Pathways and Drivers of Gross N Transformation in Different Soil Types under Long-Term Chemical Fertilizer Treatments

Microbial-mediated nitrogen (N) dynamics is not only a key process for crop productivity, but also driver N losses. Therefore, better understanding of and controlling factors in different soil types needed to manage fertilization fields. To achieve this, 15N tracing approach was used quantify simultaneously occurring transformation rates four agricultural trials (>20 years chemical fertilizer application) with contrasting climatic edaphic (three upland soils one paddy soil). The results showed that recalcitrant organic carbon (SOC) mineralization the main source NH4+ at all sites, ranging from 0.037 fluvo-aquic 3.096 mg kg−1 day−1 red soil. Autotrophic nitrification (ONH4) predominant NO3− production mechanism black soils, whereas it negligible soils. Nitrification capacity, as an indicator nitrate leaching risk, order: (1%) < (8%) (235%) (485%), implying high risk last two However, microbial immobilization (41%) abiotic adsorption (6%) decreased partial least squares path modeling (PLS-PM) SOC, temperature pH were immobilization, nitrification. In summary, even under similar conditions, are expected differ respect type. management strategies should be adjusted type control losses increase yield.