Resumen

GIL, S.B. et al. Agricultural intensification evaluated by environmental sustainability indicators. Arch. zootec. [online]. 2009, vol.58, n.223, pp.413-423. ISSN 1885-4494.

The aim of the study was to evaluate how technology adoption processes influence agro-ecosystems with incipient land use intensification, in a rural semiarid area of San Luis province, Argentina, using environmental sustainability indicators at farm and regional level. For this purpose a comparison of 19 farms (3654 ha) was carried out. Training and extension priorities for producers were identified during this study. The original vegetation corresponded to grassland and Prosopis caldenia forests with beef cattle production. The environmental sustainability indicators were: Land use -% of annual crops (CA)- (a variable); Fossil energy use (EF); fossil energy use efficiency (EEF); nitrogen balance (BN); phosphorus balance(BP); pesticide contamination risk (RPL); soil erosion risk (RE); changes in soil carbon stock (CSC) and greenhouse gases balance (GEI), evaluated according to severity scale. Farms were analyzed individually and grouped by size (<80 ha and >81 ha). Statistically significant differences (p<0.05) were observed between small and big farms for indicators EF, BN, RPL, RE and GEI. High values of EEF are important in small farms (>2 Mj EF used/Mj EF product), and negative values of BP in the 68% of the farms (up to -14.4 kgP/ha/year). Both can be related to soybean introduction without extensive fertilizers use. Nitrogen balance do not indicate contamination risk (between -4.7 and 41.7 kg N/ha/ year). Conventional tillage in forages is the cause of high CSC values in small farms. The methane emissions in big farms, were reflected by the higher values of GEI indicator because of their grazing systems. Training activities should be farm scale oriented . The use of these indicators has made it possible to understand the impact of agricultural practices at farm and at regional level in relation to production scale. These indicators show that today's Villa Mercedes farm area intensification has not had a serious impact on their environment yet.

Palabras clave : Energy efficiency; Carbon; Optimization; Training; Environmental management.

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