Optimization of Mineralized Nitrogen Uptake by Plants by Reduction of the Use of Synthetic Nitrogen Fertilization in Agriculture

Abstract

The underground transfer of nitrogen from non-food crop residues to cash crops is considered an important tool to ensure decent crop yields and balance N use in agroecosystems. Isotopic methods can be used to evaluate the circulation of nutrients and nitrogen migration. Laboratory experiments were performed to determine nitrogen migration in spring wheat at different growth stages using labelled nitrogen. In the first stage of the experiment, Artemisia dubia was grown in climate chambers, with air temperature cycles of 8h at 15°C and 16h at 20°C, and fertilization using 15N isotope enriched ammonia nitrate. In the second stage of the experiment, spring wheat was sown and grown to full maturity in two soils of differing soil acidity (pH 3.93 and pH7.07) mixed with the chopped pieces (3-5 cm mean diameter) of Artemisia dubia above-ground biomass obtained in the first stage of the experiment. Each of the two soils had four experimental treatments: non-enriched biomass; non-enriched biomass and fertilizer (170 N kg h-1); biomass enriched by 15N and no fertilizer; 15N enriched biomass and fertilizer (170N kg h-1). Spring wheat and soil were sampled every two weeks for dry matter, total N and 15N content measurements during the experiment (13 weeks). The experiments indicate that improved crop nitrogen utilization from Artemisia dubia residues was achieved when additional crop fertilizers were not used. That means that adding additional nitrogen might increase the degradation of plant biomass, but at the same time cause environmental pollution as plants slightly use it for their growth.

Keywords: Artemisia dubia, spring wheat, nitrogen migration, 15N labelling