Abstract:

Taking Quzhou City as an example, 23 red soil orchards in the subtropical low hilly region with different planting times were selected to measure pH value, exchangeable acid, bulk density, and moisture constants of both surface (0-20 cm) and subsurface (>20-40 cm) soils. The effects of planting time on soil acidification and compaction were analyzed. The results showed that pH value of the surface and subsurface soils in low hilly orchards ranged from 4.86 to 5.74 and 4.65 to 5.87, respectively, and most of them were acidic soils. Exchangeable acids of the surface and subsurface soils ranged from 1.69 to 5.14 and from 1.35 to 5.62 cmol·kg^-1, respectively. The bulk density of the surface and subsurface soils was 1.23-1.38 and 1.32-1.61 g·cm^-3, respectively, and bulk density of the subsurface soils was significantly higher than that of the surface soils. With the planting time increased, the soil pH value decreased and the exchangeability increased, and the bulk density of the surface soils firstly increased and then decreased, while the bulk density of the subsurface soils continued to increase. Correspondingly, the total porosity of the soils showed a significant decrease. Research suggested that long-term application of chemical fertilizers and lack of deep cultivation could lead to further soil acidification and compaction of the subsurface soils in the orchards, affecting the water storage capacity of the soils, precipitation infiltration, growth of fruit tree roots, and nutrient uptake and utilization by the tree. Therefore, it is necessary to implement measures such as acidity correction and deep tillage and soil loosening for low hilly orchards that have been planted for a long time.

Key words: low hilly red soil, orchard, planting years, acidification, compaction