Agriculture Reference
In-Depth Information
Table 5. Example of structure of soil data info table
(000 hectares)
SOI LS_I D CART_UNI T
FLW_CODE
FLW_LIMITA
SPR_CODE
SPR_LI MI TA DROP_CODE DROP_LI MI TA CLASS_SLOPE RANGE HECTARES
MODERATELY
SUI TABLE
MODERATEL Y
SUITABLE
1
AB08UC2203
NOT SUITABLE
PE, T
PE T
T
4
5-13%
897.035
2
999
URBAN AREAS
URBAN AREAS
URBAN AREAS
1
0-1%
2.739
MODERATELY
SUI TABLE
MODERATELY
SUI TABLE
MODERATEL Y
SUITABLE
7
AB08UC2202
PE, T
PE T
T
2
1-3%
118.523
MODERATELY
SUI TABLE
MODERATELY
SUI TABLE
MODERATEL Y
SUITABLE
10
AB08UC2202
PE, T
PE T
T
2
1-3%
5.897
MODERATELY
SUI TABLE
MODERATEL Y
SUITABLE
12
AB08UC1101
NOT SUITABLE
D
D
D
3
3-5%
4.055
MODERATELY
SUI TABLE
MODERATELY
SUI TABLE
MODERATEL Y
SUITABLE
14
AB08UC2101
PE
D
D
2
1-3%
51. 196
MODERATELY
SUI TABLE
MODERATEL Y
SUITABLE
16
AB08UC1101
NOT SUITABLE
D
D
D
3
3-5%
12. 385
FIELD LEGEND - SOILS_ID: polygon unique id; CART_UNIT: code of Soil Cartographic Unit; FLW_CODE: soil suitability class
for Flowing technique; SPR_CODE: soil suitability class for Sprinkler technique; DROP_CODE: soil suitability class for Drop
technique; *_LIMITA: Soil Main Limitation codes for each technique.
Three thousand soil pedons inside the irrigated area have been evaluated with this
criteria. The results have been reported in the soil cartographic units and organised in the
GIS info table.
Land sustainability to irrigation practices and evaluation of the water nominal
and real needs
The conceptual framework in establishing the correlation between soil suitability and
irrigation is based on the FAO studies about the “Land productivity index 6 and economic
measures of suitability” ( Guidelines: Land Evaluation for Irrigated Agriculture - FAO
Soils Bulletin 55, Land and Water Development Division, Rome 1985).
Starting from the FAO Land productivity index concept, the relationship between the
productivity index and water volumes has been estimated, based on the assumption that
the overall agronomic efficiency of water use (F ag 7 ) doesn't change in the time. On this
basis, per each map unit with same soil, land use, and irrigation technique, the soil
suitability reduction factors has been directly related to the nominal normalised water
needs in the calculation of the real CWR (Table 7.).
6.
“Land Productivity Index: this is defined as the physical productivity of land for a specific land
use, relative to that of the best land. Relative yield can be a convenient land productivity index.
This is the yield per hectare relative to that of the best land as a percentage or fraction. Thus the
top yields of Class S1 land for a given Land Unit may be taken as 100% or 1.0, the top of s2 as a
fraction of S1 (e.g. 80% or 0.8), S3 as 0.6, etc. as appropriate. Other standards such as absolute
yields or relative production can be used as alternative measures of physical productivity.
Productivity may be for a present or potential suitability classification. It would normally be
necessary to use a physical land productivity index in reconnaissance studies and as a necessary
preliminary to economic evaluation.”
7.
F ag = P/U; the ratio of crop production (total dry matter, or the gross product) on the used water
volume.
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