SOIL PREPARATION

CHAPTER 4

SUMMARY ROOT RESPONSE TO SOIL CONDITIONS

• Grapevine root distribution is the most reliable, direct and accurate indicator of soil conditions. • Potted as well as field experiments showed no compensatory root growth of grapevines in loose top soil because of compact subsoil. • Root distribution of grapevines is generally shaped by soil condi tions and cultivation practices e.g. tillage and planting density and not by genetic traits of the root stock. • Single grapevine roots can occa sionally penetrate meters deep into the subsoil through fissures and cracks. Such deep roots can help the vine to survive under adverse conditions e.g. during drought. A global study, however, showed that 80 % of grapevine roots occur within the upper one meter of soil.

• Mapping of the vertical and hori zontal spread of roots against the wall of a profile pit, the so-called profile wall method, are widely used globally to study grapevine root systems. Despite shortcom ings, this method answers most questions regarding root pene tration, helping to establish either the effectiveness of soil prepara tion or the need for it. • The excavation of whole grapevine root systems is time consuming and destructive while the use of core samples to determine root length is less destructive, but re quires large effort to wash roots from the soil. • Glass wall methods and the use of mini-rhizotrons are ideal to study chronological changes in root growth, e.g. rate as well as time of root growth.

SOIL PREPARATION | 53