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Replenishing Humic Acids in Agricultural Soils

Biogon Pty Ltd., 17b Poole Rd., Glass House Mountains, Queensland 4518, Australia
Academic Editors: Yusuf Genc and Graham Lyons
Agronomy 2016, 6(4), 45;
Received: 23 July 2016 / Revised: 12 September 2016 / Accepted: 21 September 2016 / Published: 28 September 2016
(This article belongs to the Special Issue Use of Commercial Humates in Agriculture)
For many decades, it was commonly believed that humic acids were formed in soils by the microbial conversion of plant lignins. However, an experiment to test whether these humic acids were formed prior to plant matter reaching the soil was never reported until the late 1980s (and then only as a side issue), even though humic acids were first isolated and reported in 1786. This was a serious omission, and led to a poor understanding of how the humic acid content of soils could be maintained or increased for optimum fertility. In this study, commercial sugar cane mulch and kelp extracts were extracted with alkali and analyzed for humic acid content. Humic acids in the extracts were positively identified by fluorescence spectrophotometry, and this demonstrated that humic acids are formed in senescent plant and algal matter before they reach the soil, where they are then strongly bound to the soil and are also resistant to microbial metabolism. Humic acids are removed from soils by wind and water erosion, and by water leaching, which means that they must be regularly replenished. This study shows that soils can be replenished or fortified with humic acids simply by recycling plant and algal matter, or by adding outside sources of decomposed plant or algal matter such as composts, mulch, peat, and lignite coals. View Full-Text
Keywords: humic; acid; soil; senescent; plant; algal; fluorescence; microbial; lignin; compost; mulch; coal humic; acid; soil; senescent; plant; algal; fluorescence; microbial; lignin; compost; mulch; coal
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MDPI and ACS Style

Susic, M. Replenishing Humic Acids in Agricultural Soils. Agronomy 2016, 6, 45.

AMA Style

Susic M. Replenishing Humic Acids in Agricultural Soils. Agronomy. 2016; 6(4):45.

Chicago/Turabian Style

Susic, Michael. 2016. "Replenishing Humic Acids in Agricultural Soils" Agronomy 6, no. 4: 45.

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