Response of woodland-planted ramps to surface-applied calcium, planting density, and bulb preparation.

摘要

Concern about over-harvesting wild populations of ramps (Allium tricoccum) has led to interest in planting ramps as an understorey agroforestry crop. To see if ramps would respond to Ca amendments in an acidic site, we planted three types of ramps bulbs and broadcast slaked lime (3316 kg ha-1) or gypsum (7704 kg.ha-1) on a Rayne silt loam (fine-loamy, mixed, mesic Typic Hapludults), in a stand composed of white oak (Quercus alba) and scarlet oak (Q. coccinea) with a few red maple (Acer rubrum), near Beaver, West Virginia, USA, in March 1999. After 3 years, surface-applied slaked lime raised Ca levels as deep as the 22.5 to 30 cm layer, which showed an increase of 0.34 cmolc kg-1, and increased pH in the 2.5 to 5.0 cm layer from 3.96 to 4.67. Gypsum application raised Ca concentration in the 22.5 to 30 cm layer from 0.2 in the control to 0.7 cmolc kg-1, but had little effect on pH anywhere in the profile. In plots harvested after 2 years, both amendments increased plant survival and per-plant weight compared to controls. In plots harvested after 3 years, ramps grown in the slaked lime treatment were heavier than in the gypsum treatment indicating that slaked lime, which raised pH as well as supplied Ca, was probably the better amendment. Single or joined bulbs survived better than bulbs obtained by breaking joined bulbs in two. While more research is needed to overcome limitations to commercial planting of ramps in acidic sites, our data show that Ca application is beneficial to growth and survival of ramps..