countrysmallholding.com76 Country Smallholding April 2019

W hen you wander across your fields, do you gaze with pride

at lush perfect uniformity, or feel a little embarrassed at the proliferating weeds, or do you welcomingly embrace traditional diversity?

Regardless of what you start with, how you manage your grazing will have the greatest impact on what you see. And what you see above ground is giving you feedback on what is going on below ground in the soil food web, and about the health of the life in your soil. Soil health determines plant health, growth and productivity, as well as the health and vitality of your livestock and the flavour and nutritional value of their meat or milk.

Soil health also drives which plants will flourish and

proliferate in a given pasture which, in turn, regulates how much carbon can be sequestered (stored) in the ground, building soil organic matter, fertility and long-term resilience.

To understand all these connections, we need to take a brief glimpse into the complex world beneath our feet. In every teaspoon of healthy soil there are over 1bn micro-organisms. And, just like above ground, there is an underground food chain with predators and prey, life, reproduction and death. At the very bottom of the food chain are bacteria and fungi that live in the root zone, the rhizosphere, of plants. And again, just like above ground, the food source for these bacteria and fungi relies on the sun, or, more specifically, on the energy provided by

the sun to photosynthesising plants.

Sunlight energy is the basis of all life on earth and in the earth. The micro-organisms living in the rhizosphere are fed sap from the plant which it exudes from its roots. These are called root exudates. During photosynthesis plants suck in carbon dioxide from the atmosphere through the stomata in their leaves and, combined with water, they produce oxygen, which is released, and they use the carbon to grow.

Carbon is the basic building block for plants, as with all life, but plants, like us, need more than carbon. To obtain the other nutrients plants have evolved a beautiful symbiotic relationship with soil micro-organisms in what is called the Poop Loop, which goes like this:

The world beneath our Wellingtons

In the first of a three-part series on grazing and pasture management, Christine Page looks at soil health, which in

turn determines plant health, growth and productivity

Soil health drives which plants will flourish and proliferate

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ABOVE: Plants have evolved a symbiotic relationship with soil micro-organisms in what is called the Poop LoopBELOW: The more diverse the pasture, the more diverse the underground species and the more resilient and productive the land will be

Soil health n

Photosynthesising plants use carbon to make and secrete liquid sugar via their roots to feed symbiotic soil microbes. The food source stimulates reproduction, bacteria multiply rapidly and are predated by other micro-organisms, such as nematodes and protozoa, which, once they have gobbled up their prey, excrete a highly nutritious, mineral-rich poop right in the root zone for the plant to absorb.

So vital are the nutrients given back to the growing plants via the Poop Loop that plants will ‘give away’ as much as 40% of the carbon they have taken in from the atmosphere as root exudates. This precious liquid carbon energy source primes a myriad of underground activity and, once incorporated via soil-microbial lifecycles, along with root biomass, dung from livestock and trampled plant litter, this carbon will form new soil by building organic matter through the processes of carbon sequestration and humification.

How efficiently the Poop Loop functions determines how much carbon we can sequester, how much soil fertility we can build, how fast our grass grows and, therefore, both the number of livestock our land can carry and their health. And our grazing practices have a direct impact on this natural cycle, by either supporting or hindering it.

THE ‘STOMACH’ OF THE PLANTThe green leaves of plants capture sunlight like solar panels, the more leaf area, the more energy captured, the more carbon available for the plant to grow and make food for microbes. Where leaves are grazed short the plants lose their ability to make energy, so they conserve what stores they do have, slow down or even stop feeding the soil microbes and the Poop Loop grinds to a halt.

Another aspect to consider for a healthy soil food web is diversity: that teaspoon containing 1bn micro-organisms includes many tens of thousands of different species, each with a specialised function (and many yet to be identified by soil scientists). Every species of

grass or forb in your pasture will have symbiotic relationships with different soil micro-organisms. The more diverse the pasture, the more diverse the underground species, the more resilient and productive it will be.

