Preparing the potting mix.
As mentioned in my previous article the most preferred soil for growing plants is the alluvial soil. However it is hard to find in southern states except for the locations where you have good flowing rivers but still if you can find it nothing like that. Not all red soil that is being sold is perfect. By itself red soil is poorer in nitrogen, phosphorus and organic materials but rich in potash. Our whole purpose is to convert any soil to a perfect potting mix loose well drained and rich in microorganisms thereby reducing the input of frequent additional nutrition’s.
- Good quality soil (let’s assume you have shop bought red soil)
- Vermi Compost (VC)
- Neem oil cake
- Panchagavya (PG)
- River sand (in small amount)
- Bonemeal (if you prefer)
- Powdered egg shells (if available)
- Rock phosphate (if available)
- Dry cow dung manure (CDM in small amounts if available)
- Dry leaves (in small amounts if available)
As mentioned earlier the idea is to create a potting mix loose, well drained and self-sustaining with microorganisms, hence we are not going to use packed microorganisms such as Pseudomonas, Trichoderma Viride, Azospirillum or Rhizobium. This is a lengthy process but worth the wait.
Preparing the soil: Mildly water the red soil and leave it to naturally dry for 2 days. Believe me the next process is one of the dustiest process hence please use a face mask, head cap and plain goggles and also cover yourself appropriately. This ensures the soil particles to bond first. After 2 days spread the soil and remove any visible debris. The next process is to sieve the soil and separate it to layers with a slightly larger sieve ( I use the ones used in construction sites). While sieving you get 3 different layers.
- The dusty fine soil and fine gravels that could pass through the sieve.
- Slightly larger gravels that could not enter the sieve but with slightly pressing breaks further.
- Larger stones mixed with the soil. Do not throw these away they can be used while layering the potting mix in the pot.
I normally mix grains of clayey soil as well to the above.
River soil: River soil helps in much needed root aeration. You can borrow this from any construction sites or purchase a bag full at any building materials shops. Sieve it and remove the larger gravels. Give the soil a good wash at least 2 times.
Cocopeat (CP): After expanding the CP block ensure to give it a good wash by soaking it in water at least 3 times to remove any pathogens present in them. Squeeze the excess water and allow it to shade dry at least for 6 hours. I normally give it a warm water wash in the beginning and then wash it 3 times and then tie them in a gunny bag for 2 days. This allows the excess water to drain naturally retaining correct amount of moisture.
Mixing the ingredients
The mixing proportion is going to be 1 portion of red soil in weight: 1 portion of VC in weight: 1 portion of CP in mass volume : ½ portion of river soil measured in weight. Neem cake and other ingredients constituting another portion( I will give the accurate measurements shortly)
In short it would be 1:1:1 proportion. Let’s assume we are preparing a 10kg batch.
First layer the CP measured in mass volume (let’s assume you use a 1 kg mug) add 10 mugs of CP in the bottom. The weight volume would work out to be 3 to 4 kgs tentatively.
Next apply 10 kg of VC and then add 10 kg of soil on top of it. Mix these ingredients first. Now add 5 kgs of river soil and mix well. Now we have prepared the soil mix which is well drained and rich with vermicompost. The total volume is around 28 to 29 kgs.
Start adding other ingredients for every 10 kgs as per the below measurement.
- Neem oil cake 250 gms
- Pungam oil cake if using 150 gms. (Not mandatory)
- Bone meal if using 100 gms (Preferred)
- Powdered egg shells if using 100gms. (Preferred)
- Rock phosphate if using 100 gms. (Not mandatory)
Once mixed well add a litre of PG to this mix and keep mixing well until the soil feels loose. You may add dry CDM and dry leaves to this but ensure the CDM is powdered and the leaves are finely chopped. The Idea behind adding CDM and dry leaves is to facilitate the decomposition process further and to feed microorganisms that would be developing.
Now the potting mix is ready but not completely. Sprinkle some water and dump this mix in jute gunny bags or drums and store in a cool, dry and shady location for minimum of 6 weeks. This process is called resting of soil. Ensure the mix is well aerated, jute gunny bags come in handy for this however if you are using drums ensure they are opened up at least for few hours daily and the soil I turned. 2 times a week sprinkle water over this mix.
During this soil resting period microorganisms develop in this soil mix converting it to a perfect potting mix. The end result should be a loose well drained soil which looks dry but contains moisture when squeezed. My soil resting period is for 12 weeks and the end result is as below.
The perfect potting mix :). Hope now you can feel the texture change pre and post resting period. The soil smell itself would be different with a mild moisture felt only when squeezed.
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