Effects of nitrogen and phosphorus fertilization on soil respiration and its temperature sensitivity in grassland alfalfa soil in Northwest China.

Introduction: Understanding the temperature sensitivity ( Methods: A two-year field experiment was conducted from April 2017 to March 2019 in an alfalfa grassland in Northwest China. Four treatments were established: control, N fertilization, P fertilization, and combined NP fertilization. Soil respiration, soil temperature and moisture, forage yield, root biomass, and key soil properties were measured during both growing and non-growing seasons. The temperature sensitivity of soil respiration was calculated using the Results: Nitrogen, phosphorus, and NP fertilization significantly increased soil respiration during the growing season, but had no significant effect during the non-growing season. Both N and P applied individually enhanced root biomass throughout the growing season and across the entire year, whereas no significant N × P interaction was detected. Discussion: Nitrogen and phosphorus fertilization altered seasonal patterns of soil respiration and increased the temperature sensitivity of soil carbon emissions. These findings demonstrate that nutrient management can significantly influence carbon cycling and climate feedbacks in dry and semiarid grassland ecosystems.