Agricultura de precisão em pastagens. Avaliação quantitativa e qualitativa da variabilidade espacial de uma pastagem melhorada de sequeiro no Alentejo

Mestrado em Engenharia Agronómica - Instituto Superior de AgronomiaThe main goals of this essay are the analysis of the spatial variability of a pasture and the correlation of its field variables with vegetation indices obtained by remote sensing. To achieve these goals, we conducted a flight over the field being studied to detect the reflectance emitted by each point of its surface. Based on the analysis of the images obtained, 47 sites were selected, for which we calculated different vegetation indices. These sites were also georreferenced and used for plant and soil sample collections - which constitute the database of the studied field variables. After a statistical treatment of these, it was possible to confirm the large spatial variability of a pasture in Alentejo - from 19 variables treated, 12 showed a CV > 30%. In the correlation between indices and variables, the results were not as relevant as expected. However, from 8 vegetation indices, a model to estimate the pasture yield was obtained (adjusted r2 = 0,48). It was again shown the importance that precision agriculture and its techniques development can have on the interpretation of the variability of a field and the contribution it can bring to its most efficient us