1. Christine Watson November 2015
Why does soil matter?
Christine Watson
November 2015

2. What is soil? What is soil made up of? Air Mineral Water Organic
material
Mineral
“Each soil has had its own history. Like a river, a mountain, a forest, or any natural thing, its present condition is due to the influences of many things and events of the past.” - Charles Kellogg, The Soils That Support Us, 1956
Willie Towers, JHI

3. Why is soil organic matter important for production?
Source of nutrients
Soil structure – small changes give big effects
Water holding capacity
Cation/anion exchange capacity
Soil organic matter = soil organisms + partially decomposed plant and animal residues

4. Soil carbon in Europe
Globally, twice as much carbon is stored in soils as is present in the atmosphere. This is both a threat and an opportunity. The threat is land use change. The opportunity is carbon storage. (Smith, 2012)
The world’s cultivated soils have lost 50 to 70 percent of their original carbon stock. (Lal, Ohio State Uni)
Nearly 50% of European soils contain very low levels of SOM (0-2%), which has been caused by agricultural intensification (Quinton et al. 2010)
Joint Research Centre,
European Commission 2005

5. Soil biodiversity
Soil is home to a quarter of our planet's biodiversity which is essential for food security and nutrition
A single gram of soil may contain millions of individuals and several thousand species of bacteria.
Soil is alive and it is the soil organisms (big and small) that are the engine
Soil biodiversity is (generally) not cute!

6. Fertiliser & manure Crop rotation Variety Drainage Tillage
Agrochemicals
Drainage
Tillage
Biodiversity
Soil fertility
Soil organic matter
Soil structure 6

7. Impact of crop diversification on soil carbon
Monoculture
Rotation
Rotation +
Cover crop
Baseline
+3.6% soil C + 5.3% total N
+8.5% soil C % N
20.7% soil microbial biomass
McDaniel et al Ecological Applications 24: 560–570

8. Inter-linkages between soil management, carbon flows and stocks, and crop yield (SMART SOIL project)
OTHER ECOSYSTEM
SERVICES
CROP
GROWTH
YIELD
Biological
Chemical
Physical
Water
Nutrients
Health
SOIL FUNCTIONS
SOIL PROPERTIES
SOIL
TYPE
CARBON
FLOWS
CARBON STOCKS
CARBON
STORAGE
MANAGEMENT

9. Changes in soil organic carbon content in the plough layer (0–23 cm) in three treatments of the Broadbalk Wheat Experiment at Rothamsted Research, UK.).
Annual treatments are: , no fertilizers or manure applied since 1844; , PKMg plus 144 kg N ha−1 since 1852; , farmyard manure at 35 t ha−1 fresh weight applied since 1885 plus 96 kg N ha−1 since Data from Rothamsted Research.

10. Changing soil organic carbon content
CO2 emission C sequestration
Monocrops
Ploughing
Burning residues
Bare soil
Residue removal
Negative nutrient balance
Cover cropping
Green manures
Leys
Diverse rotation
Manures/biosolids
Min till
Agroforestry
Forage legumes

11. David Atkinson

12. Soil degradation

13. Trade-offs……great expectations

14. Some more challenges associated with soil and food security
Joined-up approaches to soil protection and resource management
Social acceptability (urban and peri-urban issues) - closing the loop – food waste and sewage
Technology – precision approaches
Diets……
Fundamental understanding – scientific frontiers
Our ability to adapt to changes and challenges! - knowledge, technology, policy, ethics, economics…

15. SOIL is a non renewable resource
“We abuse land because we regard it as a commodity belonging to us. When we see land as a community to which we belong, we may begin to use it with love and respect.” - Aldo Leopold, A Sand County almanac.