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.

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