Soil: Our Only Renewable Resource


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Sustainability South West Board Member and Organic Farmer, Cate le Grice Mack, presents on the value and importance of soil at the South West Observatory Land and Food Seminar.

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  • Soil forms through the action of weather and micro-organisms on the bedrock. As it forms it acts as the life support for an ever expanding world of flora and fauna. . In turn it too expands, and managed well provides an ever growing blanket of fertility, water retention and purification.
  • What is missing from this slide is the biomass: the macrofauna (worms etc), mesofauna (small invertebrates such as nemotodes and moluscs) and micro fauna (soil animals less than 0.3 mm in length) and micro flora (bacteria ,fungi, viruses etc etc). We still don’t fully know and understand the complexity and scale of soil micro organisms, but with every bit we find out we realise how spectacular and valuable they are: and how naïve we are about their interactions.
  • Input: total precipitation, mist and fog intercepted by foliage some transpired through leaves, some involved in photosynthesis, and some evaporated off Direct to the ground: the more foliage there is the less will reach the ground That which does reach the soil: *some is evaporated off (depending on saturateion of air) *some infiltrates the soil, either reaching roots to be taken up by plants, or penetrating the soil to reach round water or contribute to baseflow *the rest becomes runoff
  • Flash flood effect – poor soil – more total water into river system in shorter time span Good soil structure effect – less water total, and even more critically, distributed over much longer period with lower peak flow But it isn’t only water that is under that red line: there will be tonnes of fertility: the softer top layers of soil will be washed away far more readily in the red scenario than in the green: larger particles will have been removed and often the underlying bedrock disturbed. The red colour of the Brue or the Exe is the farmers’ fertility being washed away
  • Tell Stroud soil story
  • Active soils gain contributions of minerals from the bed rock Deep rooting plants contribute to this: for example lucerne has 2 metre roots, breaks up plough pans, traps N from the atmosphere and fixes it through bacterial activity within the soil, ready for slower release over months and even years.
  • Protecting organisms – eg be wary of such things as livestock wormers – the ivermectin story
  • Cow pats and rented land story Australian cowpats and the introduction of dung flies Dung beetles play a remarkable role in agriculture. By burying and consuming dung, they improve nutrient recycling and soil structure. They also protect livestock, such as cattle, by removing the dung which, if left, could provide habitat for pests and parasites
  • Soil: Our Only Renewable Resource

    1. 1. Soil – our only renewable natural resource! Opportunities for farming and landscape protection in the context of climate change
    2. 2. SOIL the basis of all <ul><li>Provides minerals and plant food in a controlled, steady manner in response to temperature and moisture </li></ul><ul><li>It is the only natural resource that can actually be increased by Man’s productive activity. </li></ul><ul><li>Soil forms through the action of weather and micro-organisms on the bedrock. As it forms it acts as the life support for an ever expanding world of flora and fauna. </li></ul><ul><li>In turn it too grows, and managed well provides an ever growing blanket for fertility, water retention and purification </li></ul>
    3. 4. Soil biomass <ul><li>The macro and meso fauna are large enough to be gathered and weighed: ranging from 2 to 5 t/ha (worms making up to 75% of this weight) </li></ul><ul><li>Micro fauna are almost impossible to weigh as they are so minute. Instead their value tends to be expressed more in terms of the number of different organisms in one cc of soil: for a rich soil it is calculated to be in the millions. </li></ul><ul><li>These are the elements of soil that turn vegetable and animal wastes into plant food, in turn transferring C arbon into growing crops </li></ul>
    4. 5. Hydrological cycle under woodland
    5. 7. Soil water retention <ul><ul><li>The thicker the vegetative cover </li></ul></ul><ul><ul><li>The deeper the soil </li></ul></ul><ul><ul><li>The higher the humus content of the soil </li></ul></ul><ul><li>More water will be retained and usefully employed in producing plants and crops </li></ul><ul><li>Less surface runoff and flooding </li></ul><ul><li>Higher water filtration through soils </li></ul>
    6. 8. How do we maximise the contribution of farming to food production and water quality 1 <ul><li>Farm for soil quality </li></ul><ul><ul><li>Work with the natural complexity of soil: adding artificial N P and K to increase yields upsets the natural chemistry in the soil, changes its Ph (acidity) and affects the myriad organisms within in largely unknown ways </li></ul></ul><ul><ul><li>Use methods which increase fertility when crops are able to take it up – eg muck spreading onto growing crops, using plant mulches to fix N deep into the soil for slow release </li></ul></ul>
    7. 9. How do we maximise the contribution of farming to food production and water quality 2 <ul><li>Farm for protection of the organisms that naturally occur within our environment and climate </li></ul><ul><li>Protect soil structure: reduce disturbance and soil loss. </li></ul><ul><li>Seeking to grow the soil, through restoring vegetative matter and enhancing soil activity </li></ul>
    8. 10. How do we maximise the contribution of farming to food production and water quality 3 <ul><li>Cultivate native or long established plants and livestock that are adapted to our climate, seasons and flora/fauna </li></ul><ul><ul><li>Eg native cattle and sheep; clovers, native herbs and grasses </li></ul></ul><ul><ul><li>Understand and encourage the roles of macro organisms in distributing fertility in the soil and reducing pest invasions </li></ul></ul>
    9. 11. Farming for food and biodiversity 1. biodiversity aiding food production
    10. 12. Farming for food and biodiversity 2. Biodiversity aiding the wider farm economy
    11. 13. And finally – the SW <ul><li>Blessed with a rich variety of soils </li></ul><ul><li>The perfect growing climate </li></ul><ul><li>A strong market for food on its doorstep </li></ul><ul><li>A population aware more than many of the role of the open countryside in quality of life and food </li></ul><ul><li>A long tradition of dairying, meat production, orchards, horticulture and all the skills that go with it </li></ul>
    12. 14. BUT…….. <ul><li>- Farming is pushed into solely a primary production role for the raw ingredients of food </li></ul><ul><li>The profit making part of the food chain is largely taken away from farmers </li></ul><ul><li>They no longer control the final price of their product </li></ul><ul><li>Increasingly they are at the mercy of the business decisions of others – from supermarkets to seed companies </li></ul>
    13. 15. SO……… <ul><li>Increase the skills base in training – from soil management to marketing </li></ul><ul><li>Shorten the supply chain </li></ul><ul><li>Raise confidence of farmers through engagement in their future </li></ul><ul><li>Develop further the already welcome reimbursement for public goods </li></ul><ul><li>Require supermarkets and processors to sign up to a total vision for farming and a healthy rural society and environment in the SW </li></ul>