Tea plantations need acidic soil, but too much nitrogen can make the soil too acidic. Adding quicklime can help reduce acidity, but it can also increase nitrification, which is not good for tea plants. Adding biochar can also help with acidity, but it can keep nitrification going. The best pH for nitrification in tea soil is around 4.40. So, when trying to fix soil acidity, make sure the pH is higher than 5.10 to avoid too much nitrification.