Nitrogen and phosphorus discharge of animal origin in the Baixo Vouga: a spatial data analysis

The livestock production is a strategic and crucial activity for it fixes populations in rural areas, contributing to its conservation, and most importantly because it ensures food production. By producing meat, milk or eggs, this sector contributes to national food self-sufficiency. However, intensive livestock farming activities carry a strong pollution load on the environment, particularly through the emission of nitrogen (N), phosphorus (P), and greenhouse gases (GHG). The Baixo Vouga region in Portugal due to its climatic conditions and soil characteristics holds a high number of livestock production units mainly cattle, poultry and swine. Thus such an activity contributes to a significant portion of the wealth created in this region. This high potential has collided with the existence of environmentally sensitive areas, many of which are protected by European environmental regulations. This work studies the geographical distribution of livestock population of cattle, poultry and swine in the Baixo Vouga region and quantifies its impacts on the environment by calculating the excretion loads of N and P of these species. In the cattle and poultry sectors two clusters or agglomerations are identified, the first in the northern region and the second in the inland region. Moreover, the cattle farming cluster overlaps on vulnerable zones requiring specific monitoring on effluent treatment issues.