Effects of the Fertilizer Added with DMPP on Soil Nitrous Oxide Emissions and Microbial Functional Diversity

Anna Tedeschi,Carmen Arena,Paul Di Tommasi,Franca Polimeno,Giuseppe Maglione,Lucia Ottaiano,Anna De Marco,Luca Vitale,Vincenzo Magliulo

doi:10.3390/agriculture11010012

Abstract

Agricultural sites contribute extensively to atmospheric emissions of climate-altering gases such as nitrous oxide. Several strategies have been considered to mitigate the impact of agriculture on climate, among these the utilization of fertilizers added with nitrification inhibitors such as DMPP (3,4-dimethylpyrazole phosphate) may represent a suitable solution. DMPP inhibits the growth and activity of ammonia-oxidizing microorganisms, particularly the ammonia-oxidizing bacteria, which are involved in N2O production. At present, little information is available on the effects of DMPP on the catabolic diversity of soil microbial community. In this study, the N2O emission by soil was performed by using the static chamber technique. The biological determinations of the microbial biomass carbon and the catabolic profile were assessed by measuring the substrate-induced respiration during the entire growing season of a potato crop under two nitrogen treatments: fertilization with and without DMPP. Our results did not show a clear mitigation of N2O emission by DMPP, even if a tendency to lower N2O fluxes in DMPP plots occurred when soil temperatures were lower than 20 °C. Conversely, DMPP deeply affected the microbial biomass and the catabolism of soil microorganisms, exerting a negative effect when it accumulated in excessive doses in the soil, limiting the growth and the capacity of soil microorganism communities to use different substrates.

Highlights

Nitrogen (N) is an essential nutrient for plants and it is often the most limiting factor for crop production
Since 1950, many molecules have been identified as possible nitrification inhibitors (NI), i.e., substances constraining N loss from agricultural soils
The loss of DMPP effects with the time and under soil temperature higher than 20 ◦C enhanced the carbon microbial biomass and improved the functional diversity of soil microbial communities, emphasizing the inhibitory effect of 3,4-dimethylpyrazole phosphate on microbial communities when this NI is accumulated in the soil at high doses

Summary

Introduction

Nitrogen (N) is an essential nutrient for plants and it is often the most limiting factor for crop production. Microbes are intimately involved in the biological and biochemical transformations occurring in the soil They are responsible for the mineralization of organic matter and the release of nutrients absorbed by plants. Since 1950, many molecules have been identified as possible nitrification inhibitors (NI), i.e., substances constraining N loss from agricultural soils These compounds added to the fertilizer act to mitigate N loss as NO3− and N2O by inhibiting biological NH4+ oxidation, and at the same time, increasing the nitrogen use efficiency (NUE) and yield of crops [8,9]. We investigated (1) the effectiveness of DMPP in mitigating N2O emission and (2) the outcomes of DMPP application to soil on microbial biomass, and the development of the functional responses by soil microbial community after nitrogen fertilization

Materials and Methods

Biometrical and Physiological Determinations

Soil Biological Analisys

Statistical Analysis

Results

Conclusions