According to the manufacturer Stockosorb AGRO does the following:

Creates a reservoir of water that is available to crop roots on demand. Through controlled release of moisture, it reduces plant shock and the effects of drought and can enhance soil aereation.
Environmentally, it can provide assistance through increasing the ability of soil to hold water, and decreasing nutrient leaching into ground water.
Will last in the soil 4-5 years when used in accordance with product label specifications.

How does it work?

In dry form, Srockosorb AGRO resembles sugar crystals. When introduced to water, the crystals expand and swell quickly to hold several hundred times their weight in water and water-soluble compounds such as fertilizers. When added to soil, plant roots grow directly thru the water-swollen polymers, tapping the reserve as needed. As the plant extracts water, the polymer dehydrates and returns to its original size until more water is available for it to absorb. Stockosorb retains its ability to expand and contract, and therefore is an effective water management tool for appoximately five years.

We have packaged this polymer in 8 oz bags which is enough for about 50 trees. You can use it all over your garden and on your potted plants to prevent the soil from drying out.