Forage quality and methane production of the grazing portion of grass produced under elevated [CO 2 ]

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1 Greenhouse Gas and Animal Agriculture Conference February 2016 Melbourne, Australia. Forage quality and methane production of the grazing portion of grass produced under elevated [CO 2 ] A.L. Abdalla 1 ; R. Ghini 2 ; A.S. Natel 1 ; A.L. Abdalla Filho 1 ; H. Louvandini 1 ; M.C. Piccolo 1 ; A. Torre Neto 3 ; K.L. Nechet 2 (1) Centre for Nuclear Energy in Agriculture, University of Sao Paulo, Piracicaba, SP, Brazil (2) Embrapa Environment, Jaguariuna, SP, Brazil (3) Embrapa Instrumentation, Sao Carlos, Sao Paulo, Brazil

2 Cerrado biome - Savannah - Extend over 200 million ha - Brazilian agricultural frontier - commodity markets -~ 34% Brazilian beef production a. Brazilian livestock = 90% grass-fed b. Brachiaria genus = 80 million ha improving productivity increases soil carbon stocks degraded to improved pastures CO2 removals 2

3 Elevated [CO 2 ]: positive effect on crop yield; plant growth & C sequestration in plant biomass C4 plants less than C3 plants meta-analysis Mediterranean grassland forages increase NFC, reduction NDF and digestibility quality of tropical C4 plants 3

4 Objective to determine the effects of season and elevated [CO 2 ] upon biomass production, fiber quality and methane production of the grazing portion of Brachiaria decumbens 4

5 Site: FACE facility Embrapa Environment, Jaguariuna - Brazil Free-Air Carbon Dioxide Enrichment (FACE): Twelve 10m Ø rings in 7 ha coffee plantation Six rings control treatment Six rings pure CO 2 injected during day light to increase [CO 2 ]: controlled by automatic environmental sensors Increases of CO 2 began on August, 2011 Target level 550 ppm (Ghini et al., 2015) 5

6 Site: planting, sample collection 22 nd November plots 0.25 m 2 Brachiaria decumbens cv basilic standardization after 10 weeks cutting with scissors the grazing portion of the stand (at 20 cm height) forage availability estimated and collected every 21 days Jan 2012 through Feb

7 Site: analysis CENA / USP, Piracicaba - Brazil Biomass production Forage quality 7

8 Performance of FACE system Frequency distribution of daytime CO 2 air concentration measured in the center of the rings during 2012 and 2013 (a) and hourly concentration during December 2012 (b). Bars represent standard errors (Ghini et al., 2015) 8

9 Rainfall and Temperature Climatic condition at the FACE facility in which the forage samples were collected from February 2012 to January

10 g DM/m2 Biomass production CO2: P < 0.11 Season P < 0.01 CO2 x Season: P > CO2 ambient + CO2 ambient + CO2 ambient + CO2 ambient spring summer autum winter Biomass available (gdm/m 2 ) of Brachiaria decumbens grown under two contrasting concentration of CO 2 and harvested at 20 cm high every 21 days from February 2012 to January

11 Forage quality spring summer autumn winter + CO 2 ambient + CO 2 ambient + CO 2 ambient + CO 2 ambient SE Fiber composition (g/kg DM) ADF ADL CEL NFC In vitro degradability (g/kg DM) OMD NDFD ADF: acid detergent fibre, ADL: acid detergent lignin, CEL: cellulose, NFC: non fibre carbohydrate. OMD: organic matter degraded, NDFD: NDF degraded after 24 h in vitro incubation 11

12 Forage quality 8.50 Net CH4 (ml/g OMD) CO2 ambient + CO2 ambient + CO2 ambient + CO2 ambient spring summer autum winter Net CH4 (ml/g OMD) after 24h in vitro incubation of Brachiaria decumbens grown under two contrasting concentration of CO 2 and harvested at 20 cm high every 21 days from February 2012 to January

13 Discussion - Long term observation (two years) for Brachiaria decumbens at 21 days interval: - Biomass production - elevated [CO 2 ]: - only tendency vs 261 g DM/m 2 (P < 0.10), - rain season (spring & summer): - increase in biomass production up to 14% (P < 0.01), - improvement of water use - growth limited by nutrient and water availability - Forage quality - C4 plant - differences on ADF, ADL and NFC (season) (P < 0.10), - No significant effect on OMD and NDFD. - C3 Mediterranean grasses meta-analysis - No differences on fiber composition - Reduction on digestibility 13

14 Conclusions Elevated [CO 2 ] and rain season: significantly increased forage production, contribute to sequester carbon in plant biomass. Tropical conditions and C4 grasses: feeding at its best protein and fermentable carbohydrate ratio for: sustainable intensification in beef production systems advantages in the microbial synthesis methane production intensity (L/Kg OMD) 14

15 Thank you for your attention Acknowledgments The authors would like to thank the fellowship grant and financial support from CNPq, FAPESP and Embrapa Project CLIMAPEST. 15