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Land Use and Water Management in Rainfed Agriculture for Enhanced Systems Productivity:The case of Vertisol Areas in the Blue Nile Basin T. Erkossa 1, A. Haileslassie 2, C. MacAlister 3
Nile Basin Development Challenge (NBDC) Science Workshop
Addis Ababa, Ethiopia, 9–10 July 2013
Agriculture- Crop and Livestock farming is the main source of livelihood in the basin
Challenges to Agriculture in the Basin:– Extreme biophysical variations – Population pressure and land degradation
Shortage of landEncroachment to marginal landsReduced land and water productivity (average
grain yield < 1 T/ha)– Lack of site specific technologies
• Limited use of improved technologies
Incr
ease
d po
vert
y, fo
od in
secu
rity
&
Vuln
erab
ility
to c
limat
e ch
ange
Required: Identification +Disseminate of Site specific Technologies
Introduction
The Case of Vertisolso Among the high potential
soils o Located in areas with
favorable climateo LGP ranges from 120-190
dayso About 12 million ha in
Ethiopiao 12% of the Abay Basin (≈ 12% of the Abay Basin (≈
2.7 million ha)2.7 million ha)o
o Productivity is constrained by their hydro-physical characteristics
o Severe water logging during rainy season
Required level
Deficit
Water Management Challenges
Growing Season
Excess Water logging
Deficit
Agricultural Constraints of Vertisols
• Traditional: Late planting on flat beds- Late planting on flat beds- crops grow on crops grow on
residual moistureresidual moisture Tolerant crops- Tolerant crops- low yielding or not preferable low yielding or not preferable • Hand made BBF- Hand made BBF- backbreaking taskbackbreaking task
Management Options
Hand made BBF
BBF made by BBM
• Improved: Surface drainage (BBF)- Surface drainage (BBF)- made by animal made by animal
powerpower Tolerant and high yielding cropsTolerant and high yielding crops
CROPWAT: ETc and Eff. rain
Vertisols
Drainable (2-5%) slope
Undrainable (<2% slope)
Alternatives
Weather, soil, Climate
National Met. Stations,
NewLocClim Estimates
Surface drainage + Early plantingFlat bed + Late Planting
System WP
Livestock WP
Livestock feed (Straw)
Crop WP
Tolerant and high yielding cropsNatural pasture
Crop yield: field monitoring, research reports
18/11/2009, Addis AbabaSupported by: CPWF
• Globally agriculture accounts for 70% of all fresh water withdrawals and 90% of the consumption
• Agricultural WP increase by 1% means 10% increase in water availability for other uses
• Rainfed agriculture dominates the farming system (>90%)
• Improving WP of the rainfed system enhances livelihood in the US and increases water availability for the DS
Why Agricultural Water Productivity
Location and year
Grain Straw
BBF Flat % increase due to BBF
BBF Flat % increase due to BBF
Enewari (1986) 1105 1072 3 1590 1543 3
Dogollo (1986) 1844 1258 47 2654 1810 47
Dejen (1987) 1263 918 38 1817 1321 38
Bahir Dar (2007)
2600 2000 30 3741 2878 30
Merawi (2007) 1700 600 183 2446 863 183Bichena (1997) 1600 900 78 2302 1295 78
Average 1685 1125 63 2425 1618 63
Location and year Grain WP with respect to eff.
rainfall (kg m-3)
WP with respect to actual ETc (kg m-3)
BBF Flat % increase due to BBF
BBF Flat
Enewari 19860.23 0.22 5 0.37 0.99
Dogollo 19860.32 0.22 45 0.58 0.49
Dejen 19870.22 0.16 38 0.42 0.77
Bahir Dar 20070.34 0.26 31 0.93 0.82
Merawi 20070.30 0.10 200 0.54 0.50
Bichena 19970.34 0.19 79 0.53 0.83
Average 0.33 0.24 57 0.66 0.89
Land Preparation Methods Effect on Grain WP of wheat with respect to eff. rain and ETc
Location Gross return (USD ha-1)*
WP (USD m-3)
BBF Flat BBF Flat % increase due to BBF
Enewari 1986 545 529 0.12 0.11
3
Dogollo 1986 910 621 0.16 0.11
47
Dejen 1987 623 453 0.11 0.08 38Bahir Dar 2007 1282 986 0.17 0.13
30
Merawi 2007 839 296 0.15 0.05
183
Bichena 1997 789 444 0.16 0.09
78
Average 831 555 0.14 0.09 56*Wheat grain price estimated @ 0.4932USD kg-1
Effect of Land use on WP with respect to effective Rainfallof Undrainable Vertisols
Land use Average grain
yield (kg ha-1)
Average eff.
rain (m3 ha-1)
Grain WP
(kg m-3)
Biomass (grain + straw)
WP (kg m-3)
Rice 3596 7900 0.46 1.0Grass-pea 4662 7900 4895 1.8Natural pasture
Biomass (kg ha-1) Average eff.
rain (m3 ha-1)
2793 6330 0.44
Results- Undrainable Areas
Integration (Systems approach)
• Improving crop water productivity
• Value addition: Feed crop residue to livestock
• Improving livestock productivity• Improve livestock
management • Improve crop-livestock
System Productivity
Example: Crops - livestock
US
D h
a -1
• BBF increased crop yield and WP with respect to effective rainfall, and reduced evaporation loss
• Growing rice increased overall WP despite increased water consumption, due to its reduced evaporation
• Use of BBF on drainable land and rice on flat land increased Economic WP
• Integrating crop-livestock system; for example through feeding the crop residues to the livestock enhanced overall SWP