Analytical laboratories for soil fertility assessment, in Portugal
The main objective of this work was to obtain updated data from soil fertility laboratories located in Portugal. A survey was sent to the Heads of 32 laboratories and a reply was received from 25 of them. 14 of these labs belong to the Ministry of Education, 7 are private and 4 to the Ministry of Agriculture. In addition to soil they also analyse plant material and, the majority, organic soil improver and irrigation water. In the minimum package of analyses they offer (Summary Analysis) pH, organic matter, extractable phosphorus and potassium are always included and 72 % of them also include field texture. But this package differs greatly between labs with regard to the inclusion of other parameters. 76 % of the labs issue fertilisation recommendations, but only 20 % do so automatically. There is a relative homogeneity of methods for the parameters of the summary analysis, except for organic matter. Only two laboratories have accredited tests. The existence of a national interlaboratory test is felt to be important for internal quality control and harmonisation of methodologies.