DOES LIQUID FERTILIZATION AFFECT FINE-ROOT DYNAMICS AND LIFE-SPAN OF MYCORRHIZAL SHORT ROOTS

We studied effects of nitrogen, other nutrients and water (liquid fert ilization; LF) on fine root dynamics (production, mortality) and life span of mycorrhizal short roots in a Norway spruce stand, using minirh izotrons. Data were collected and analyzed during a two-year period at depths of 0-20 cm, 21-40 cm and 41-85 cm, six years after the start o f treatment. Relative to control (C), root production was lower in LF plots at depth 0-20 cm. Root production increased significantly at dep th 41-85 cm. Fine root mortality in LF plots was higher at all depths. Life span of mycorrhizal short roots in LF plots was significantly lo wer than C plots and at the end of the study no mycorrhizal short root s were alive. It is suggested that the water and nitrogen input lower longevity of mycorrhizal short roots and promote fine root production at deeper soil layers.