Nitrification of Five Types of Soils at Tea Plantations in Fujian

A lab experimentation on soil nitrification was conducted on 5 types of tea plantation soils, including yellow, red, moist sandy, alpine meadow and purple soils, found in Fujian. The tests were carried out at 28℃ with the soil samples maintained at a maximum moisture holding capacity of 60%. Factors affecting the nitrification were analyzed to show the following results. （1）The nitrate content in the soil changed with time in a “J” shaped curvature; i.e., after an initial stagnation during 3～7 d, an exponential function followed: N=N₀e^kt（p<0.01）.（2）The net nitrified nitrogen（△N）, nitrifying capacity（N_t）, nitrification ratio（N_r）and k value of the soil samples ranged from 7.70～98.23 mg·kg^-1, 0.22～2.81 mg·kg^-1·d^-1, 55.41～95.67% and 0.151～0.328 mg·kg^-1·d^-1, respectively.（3）△N, N_t and N_r in the alpine meadow and yellow soils were significantly higher than those in the others（p<0.05）; and, they were followed by those in the moist sandy and purple soils, while those in the red soil being the lowest of all.（4）At the end of the test, the soil pH declined 0.11～0.30. And,（5）Nitrification potential（N₀）,△N and N_r either significantly or very significantly correlated with the organic carbon, total N, and NO₃^－-N in the soil, and either significantly or very significantly correlated negatively with the soil bulk density; but not significantly correlated withIt appeared that these 5 acidic soils from the tea plantations had a high nitrification activity after initial 3～7 d, and that the organic carbon, total N, NO₃^－-N and bulk density of the soil could be considered the critical factors controlling the nitrification in the soils. C/N, pH value, sand or silt in the soil.