Protecting Soil Through Conservation Agriculture, in Europe; Soil and Water & ProTerra Projects
Conservation Agriculture and the Environment
What is Conservation Agriculture?
- Minimum soil disturbance through conservation tillage rather than mouldboard ploughing
- Permanent plant or crop residue cover
- Diverse crop rotations to reduce the need for inputs.”
(p9, Jones et al, 2006)
See also: http://www.sowap.org/comms/pres/CA/CA15.htm
Where the conditions for Conservation Agriculture are right, the potential rewards to the environment, to society and future generations of farmers are significant. The benefits to current farmers in strengthening farm balance sheets or improving profit and loss accounts are harder to spot.
Conservation Agriculture and Soil Health.
The major threats to soil health are said to be:
- Soil Erosion
- Organic matter decline
- Surface Sealing
Generally it is soil erosion, organic matter decline, compaction and salinisation that frequently degrade good agricultural land; applying the principles of Conservation Agriculture can have a positive impact on the first three and possibly the fourth.
Soil erosion; natural soil erosion rates are hugely increased by agricultural activities which compromise soil structures. Soil structures are especially compromised by cultivation, in particular by mouldboard ploughing which
- rips apart the soil and also
- reduces earthworm populations and thus the network of earthworm tunnels (macropores) which encourage better drainage and conversely improve water retention.
Organic matter decline; Organic matter and organic carbon are important to soil health both as source of structure in itself and for sustaining a rich soil biota and thus nutrient recycling. The Conservation Agriculture principle of maintaining a permanent soil cover will entail either planting a cover crop or using crop residues. Both of these techniques will (eventually) increase the amount of organic matter and aorganic carbon available in the soil.
Compaction; A reduction in the number of passes over the soil due to a reduction in the number of tillage operations can reduce the risk of compaction. Conversely where the techniques of Conservation Agriculture are applied inappropriately, or excessive tillage used, compaction can be made worse.
Salinisation; secondary salinisation can be caused by inappropriate irrigation and poor drainage. Improved drainage achieved through an improved soil structure may help avoid salinisation.
Conservation Agriculture and Air Quality
- Fewer passes over the soil by agricultural machinery will reduce emissions due to agriculture.
- Improved soil structure will improve carbon sequestration (153Kb pdf file)
- Non-inversion of the soil avoids the release of carbon to the atmosphere.
Conservation Agriculture and Water
Soil erosion is problematic not only because of the loss of a virtually non-renewable resource but also because soil sediment and ‘attached nutrients’ can damage aquatic biodiversity by damaging the aquatic habitat in streams and rivers or ponds.
Improved soil structures achieved through the application of the techniques of Conservation Agriculture can also reduce run off thus reducing pollution from recently applied pesticides. Improved water retention allows natural processes to occur and soil biota to break down pesticides, reducing the pollution caused by leaching.
Conservation Agriculture and Habitats
As well as improving the habitat for soil biota and reducing the risk to aquatic habitats (see above), Conservation Agriculture can improve food supplies for birds and small mammals on farm land by leaving more seeds on the surface. This is especially important over winter when food can be scarce. However, there are indications that extending wildlife habitats from field margins and woodlands to open fields, can make those birds and small mammals more vulnerable to predators since open field habitats provide less cover
References and Bibliography
Holland, J. M. (2004). The environmental consequences of adopting conservation tilage in Europe: reviewing the evidence. Agriculture Ecosystems & Environment, 103(1), 1-25. (261.3 Kb pdf file)
Jones, C. A., Basch, G., Bayliss, A. D., Bazzoni, D., Biggs, J., Bradbury, R. B., et al. (2006). Conservation Agriculture in Europe: An approach to sustainable crop production by protecting soil and water? Jeallott's Hill, Bracknell RG42 6EY UK: SOWAP. (4,552 Kb pdf file).
Kertesz, A. (2004, 25-29 May). Conventional and conservation tillage from pedological and ecological aspects; the SOWAP project. Paper presented at the 4th International Congress of the European Society for Soil Conservation; "Soil conservation in changing Europe", Budapest, Hungary. (46 Kb pdf file)