Municipal composts improve landscape plant establishment in compacted soil

摘要

Urban landscape soils are often compacted by construction activities, thereby restricting plant establishment. Common approaches to improve plant establishment on compacted soils are to till soil before plant installation, to apply compost, or to choose plants that can tolerate drought. This research was undertaken to evaluate the relative importance of remedial practices (tillage, compost application, and plant selection) on survival and growth of landscape plants in compacted, non-irrigated soil ina mediterranean climate (western Oregon, USA), In 2008, moist silt loam soil was compacted with a vibrating roller, followed by application of compost, tillage, and plant installation. Planting holes (25 cm deep x 15 cm diameter) for installation of transplants from 3.8-L pots were drilled into compacted soil using a power auger. We report soil and plant data for 2009. Pre-plant compost application increased plant growth and quality of both standard and drought-tolerant landscape plants. The first-year plant growth response to compost was the same for compost left on the soil surface or compost incorporated via roto-tilling. Apparently, enough compost fell into the planting holes on the "no till" plots to stimulate plant establishment. Biosolids compost provided more plant-available nitrogen than yard debris compost, but compost effects on plant growth and quality were similar for most plant varieties. Groundcover plants grew more with the biosolids compost than with the yard debris compost. We conclude that compost application is beneficial for plant establishment for all landscape species tested, and that it is not essential to incorporate the compost into soil before planting.