Effects of Temperature on Nitrification of Acidic Soil inTea Plantation

Effect of temperature on the nitrification of soil at tea plantations was investigated under artificial cultivation in the laboratory. The acidic soil samples from tea plantations were incubated under a constant moisture content at 10, 20, and 30℃. Accumulations of the extractable NH₄⁺-N and NO₃-N, as well as pH, in the soil were monitored continuously for 36 ds. The results showed that, after an apparent initial delay for 11 ds, NO₃^--N changed with time following an exponential function of N=N₀e^kt (P<0.01). The increased temperatures did not affect the delay. However, the net nitrified nitrogen, net nitrification rate, nitrification ratio, and k value of the soil increased with the elevated temperatures from 10℃ to 30℃, while the greatest nitrifying potential (N₀) occurred at 20℃. At 30℃, the nitrification rate was significantly higher than that at 10℃ or 20℃, with no significant difference between 10℃ and 20℃. It appeared that by raising the incubation temperature the nitrification rate could be accelerated, but the NO₃^--N accumulation in the soil remained unaltered. And, the 11 d initial delay on the nitrification activity seemed to be conducive for the soil absorption of NH₄⁺-N.