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Fig. 3. Variation in the concentration of total phosphorus (TP) for different size fractions collected in near-surface flow to 30 cm from 30-m2 replicated plots for each of four treatments: (i) untreated plots (zero P), and treated plots receiving (ii) the equivalent of 38 kg P ha–1 in the form of triple superphosphate (TSP), (iii) TSP + dairy manure slurry, and (iv) dairy manure slurry, for a single storm on 14 Apr. 1999. The data are means of six replicated plots; the error bars represent 1 SE. The difference in TP in runoff for zero-P vs. P-treated plots is significant (p = 0.05) but only for the >0.45-µm particle-size fractions. There was no significant difference in TP concentration between the P-treated plots (p = 0.05).
