Saturday, November 15, 2008

Fertilizer - Feeding the Soil - Part 3

by Richard Chew

As I uncover more research on microbes and soil science, I began to realise and more appreciative of the little things that God has blessed mankind with. These lowly creatures though invisible to our naked eyes, they were there at the very beginning providing the crucial link in our food chain long before we ever discovered its existence.
If we understand the functions of these creatures correctly and work with them, we allow God's creation to work wonders in our garden. It is unfortunate, perhaps due to ignorance or lack of knowledge that man chose a different route. Chemicals, pesticides and are other 'synthetic' methods are being used to get the maximum yield. Unfortunately I belonged to that category.
Nevertheless it is never too late to learn and change.
One of the important lesson that I learned was to understand the carbon and nitrogen relationship. It is generally accepted that the best ratio is 30:1, that means the fertilizer mixture should have 30 parts of carbon to 1 part of nitrogen.
Previously I usually use a pre-mixed fertilizer that contains all the necessary ingredients that includes large amount of saw dust, chicken manure, fish meal and newspaper cuttings. Not knowing the ratio, I applied on young and establised roses. I had mixture of results. Some works well and some not. I didn't understand, till I picked up materials that explains the carbon nitrogen relationship.

The most noticeable 'side effects' was the yellowing black spots leaves. It only happened on the roses that I applied with the pre-mixed fertilizer that contains large amount of saw dust.
After applying for a week, I noticed the top soil was quite tight as I tried to loosen it. It was later that I learned that the saw dust has very high carbon content (about 400:1 ratio). And that probably explains the depletion of nitrogen in the early stage of decomposition.

I had to quickly, replace the top soil by mixing with compost soil that has ratio of 10:1. It helps to decompose faster and at same time provide higher nitrogen to bring down the total carbon nitrogen ratio. The following week, I noticed the number of yellow black spots leaves remain the same (no increased). So far it is working well.

In the same period of mixed, I water the roses with Miracid regularly. I don't expect a dramatic turn of results, but would expect greener foliage in 2 weeks time.

As for my Nozomi rose, I noticed it has greener shoots since I started aggressive watering with Miracid. It was quite badly infected with chlorosis. The leaves turned to very light green, almost yellow. Fortunately it has improved with this recent new shoot.

The diagrams below illustrates the Ion exchange responsible for cation & anion exchange in soil solution. Rhizo bacteria assist in the absorption of essentials minerals into the roots system. This goes to show, how important microbes are in assisting plant growth.

Calcium and Magnesium uptake

Phosphorus, Zinc & Copper uptake

Just as I am writing this post, I faced with a challenge to recover one of my rose that got injured during transplanting. To make matter worse, the rose was infected with initial chlorosis. The older leaves had lighter green tone.

And to add on the disaster, the soil that I replaced with were not fully compost. After transplanting, the following day the rose was droopy. My initial thought was that I didn't water enough. It was the following day, my worst fear confirmed. It was still as droopy.

I realised the problem is more severe. There was high chance that I may had injured the roots. At this time I noticed dieback at one of the main stem.

I immediately engaged into aggressive recovery. Cut out affected stems. Replaced the soil. Applied compost soil, rotted manure and vermicompost. Regular water with Miracid and fork the soil to create better aeration.

Chances are pretty slim that it can fully recover. But it is worth a try. Hopefully this would be sufficient to turn it around.

Read continuation in Part 4

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