Growth Factors I. Water

The water is the most important and limiting growth factor of all. Its molecule is made up of two hydrogen atoms and one oxygen atom joined by a covalent bond.

These molecules are polar in character, bonding to each other through hydrogen bonds.

The interaction of these dipoles is responsible for the surface tension of the water, i.e. the ease with which the soil "wets out".

This is where surfactants (surfactants) come into play, which are widely used in the world of greenkeeping. This reduces the surface tension of the water, decreasing the formation of dew on the surface of the greens and in turn the proliferation of fungal diseases, such as dollar spot on greens covered with dew and low in nitrogen.

Another very important effect of the use of surfactants is the elimination of hydrophobic zones, the "dry patches". These are attributed to the decomposition effects of basidiomycete fungi. Fungi of the same group as the micro-organisms that cause the typical "fairy rings" in the soil.

Hydrophobia is caused by the decomposition of fungal mycelial debris and organic matter, Dernoeden. P.H, Creeping Bentgrass Management, 2002.

The amount of water that can be taken up by the roots is the amount of water surrounding the roots and will therefore depend on different soil characteristics such as:

1. Texture. The water retention capacity follows this increasing order, according to the type of soil: Sandy <Sandy loam <Silty loam <Silty loam <Clayey.
2. Root length. The greater the root length, the greater the water reserve.
3. Species and varieties, in the following order of increasing drought tolerance: Bahiagrass> Blue grama> Zoysiagrass and Bermuda hybrids, St Augustinegrass> Seashore paspalum> Festucas> Poa Pratensis> Rye grass> Agrostis> Poa annua.