Impacts of long-term nitrogen fertilization on acid buffering rates and mechanisms of a slightly calcareous clay soil

摘要: Abstract Acidification of cropland soils is a serious problem in China that may cause long term pH decline, which threatens the sustainability soil fertility and crop yields. The objective this research was to investigate those rates mechanisms for slightly calcareous soil. field data were based on selected treatments from long-term (1991–2015) N fertilization experiment at rice-wheat rotation (pH 7.7), young hardly weathered clay (Regosol), including two plots with urea NH 4 Cl control plot (no fertilization). Urea applied annual 300 kg (1991–1996) 285 kg (1997–2015) ha − 1 . Soil exchangeable Ca 2 + Mg declined first 12 years treatments, but remained constant thereafter. For treatment, base cations showed an oscillating decrease over 25 years. , levels significantly ( P treatment than control. After 25 years, receiving 0.9 2.0 units lower control, respectively, while total about 10% 16% lower, respectively. Carbonate dissolution, cation exchange mineral weathering main H + buffer pathways Regosol. Long-term favored formation smectite vermiculite accelerated mica, potassium feldspar, illite. This more evident treatment. Consequently, acid-buffering capacity enhanced after year 13 order urea > control > NH Cl. increased primary minerals reason stayed 12 years.