Realizing the benefits of cover crop legumes in smallholder crop-livestock systems of the hillsides of Central America: Trade-off analysis of using legumes for soil enhancing or as

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)