Optimal sample size for DRIS model parameterisation to diagnosis nutrients status in fruit crops

Abstract

Diagnosis and Recommendation Integrated System (DRIS) is an approach to nutrient diagnosis of crops, holistically through the relationship between nutrient balance of plants and soil. The objective of this study was to investigate the influence of sample size in DRIS model parameterisation, to diagnose nutrients status in fruit crops. Published data were resampled to obtain different sample sizes, ranging from 40 to 1000, with steps of 30. For each sample size, 1000 replications were generated to determine the mean value of the desired parameter (nutrient indices and Nutrient Balance Index). All nutrient indices decreased rapidly as sample size increased from 40 to 200. For each nutrient considered, indices varied slightly from 200 to 1000. This study has revealed that the size of sample used to establish DRIS norms, determines the accuracy of nutrient diagnoses in pineapple (Ananas comosus (L.) Merr.). The optimal data bank for nutrient diagnosis in the crop (pineapple) used in this study is 200.