Effects of 3,4-dimethylphyrazole phosphate-added nitrogen fertilizers on crop growth and N<sub>2</sub>O emissions in Southern Italy

Abstract

The effect of the nitrification inhibitor 3,4-dimethylphyrazole phosphate (DMPP) on N-fertilized crop growth and soil N<sub>2</sub>O emissions were studied at two experimental sites in Southern Italy, characterised by a Mediterranean climate and different soil texture. The experiments were a randomized block design of two treatments: crop fertilized with NH<sub>4</sub>NO<sub>3</sub> (considered the control treatment) or amended with DMPP plus NH<sub>4</sub>NO<sub>3</sub> (considered the DMPP treatment). ANOVA was performed to assess differences between treatments and fertilization periods whereas simple and multiple linear regressions were performed in order to assess the effect of the soil-related in-dependent variables on soil gases emissions. Growth of potato plants fertilized with DMPP-added nitrogen was enhanced compared to control plants, whereas no benefit on maize plants grown during summer was observed. N<sub>2</sub>O emissions measured from soil to potato after the first fertilization with DMPP-added nitrogen was reduced during winter, but was higher than control after the second fertilizer application in spring, leading to comparable N<sub>2</sub>O emission factors (EF1) between treatments. In maize N<sub>2</sub>O emissions and EF1 were lower for DMPP compared to control treatment. The effectiveness of reduction in soil N<sub>2</sub>O emission was influenced by soil temperature and water-filled pore space (WFPS) in both experimental sites. However, the overall effect of WFPS was contrasting as N<sub>2</sub>O emissions were decreased in potato and enhanced in maize.