Realizing the benefits of cover crop legumes in smallholder crop-livestock systems of the hillsides...
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Realizing the benefits of cover crop Realizing the benefits of cover crop legumes in smallholder crop-livestock legumes in smallholder crop-livestock
systems of the systems of the hillsides of Central Americahillsides of Central America
Trade-off analysis of using legumes for soil enhancing or
as animal feed resource
M. Quintero, R. D. Estrada, F. Holmann, I. Rao, S. Martens, M. Peters, R. Van der Hoek, M. Mena,
S. Douxchamps, A. Oberson, and E. Frossard
Presentation: CGIAR Systemwide Livestock Programme
Livestock Policy Group, 1 December 2009
BackgroundCGIAR-SLP funded CIAT-ILRI-INTA-ETHZ Project
Lead Center: CIAT
Collaborating Institutions: ILRI, INTA-Nicaragua,
ETHZ-Switzerland, University of Zurich
Project duration: 3 years
Project Budget: US$195,300
Addressing
Feed shortages, particularly in the dry season
Declining soil fertility versus high fertilizer prices
High demand for livestock products and fluctuating
availability and prices for dairy products
Objectives
Enhance and sustain crop-livestock productivity in
smallholder systems through the integration of
legumes as cover crops (ETH-CIAT-INTA Project)
Assess the biophysical and socio-economic trade offs
of introducing legume cover crops either as green
manure for improving crop productivity and soil
quality or as forage for improving animal
productivity (CIAT-ILRI-INTA-ETH Project)
Agronomic and Animal trials
N - fluxes (with and without grazing),
physiological studies (not presented here)
Agronomic performance, milk production and
quality (improving maize crop residues with
Canavalia)
Farmer preferences
Trade-off analysis of using legumes for soil enhancing or as
animal feed resource
Quantify the expected benefits from the use of
Canavalia brasiliensis:
as dry season forage to increase the productivity
of milk
as green manure to increase the productivity of
maize and beans
Effect of incorporation of Canavalia on environmental
externalities such as sediment and water yields
Materials and Methods (SLP)
Quantify land and resource use
Estimate production costs and quantify the productivity of maize, beans, and milk
Quantify the expectations of producers for use of Canavalia as dry season forage for milk production or as green manure for improving soil fertility
Surveys conducted with 10 smallholders
in September 2007
Materials and Methods (SLP) Ex-ante analysis by simulation of survey data (2008)
ECOSAUT, a linear programming model that allows the evaluation of changes in land use on productivity under multiple criteria (social, economic, and environmental conditions)
SWAT (Soil & Water Assessment Tool) to analyze environmental externalities
Ex-post analysis by adjusting input values using data from field measurements (2009)
Ex-ante economic analysis – Five scenariosScenarios Description1. Baseline Current farm situation(12 ha; 2 ha maize &
beans; rest is pasture)
2. Canavalia as feed Canavalia is adopted as dry season forage
3. Canavalia as green manure
Canavalia is adopted to improve crop productivity
4. Canavalia as feed with sorghum
Canavalia is adopted together with sorghum to increase milk production
5. Canavalia to improve soil quality
Canavalia/maize is rotated throughout the farm area over time (8-10 years) and then rotation is followed by planting an improved grass (Brachiaria brizantha)
Ex-post economic analysis – Three
scenariosScenarios Description Adjusted input values with information on:
1. Base line Current farm situation(12 ha; 2 ha maize & beans; rest pasture)
Beans and maize productivity reported for field trials during 2007-2008 in Nicaragua
2. Canavalia as feed
Canavalia is adopted as dry season forage
Milk productivity data reported for field trials in Santander de Quilichao Station (Colombia) and Canavalia and maize productivity –when rotated with Canavalia from Nicargua trials
3. Canavalia as green manure
Canavalia is adopted to improve crop productivity
The effect of different treatments was analyzed for the maize grain yield harvested in 2007 and 2008 by applying an ANOVA analysis (Nicaragua trials)
Treatments:
i) the traditional maize-bean rotation
ii) the maize-Canavalia rotation
Ex-ante environmental analysis
Climatic, soil, and topographic data were integrated into SWAT to derive the values of sediment and water yields, surface runoff, lateral flow, percolation, evapotranspiration, and soil water for the following scenarios:
Current farm situation
Canavalia as forage for animal production
Canavalia as green manure for soil improvement
Land use scenario Jan Feb Mar Apr May Jun Jul Ago Sep Oct Nov Dec
Tradditional maize rotation
Maize rotated with C.brasiliensis as green manure
Maize rotated with C.brasiliensis as forage Fallow Maize C.brasiliensis- grazing
Maize FallowFallow
Maize C.brasiliensisFallow with residues of C.brasiliensis
Grazed after 90 days of growth
Dry Wet
Results
Agronomic and Grazing Trials
N - budget [ lb of N/mz] :
(seed + fertilizer + air) – (harvest)
NPKUREA
NPKUREA
(5 +100 + 8)-(70 + 15) = + 28 Without grazing: (4 +100 + 36)-(70) = + 70
With grazing: (4 +100 + 36)-(70 + 50) = + 20
NPKUREA
NPKUREA
Maize - bean Maize - canavalia
0
20
40
60
80
100
120
140
Ap
B
C
Cm
C
Cb
CBm
0
20
40
60
80
100
120
140
Ap
B
C
Cm
C
Cb
CBm
Ap
B
C
Cm
C
Cb
CBm
0
20
40
B
Cm
0
20
40
B
Cm
0
20
40
60
80
100
120
140
A
B/C
C
0
20
40
60
80
100
120
140
A
B/C
C
A
B/C
C
