Effect of the addition of organic amendments to an ultisol subsoil on soil properties and ornamental plant growth.

摘要

This study evaluated the effects of two tillage depths, 10.2 and 20.3 cm, and addition of pine bark based soil amendments at 7.6 and 15.2 cm on soil properties of a clay soil and the subsequent growth response of landscape plants in the amended plots.; Soil bulk density, gravimetric water content, and soil compaction were improved by the addition of pine bark based soil amendments. 15.2 cm of soil amendment were more effective than 7.6 cm in altering soil properties. Growth of pansies during the 1999–2000 winter growing season was enhanced by pine bark plus nitrogen at the 15.2 and 7.6 cm rate and pine bark plus cotton gin waste at the 15.2 cm rate. This was not observed in the 2000–2001 growing season due to severe cold during December which impeded pansy growth. The trend observed with pansy growth was not observed with vinca grown in the 2000 summer season. Plant size and flower production were reduced by pine bark at the 7.6 and 15.2 cm rates, however. Crapemyrtles grown in plots amended with pine bark plus cotton gin waste at 7.6 and 15.2 cm rates and pine bark plus nitrogen at 7.6 and 15.2 cm rates produced more shoot growth than plants grown in the other plots. Based on the results observed of plant response of four crops of plants grown in the research plots and soil properties measured for sixteen months, amending the Savannah clay soil with pine bark with added nitrogen at a rate of 15.2 cm and tilling the soil 20.3 cm deep produced the best growing conditions for plants. Amending planting beds with pine bark without nitrogen at the rate of 7.6 cm was not beneficial to plant growth and in some instances reduced growth.