“‘Solid Water’ With Air Pockets” for Watering City Trees

Newly planted trees typically carry a one-year warranty, but it doesn’t mean these trees are established when the warranty expires. Research has shown newly planted trees, whether B&B, bare root or containers, may take 2-5 yrs of supplemental water to become established.

Manual watering, automatic irrigation and slow release watering coupled with manual/automatic watering methods are used, but all methods will have to deal with one common limiting factor: Plant Available Water (PAW). This volume of water available to plants is between the Field Capacity (FC) and the Permanent Wilting Point (PWP) (see diagram). Both FC and PWP are intrinsic properties of soil composition and texture. Water that exceeds the FC is either wasted (e.g. runoff, evaporation, competition and drainage) or stays in/on the soil to deplete air from roots and causes root rot issue. This is commonly known as overwatering. Water below PWP cannot be used by plants. The compacted soils and limited soil volume that are very common for urban environment further reduces the amount of PAW.

A solution is “‘Solid Water’ with Air Pockets” (SWAP), in a patented technology available on the market under TreeDiaper? and SteadySpring? tradenames. SWAP is the water above FC. But the presence of air pockets allows vital air supply to roots. So, it significantly increases PAW without causing the overwatering issue. As soil dries, it triggers SWAP to rehydrate the soil via osmosis. And because osmosis is a mutual process driven by osmotic pressure, SWAP can capture and recharge with some of the excess water that is otherwise wasted. The combination of auto-recharging with rain / irrigation water, on-demand release and extra PAW helps to reduce the watering need. In the areas without long term severe droughts, it may eliminate the watering need, as demonstrated below.

Stabilized and healthy soil moisture is the game changer in a road median field study in Richmond Va (see chart). With only natural rainfall, SWAP sustained trees in this harsh environment. Trees that were irrigated with a popular alternative product died after a short drought (see images captured by Google Maps).

In another field study in the Denver, Co area, while  a sprinkler system kept the turf healthy, the shallow watering almost killed the trees (Right: tree already marked with red paint). Three weeks later after SWAP was installed, the trees were saved. The game changer, again, is the soil moisture.

How about cost comparison between? SWAP can significantly reduce the labor costs. Below is a direct cost comparison with watering bags in Chesterfield County Arboretum (Chester, Va) from 2013-2015 for 10 trees each group. Keep in mind that the site is only 2 miles from their station where the water tanks are refilled. If you have to haul water from 10 miles away, the water delivery costs can easily be the most costly item.