Row-centred log ratios as nutrient indexes for saturated extracts of organic soils

Abstract

G. 1997. Row-centred log ratios as nutrient indexes for saturated extracts of organic soils. Can. J. Soil Sci. 77: 571-578. Composition of soil solution was investigated in the top layer of a Typic Mesisol across seven crop sequences. Each sequence started and ended with carrots (C) and included onions (O), barley (B) and weeded fallow (F) as follows: CCCC, CCBC, CBCC, CCOC, COBC, CBOC and CFFC. The soil showed adequate pH and electrical conductivity values. Soil solution composition was assessed by the saturated soil extraction procedure. The changing levels of nutrients in the saturated soil extracts over seasons, years and crop sequences were analyzed using absolute values of nutrient concentrations, nutrient percentages relative to total soluble salts (the nutrient intensity and balance concept) and row-centred log ratios of nutrient concentrations or activities (compositional data analysis). The row-centred log ratio is the log-transformed ratio of a given element to the geometric mean of soluble elements. Nutrient percentages were highly correlated with row-centred log ratios. The three relative nutrient expressions reduced seasonal variations as compared with raw nutrient concentrations by incorporating component proportions. Concentration of total soluble salts was significantly correlated (P < 0.01) with concentrations of NO 3 -N (r = 0.37), P (r = 0.80), K (r = 0.80), Ca (r = 0.96) and Mg (r = 0.92) in saturated soil extracts. Between-years homoscedasticity as well as reduced skewness and kurtosis for all nutrients were obtained using row-centred log ratios of ion activities. Other advantages of using row-centred log ratios are discussed. . Le rapport logarithmique centré est le logarithme du rapport d'un élément donné à la moyenne géométrique des éléments solubles. La couche arable montrait des valeurs optimales de pH et de conductivité électrique. Les expressions relatives ont réduit la variation saisonnière par rapport aux concentrations en éléments nutritifs car elles tenaient compte des proportions entre les composantes. La concentration en sels solubles totaux montrait une corrélation significative (P < 0.01) avec les concentrations en NO 3 -N (r = 0.37), P (r = 0.80), K (r = 0.80), Ca (r = 0.96) et Mg (r = 0.92). L'homogénéité de la variance annuelle ainsi qu'une asymétrie et un aplatissement réduits ne furent obtenus pour tous les nutriments qu'avec les rapports logarithmiques centrés des activités ioniques. D'autres avantages des rapports logarithmiques sont discutés.

Determination of diagnostic standards on saturated soil extracts for cut roses grown in greenhouses

“…The R 2 correlation coefficients obtained for the “Validation” database between CND f and CND s are much higher than those found with the DRIS methodology for equivalent NBI f and NBI s . This aspect can be based on the methodology proposed by Parent et al [ 30 ], which does not determine the concentration of the element in the solution, but their participation percentage in the total soluble salts. Thus, the participation percentage of each element is related to the participation of the other elements in the total soluble salts in solution.…”

“…In order to calculate the CND norms, or centered proportions, the methodology proposed by Parent [ 12 , 30 ] was applied to the analysis of each SSE. CND as used here consists of centered log ratios.…”