Impact of common reed and complex organic matter on the chemistry of acid sulfate soils

Abstract

Acid sulfate soils (ASS) are naturally occurring soils or sediments formed under reducing conditions that either contain sulfuric acid or have the potentail to form it, in an amount that can have adverse imapcts on the environment. The negative impacts of ASS are associated with the release of acidity produced and the release of toxic metals and metaloids from solubulised soil matricies into the environment. It has been shown recently that addition to ASS of dead plant material as organic matter creates microenvironments for soil microbes to ameliorate sulfuric soil and prevent sulfidic soil oxidation. Initial breakdown of the organic matter results in an oxygen demand that generates anaerobic conditions conducive to the reduction of sulfate to sulfides by sulfate reducing bacteria using the residual organic material as a carbon source and causing the pH to rise. There is also evidence that live plants increase acidification, potentially by aerating the soil. In nature, plants shed dead material as they grow, so that both live and dead organic matter co-exist. It is not known what happens to ASS chemistry, particularly pH, under such natural conditions. In this study, Phragmites australis was used to examine the combined effect of growing plants and incorporated organic matter on ASS chemistry (pH, redox potential and sulfate content) under aerobic and anaerobic conditions. In almost all cases, live plants enhanced sulfuric soil acidity and sulfidic soil oxidation. The mechanism for these changes on ASS chemistry appears to be the facilitation of oxygen penetration into the soil via aerenchymatous tissues in the plant roots.

Potential of Mn2+-Resistant Purple Nonsulfur Bacteria Isolated from Acid Sulfate Soils to Act as Bioremediators and Plant Growth Promoters via Mechanisms of Resistance

“…Their proliferation was evident in their abundance in soil collected from flooded paddy fields and also in pots of acidic paddy soils (Kantachote et al 2016;Khuong et al 2018). They proliferated because organic matter derived from dead plant material in soils promoted the growth of soil microbes including inoculated PNSB, while in the case of ASS sulfate reducing bacteria helped to increase pH as sulfate is used as a final electron acceptor to form sulfide under anaerobic respiration (Michael and Reid 2018). Manganese was found in different parts of PNSB cells (Table 2) and its toxicity altered cell morphology ( Fig.…”

The Importance of Sustainable Management of Acid Soils in the Humid Tropics Under Climate Change and the Future Research Directions

“…This research is essential, especially in the sulfidic soil of ASS, where rhizosphere oxygenation can lead to acidification. Among the options available to manage such plants, slashing them down and leaving the chopped materials on the dry surface as mulch or incorporating them in the soil is more promising (Michael and Reid, 2018). On a large area, liming agents can be broadcasted aerially; the efficacy of such is yet to be established in places where affordability is not an issue.…”

Sweet potato is a strategic root crop in Oceania: A synthesis of the past research and future direction

“…A strategic approach to managing the deficient nutrient can be made based on the chemical analysis, especially by applying an appropriate inorganic fertilizer. And in most economies, the affordability of chemical fertilizer or the facilities to do chemical analysis of plant and soil samples is still an issue (Michael & Reid, 2018). An integral part of managing a deficient nutrient is to contain minerals that cause toxicity by approaches such as reduced application, soil pH management by application of alkaline material, e.g., agricultural lime, or organic matter addition (Michael et al, 2015(Michael et al, , 2016(Michael et al, , 2017.…”