106 M. Smith Agricultural and Forest Meteorology 103 2000 99–108
Table 3 :CROPWAT–Calculated crop evapotranspiration and irrigation requirements for spring wheat at Bishkent, Uzbekistan
a
Month Dec
Stage Coefficient
ET
crop
ET
crop
Effective Rain Irrigation require-
Irrigation require- K
c
mmday mmdec
mmdec ment mmday
ment mmdec April
1 Init
0.50 1.39
11.1 23.4
0.00 0.0
April 2
Init 0.50
1.75 17.5
40.0 0.00
0.0 April
3 Init
0.50 1.83
18.3 31.1
0.00 0.0
May 1
InDe 0.59
2.20 22.0
19.0 0.29
2.9 May
2 Deve
0.80 3.09
30.9 11.8
1.91 19.1
May 3
Deve 1.05
4.65 51.2
9.0 3.83
42.1 June
1 DeMi
1.19 6.01
60.1 5.7
5.43 54.3
June 2
Mid 1.20
6.73 67.3
2.0 6.53
65.3 June
3 Mid
1.20 7.12
71.2 2.7
6.85 68.5
July 1
Mid 1.20
7.76 77.6
4.0 7.36
73.6 July
2 MiLt
1.11 7.65
76.5 4.3
7.22 72.2
July 3
Late 0.91
5.62 61.9
4.0 5.26
57.8 August
1 Late
0.70 3.76
37.6 3.4
3.42 34.2
Total 603.1
160.4 490.2
a
Rain climate station: Bishket-7; ET
o
climate station: Bishhket-7; Crop: spring wheat; Planting date: 3 April.
spells on crop production due to water stress, based on the methodologies presented in FAO Irrigation and
Drainage Paper No. 33 ‘Yield response to water’ Doorenbos and Kassam, 1979.
An printout of the standard CROPWAT calculations showing the crop evapotranspiration and irrigation re-
quirements of spring wheat in Central Asia is included in Table 3.
Table 4 provides an example of the water balance calculations, with an assessment of the effects of rain-
fall and irrigation on yield and water use efficiency. The results show that water stress occurring in the matur-
ing phase causes a substantial yield reduction 21.7. The irrigation application has been fully effective, but
rainfall is exceeding actual requirements, resulting in losses.
5. WMOFAO roving seminars
Adequate strategies and policies need to be defined in order to come to effective national programmes in
drought management and effective water use for crop production. To assist member countries to strengthen
the national capacity to plan and manage national pro- grammes for sustainable rainfed and irrigated crop pro-
duction, FAO in close cooperation with the WMO, developed a special training programme on the
application of climatic data for effective planning and management of sustainable irrigated agriculture. Two
week roving seminars are organized on request of mem- ber countries to train staff from national meteorologi-
cal services and irrigation and agricultural agencies on recommended methodologies for more effective and
sustainable use of water in irrigated agriculture. Since 1991, roving seminars have been organized in over 25
countries.
The course introduces basic concepts on climate and soil–water–plant relationships, and provides practical
training on computerized procedures to determine ef- fective rainfall and variability assessment, potential
evapotranspiration, crop water requirements, and crop response to water stress. With practical examples,
trainees are instructed in the use of specialized com- puter software and how to determine the yield level
for rainfed crops under varying rainfall patterns and drought conditions, and the water supply for irriga-
tion of various field crops under different management conditions.
Within the framework of the United Nations Con- vention to Combat Desertification UNCCD, initia-
tives are presently made to develop roving seminars on drought management and mitigation in order to develop
and strengthen the national capacity in the planning and implementation of National Action Plans NAPs and
in the use and application of climatic data for drought preparedness and the management of sustainable agri-
culture.
M. Smith Agricultural and Forest Meteorology 103 2000 99–108 107
Table 4 CROPWAT -Evaluation of irrigation scheduling for spring wheat at Bishkent, Uzbekistan
108 M. Smith Agricultural and Forest Meteorology 103 2000 99–108
6. Conclusions
