Mulching with Wood Chip Compost Recovers Growth of ‘Masui Dauphine’ Fig Trees Weakened by Soil Sickness

Abstract

‘Masui Dauphine’ (synonym of ‘San Piero’) fig trees in a study field were found to have grown progressively weaker over the last five years, and showed typical symptoms of soil sickness. Compost produced from the branches and leaves of roadside trees (about 0.4 m³・m^–2) was used to mulch the ground under these trees. Two years after mulching, the fig trees had partially recovered from the weakness as compared with un-mulched trees. This recovery lasted for six years after mulching. In addition, the decline in both fruit size (estimated from young to mature fruit size) and fruit number caused by tree weakness also recovered in the mulched trees. Compared with the un-mulched soil, the mulched soil showed a higher cation exchange capacity (CEC), as well as higher humus, NO₃-N, and K₂O contents. The results of the present study show that compost mulching is helpful to restore the health of fig trees weakened by soil sickness, and the improvement of soil physicochemical properties may have been a factor in this effect.