1 23 Precision Agriculture An International Journal on Advances in Precision Agriculture ISSN 1385-2256 Volume 13 Number 3 Precision Agric (2012) 13:393-410 DOI 10.1007/s11119-011-9254-1 Spatial variability in grape yield and quality influenced by soil and crop nutrition characteristics J. Arnó, J. R. Rosell, R. Blanco, M. C. Ramos & J. A. MartÃnez- Casasnovas