|
1. Definition
| Name |
TILLAGE
OPERATIONS |
| Brief
definition |
Tillage operations includes
the cultivation practices conducted by the various tillage
implements such as mouldboard, chisel, duckfoot chisel, harrow,
etc. The downhill redistribution of soil by tillage implements
has been defined as tillage erosion. It is considered as the
main cause of land degradation and desertification in hilly
cultivated areas in Mediterranean region. There are several
factors affecting tillage erosion such as type of tillage
instrument, plough depth, wheel speed of the tractor, soil
moisture content, slope gradient, direction of tillage operation,
etc.
 |
Hilly
areas cultivated with olives and subjected to high rates
of erosion as detected from the lowering of soil surface
around the trees for about 70 cm (photo by C. Kosmas)
|
|
| Unit
of measure |
Number
of tillage operations per year |
2. Position
within the logical framework DPSIR
| Type of Indicator |
Driving force |
3. Target and
political pertinence
| Objective |
Contribution
to the definition and mapping of ESAs and evaluation of the
desertification risk of an area. |
| Importance
with respect to desertification |
Tillage erosion
resulting from tillage operations is considered as a major degradation
process in cultivated hilly areas. Tillage erosion has a great
impact on the productivity of cultivated hilly areas. Redistribution
of topsoil from the upper landscape positions by the various
tillage operations reduces significantly the effective soil
depth and the water holding capacity which is the most serious
long term loss, restricting production. Under adverse climatic
conditions, such as those prevailing in the Mediterranean region,
production of rainfed crops has rapidly declined and farming
is no longer profitable Furthermore, tillage erosion exposes
subsoil, which may be highly erodible by wind or water, and
fills in ephemeral blow areas, acting as a delivery mechanism
for water erosion. The various tillage implements cause various
erosion rates. For example a tandem disk may be more erosive
than a mouldboard plough operation because it translocates more
soil with greater variability throughout the landscape. The
chisel plough may be equally erosive as the mouldboard plough.
Large aggressive tillage implements, operating at excessive
depths and speeds are more erosive than conventional ones |
| International
Conventions and agreements |
The CCD emphasizes
that combating desertification must be tackled within the general
framework of actions to promote sustainable development.
|
| Secondary
objectives of the indicator |
Within
the ESA model investigation of the individual processes linked
to land degradation and desertification.
|
4. Methodological
description and basic definitions
| Definitions
and basic concepts |
In hilly areas along the
northern Mediterranean cultivated with cereals, vines, almonds,
olives, etc, farmers use to till the soil at least once by
a mouldboard following by disc harrow if a seed bed has to
be prepared. Soils are mouldboard ploughed at depths ranging
from 25 to 40 cm in directions from parallel to perpendicular
to the contours. Several studies have shown that there is
an important net soil flux down-slope as the result of tillage
implementation. Soil is displaced from the upper hillslope
positions (convexities and linear parts) and deposited in
the lower hillslope positions (concavities).
 |
Changes
in Distribution of water holding capacity due to tillage
erosion along a hillslope (Kosmas et al., 2001) |
Tillage erosion affects
chemical and physical properties of soils such as organic
matter content, available nutrients, soil structure stability,
water holding capacity, etc. It exposes subsoil materials
in the soil surface with low fertility and high content of
rock fragments in many cases.
Ploughing depth and tillage
direction are very important factors controlling downslope
soil displacement. Measurements have shown that the rate of
soil loss from the upper steeper slopes can range from 0.2
to 1.4 cm, depending on slope gradient and surface characteristics.
|
| Benchmarks
Indication of the values/ranges of value |
|
| Methods of
measurement |
By conducting
the land user or the extension services of the related institutes.
|
| Limits of the
indicator |
Tillage operations
and tillage erosion are especially important for hilly cultivated
areas. It is not important in plain areas where soil displacement
is limited. |
| Linkages
with other indicators |
Tillage
direction, Slope gradient,
Soil depth, Soil
texture, Rock fragments,
Soil organic matter content, Soil depth |
5. Evaluation
of data needs and availability
| Data required
to calculate the indicator |
Ploughing or
not ploughing of the study area.
|
| Data sources |
Necessary data
are usually available and accessible for a region depending
on the land use type. |
| Availability
of data from national and international sources |
Data
can be easily obtained from various regional, national or international
institutions and land users or using aerial-photographs taken
the period of cultivating the land.
|
6. Institutions
that have participated in developing the indicator
| Main institutions
responsible |
Agricultural
University of Athens
|
| Other contributing
organizations |
Universities
of Lisbon, Murcia, Basilicata, Amsterdam, Leeds
|
7. Additional
information
| Bibliography
|
TERON project
- Tillage erosion: current state, future trends and prevention.
Contract: FAIR3-CT96-1478 |
| Other references |
Govers, G., Vandaele,
K., Desmet, PJJ Poesen, J. & Bunte K., 1994. The role
of tillage in soil redistribution on hillslopes. European
Journal of Soil Science 45, 469-478.
Govers, G., Quine, TA.,
Desmet, PJJ & Walling DE 1996. The relative contribution
of soil tillage and overland flow erosion to soil redistribution
on agricultural land. Earth Surface Processes and Landforms
21, 929-946.
Kosmas, C., Gerontidis,
St., Marathianou, M., Detsis, V., and Zafiriou, Th., Nan Muysen,
W., Govers, G., Quine, T., and Vanoost, K. 2001. The effect
of tillage erosion on soil properties and cereal biomass production.
Soil & Tillage Research J. 58:31-44.
Lobb, D.A., Kachanoski
R.G. & Miller M., 1999. Tillage translocation and tillage
erosion in the complex upland landscapes of south-western
Ontario, Canada. Soil Tillage Research Journal 51, 189-209.
Tsara, M., Gerontidis,
S., Marathianou, M., & C. Kosmas, 2001. The long-term
effect of tillage on soil displacement of hilly areas used
for growing wheat in Greece. Soil Use and Management, Vol.
17, pp. 113 - 120.
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| Contacts
Name and address |
Agricultural
University of Athens
Dr Constantinos Kosmas
email: lsos2kok@aua.gr |
|
