Sustainability of different production systems papaya ( Carica papaya   L.) and sorghum ( Sorghum bicolor   [L.] Moench) in the semi-arid region

Agricultural production in the semi-arid region is critically important for ensuring food security and agricultural development in world. However, due to the environmental impact generated by agricultural activity, and the challenge of producing food for a growing demand, agriculture is dependent on a constant flow of non-renewable environmental and economic resources. The aim of this study was to quantify the sustainability of different agricultural production systems papaya (Carica papaya L.) and sorghum (Sorghum bicolor [L.] Moench) in the semi-arid region using emergy analysis. The research was carried out in the Curupati Irrigated Perimeter, located in the municipality of Jaguaribara, Ceará (CE), Brazil, corresponding to the cultivation of the irrigated papaya and in the Lagoa Grande settlement, in the Chapada do Apodi, municipality of Tabuleiro do Norte, CE, referring to sorghum cultivation in the rainfed. The rainfed production system had an emergy value of 1.06E+16 seJ ha^-1 yr^-1, and was lower than in the irrigated system 1.69E+17 seJ ha^-1 yr^-1. The following values were obtained for the emergy indicators in the irrigated system: emergy yield ratio (EYR) = 1.51; renewability (R%) = 74.29%; environmental load ratio (ELR) = 0.35, and emergy sustainability index (ESI) = 4.37. Where as in the rainfed system, the EYR = 1.13; R% = 83.81%; ELR = 0.20 and ESI = 5.86. The system of production under the rainfed regime therefore displayed better economic, social and environmental performance in relation to the irrigated production system. Both of the studied production systems contributed to the economic growth of the semi-arid region, with low environmental loads.

Keywords
Emergy; irrigated agriculture; rainfed regime; sustainable development.