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

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 (N 2 O) and carbon dioxide (CO 2 ) 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 N 2 O and CO 2 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 N 2 O emission was significantly higher in P0 soils (1.08 ± 0.09 g N 2 O-N m −2 ) than P45 soils (0.63 ± 0.03 g N 2 O-N m −2 ), with the loam soil (1.04 ± 0.04 g N 2 O-N m −2 ) producing significantly higher emissions than the sandy loam soil (0.88 ± 0.05 g N 2 O-N m −2 ). We conclude that P-limitation stimulates N 2 O 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.