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 (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.