One of the problems which arises when analysing and interpreting results from field trials designed to test the efficacy of fertilisers and fertiliser-type products on pastures and crops is the conundrum of Type 1 and Type 2 statistical errors: is the product having literally no effect, or is the trial not "powerful" enough to detect small differences. This problem can be objectively and pragmatically solved, when sufficient trial data are available, by using cumulative frequency distribution

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... nctions. In this paper we explain what cumulative frequency distribution functions are and their usefulness for determining the agronomic effectiveness of products. This technique is then applied to field trial data testing the effectiveness of a number of fertiliser and fertiliser-type products used in agriculture today. It is concluded that this approach provides a more objective basis for determining the efficacy or otherwise of fertilisers. Keywords: fertilisers, agronomic effectiveness, testing, field trials, cumulative frequency distribution.