Sustainable intensification of forage crop sequences in the Argentinean Pampas: dry matter production and water productivity

3. OJEDA, J.J.; PEMBLETON, K.G.; CAVIGLIA, O.P.; ISLAM, M.R.; AGNUSDEI, M.G.; GARCIA, S.C.

Congreso; 7th World Congress on Conservation Agriculture; 2017

The Argentinean Pampasis one of the most important livestock production areas worldwide, in which inthe last years animal feed has been based predominantly on forage cropssequences (FCS) (i.e. sequences basedon annual crops for grazing, hay or silage). However, it is unclear howyear-by-year precipitation variability affects FCS dry matter (DM) yield inthese environments. Crop models are potential tools to assess crop yieldvariability across several climate and soil conditions. Agricultural ProductionSystems Simulator (APSIM) is a crop simulation model that integrates agronomicmanagement with weather and soil data in a mechanical way to predict growth andcrop development on a daily time-step. The aims of this work were to assess theAPSIM capacity to simulate: (i) sole crop and total FCS DM yield, (ii) thespatial and temporal variations of DM yield and water productivity (WP, i.e. defined as the DM yield producedper unit of water supply) of crops as a component of a FCS and (iii) FCS DMyield and WP. Thirteen FCS involvingsummer (maize [Zeamays L.] and soybean [Glycine maxL.]) and winter forage crops (oats [Avena sativa L.], annualryegrass [Lolium multiflorum Lam.], barley[Hordeum vulgare L.], wheat [Triticum aestivum L.]), were simulated by APSIM infive sites across the Argentinean Pampas. Generally, our results indicated that the model was capable to simulate crop DMyield (1.7 Mg ha-1 and 0.96 for root mean square error [RMSE] and concordancecorrelation coefficient [CCC]), FCS DM yield (RMSE=3.2 Mg ha-1; CCC=0.93),seasonal (RMSE=1.9 g m-2 mm-1; CCC=0.71) and annual WP (RMSE=0.4g m-2 mm-1; CCC=0.94). The APSIM ability to predict WP declinedwhen the seasonal WP was higher, i.e.for low precipitations. For seasonal precipitation inputs, less than 200 mm, APSIMtended to under predict WP. Ourresearch demonstrated the capability of APSIM to accurately predict DM yieldand WP of several forages species growing in sequence over a wide regionencompassing numerous soil-climate combinations. Indeed, APSIM appears apotential tool for further evaluate the sustainability of the intensifiedforage cropping systems based on FCS in the Argentinean Pampas.