[en] The aim of this Ph. D. thesis was to assess various indicators to measure the sustainability of fields owned by some producers of cacao in the province of El Oro-Ecuador taken into account economic, social and environmental dimensions. The population studied consisted of fields cultivated with CCN51 (n=49) and cacao National (n=24), where, first a survey has been performed to obtain economic and social indicators. The environmental indicators were obtained from 30 soil samples, selected from the whole population studied, and these samples have been collected in the first 30 cm. Subsequently, the soil physicochemical properties were analysed for obtaining an index of soil (ISQ). The studied soils belonged to the Alfisols, Inceptisols and Entisols orders. Principal component analysis has been applied using an adimensional procedure, after normalisation of the selected indicators between 0 and 1. To verify the effects of agronomical management on organic matter (MO) content analysis stable isotopes13C and 15N have been performed and the degrees of aromaticity versus aliphaticity have been characterised by means of infrared spectroscopy of infrared (IR), in soil and cacao litter. The main results from the economic point of view were the production of the cacao type CCN51 (2337.63 Kg ha-1) and the resulting earned income ($1204) that were higher than those corresponding to the cacao National (476.92 Kg ha-1 versus $919.68). Considering the social aspect, 32.88% of the field owners were of more than 60 years of age and 53% had primary education. The soil properties of showed predominance of silt and clay contents, with mean values of soil organic matter (MO) lower than 3% and mean pH=6,9; no statistical differences were appreciated between soil order or cacao type. The cation exchange capacity (CEC), sum of bases (SB), pH, organic C, available phosphorus (P) sand, silt and clay contents were the properties selected as Indicators of Soil Quality (ISQ). The averages of 13C (-25.11‰) and 15N (8.8‰) corresponded to thresholds of moderate application of synthetic fertilizers. The soil IR spectra indicated aromaticity in the region 1650 cm-1, whereas for the litter, the features observed in the region around 2950 cm-1 indicated typical peculiarities of the aliphatic groups. In average the value of normalised indicators was 0.52, so that the studied fields can be ranked in the class of week sustainability.

[gl] O obxectivo da tese foi deducir varios indicadores segundo as dimensións económicas, sociais e ambientais, para medir a sustentabilidade dalgúns produtores de cacao na provincia de El Oro-Ecuador. A poboación estaba formada por explotacións cultivadas de cacao CCN51 (n=49) e cacao Nacional (n=24), onde se realizou unha enquisa para obter indicadores económicos e sociais. Os indicadores ambientais obtivéronse a partir de 30 mostras de solo da poboación de estudo, que se tomaron nos primeiros 30 cm da superficie. Posteriormente, analizáronse as súas propiedades fisicoquímicas para establecer un índice de calidade do solo (ICS). Os solos estudados pertenceron ás ordes dos Alfisoles, Inceptisoles e Entisoles. Por dimensión, levouse a cabo unha análise de compoñentes principais e de normalización entre 0 e 1 dos indicadores. Para determinar o impacto da xestión agronómica sobre a materia orgánica (MO) analizáronse os isótopos estables 13C, 15N e caracterizouse o grao de aromaticidade e alifaticidade mediante espectroscopía de infravermellos (IV), no solo e os restos vexetais do cacao. O resultado destacado no desempeño económico foi que o rendemento do cacao do tipo CCN51 (2337,63 Kg ha-1) e os ingresos ($ 1204), foron máis altos que os do cacao Nacional (476,92 Kg ha-1; $919,68). En termos sociais, o 32,88% dos propietarios dos terreos tiñan máis de 60 anos e o 53% tiñan estudos primarios. As propiedades do solo mostraron predominio de limo e arxila, con valores medios de materia orgánica do solo (MO) inferiores ao 3% e pH=6,9, sen apreciar diferenzas estatísticamente significativas entre ordes de solo e tipos de cacao. A capacidade de intercambio catiónico (CEC), suma de bases (SB), pH, C orgánico, fósforo dispoñíbel (P), area, limo e arxila foron as propiedades seleccionadas como Indicadores da Calidade do Solo (ICS). As medias de 13C (-25,11‰) e 15N (8,8‰) corresponderon a umbrais de aplicación moderada de fertilizantes sintéticos. Os espectros de IV indicaron aromaticidade na rexión de 1650 cm-1, mentres que para os restos vexetais observouse na rexión de 2950 cm-1 típico dos grupos alifáticos. A media dos indicadores estandarizados foi de 0,52, o que permite que as parcelas estudadas sexan catalogadas cunha sustentabilidade débil.