rio
LP
AR1
AR2
MP2
OA
C/Bh
Bk
0
20
40
60
80
OA
C/Bh
Bk
0
20
40
60
80
Farmer interest in Canavalia as green manure
nitrógeno
Nitrogen fixation
Remains green in dry season and is
cover
Increased crop yields
and …
Component IVDMD NDF ADF PC Biomass
Canavalia 2008 65.0 57.2 57.2 8.8 1631
2009 61.5 64.7 41.9 9.5 1741
Weeds 2008 40.4 38.7 38.7 4.9 660
2009 37.1 67.0 55.5 5.7 333
Maize residues
2008 41.1 73.8 73.8 2.6 2059
2009 34.7 86.1 61.5 1.5 4182
Nutritional quality (% of DM) and biomass production (kg DM/ha)
Milk production (lt/cow/day)
Treatment Average 4 farms
Maize residues only 2008 2.9
2009 3.0
Maize residues + Canavalia 2008 3.4
2009 3.8
Ex-ante economic analysis
Ex-ante economic analysis:Canavalia as forage (Scenario 2)
Farm net income increased 6% due to an increase in income from milk of 32% because milk yield per cow increased from 3 kg/d to 3.7 kg/d
Increment of 57% in the use of hired labor (from 90 d/year to 141)
Ex-ante economic analysis:Canavalia as green manure (Scenario 3)
Farm net income decreased by 5% due to:
Income from maize and beans increased by 4% but …
Hired labor increased by 50% (from 90 d/year to 135)
Ex-post economic analysis
Comparison of values adjusted for the ex-post analysis
Variable Ex-ante Ex-post
Canavalia productivity (t/ha) 2 2
Maize production costs (when rotated with Canavalia) 64
99*
Milk production (lt/day per cow) - Baseline 3 3
Milk production (lt/day per cow) - Canavalia as forage 3.7
3.45*
*
Maize productivity t/ha (baseline and Canavalia-based rotation) 2.3 2.4
Bean productivity (t/ha) 1.3 0.16
*In Douxchamps (2009) the urea was not suspended due to the incorporation of Canavalia in the rotation
** In Martens (2009) results, a 15% of milk production increase was obtained when Canavalia was used for animal nutrition
Note: Same prices were assumed in the ex-ante and ex-post analysis
Example:Ex-ante vs. ex-post economic analysis: Canavalia as forage (Scenario 2)
The income change in percentage terms is very similar
Mostly explained by the fact that input data used during the ex-ante analysis was very close to the values actually measured in the field during the trials
In absolute terms, the ex-ante analysis overestimated the net revenues of the simulated baseline and scenario 2 in 26%
This overestimation is explained by the difference on beans productivity reported by the farmers during field surveys in 2007 vs. Douxchamps et al. (2009)
Example:Ex-ante vs. ex-post economic analysis: Canavalia as forage (Scenario 2)
Thus the economic methodology for estimating ex-ante impacts of introducing Canavalia as forage showed a good performance and this is a function of the accurateness of available secondary data, especially data related to expected crop and milk productivity increases
However, it is clear that ex-ante analysis approaches and tools can not anticipate atypical behavior of some variables as was the case of the bean productivity that decreased below the levels reported by the farmers
Cont.
Ex-ante environmental
analysis
Ex-ante environmental analysis The incorporation of Canavalia – regardless of whether it is
used for green manure or forage increases both, the sediment and water yield
Water yield increase occurs also during the dry months Also the lateral flow and percolation are improved
However there is a different effect on surface runoff of incorporating this legume depending on the soil type. Surface runoff is reduced in the sandy loam soil (Soil Type 1) while it is increased in the clayey soil (Soil Type 2)
The incorporation of Canavalia improves the retention of water in the soils particularly during the dry months
Conclusions
Ex-ante and ex-post results showed that the use of Canavalia brasiliensis as forage improved milk productivity.
An atypical low bean productivity measured during the experimental period caused disparities between ex-ante vs. ex-post income estimation when using Canavalia as forage
Probably, the adoption of this forage legume crop should be combined with the use of other energy sources such as sugarcane and improved grass pastures to increase the carrying capacity of farms
Conclusions cont. One major simulated environmental benefit of
cultivating Canavalia either as forage or green manure could be increase in water yield and soil moisture during the dry season
The magnitude and significance of this effect is affected by the type of soils, being significantly higher for soil moisture and for water yield in sandy loam soil than in clayey soil
Nevertheless, these results need to be calibrated with longer-term field measurements
Modeling results are very sensitive to the level of uncertainty of input data (primary vs. secondary data) but still the trends of predictive results are maintained
Overall conclusions The inclusion of Canavalia brasiliensis in crop
residue grazing has shown to be economically and environmentally beneficial, and in on-farm experimentation benefits look even higher
Consequently high interest of farmers
Combination of economic, agronomic and animal trials has proven very useful
Limitations in modeling due to high requirement of primary data
Next Steps Economic analyses need to be validated
Validation of Canavalia across sites (on-going in Colombia and Nicaragua)
Facilitation of Farmer to Farmer extension (planned for 2010 in Nicaragua, partly on-going in Colombia)
Seed production (Basic seed and farmer led, expanded in 2010 in Nicaragua)
Cultivar release planned for 2011 (in Nicaragua and/or Colombia)