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Fig. 3. Relationship between severity of root rot of snap bean and (a) free particulate organic matter, (b) FDA activity, (c) microbial biomass C, and (d) water-stable aggregates. Regressions are across three sample times, 2 mo after the first amendment (
), 12 mo after the first amendment (), and 2 mo after the second amendment (
). Each solid line represents a statistically derived "suppressive threshold": the level of disease severity significantly different from the control (P < 0.05).