We consider many things in evaluating the productivity, economics and robustness of our farming operations. Gross margins, machinery & input costs, labour, rent etc. But how often do our soils and carbon form part of the conversation and of the budgets we regularly revise? A quick look through my latest John Nix Farm pocket handbook and no mention of soil or carbon in any of the budgets or calculations. You can not even find soil in the index. This is quite surprising, in that soil is the most fundamental and precious resource on the farm. Without it what would we farm?
Whilst soil is fundamental to farming activity, not all soils are the same. From the silts of Lincolnshire, to the clay in Essex, the chalk downs of Wiltshire and to the sand in Shropshire, all differ in workability, capacity and resilience. However what is common to all these soils is that they all contain a level of carbon, often referred to as ‘soil organic matter’. Some of this carbon is old stable humus, important for structure, drainage and workability. Some is new fresh carbon, such as plat residues or manures and is important for feeding the soil and soil organisms. The carbon in all its forms is a key driver of soil function. It helps create and maintain soil structure, improves soil water holding capacity and drainage, intensifies nutrient exchange through cation exchange capacity and importantly provides a food and fuel source for the livestock in the soil, many of which are microscopic in size, like beneficial bacteria and fungi. With 85% of all nutrient mobilisation mediated in some form by microbial populations, creating the right habitat and feeding these soil microbes should be in every farmers “to do” list.
So why is carbon important?. There is no denying that agriculture has become vastly more productive over the last 80 years. Productivity increases have resulted from improvements in breeding, genetics, mechanisation and management skill. They have also in part increased as a result of using up embedded carbon in the soil. Carbon that was laid down in the soil millions of years ago and released through farming activity. Carbon that has been liberated to fuel productivity. When ‘Jethro Tull’ said ploughing is fertiliser, what he was describing is the oxidation of carbon through cultivation, which fuelled soil microbial activity and resulted in improved yields. All Fine then?. Well yes as long as we keep putting carbon into the soils. The problem is that for many decades we have put less carbon into our soils then we have taken out. The result has been declining soil carbon (soil organic matter) and with it long term resilience and productive potential.
So how should carbon be part of the conversation?. With plateauing productivity, farmers are increasingly recognising that the health of their soil is key to future prosperity. Interest in cover crops, conservation tillage, no till and organic, all focus on building and maintaining soil carbon, to help drive farm performance. As we enter a new era of farming outside of the Common Agricultural Policy (CAP) the English Government has soil health and soil carbon centre stage in new policy roll out, recognising its role in productivity, resilience and the wealth of the nation. Policies and programmes are likely to reward those farmers that respond to building carbon & soil health as a ‘public good’ and penalise those that degrade soils and their long term capacity. This makes sense, as there can not be many farmers who would wish to see their productive capacity eroded?.
So, if soil carbon will become increasingly important as a driver of productivity, soil health and Gov policy, as farmers where and how do we make this part of our day to day conversation and activity?
A good place to start is to establish where the farm is on the carbon roadmap. In its simplest form, just like you would create a gross margin budget for a crop, start by creating a farm gate carbon and nutrient budget. Measure or estimate the nutrients and carbon imported into the farm (fertilisers, feeds, seeds, manures), produced on the farm (crop biomass, cover crops, manures, digestate etc) and exported from the farm (crops, meat, milk etc). This will highlight if the farm is building or diminishing carbon and nutrient stocks, the peaks and troughs in the system and where replacements come from. Carbon and nutrient levels can be related to soil analysis (including soil organic matter levels) to create a baseline of current status. For most farms, the precision of any measurement will be less critical than establishing the direction of travel of carbon and nutrients on the farm – weather building or declining productive soil capital.
So, at the start of another decade, where soil and carbon become increasingly recognised as fundamental drivers of productivity and resilience, making carbon a keystone of currency and part of the management conversation in your farming operation will be key.
As the Chinese proverb says “ look after your soil, because one day it will be looking after you”
Written by Stephen Briggs, head of Soil & Water at Innovation for Agriculture. For more information on soil health, carbon and budgeting contact firstname.lastname@example.org