Root growth and survivorship in cow manure and compost amended soils

The effect of the application of compost and cow manure on nectarine (Prunus persica L.) root growth and survivorship was investigated in a commercial orchard during the growing seasons 2003, 2004 and 2005. Our main objective was to determine whether compost affects root dynamics differently than cow manure. The experiment was a complete randomized block design with four replicates of two treatments: cow manure and compost applied at planting in 2001 at 10 t dry weight (DW)/ha and from 2004 at the rate of 5 t DW/ha. The compost fertilization represented a yearly rate of 120 kg N/ha, while cow manure was approximately 80 kg N/ha/year. Both root growth and survival were evaluated at 20-day intervals during the growing season by the minirhizotron technique. Cow manure increased the production of new roots compared with compost (P ≤ 0.001). Roots were mainly produced at a depth of 21–40 cm for compost and 61–80 cm for cow manure. The root lifespan was longer in compost than in cow manure treated trees (P ≤ 0.05) and was strongly affected by depth. No differences were observed in root length and diameter.