Friday, March 13, 2009

Soil Mix - Transplanting - Part 2

by Richard Chew

This is continuation of my posting on Soil Mix - Transplanting.

There are some new things that I learned in the past couple of months, that I like to share here.

Below is the soil structure that I used in my previous posting.

In the following, I like to share some changes made that I believe may help improve the soil structure.

I learned by adding perlite into the mixture it improves water drainage dramatically. I extracted the description of Perlite material as below.

Perlite is a unique volcanic mineral which expands from four to twenty times its
original volume when it is quickly heated to a temperature of approximately
1600-1700 degrees F. This expansion is due to the presence of two to six percent
combined water in the crude perlite rock which causes the perlite to pop in a
manner similar to that of popcorn.

When expanded, each granular, snow-white
particle of perlite is sterile with a neutral pH and contains many tiny, closed
cells or bubbles. The surface of each particle is covered with tiny cavities
which provide an extremely large surface area. These surfaces hold moisture and
nutrients and make them available to plant roots.

In addition, because of
the physical shape of each particle, air passages are formed which provide
optimum aeration and drainage. Because perlite is sterile, it is free of
disease, seeds, and insects.

The difference was very obvious. The potting mix that included the perlite material drained out very quickly, almost immediately, however for the potting mix without perlite, water retains above the soil for a few seconds longer. Therefore during continous heavy pouring rain, the mix without perlite is literally submerged in water due to poorer drainage.

Another advantage of mixing perlite is that it improves soil aeration. The soil organism need sufficient air to perform aerobic activities.

The other changes were the soil medium material that I used. I tried compost with mixtures of sand and silt in it; which is also known as Sandy Loam mixture. This helps improve a lot in drainage especially if it is exposed to heavy rain fall. I noticed for soil mixture without Sandy Loam mixture, the soil structure changed during rainy months. The soil became more compact and the heavier soil properties tend to make its way to the lower base, thus increased water retention and may impede water drainage at the base.

When soil is compact, soil aeration is reduced thus changes the organism metabolic activities in the soil. Lesser air in soil, raises anaerobic activities. The increased of anaerobic activities will affect the soil pH and eventually affect the nutrients availability for the roots.

Some of the symptoms of lack balanced nutrients are leaves defoliate rapidly, new buds turn black, some stems may suffer dieback and many leaves turning yellow.

The above is the improved version.

I realised each supplier/producer package the peat moss differently. Some of them are pre-mixed with compost, that makes up to soil pH of 6. However there are some that is not pre-mixed with compost, therefore their soil pH could go as low as pH 4.5 to 5. It is always good to check the peat moss pH before using for top soil layer.

The correct top soil layer should have a pH 6, slightly acidic.

In my earlier posting, I mentioned using 50% of peat moss for top soil layer, that is because the peat moss that I purchased was pre-mixed with compost, the pH was slightly acidic.

If your peat moss is less than pH6, then it is advisable to mix it with some compost, otherwise the soil will be too acidic and may stunt the growth.

Apart from using brown mulch, coconut powder can also be applied if loose brown mulch is not available. The objective of including brown mulch or coconut powder in the mixture is too loosen the soil and provide some additional organic material to fuel soil organism activities for decomposition.


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