We will always advise you to use a bit of soil and leaves of the species you plant. Take it away from the surface of the soil under an old tree of the species. A quarter of a gallon per planting hole is sufficient, this will inoculate your soil quickly. We advise you to do the following: 

• Find an old healthy copy of the tree you want to plant. If you are going to plant 'Neem', you have to search for a healthy old one. That tree certainly has the right healthy fungus at the roots he prefers;
• Stand under the tree;
• Scrape 1m2 approximately 1 decimeter thickness off the soil (not the upper dry layer, but you take it from the actual soil);
• Now the question is: how many young trees are you going to plant?
• Suppose you want to plant 10,000 trees, and your pot size (bag size) is 0.5 liters, then you need 5 m3 of potting soil;
• Then you mix 10 liters of soil per m3 of potting soil;
• In this case, 50 liters of soil;
• You get that 50 liters of soil under that tree, under that scraped decimeter;
• If you have mixed the 50 liters through the 5m3, you then plant your young trees;
• The mycorrhizae that you have inoculated into the potting soil will now multiply and the whole pot will be full of it;
• After 9 months you plant the tree with the inoculated soil under the Growboxx plant cocoon;
• It will be moisty due to the 40 liters in the soil that you've added before you have planted a small tree, and it will be cool thanks to the Growboxx;
• You can now inoculate the ground by your young tree;
• Within 2 weeks, the entire plant column isincandescent.

This method is cheap and the best.