Identification of Fertility Regimes that Enhance Long‐Term Productivity of Alfalfa Using Cluster Analysis

Autor: S. M. Cunningham, Jeffrey J. Volenec, Sylvie M. Brouder, S. Lissbrant
Rok vydání: 2010
Předmět:
Zdroj: Agronomy Journal. 102:580-591
ISSN: 1435-0645
0002-1962
DOI: 10.2134/agronj2009.0300
Popis: Recommendations regarding P and K fertilization and critical soil and tissue concentrations for alfalfa (Medicago sativa L.) are inconsistent. Our objective was to use cluster analysis and binary logistic regression to determine if soil and herbage P and K concentrations can be used as diagnostics ofP- and K-limited alfalfa yields across soils with variable P and K soil test values. Samples were obtained from 28 consecutive harvests (four per year) of plots fertilized with four rates ofP and five rates ofK. Moderate to high rates of both nutrients were required to maintain high yields. Cluster analysis using May 2004 data for mass shoot -1 and shoots m-2 identified six clusters that also differed in yields. Averaged over the seven May harvests the two lowest yielding clusters had low herbage K (10.3-15.9 g kg -1 ), while intermediate yields were associated with low herbage P (1.6 g kg -1 ). Herbage P and K of the highest yielding cluster were 2.5 and 21.5 g kg -1 , respectively. Plant populations in 2004 were the greatest with intermediate yields (61 m -2 ) and lowest for the poorest yielding plots (6 m -2 ). High taproot N reserves were associated with high yields. Prediction of acceptable (high-yielding clusters) vs. unacceptable (low yielding clusters) performance was best achieved using the combination of herbage K and P concentrations and their ratio as independent variables. Results illustrate a varying, interdependent nature for alfalfa critical P and K tissue concentrations and suggest the need to account for both nutrients simultaneously.
Databáze: OpenAIRE
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