Effect of contrasting phosphorus levels on nitrous oxide and carbon dioxide emissions from temperate grassland soils

Amanuel W Gebremichael,Dominika J Krol,Karl G Richards,Gary Lanigan,Rosie M O’Neill,David P Wall,Fiona Brennan

doi:10.1038/s41598-022-06661-2

Amanuel W Gebremichael, Dominika J Krol + Show 5 more

Open Access

https://doi.org/10.1038/s41598-022-06661-2

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Abstract

Agricultural practices such as repeated fertilization impact carbon (C), nitrogen (N) and phosphorus (P) cycling and their relationships in the plant–soil continuum, which could have important implications for the magnitude of greenhouse gas emissions. However, little is known about the effect of C and N additions under contrasting soil P availability status on nitrous oxide (N2O) and carbon dioxide (CO2) emissions. In this study, we conducted a field-based experiment that investigated the impact of long-term (23 years) P management (no (P0, 0 kg P ha−1), low (P15, 15 kg P ha−1) and high (P45, 45 kg P ha−1) P inputs) on N2O and CO2 emissions following two C + N application events in two managed grassland ecosystems with loam and sandy loam soils. The magnitude of fluxes varied between the soil P availability levels. Cumulative N2O emission was significantly higher in P0 soils (1.08 ± 0.09 g N2O-N m−2) than P45 soils (0.63 ± 0.03 g N2O-N m−2), with the loam soil (1.04 ± 0.04 g N2O-N m−2) producing significantly higher emissions than the sandy loam soil (0.88 ± 0.05 g N2O-N m−2). We conclude that P-limitation stimulates N2O emissions, whereas P-enrichment promotes soil respiration in these temperate grassland sites. Our findings inform effective nutrient management strategies underpinning optimized use of N and P inputs to agricultural soils as mitigation measures for both food security and reducing greenhouse gas emissions.

Highlights

Agricultural practices such as repeated fertilization impact carbon (C), nitrogen (N) and phosphorus (P) cycling and their relationships in the plant–soil continuum, which could have important implications for the magnitude of greenhouse gas emissions
Nitrous oxide is primarily produced through microbial nitrification and denitrification, and its production via these pathways are affected by microbial composition as well as the availability of soil mineral N and phosphate, C substrate, oxygen, soil moisture, pH, and soil temperature[17,19]
Lower P levels were associated with a significant increase of arbuscular mycorrhizal fungi (AMF) colonization in a study conducted in the same experimental field of the current investigation[24]

Summary

Introduction

Agricultural practices such as repeated fertilization impact carbon (C), nitrogen (N) and phosphorus (P) cycling and their relationships in the plant–soil continuum, which could have important implications for the magnitude of greenhouse gas emissions. Farmed grassland soils are routinely supplemented with nutrient inputs, such as nitrogen (N) and phosphorus (P), to increase herbage biomass production, as these nutrients support plant photosynthesis, protein synthesis, and energy transfer Despite their importance, imbalanced use or availability of N and P may induce significant alterations in ecosystem structure and functioning, and thereby dynamics of carbon (C) and nitrogen cycles[6]. In a recent laboratory-based study, significantly higher N2O emission was observed in a P-limited soil than in a P-enriched soil following the same input of C and N in the two varying P-levels[29] This relationship requires further investigation and verification under natural field conditions with plants present. The main objective was to understand how N2O and CO2 emissions are affected in response to C + N additions across a soil P gradient

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