How organic matter increase helped farm hit net-zero target
© Hugh Nutt Soil organic matter levels have seen a 1.1% increase at the Lockerley Estate in Hampshire, thanks to a diverse arable rotation, integrating sheep, cover crops, clover leys and organic manures.
With a strong focus on improving soil health, Craig Livingstone, head of farming at the estate, is in his seventh year of his regenerative agriculture journey, which has helped the farm achieve a carbon-negative status.
He has not only improved soil and crop resilience, but substantially cut artificial fertiliser use and spend on pesticides, enabling the arable enterprise to become carbon negative within its own right.
See also: How this arable farm became carbon negative and cut costs
“The change in rotation and shift to zero tillage enabled us to successfully scale back on inputs. We now achieve a better rotational net margin, which is a financial and environmental win-win but also goes a long way towards achieving net-zero carbon emissions,” he says.
The estate
Owned by siblings of the Sainsbury family, the 1,800ha business is split between two sites in Hampshire, 30 miles apart – Lockerley Estate and Preston Candover.
Mr Livingstone and his team have switched up the previous wheat, spring barley and oilseed rape rotation into a diverse cropping mix, incorporating both spring and winter wheat and barley, peas, beans, winter oats and clover leys. Niche crops, such as miscanthus for a power plant, are also being grown
About 40% of the farm is planted to spring crops each year, which is preceded by a cover crop grown for nutrient capture and food source above and below ground. No soil is left bare over winter, farming to the regenerative principle to keep the soil covered.
Woodland management
The 300ha of woodland at the estate has been actively managed by the family since 1983 and provides a wealth of environmental and landscape benefits.
A continuous cover management system is used and the woodland consists of a range of species (mostly native broad-leaves with a small conifer element).
There are many benefits of mixed woodland, such as greater biodiversity, improved disease resistance, greater root activity, larger crown areas and more photosynthetic capacity.
In fact, mixed woodland can sequester four times more carbon than monoculture woodland, explains Matt Bloor, woodland and conservation manager at Lockerley Estate and Preston Farms.
He says that trees aged 20-25 years sequester the optimum amount of carbon.
“It is a common misconception that most of the carbon in woodland is locked away in the tree itself, when actually 70% of carbon is locked in the soil,” he says.
The average UK woodland sequesters about 10t/ha of carbon dioxide a year, while some non-native trees, such as hybrid eucalyptus, can sequester 25-30t/ha a year.
The government has pledged to increase tree planting to 30,000ha/year by 2025 to increase tree cover from the current 13%, which will sequester an extra 14m tonnes of carbon dioxide a year – double what UK forests and trees sequester currently.
However, this currently only accounts for 4% of total UK emissions, so planting trees is not the only answer to a much wider issue.
A species mix comprising phacelia, vetch, linseed, radish and clover (before cereals) and buckwheat, radish phacelia and linseed (before pulses) is planted. This can produce 20-50t/ha of freshweight.
Mr Livingstone explains that reduced tillage and cover cropping provides a rapid way of building organic matter levels, which have seen a rise by 1.1% to an average of 5.1% across the five soil stations they created on the estate.
This has gone a long way to improving soil health and offset carbon emissions across the arable enterprise.
“For every 1% increase in organic matter, soil is able to store an additional 230,000 litres of water/ha, which is helping make our land more resilient to dry springs.”
Nutrition
Cover crops also provide a valuable role in nutrient retention. Mr Livingstone takes freshweight cutdowns each year looking at the biomass of the cover.
A tissue test is analysed and overlaid with the pence/kg of major nutrients and the nutrient capture calculated.
The C:N ratio is used to predict how quickly the recycled nutrients may become available to following crops.
Covers are then grazed off by a local grazier’s sheep, leaving a 20% residue to be sprayed off with glyphosate at a reduced rate of 1.25 litres/ha prior to planting the following spring crop.
Mr Livingstone is beginning to look at the addition of humic/fulvic acid to glyphosate to help buffer any negative effect to soils.
In total, 2,000t of organic manure or compost is applied to land. The addition of field beans and peas has facilitated good entry for direct-drilling of winter wheat.
Wheat crops now receive 190kg N/ha instead of the previous 250kg N/ha, while spring barley rates receive 95kg N/ha rather than 150kg N/ha.
“This reduction over the past six years has been cautious. We know there are others growing strong crops on less nitrogen, but we must go at our own pace. Our soils will dictate what we are capable of.”
Net zero
As a Linking Environment And Farming (Leaf) demo farm, beacon for regenerative agriculture and Leaf Marque assured, Mr Livingstone is passionate that growers can farm in harmony with the environment.
He believes farmers should not be left to sell carbon credits as we have a huge responsibility to produce food.
“However, we should be able to do both – produce food responsibly but link carbon credits with the manner in which food has been produced.”
Carbon calculators
At present, Mr Livingstone has used two different carbon calculators to compare results and findings – both of which revealed a negative carbon footprint.
Although he hasn’t traded any credits yet, he is growing in confidence in the world of carbon and hopes to sell a percentage of his “stable carbon”, which consists of a 300ha woodland, 20km of hedges and five years of detailed soil analysis, sampled using the solvita test.
“I would never sell all my grain forward, nor would I with carbon. We don’t have the luxury to “leave money on the table”, so if there is a marketplace developing that will recognise the steps forward we have taken, then we should be open-minded.”
There are other simple product swaps that make significant changes to carbon emissions on farm. Last year, Lockerley estate worked with Green Bio fuels and swapped red diesel for Green D+, which is a hydrotreated vegetable oil (HVO) biofuel.
About 40% of the farm’s cereals were dried on the continuous flow dryer, and the simple fuel swap (which consisted of an extra filter in the fuel line) saved more than 55t of carbon dioxide equivalents.
The Small Robot Company
Lockerley Estate is one of the first farms in the UK to sign up for a robotic commercial offering, with the Small Robot Company (SRC), and sees this as a part of its future regenerative strategy.
The SRC is currently conducting a pilot on the estate with its “Tom” scanning robot, which assesses soil health.
This data will build on the farm baseline to establish a reliable measurement framework to be rolled out across the UK, accelerating carbon sequestration to reach net zero and providing evidence for Environmental Land Management payments.
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