Water footprint of soybean under different tillage practices

PIASTRELLINI, R; CIVIT, B; ARENA, A.P.

Mendoza

Conferencia; Vth International Conference on Life Cycle Assessment CILCA 2013; 2013

Grupo CLIOPE, Universidad Tecnologica Nacional, Facultad Regional Mendoza

Purpose The conventional tillage (CT) was the agricultural model that the humanity applied since its earlier stages. From the decade of the 90, the no till (No-T) model set in motion a new paradigm, permitting to improve the fertility and to increase the soil productivity. Nowadays the No-T cultivated area in Argentina surpasses the 70% of the total. Diverse authors have studied the effect of tillageand stubble management on soil parameters, agreeingthat an increment in coverage originates an increase in the water infiltration and retention and a decrease of the surface runoff and the evaporation, causing variations in the water requirement of the crop. However, the application of the water footprint as indicator of consumption and use of water without including these considerations does not distinguishbetween different types of tillage. The purpose of this study is to quantify the water consumption of a soybean crop destined to the production of biodiesel using the water footprint indicator, incorporating in the calculation the distinctive characteristics of the majorfarming systems applied in Argentina. Methodology The calculation of the Water footprint was performed according to the methodology of the Water Footprint Network. The crop coefficient was adjusted according to the procedure proposed by FAO in Guidelines for computing crop water requirements (1998), and the values of evapotranspiration were estimated according to the CROPWAT model. The area of the study corresponds to the south of the province of Buenos Aires, Argentina. In this area two productive processes are distinguished: 1) Soybean -CT system, and 2) Soybean-No-T system. The Functional Unit defined for both systems is 1 MJ of energy obtained from soybean biodiesel. Results The indirect water footprint is approximately 30% higher for the Soybean-CT system, however it contributes negligibly to the total water footprint. The direct water footprint is reduced at least in 7% incorporating in the calculation the soil coverage by crop stubble in theNo-T system. This percentage represents around 600 m3 of water per tonne of biodiesel produced. Conclusions The results show the importance of adapting the water footprint methodology for considering the farming practices used in each region and for each crop, in order to get representative values for the studied case.