NABF Newsletter #7

Feature #4

Bonsai Fertilizer - Most Efficient

By Edgar Llorens

The Febopri Study Group, under the direction of Pedro J. Morales, assigns bonsai-related experiments to its members to be presented to the group during our monthly meetings. Two years ago, I was assigned to do an experiment on the efficiency and general reaction on potted tress to the different types of fertilizers. I selected 9 varied fertilizers of different chemical contents, different types (liquid, granular and slow release) plus a hormone and B vitamin.

Four of the selected were granular, one was a slow release, and 4 were liquid (diluted in water) plus the hormone and the vitamin.

Twelve trees from the same nursery of the "Rain Joe" (Duranta repens "Rain joe") variety were selected because of their rapid growth. The experiment lasted four months only. All the trees were of similar development and growth and were all planted in similar half gallon clay containers with the same soil mixture. They were all clipped to about the same size. A marking pen was used to mark the trees from 1 to 12. No 1 was the base tree and received only water.

The other 11 trees were clearly labeled as to the fertilizer they were to receive. The trees were watered daily in equal amounts and fertilized once a week (Saturdays) as per the instruction on the manufacturer's label. They were placed all on one table to assure equal sunshine, wind and climate conditions.

Of the 4 granular fertilizers selected, three were 20-20-20, equal parts of nitrogen for plant growth, phosphorus for flower and fruit and potassium for root and trunk growth. The other one had higher phosphorus content. Of the 4 liquid fertilizers, 2 were orchid (high phosphorus) or flowering and the other 2 were balanced fertilizers. The hormone has no chemical break down as neither does the vitamin B-1. They are both designed to treat plants during transplantation or other hazardous handling of the trees.

The effect of the experiment was originally to be measured by weight and measuring the foliage. The weight factor had to be eliminated because rain would alter the weight measurement making it inefficient. Growth was measured by the width of the foliage and the height. They were added and then averaged to get a general growth factor. The trees were photographed individually once a week at the same distance, so the photos could be used to estimate foliage growth.

The procedure was followed for four months and the results were not only startling, but very educational.

Results:

The trees showing the most growth, health and vigor had been given granular fertilizer, and those trees given slow release fertilizer also showed exceptional growth. The trees given liquid fertilizer showed moderate growth and vigor, and those given hormone and vitamin showed the same growth as the no. 1 tree that received only water.

Interesting to note is that the 1 granular and 2 liquid fertilizers with high phosphorus content were the only ones that produced the blue flowers of the plant.

These results favoring the slow release and granular fertilizers over the liquid types worried me that I may have unknowingly biased the results of the experiment. It was very obvious that granular and slow release fertilizers produced a much higher growth rate than liquid fertilizers, while the hormone and vitamin B-1 had produced the same results as water. So, I telephoned the director of the Botany Department at the University of Puerto Rico, Mayaguez campus. This gentleman is a PhD. in Botany. After explaining in detail the procedures used in the experiment, he shed light on why the lop-sided results favoring granular and slow release fertilizers.

The difference was in the fact that these were potted trees that are watered daily and not trees planted in the ground. His theory is that whatever liquid fertilizer used today will be washed away when we water the tree the next day. The nutrients are absorbed by the tree only for 24 hours. On the contrary, when granular or slow release fertilizers are used, every day when we water our trees, we are adding more nutrients to the roots of the tree. In general, on potted trees, as are all bonsai, the granular or slow release fertilizers are much more efficient.

All fertilizers achieve the purpose of feeding the trees and depending on chemical contents will fulfill the desired results. Not considering cost, in the case of bonsai, it is much more efficient to use granular or slow release fertilizers. It is worth mentioning that in all cases, both granular and liquid fertilizers that have minor ingredients, such as iron, boron, etc, are more efficient than fertilizers with similar chemical contents of nitrogen, phosphorus, and potassium, than those who do not have minor ingredients. Minor ingredients act as catalytic agents to help speed in the absorption on the basic ingredients.