Abstract

GONZALEZ-SALGADO, Martha E.; GARCIA-CALDERON, Norma E.  and  ALMENDROS, Gonzalo. Structural characteristics of humic acids and their effect on Tagetes erecta L. in a Salts Affected Soil. Terra Latinoam [online]. 2010, vol.28, n.1, pp.27-33. ISSN 2395-8030.

Humic acids (HA) isolated from the soil commonly known as Chinampa soil of 4 selected treatments and from the compost of plots that were cultivated with zempasuchil (Tagetes erecta L.) were characterized through visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and electrophoresis in an attempt to explain their positive effect on the plant yield. Carbon mineralization curves were obtained from the soil of each one the selected treatments as an index of organic matter stability. Results showed that the highest structural condensation of soil organic matter (SOM) was found in the control soil, followed by the treatments with HA (240 mg kg^-1), compost (120 mg kg^-1) and lactic acid (3.4 L m^-2). The FTIR spectra indicated the presence of little altered forms of lignin, typical of the HAs isolated from the compost and also from the treated soils that produced the best plant yields. In these soils, the presence of indicative features of recently formed, immature HAs originating from the direct alteration of plant macromolecules was predominant. Electrophoresis showed that HA of the treatment resulting in the best yield (H2C1M1) had high ionic mobility, and the visible spectra showed a low degree of aromaticity. AH spectra from the amended soils showed a low content in functional oxygen groups and the presence of associated proteins, which could explain the high mineralization coefficients recorded in the respirometric curves. This suggests the improvement of the soil through readily biodegradable pre-humic material as an index of the amelioration in the production of zempasuchil.

Keywords : anthrosols; compost; C mineralization; spectroscopy; rehabilitation.

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