Influence of soil water content and soil amendments on trace metal release and seedling growth in serpentine soil

Abstract

Purpose This study was conducted to evaluate the synergistic effects of organic amendments and soil water status on trace metal release from serpentine soil. Materials and methods Two organic amendments, dendro-biochar (BC) and municipal solid waste compost (CM), were added to serpentine soil at four different ratios, specifically 2.5:0.0, 2.5:1.0, 2.5:2.5, and 2.5:5.0% (w/w). Along with the control (with no organic amendments), each soil treatment was incubated separately under saturated point (SP) and field capacity (FC) water content for 10 days. Subsamples were obtained from each treatment to analyze the bioavailable trace metal concentration and related edaphic parameters, namely total organic carbon (TOC), nitrate (NO 3 −), phosphate (PO 4 3−), and cation exchange capacity (CEC). Then, the soil solution was eluded from each treatment and incubated for 10 days under permanent wilting point (PW). Furthermore, a seed germination test was performed under the different treatments. Results and discussion Significant reductions (p < 0.05) in bioavailable concentration of all four trace metals were observed in all the amendment ratios under all water status treatments (SP, FC, SP-PW, and FC-PW), compared with the control. Furthermore, FC-PW with the highest amendment ratio (2.5% BC:5.0% CM) reduced Ni by 67.6%; FC-PW with 2.5% BC + 2.5% CM immobilized Mn and Co by 92.1 and 96.9%, respectively, and SP water status with all four amendment ratios immobilized 100% of bioavailable Cr. Maximum amendment ratio under all four water status enhanced %TOC and significantly increased PO 4 3− concentration in SP-PW. However, FC showed comparatively high NO 3 − concentration than other treatments. Germination index (GI) for mung beans and tomato did not show a significant difference in response to amendment ratios or soil water status; however, SP treatment expressed significantly high seedling vigor (SVI) for mung beans. Conclusions Treatments of BC and CM effectively immobilize the bioavailable fraction of trace metals in serpentine soils. Increasing amendment ratio increases the %TOC regardless of the soil water status, whereas SP-PW is favorable for the availability of PO 4 3− , and FC is favorable for availability of NO 3 −. The GI for mung beans and tomato seed was not influenced by the soil water status nor by the amendment ratios. However, the SVI of mung bean seedlings was controlled by the soil water status.

Assessment of ecological risk potential in metal-contaminated soils of Baghdad city, Iraq

“…As related to soil moisture properties and metals, we found correlations between WP and Co (0.95), and WP and Mn (-0.86) in farm soils. In a similar study that investigated the effects of soil water status on metals in serpentine soil (Gunarathne et al, 2019), there was a positive relation between WP and Mn and Co. They attributed it to the microbial reduction that occurs by water deficiency below the WP.…”

Decoding Heavy Metal Stress Signalling in Plants: Towards Improved Food Security and Safety

“…Studies reporting on the impact of in-field heavy metal stress on crop yield are still very limited, even though the studies reported here clearly show the impact of heavy metal pollution on crop yield, and the predominant data comes from greenhouse pot experiments or hydroponic experiments. Some experiments used irrigation water from mining sources to treat plants for biomass and yield analysis [ 43 ], and others used contaminated soils to grow plants for further analysis [ 44 , 45 ]. Hydroponic experiments, to test the impact of heavy metal stress on plant growth, have become an attractive method [ 46 , 47 ], but the method using soils (contaminated or uncontaminated) with heavy metal supplementation (spiking) remains the method of choice for crop biomass experiments.…”

Effect of the Interaction between Wood Vinegar and Biochar Feedstock on Tomato Plants

“…Reports indicate that increased application of biochar in the root zone of soil deficient in phosphorus increases plant-available phosphorus concentration, increasing plant growth and phosphorus uptake by 59% and 73%, respectively (Meyer 2022). Biochar influences phosphorus mineralization and phosphatase enzyme activity, which is responsible for converting organic phosphorus into inorganic forms for uptake (Viraj et al 2019). Nutrients are labile and supplied through mineralization over time (Kammann et al 2015;Nele et al 2018;Schmidt et al 2015).…”