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 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

Ex-ante economic analysis – Five scenarios Scenarios Description 1. 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 p roductivity 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 scenarios Scenarios 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 p roductivity 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

Results

Agronomic and Grazing Trials

N - budget [ lb of N/mz] : (seed + fertilizer + air) – (harvest) (5 + 100 + 8)-(70 + 15) = + 28 Without grazing: (4 + 100 + 36 )-(70) = + 70 With grazing: (4 + 100 + 36 )-(70 + 50) = + 20 NPK UREA Maize - bean Maize - canavalia NPK UREA NPK UREA NPK UREA

rio LP AR1 AR2 MP2

Farmer interest in Canavalia as green manure Nitrogen fixation Remains green in dry season and is cover Increased crop yields and … nitrógeno

Nutritional quality (% of DM) and biomass production (kg DM/ha) 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

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-post economic analysis

Comparison of values adjusted for the ex-post analysis *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 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

Ex-ante environmental analysis