carbon: nitrogen (C: N) ratio, and those with a high C: N ratio.
- Low C: N ratio ‘feeds’ include incorporated young, green cover crops, chicken and pig manure, and some dairy slurry. These ‘feeds’ are rapidly decomposed by soil bacteria, releasing a large burst of nutrients for the growing crop. Young cover crops do not need to include a legume species to provide nitrogen for the growing crop, as young plants are rich in nitrogen.
- High C: N ratio ‘feeds’ include mature cover crops, crop residues (stubble and straw), and farm yard manure. These ‘feeds’ are decomposed more slowly, mainly by fungi, to release some nutrients for plant growth. The majority of the carbon in these ‘feeds’ is utilised by the fungi to build humus – very stable carbon compounds in the soil, with huge benefits to soil fertility.
By providing a balance of these two types of ‘feed’, we encourage a balanced population of bacteria and fungi in the soil – ideal for crop production. The more diversity we include in crops (and animals) above ground, the more diverse the populations below ground. This results in rapid cycling of nutrients, combined with the gradual building of humus.
In order to help this biology work efficiently, it, like the above ground livestock requires a full range of major and trace minerals. We regularly supplement above ground livestock, due to deficiencies in forage, ultimately due to a lack of available nutrients in the soil. In order to really kick-start the system, some form of supplementation must be given to the soil biology. This can either be spread directly onto the soil, or foliar applied to a growing cover crop before incorporation.
When incorporating these cover crops, they should be thoroughly mixed into the top 3-4 inches of soil (with discs or rotovator) to ensure they are utilised by the biology in aerobic conditions. It is important when carrying out cultivation tasks, that we consider why we are doing the job, if we are using the correct machine in the right conditions, and what the effects are going to be on the below ground populations.
Once the soil biology is working, the constant cycling of nutrients through manures and cover crops will help maintain availability, so reducing the need for supplementation. As the level of humus in the soil increases, so does the soil’s nutrient holding capacity (in a plant available form). Humus can hold 6-10 times the nutrient load of the same weight of clay, not only essential for a well fed crop, but also in reducing loss of nutrients through leaching.
As I travelled last year, I met organic farmers in the US and Australia who, following these principles are matching / out yielding their non-organic neighbours. In Wisconsin, USA, Gary Zimmer is using cover crops on his organic dairy farm. Using these crops, with timely incorporation (thoroughly mixed in the top four inches of soil), is helping produce high yields of maize grain – he routinely exceeds 200bushels/ac when his conventional neighbours average 150-200 bushels/ac. The use of cover crops is maintaining his soil carbon levels. In Australia, the emphasis was orientated around compost.
In Young, New South Wales, YLAD Living Soils were using humus compost as the core of their biological growing program. Using application rates of only 500-1000kg/ha, they are achieving tremendous results. In trials (the results are on their website), they are achieving the same or better results than replica trials using fertilizers.
Near Camperdown, Victoria, I visited a conventional dairy farmer who had been using 300kgN/ha plus phosphate fertilizer. His grass was looking sick and his cows were requiring extra inputs and veterinary attention to maintain health and output. Three years ago, he switched from fertilizer to compost. His pasture health and output has improved, along with that of his cows. These autumn calving cows are outside all year round, producing 9000litres of milk from pasture plus grain. This year he planned to make 3,000tonnes of compost – including 1,000tonnes bought in chicken manure and 1,000tonnes bought in green waste. He employs contractors to make the compost, and then spreads it himself. Total cost is half of what he was spending on fertiliser, to achieve better results. This composting process is not just a heap of farm yard manure, turned a couple of times and called compost. The ingredients are balanced to give a carbon: nitrogen ratio of 25-30: 1. The windrows are then regularly turned according to temperature and carbon dioxide production. This is a modern day version of the Indore process, and is producing financial and physical results.
In my opinion, the only way to build soil carbon (humus) levels is by the rotational grazing of bio diverse pastures. Well managed, this can produce increases in soil carbon of one per cent every three years – this is equivalent to sequestering twenty tonnes of carbon per hectare per year. Building soil carbon has many benefits to agriculture and the environment.
I feel that only by embracing and managing biology, rather than concentrating on nitrogen, can we achieve these goals. Only when we can demonstrate that organics can produce the food to feed the growing world population, while having many environmental benefits, and rebuilding the fertility of our soils, can we show that there is a real alternative to the non-organic approach. Only then will it become apparent that the only good in GM is in allowing large multi national companies to patent the seeds of our food supply.
Rob Richmond is a farm manager at a mixed organic dairy farm in Gloucestershire, which converted to organic in 2007. He has been using bio diverse leys and min till since 2005 – a period he describes as a learning curve that has been beneficial to the soil. He is also a 2011 Nuffield Scholar, and will be publishing his full research later in the year. Rob’s full research report will be published by Nuffield Farming Scholarships later this year, titled ‘The benefit of Rebuilding Soil Carbon to Agriculture and the Environment’.
This article was first published in Mother Earth, the Soil Association's journal of organic thought and policy. We hope you enjoyed this article, please feel free to share this with your contacts. If you wish to support the production of Mother Earth in future, and receive the latest issue direct to your door, then please subscribe to Mother Earth, for just £12 a year.