The phosphorus compositional nutrient diagnosis range for potato

Leaf analysis could assist in adjusting the P fertilization of potato (Sola num tuberosum L.) to specific soil-plant systems to achieve high yield cond itions. Our objective was to derive and validate Compositional Nutrient Dia gnosis (CND) norms and ranges for a potato cultivar (Superior) and to compa re CND to Diagnosis and Recommendation Integrated System (DRIS) and the Cri tical Value Approach (CVA). Survey data were obtained from 563 field observ ations and validated using 100 independent samples and across four P fertil izer trials. The databases included tuber yield and analyses (N, P, K, Ca, and Mg) of the upper fully expanded leaf collected at beginning of bloom. Y ield cutoff between low- and high-yield subpopulations, selected from cumul ative variance functions across survey data, was 34.1 Mg ha(-1). The sum of squared values of CND indexes was distributed like a chi-square value, The critical chi-square value was 4.2, The critical CND P index range was betw een -0.80 and 0.80. Similar critical values were obtained for the validatio n population and fertilizer trials. The CND P index appeared symmetrical ab out the zero nutrient balance and was more closely related to yield compare d with DRIS and CVA, The CND provides an inferential las chi-square) and sy mmetrical (about zero balance) diagnosis at low cost, could provide nutrien t index ranges adjusted to yield goal, and could thus be developed advantag eously for specific soil-plant systems.