Ploughing and tillage have been cast as the pantomime villain to the fairy godmother of no-till agriculture. But is this demonisation of tillage really fair? This session at the Oxford Real Farming Conference sought to counteract that, demonstrating that far from being damaging, cultivation and plough-based organic systems can maintain or increase soil organic matter levels, ensure good soil structure and increase biological activity.
Renowned organic farmer and adviser, and former head of the Organic Advisory Service at ORC, Mark Measures chaired the session and started by putting the case for tillage. Mixing air into the soil activates soil life and mobilises soil nutrients making Nitrogen and Phosphorus available – crucial for plant growth. This stimulation of soil biology, using carbon as an energy source breaksdown soil organic matter (SOM) to form humus – stable SOM which is the foundation of good soil sructure.
Mark says that there are unsubstantiated claims that no-till is the ‘holy grail’ of organic farming (See: Living mulches: The holy grail of no till?), which he thinks reflects a misunderstanding of soil fertility and the impact of tillage. Poor cultivation practices can lead to soil erosion, compaction, loss of organic matter, damage to soil life, and excessive fuel consumption. In reality, only about 7% of arable land in the UK is farmed using no-till methods. Organic and agroecological farming should not be bound to no-till practices, which many conventional farmers have adopted due to what he describes as “flawed agricultural systems driven by agrochemical sales.”
The role of (reducing) tillage in climate mitigation is he says widely overstated. The potential to continually increase SOM levels is limited and does not increase exponentially. It is influenced by soil type and the starting point. You need to consider the full soil profile. Evidence from the long-term DOK trials in Switzerland shows that organic and biodynamic farming can increase soil organic matter levels over time. “Organic farming already includes diverse leys, green manures and often livestock manures and prohibits pesticides – so why does it need to focus on no-till?”
Iain Tolhurst MBE (Tolly) has been an organic grower for nearly 50 years and built up an impressive tillage-based vegetable production system at Hardwick over the last 38 years. Tillage is great, he says, for dealing with green manures, which are the driver of his system. Tillage is also necessary for weed control (perennial weeds can be a real problem with no-till), soil aeration and for managing crop debris. The use of the plough needs to be done with care and consideration for soil life. They shallow plough and timeliness is key on their soils. Tolly incorporates a lot of green manures into the rotation and has increased soil health and sequestered carbon at depth over time. Research by Agricarbon has shown that their soils are maintaining or slightly increasing carbon levels whilst growing 14 tonnes per hectare of food per year of vegetable crops. The average weight of carbon in their soils is equivalent to 80 tonnes or 12.5 mature oak trees per hectare. Tolly also cited earthworm counts by researchers at ORC which recorded 1500 earthworms per square metre equating to 15 million per hectare, approximately 7-10 tonnes.
Research agronomist Dominic Amos of Cope Seeds (formerly a researcher at ORC), started by saying that in his view the demonisation of tillage and the plough is not reasonable and removing tillage is not essential. Organically farmed soils are healthy and recover quickly from tillage. Dominic presented results from his work at ORC on living mulches including the Innovative Farmers field lab and subsequent work investigating if living mulches could be a solution for reducing tillage in organic farming. While there are challenges (slugs) and risks (e.g. spring cropping) there are benefits of improved soil health and biodiversity. By undersowing in spring, direct drilling of a cereal cash crop in the Autumn, followed by 2 years of ley, then a conventionally established Spring crop = 4 years organic no-till! (66% of a 6 year rotation, 80% of a 5 year rotation). Dominic calls this the ‘no-till transition’ whilst still utilising ploughing. With living mulches the oft discusssed ‘yield penalty’ is likely to be offset by reduced costs and increased yields acros the rotation.
Through the Sustainable Farming Incentive (SFI) it is possible to receive payments that can be stacked on top e.g. OFA6: Undersown cereal crop (organic land), CNUM3: Legume fallow and SOH1: No-till farming
Dr Richard Gantlett is a large-scale biodynamic farmer from Wiltshire who takes an intense researcher’s interest in his farming system. His proud headline statement is that Yatesbury House Farm is sequestering (capturing from the air) 10x more carbon than it is emitting. He began by citing his paper:
Gantlett R, Bishop J, Jones HE, Lukac M (2024). Modern arable and diverse ley farming systems can increase soil organic matter faster than global targets. Renewable Agriculture and Food Systems 39, e17, 1–9. https://doi.org/10.1017/S1742170524000103
“Our results demonstrate that incorporating a 2-year diverse ley within arable rotations surpasses the COP21 global target of a 0.4% annual increase in soil organic carbon. These findings, derived from a working farm’s practical and economic constraints, provide compelling evidence that productive arable agriculture can contribute to climate change mitigation efforts.”
Richard sold his plough in 2003 as “ploughing is a party for docks and couch, the pioneer weeds” and is worse for conserving soil and water, but has no effect on total soil carbon, only where it is stored in the soil – nearer the surface (See Blanco-Canqui (2008)). They do till, however, to repair damaged soil from machinery/cattle/sheep, to establish seedbed and for weed control. They use light machines “In gardening terms, we use a hoe rather than a spade.” Weeds are really important to Richard for hosting beneficial insects and biodiversity generally: “We never have a monoculture at Yatesbury, even when we are growing wheat because we always have weeds, but we are always working to favour the right ones.”
“We create biodiversity by growing 29 species in our diverse ley which feeds our farming system and drive the carbon storing process. We grow it for 2 or 3 years. This is what drives our healthy living soil.”
A wide-ranging discussion followed, which focused on weeds, both the issues of dealing with difficult perennial weeds, but also on the benefits of weeds and the panellists approaches and attitudes towards them.
