A study was conducted to examine nursery protocols for production of planting stocks used in wetland mitigation projects. Two commercial soil mixtures were tested along with waterlogging, fertilization, and combination treatments. Two marsh species, Panicum hemitomon and Sagittaria lancifolia, were subjected to a two-phase study. During Phase I, watering and fertilization treatments were applied in a 2 × 2 × 2 factorial design with two soils, two watering regimes, and two fertilizer treatments. In Phase II, all plants were subjected to continuous waterlogging (no fertilizer). Soil redox potential was measured, along with plant gas exchange and growth responses. Our data do not support the hypothesis that flood “pre-conditioning” alone can significantly improve plant growth under subsequent flooding. However, fertilization alone or in combination with flooding appeared to enhance shoot and root production in both species during the subsequent flooding. In contrast, flooding alone produced Panicum plants that appeared to remain somewhat susceptible to subsequent flooding as compared to fertilized plants. Sagittaria plants subjected to fertilizer treatment alone did not produce significantly greater total dry weights compared to their controls. Our data indicate that the growth of planting stocks for wetland mitigation can be improved by fertilization in the nursery.
Key words: fertilizer, flooding, nursery production, wetland mitigation.