Erratum to: Chemical and Biological Technologies in Agriculture (2015) 2:17 DOI 10.1186/s40538-015-0042-4

After the publication of the original article [1], we noticed that Figs. 1–4 were ordered incorrectly and the figure captions did not correspond to the correct figures. The correct figure order and captions are provided below (Figs. 1, 2, 3, 4) and have also been updated in the original article. The publisher apologizes for any inconvenience caused.

Fig. 1
figure 1

Potentiometric titration curve for humic acids and the calculated results for models M1 and M2 (calculated models were obtained with resulting error function σfit < 0.02)

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Fig. 2
figure 2

pH stabilization curves for three selected titration points. The values for parameters a, b, and c (Eq. 5) of all titration points were used in the construction of Fig. 4

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Fig. 3
figure 3

Species distribution diagram obtained using model M2. The components are represented by the following symbols: open circle carboxylic, open square phthalic, open triangle phenolic, closed triangle catechol, closed square salicylic, and open diamond supramolecular

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Fig. 4
figure 4

Out-of-equilibrium potentiometric response patterns for parameters b (bottom) and c (top) as functions of a (see Eq. 5). Color lines represent the triplicate results

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