Effect of Particle Size and Quality of Pruning Wood Residues of Asian Pear (Pyrus pyrifolia and Pyrus communis) On C-And N-Mineralisation in Soils of Contrasting Textures

A laboratory incubation study (22 o C ± 2 oC) with pruning residues of Asian pear (P. pyrifolia, cv. Hosui) was carried out to determine the effects of residue particle size (< 0.5 mm, 0.5-2 mm and 2-4 mm), residue quality (defined as C-to-N ratio, and total fibre content of each size class) and soil texture on C- and N-mineralisation in two Chilean soils. Particle size had a significat impact on C-mineralisation; however, no differences were observed for N-mineralisation. After 10 days of incubation, particles < 0.5 mm evolved more C-CO 2 than medium (0.5-2 mm) and coarse particles. Thereafter, no significant (P < 0.05) differences were observed for the smaller particles, while coarse sizes showed low C-CO 2 evolution during the all incubation period, except at the last sampling where C-CO 2 tended to be similar than < 0.5 and 2-4 mm particles. The higher C-CO 2 evolved from the smallest particles coincided with their low C-to-N ratio and low fibre content. There was no effect of soil texture on C and N-mineralisation. These results were explained on the basis of residue quality rather than soil type.