Plants also have different micro-nutrient needs throughout their lifecycle, whether in fast early growth, reproduction or, for example, if under attack by pests or other encroaching plants. Many of the aroma and flavour compounds plants produce are made to either attract or deter other flora or fauna. To synthesise these compounds require energy and nutrients which the plant needs to prioritise away from other vital growth and survival functions.

Plants with plenty of photosynthesising leaf area and the greatest access to nutrients, via the Poop Loop from a healthy diverse soil microbial world, can afford to expend energy in developing robust defence and attraction mechanisms. They will have cultivated symbiotic relationships with a multitude of different soil micro-organisms to ensure that they are provided with the micro-nutrients they need at the right time. In effect, soil is the stomach of the plant.

Conversely, plants grown in poor soils, or those that have been over-grazed, will not only lack access to a diversity of soil-microbes, but lack the leaf area to generate the energy to feed those that are there. These plants will, therefore, lack vigour, flavour and be less nutritious.

This is why vegetables grown organically at home almost always taste better than shop bought industrially produced veg. This is also why the meat or milk from livestock raised on diverse, healthy pasture has significantly better flavour and nutritional profile than the mass-produced equivalent. And providing your livestock with a nutritious, mineral-rich food source, by giving them access to diverse pastures, means that they can self-medicate to keep themselves healthy naturally too. 4

countrysmallholding.com78 Country Smallholding April 2019

IGNORE AT YOUR PERILPlants are further connected underground by mycorrhizal fungi creating a complex intimate network of fibres that move water, minerals and even send chemical messages between plants and soil organisms. It is a fascinating world that we ignore at our peril.

Now is the time to embrace a return to more traditional mixed species, each with different rooting depths. As microbes track root growth, deeper rooting plants encourage microbial activity deep in the soil, providing access to more nutrients and water, sequestering more carbon and further building soil health and depth.

As weather patterns become more extreme, with heavier rain events and longer droughts, a deep, fertile, healthy soil will become priceless. Modern grass species, like the shallow-rooting perennial rye grass bred to be fed on artificial fertiliser, which breaks the plant-to-soil microbe bridge, will become less attractive.

Healthy soils with diverse, deep-rooting pasture species have amazing water retention capacity as every gram of additional soil carbon stored

holds 8g of water. Thus, every 1% increase in organic matter increases the water holding capacity of soil by 80,000ltr per acre, which is close to an inch’s worth of rain. This means that not only in a drought will you have more water available for your grass to grow, but with heavy rain your soil acts like a sponge, soaking up water, helping to alleviate run-off, soil erosion and down-stream flooding. And, of course, all the time the carbon is locked in the soil it is not up in the air heating the planet.

Every plant has a purpose, fulfilling its role in ecological succession and, once fulfilled, it paves the way for the next species to take over, thus increasing diversity and soil health. And as soil health improves, building organic matter, grass growth rates also speed up in a positive feedback loop. It can take three to four years of good grazing practice to finally see marked improvement, but when it does come we see exponential growth and livestock will be more robust and less prone to disease, fly strike or illness.

Having delved a little into life below ground, will you view your pastures with a little more

compassion? Will you think of that world beneath your feet? What messages might your plants be conveying. Are they relaying a plea for help by starving soil microbes?

We may think of ourselves as producing food by grazing pastures and turning that grass into meat or milk, but really we are all light farmers and our aim should be to capture as much sunlight as possible on green growing leaves in symbiosis with healthy soils, then the natural outcome will be productive, healthy livestock and nutritious food. n

Next month: How the compounds in ruminant saliva stimulate grass growth and how you can replicate nature using holistic grazing practices to fuel that underground world with liquid carbon by maximising photosynthesis, supporting healthy plant growth and, following grazing, give the plants the right amount of rest to recover before being grazed again.

Christine Page runs events on soil health and holistic grazing management at her farm in south Shropshire. For more information, visit www.smilingtreefarm.com.

BELOW:Herbal leys — healthy soils with diverse, deep-rooting pasture species have amazing water retention capacity

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