Artificial Root Exudates Increase Extracellular Enzyme Activity In Metal Contaminated Soil

Plant-soil interactions in healthy soils are indicative of the physicochemical communications between plants and soil. The plant roots exude nutrients into the soil to nourish the microbial communities, and in exchange, the soil microbes protect the plant from soil pathogens and enhance plant-soil ecosystem functions. Similar interactions in heavy metal contaminated soils although necessary for soil remediation practices are rare in the literature. Here, we investigate the effect of natural and artificial root nutrients on soils tainted with hydrocarbons and heavy metals, collected from the study sites 25R and 25F at the Liberty State Park near Jersey City (New Jersey). A previous comparison of these sites reported the existence of a robust natural forest and high extracellular phosphatase enzyme activity at site 25F while adjacently located site 25R remains barren and along with negligible enzyme activity, exhibiting poor soil health. Furthermore, 25R soil showed plant growth and improved soil health when maintained in a growth chamber for 70 days. The presence of plants, specifically its root nutrients transformed the contaminated soil. Therefore, we examined the effect of adding artificial root exudates (organic acids, amino acids, sugars), chemically similar to the natural root nutrients, in contaminated soils 25F and 25R. Preliminary results revealed enhanced phosphatase activity in 25R compared to field 25F soil monitored in a growth chamber over 205 days. A subsequent study will inspect the impact of organic acids separately and paired with other chemical exudates in restoring function to 25R soil.