Monday, July 15, 2024
General Agriculture

Effects of Redox Reaction in Aerated Soils on Nutrient Availability and Plant Growth

Effects of Redox Reaction in Aerated Soils on Nutrient Availability and Plant Growth: The redox potential, Eh of most soils under aerobic situations and under the pH range prevalent in most agricultural soils lies between 0.5 and 0.8 volts.

Some biochemical transformations that proceed in well-aerated (aerobic conditions) soils are discussed below.

Generally, there is the biological transformation of C, N, Mn, Fe, and S to CO2, NO , Mn4+, Fe3+, and SO2- respectively in well-aerated soils. These transformed species are the forms utilizable by plants.

That is, under aerobic conditions most elements are available in forms that can be absorbed by plants even though nutrients such as ferric, Fe3+, and magnate Mn4+ may become insoluble and with difficult availability.

Under aerobic soil conditions, there is usually an initial decomposition of organic matter by heterotrophic microbes whereby organic carbon serves as an electron donor and oxygen O2 serves as an electron acceptor.

Read Also: Soil Aeration on Biological Activities and Plant Growth

Nutrient elements contained in organic matter are released during the decomposition process. Nitrogen, in particular, is released in ammonium (NH+4) form and the process is termed mineralization.

It has been estimated that soil organic matter contains about 5 percent by weight of Nitrogen and only about 1-3 percent of that total amount is released yearly by decomposition (Miller and Donahue, 1984).

Furthermore, mineralizing 1.5 percent of the content of 4 percent would release about 70kg/ha of nitrogen as ammonium, NH4+.

Under continued conditions of aerobic, autotrophs (nitrifiers) now oxidize NH4+ which is released during the decomposition of organic matter (and mineralization of organic nitrogen) in two coordinated steps to nitrite (NO2) and nitrate (NO3).

The oxidation of ammonium cations (NH +) to nitrate anions (NO ) by the autotrophic nitrifying bacteria (Nitrosomonas and Nitrobacter spp.) is called nitrification.

Another group of aerobic bacteria uses reduced elemental sulphur, S0, as a source of energy thus oxidizing sulphur So to SO4=.

Thiooxidans

There are some organisms that grow well in an acid medium (pH< 4.0) and are usually not considered important in agricultural soils that are normally kept between pH 6.0 – 7.3. These microorganisms under aerobic conditions could oxidize Fe2+

The reactions above are carried out by aerobic autotrophs that utilize oxygen therefore, the reactions are subject to oxygen O2 tension and they occur in well-aerated soils.

In all these cases, energy for growth is released while the plant utilizable forms of the various nutrients elements are released, viz; NO3, SO=4, Fe3+, Mn4+, and CO2.

However, ferric ions (Fe3+) and Mn4+ are very highly insoluble and are therefore not found in high concentrations in agricultural soils.

Read Also: Conditions that Affect Soil Air Composition

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Benadine Nonye is an agricultural consultant and a writer with several years of professional experience in the agriculture industry. - National Diploma in Agricultural Technology - Bachelor's Degree in Agricultural Science - Master's Degree in Science Education - PhD Student in Agricultural Economics and Environmental Policy... Visit My Websites On: 1. Agric4Profits.com - Your Comprehensive Practical Agricultural Knowledge and Farmer’s Guide Website! 2. WealthinWastes.com - For Effective Environmental Management through Proper Waste Management and Recycling Practices! Join Me On: Twitter: @benadinenonye - Instagram: benadinenonye - LinkedIn: benadinenonye - YouTube: Agric4Profits TV and WealthInWastes TV - Pinterest: BenadineNonye4u - Facebook: BenadineNonye

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