Alireza Mohammadzadeh

Liposomes are microscale lipid vesicles used in pharmaceuticals, food products, and most recently, agriculture. Several studies have shown that liposomes can deliver nutrients to plant leaves, often more efficiently than traditional forms. However, the delivery of plant nutrients to soil via liposomes remains understudied. Interactions between liposomes and soil microbes, including metabolism of the lipid carbon (C) and assimilation of liposome-encapsulated nutrients into soil microbial biomass, could alter the availability of nutrients within the soil. We assessed the impact of lecithin liposomes with nitrogen (N) cargo on C and N cycling during a 7-day incubation experiment. We quantified changes in concentrations of carbon dioxide, nitrous oxide, oxygen, and soil inorganic N pools including soil extractable nitrate (NO₃ ^–-N) and ammonium (NH₄ ⁺-N). Liposome additions increased microbial respiration and resulted in rapid soil NO₃ ^–-N immobilization, suggesting that liposomes may be a tool to immobilize N and reduce agricultural N losses.

The use of inorganic nutrient fertilizers in crop agriculture is often inefficient due to rapid leaching of nutrients with percolating water in soil. To address this, a liposomal carrier was developed to slow transport and reduce leaching of inorganic nutrient loads within agricultural soils. Liposomes, spherical lipid bilayers, have been widely used in medicine but remain under-characterized for agricultural applications. Their biocompatibility, high loading capacity, and stability under certain compositions and environmental conditions suggest they could effectively deliver agrochemicals to crops. We present soil column experiments to evaluate the ability of a liposomal carrier to reduce the transport of an ionic tracer load, sodium bromide, under varying soil and water saturation conditions. Results from saturated column experiments demonstrate that encapsulation in liposomes slowed tracer transport and reduced leachate concentrations in sand and silty clay loam soils. Reduction in tracer leachate was also observed for unsaturated column experiments in silty clay loam soil. Subsequent experiments suggested a combination of processes (i.e., attachment, aggregation, physical exclusion, and biogenic immobilization) were responsible for the observed behavior of liposome encapsulated tracer in the soil column experiments. These findings support the use of liposomes as an effective carrier of inorganic nutrients to reduce leaching.