Effects of applying lime and calcium montmorillonite on nitrification dynamics in acidic soil.

Effects of Applying Lime and Calcium Montmorillonite on Nitrification Dynamics in Acidic Soil WANG Mei, JIANG Xian-jun * (College of Resources and Environment, Southwest University, Chongqing 400716, China) Abstract: Soil acidification is known as a natural and slow process along with clay mineral weathering. In recent years however, with inten原 sive soil utilization in agriculture, soil acidification has increased dramatically and nitrification of ammonium nitrogen fertilizer is one of the main contributors to soil acidification. Lime application is the traditional practice to improve acidic soils but it often makes the soil acidic a原 gain leading to soil compaction in most cases. Montmorillonite is the main clay mineral component of alkaline or neutral soils, more so it is known to undergo further weathering processes during soil acidification. The laboratory-based incubations were used in this study, and nitri原 fication was measured while kinetic curves were fitted to check the effects of decreasing soil acidity by lime(Ca-OH)and montmorillonite (Ca-M)on nitrification of the acidic soil. The results showed that significant nitrification was observed both in Ca-OH and Ca-M treatments, and the nitrification process was fitted in the first-order kinetic model, NNO3=N0+Np (1-exp(-k1t))(P<0.001). The net nitrification rate of Ca-OH treatment(3.429 mg·kg-1·d-1)was significantly higher than that of Ca-M treatment (2.381 mg·kg-1·d-1). The potential nitrifi原 cation rate(V p)were 6.42, 8.58 mg N·kg-1·d-1 at pH 5.7 and 6.2 respectively, and the average nitrification rate(V a)of Ca-OH treatment were 2.71, 3.88 mg N·kg-1·d-1 respectively, which were significantly greater than those of Ca-M treatment(V p were 3.40, 4.56 mg N·kg-1·d-1 and V a were 2.36, 3.04 mg N·kg-1·d-1 at pH 5.7 and 6.2 respectively). Therefore the net nitrification rate, potential nitrification rate(V p) 王 梅,蒋先军.施用石灰与钙蒙脱石对酸性土壤硝化动力学过程的影响[J].农业资源与环境学报, 2017, 34(1): 47-53. WANG Mei, JIANG Xian-jun. Effects of Applying Lime and Calcium Montmorillonite on Nitrification Dynamics in Acidic Soil[J]. Journal of Agricultural Resources and Environment, 2017, 34(1): 47-53.