To increase soil nitrogen

We are making a major review of the fertilizer application design.
During this period, fast-acting chemical fertilizers such as ammonium sulfate are often applied as “thank you fertilizer” for the second tea.
However, the contribution rate of summer fertilizer in the second tea is only about 6%.
Recent research results have revealed that tea plants actively absorb soil-derived nitrogen, so-called “geotrophic nitrogen,” from June to August due to increased microbial activity due to increased temperature.
70% of the nitrogen absorbed during this period becomes soil nitrogen. In addition, 52% of the annual nitrogen absorption is derived from soil nitrogen.
It seems that the expression level of soil nitrogen varies depending on the field and the history of organic matter application, and it is said that compost, crop roots, green manure, etc. are the sources of soil nitrogen.
Since it is expected that the amount of nitrogen supplied will increase due to the continuous application of organic fertilizer, oil residue is applied.