Hello everyone, this is Will from Nio and today we are going to talk a little bit about the types of fertilizers used in organic green tea production. After meeting with dozens of farmers and asking them how they fertilize their tea without chemicals, we've heard a lot of interesting answers. Most farmers seem to have found their own unique way of fertilizing the tea, and none of them involve the use of artificial chemicals.
The purpose of fertilizer is to return nutrients to the soil. When plants grow in a particular soil, they tend to deplete the nutrients of the soil over time. By applying different types of organic material to the ground, you are able to replenish the nutrients of the soil and create a healthier growing environment for the following year.
Types of Organic Green Tea Fertilizer
Bokashi Fertilizer: This is the type of fertilizer used by Mr. Sakamoto. During our 1 hour discussion on soil health, Mr. Sakamoto explained to us that sedimentary rock is an untapped reservoir of nutrients. Sedimentary rock is made out of layers of plant and animal matter that have been deposited over millions of years. He then "activates" these sediments with Bokashi fertilizer, a type of compost made from organic material. This is how he is able to keep his Gyokuro plants strong and healthy even going without shade for 21 days.
Rice Hull Fertilizer: This is the main fertilizer used by Mr. Issin, a famous Kamairicha farmer in Takachiho. In order to limit food waste, he takes leftover organic materials like rice hulls, grass and grapeseeds to create a nutrient-rich fertilizer that is perfect for growing tea plants in a mountain environment.
Charcoal and Kelp Fertilizer: This is a fertilizer used by one of the more recent farmers we visited at Zenkouen. He used a combination of different fertilizers made from charcoal, kelp and seashells. He mixes these fertilizers together in specific ratios and fertilizes the soil each fall.
Tea Leaf Fertilizer: Perhaps the simplest way to fertilize tea plants is with extra tea leaves. A perfect example of this is on the island of Yakushima where the farmers harvest tea leaves in the fall and then instead of using them to make a tea, they actually return them to the soil. The tea leaves then form a nutrient-dense mulch that helps the plants grow. The soil doesn't become depleted as quickly because the nutrients that were extracted from the soil are returned to it every fall.
What's the Difference?
The picture above was taken at Mr. Sakamoto's Gyokuro farm in Shibushi. The plant on the left is organically fertilized and the plant on the right is conventionally fertilized. After two weeks out of the ground, the organic plant is still strong and healthy and the non-organic plant is beginning to die. This is because the additional nutrients from the organic soil can actually change the cellular composition of the leaves, making them more dense and healthy. This is key because Gyokuro needs to be kept alive for 21 days without complete sunlight in order to develop its trademark sweet-umami flavor.