By Professor Steve Banwart, Professor Pippa Chapman, Dr Gesa Reiss, Professor Lisa Collins. Global Food and Environment Institute, University of Leeds.
Increasing the amount of organic matter to support microbial activity in each kilogram of soil, especially in degraded soils, is just the first step in regenerative agriculture. Fresh plant litter is colonised by soil bacteria and fungi and begins to decompose. As the microbial colonies form and grow, surrounding microscopic fragments of parent rock and soil minerals adhere to the living cells and form larger particles. The resulting clumps of microbes, minerals, water and air are the building blocks of productive soil. These soil aggregates hold water within their internal pores, which keeps plants hydrated during times of drought. As aggregates form, between them, larger, connected pores are created that allow water to drain freely during wet conditions. The drainage allows oxygen from the atmosphere to enter soil and support microbial and plant root respiration, which is essential to good crop growth.
The pore architecture that is created within and between aggregates defines the soil structure. This important soil property controls water content and flow along with transport of dissolved nutrients, heat conduction and the diffusion of gases through soil. Water content strongly influences drought stress and the seasonal heating and cooling of soil that affects seed germination and microbial activity.
These characteristics along with the local mineralogy help determine the mix of soil microbes that can thrive in a particular soil. The composition of the active soil microbial communities determines the transformation and release of nutrients as organic matter decomposes. All of these physical, chemical and biological soil properties, together with climate, are the conditions in place to determine the types of crops and their root functions that are best adapted locally.
Regenerative agriculture is built on developing and maintaining soil structure. This approach often starts with changes to tillage, which is a physical disturbance that degrades soil structure. In addition, controlling traffic over the soil reduces compaction, protecting soil structure and the aggregates within. Reduced tillage and compaction help to protect aggregates, decrease erosion and build soil organic matter. This initial step might provide insight and a realisation of the potential to change the whole interacting system of crops, soil and water.
Regenerative agriculture practices often consider cover crops to sustain carbon inputs, manure management to support carbon inputs and plant available nutrients, with the potential to reduce artificial fertiliser inputs. The choice of crops is important. The type of vegetation cover determines the plant litter composition as organic matter inputs to the soil microbial community. The root traits of crops influence below-ground organic matter inputs during plant growth. Soil displacement is affected as roots grow and the below-ground biomass composition of plant litter is influenced when roots die.
Practices may include introduction of perennials and legumes in the rotation, experience of the response of insect pest populations to cropping changes, and experimenting with grazing. Rotations with livestock can help to manage the mix of crops, vary the type of manure input and add income streams. Changes to practices like these don’t happen overnight. Development might start with trials in the corner of a field and expand over time as a farmer gains knowledge through experience and begins to see net gains.
Business and environmental benefits
Regenerative agriculture offers business value through reduced overheads on fuel for tillage and fertiliser use. However, the benefits of soil organic matter and soil structure go far beyond soil fertility and the market value of crop yield. Building organic carbon stocks in soil removes carbon dioxide from the atmosphere and helps mitigate the extent of climate change. Carbon market schemes are exploring the potential to pay farmers to lock more carbon into soils by building up soil organic matter.
Improved soil structure helps flood prevention by increasing surface infiltration and storage of water in soil thereby reducing rapid runoff that contributes to flood peaks in streams and rivers. Insurance markets are considering land management incentives that reduce flood peaks. There is potential for lower premium costs to affected regions, especially for downstream cities at risk of flood damage to infrastructure.
The greater variety of crop cover and its rotation with time increases vegetation, insect and microbial biodiversity. More complex and variable diversity of organisms can help control persistent pathogens and pests. Better control offers the potential to reduce application rates and costs of pest control compounds. The multiple environmental benefits of regenerative agriculture can be substantial and can be accounted for. Information on positive environmental outcomes can be tracked and conveyed to consumers. This accounting offers brand value to processors and retailers seeking to meet household choices for more environmentally sustainable diets.
A reality check
The benefits of regenerative agriculture are not a magic bullet to the challenges of agricultural livelihoods, food security and global environmental sustainability. There is no blueprint or manual for regenerative agriculture. It is based on the observations of farmers gained from working with the connections between soil structure, water, plants and livestock. It depends on each farmer’s experience and knowledge of their soils, growing conditions and local geography. There is still much for us to learn about regenerative practices. Scientists working in close partnership with farmers will help to uncover how these local lessons can be generalised and made more widely applicable.
Regenerative agriculture cannot solve all the problems and feed all the people. It’s hard to imagine keeping food prices low, especially for the large and growing urbanised centres around the world, without large scale intensive agriculture that strives to be more sustainable. However, it’s also hard to imagine a world that does not have substantial, highly personalised production built on understanding local conditions. Regenerative agriculture can create business value by meeting regional markets and cultural preferences. It has the potential to provide high value exports that are transparently produced to high standards of animal welfare, environmental sustainability and hold high social and ethical value.
Building our planet’s future
Regenerative agriculture offers a vision of farming beyond 2050 with practices that will continue to thrive and develop. It will continue to offer lessons to agriculture, including more sustainable intensive farming, that contribute to improving planetary health into the 22nd century. Regenerative agriculture starts with soil but it has the potential to do so much more. The opportunity as it becomes more mainstream is to improve farm livelihoods, feed communities, mitigate climate change, reduce flood risk, enhance biodiversity and offer cities within a region a connection to the land that feeds them.
A link to this blog on the University of Leeds website can be found here.