Proximus®, a New Tool for Reducing Nitrogen Leaching in Agricultural Soils.

Proximus®, developed by Actagro LLC using a patent-pending composition, is a liquid preparation designed for use as a nitrogen management tool. It is applied in mixture with liquid N fertilizers such as urea ammonium nitrate. Its effect is to reduce nitrate leaching in agricultural soils. Proximus® is neither a pesticide nor a nitrogen stabilizer. Our results support the hypothesis that it works by enhancing microbial uptake of mineral nitrogen in the soil. We demonstrated this by measuring microbial biomass carbon in treated vs. untreated replicates in both field and laboratory. Proximus® works in the soil with or without a crop present. The first step in Proximus® efficacy is reduced nitrate concentrations in the upper layer of soil, typically by about 10-20% when compared to the control in replicated studies. Using suction lysimeters, we observed that thereafter Proximus® significantly reduced nitrate leaching by up to 69% compared to the N-only control, when data were normalized. There was minimal effect on ammonia volatilization, nitrification, or denitrification. In corn field studies in 2016, we found that the Proximus® treatment was associated with 31 kg N ha^-1 greater nitrogen uptake by the crop. This was in turn associated with 22% greater biomass and approximately 12% greater corn yield across eight locations (p = 0.01). This technology represents a novel approach to nitrogen management in agricultural soils, with the opportunity for both reduced nitrate leaching and enhanced corn yields.