Effect of subsoiling on soil physical properties and fruit quality in organic conversion kiwifruit (Actinidia chinensis 'Haegeum').

摘要

Subsoiling is often practiced in Korean fruit orchards for the enhancement of soil aeration and drainage as well as the formation of fine roots. Surface soils in most Korean kiwifruit (Actinidia chinensis 'Haegeum') orchards are shallow (<30 cm deep), and compacted due to frequent machine traffic and bare soil conditions. Organic compost (1.96% total nitrogen applied at 60 kg vine-1) was applied to a kiwifruit orchard in conversion to organic management. Subsoil fracturing, using pressured air at a depth of ca. 60 cm, was performed parallel to the vine row at 1.8 m from the vines during early spring to improve soil structure in a kiwifruit orchard and incorporate the compost. Soil resistance, measured with a soil penetrometer, was reduced 30 to 50% immediately after treatment and persisted 7 months later (28 to 32% at 25-30 cm depth). Surface soil porosity increased by 16%. At harvest, kiwifruit vines with subsoiling produced larger fruit (86.5 g) compared with the controls (81.1 g). Fruit from the subsoiled vines also tended to have slightly higher soluble solids content and average yields (not statistically significant). These results suggest that subsoiling can be useful for remediating poorly structured soils at the start of organic conversion, which can help maintain orchard productivity during this transition period from conventional to organic management when yields often fall due to initial exclusion of synthetic pesticide sprays, plant growth regulators, and soluble fertilizers