Abstract: This study comparatively analyzed the soil chemical properties of different aged poplar (Populus spp.) plantations with and without site preparation. After its calcic horizon was broken by ditch ploughing, the soil took about 10.7 yr for its chemical properties recovering to the state of no site preparation. After that, soil nutrients decreased rapidly, and even below to the level of no site preparation. Twenty years later, with the accumulation of organic matter,soil nutrients increased again, and ultimately higher than before site preparation. The successive order of soil nutrient recovery was organic matter, CaCO₃, available N, total P, total N, rapidly available K, and available P, with the recovery cycle of 6,7,7.5,9,10,17 and 17.5 yr, respectively; while the recovery cycle of soil nutrients in calcic horizon was 11.4 yr, and the successive order was available N, total P, organic matter, rapidly available K, CaCO₃,total N, and available P, with the recovery cycle of 5.5, 6, 6,8.5, 9.5, 10 and 34 yr, respectively.

Key words: Chestnut soil, Calcic horizon, Chemical properties, Disturbance, Recovery cycle