Micronutrient extraction in calcareous soils treated with humic concentrates

Abstract

The use of humic concentrates in drip irrigation cultures in Spain has increased recently. Several companies offer different products to the farmers. It is suggested that such products are useful in improving the structure of the substrates, in increasing CEC of soils, in mobilizing micronutrients towards the roots and in acting as biological hormones. In our work, we have studied the effect of 11 different humic concentrates on extraction of iron and other micronutrients in the soil. Two substrates were used, a calcareous soil and a mixed substrate called “soil standard” since it has been made with components similar to those of a soil, but with standard materials. These soils were incubated with 11 different commercial humic concentrates. After the interaction, soils were extracted by the AB‐DTPA method. The results show that, in general, all commercial products increased extraction of micronutrients, but large amounts of humic concentrates were needed to increase them significantly. These quantities were greater than those reached in the bulk soil with the doses proposed by the distributors. However the amounts of humic substances used in this experiment can be reached in microsites near the droppers in a drip irrigation system. Although all humic concentrates increased micronutrients extraction, differences were noted on the efficiency of the different products. Humic rather than fulvic acids were responsible for this increase in extraction.

Notes

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