|
1. Definition
| Name |
TILLAGE
DIRECTION |
| Brief
definition |
The soil can be tilled
in various directions parallel or perpendicular to the contour
lines or in oblique lines depending on the slope gradient,
the farm size and farm shape. When the physiographic conditions
allow the movement of tractor along the contour lines, then
soil displacement is reduced. In hilly areas with steep slopes,
where contour farming is impossible, the soil is ploughed
in directions perpendicular to the contour lines or in oblique
lines favouring tillage erosion.
 |
Deep
ploughing of soil in the up-slope direction and perpendicular
to the contour lines (photo by C. Kosmas) |
|
| Unit
of measure |
Direction
of tillage |
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 desertification
risk of an area. |
| Importance
with respect to desertification |
Tillage
erosion caused by various implements can be considered as the
major degradation and desertification process in cultivated
hilly areas. The downslope soil displacement from upper convex
landscape positions and deposition in lower concave landscape
positions reduces significantly rooting depth and therefore
soil water storage capacity in the upper sloping areas. The
rate of soil displacement is related to the tillage direction. |
| International
Conventions and agreements |
The CCD emphasizes
that in order to combat desertification it must be tackled within
the general framework of measures that promote sustainable development.
|
| Secondary
objectives of the indicator |
Tillage
direction affects tillage erosion as well as surface water runoff
erosion. By ploughing the soil perpendicular to the contour
lines water rill erosion is highly induced. |
4. Methodological
description and basic definitions
| Definitions
and basic concepts |
Soil displacement is generally
greater for all ploughing depths for the perpendicular to
the contour lines tillage operation than for contour tillage.
Ploughing the soil perpendicular or parallel to the contour
lines (contour farming) with the plough layer moving to the
upslope direction tillage erosion is minimized. The rate of
soil displacement by tillage is related to the diffusion constant,
slope gradient, tractor wheel speed, ploughing depth, etc.
Studies have shown that diffusion constant increases almost
linearly with increasing soil depth for the case of contour
ploughing. In contrast, diffusion constant increases exponentially
with increasing plough depth for the perpendicular to the
contour lines tillage operation.
 |
Soil
diffusion constant (k) measured for three plough depths
and two tillage operations (Gerontidis et al., 2001). |
Studies conducted in hilly
areas of Greece with steep slopes (slope gradient >22%)
have shown a downslope displacement greater than 97 cm after
ploughing the soil at the depth of 40 cm and perpendicular
to the contour lines. Under the same soil conditions and management
practice, soil displacement was reduced to 69 cm after ploughing
the soil along the contour lines. The up slope reversion of
furrow with the tractor moving parallel or perpendicular to
the contour lines can significantly reduce soil displacement
by one third or less compared to downslope reversion of furrow.
Soil loss due to tillage can be minimized by making plans
for each farm for the directions of ploughing the soil each
year so that the down soil displacement to be about equal
to the up slope displacement.
|
| Benchmarks
Indication of the values/ranges of value |
- downslope
- upslope
- parallel to contour
upslope furrow
- parallel to contour
downslope furrow
- downslope oblique
- upslope oblique
|
| Methods of
measurement |
By checking
in the field or advising the land user. |
| Limits of the
indicator |
This indicator
is especially important for hilly cultivated areas. There is
no any meaning for plain areas. |
| Linkages
with other indicators |
Slope
gradient, Tillage operations,
Soil depth, Rock
fragments, Soil erosion,
Vegetation cover, Water
storage capacity. |
5. Evaluation
of data needs and availability
| Data required
to calculate the indicator |
Dominant tillage
direction for each parcel inside a farm.
|
| Data sources |
Necessary data
are usually available and accessible and the cost/benefit ratio
is reasonable. |
| Availability
of data from national and international sources |
Data
cannot be obtained from various regional, national or international
institutions involved in the collection and analysis such data.
The most accurate information can be obtained from the land
user.
|
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 |
Gerontidis St., Kosmas,
C., Detsis, V., Marathainou, M., Zafiriou, Th., and Tsara,
M. 2001. The effect of mouldboard plough on tillage erosion
along a hillslope. Soil and Water Conservation J. 56:147-152.
Govers, G., Vandaele,
K., Desmet, P., Poesen, J., and Bunte K., 1994. The role of
tillage in soil redistribution on hillslopes. European Journal
of Soil Science. 45: 469-478.
Guiresse, M., and Revel,
J.C., 1995. Erosion due to cultivation of calcareous clay
on hillsides in south-west France. II. Effect of ploughing
down the steepest slope. Soil and Tillage Research. 35:157-166.
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.
|
| Contacts
Name and address |
Agricultural
University of Athens
Dr Constantinos Kosmas
email: lsos2kok@aua.gr |
|
