Abstract
In response to agriculture’s contribution to surface water quality, considerable effort is being made to develop best management practices to reduce nutrient loss. To evaluate the efficacy of gypsum as a horticultural media amendment for controlling phosphorus (P) leaching, flue gas desulfurization (FGD) gypsum was added to a standard horticultural growth medium at 0, 2.5, 5, 10 or 15% (v/v). FGD gypsum was either mixed with the growing medium or placed at the bottom of the containers. A fast-release or a control-release fertilizer was top-dressed to containers. The greatest P leaching occurred with the fertilizer-only treatments (no gypsum). Dissolved reactive P (DRP) losses were highest on the initial day of measurement for the fast-release fertilizer and then decreased rapidly. There was a delayed release of DRP from the controlled-release fertilizer. Increasing rates of FGD gypsum addition resulted in decreasing DRP leaching concentration loss and load. The FGD gypsum decreased leachate DRP concentration loss by a maximum of 75%, with an average decrease of 46%. Mixing the FGD gypsum with the medium (an easier/less expensive means of incorporation) was most effective with the fast-release fertilizer. These preliminary results indicate that less gypsum may be needed to reduce P loss from fast-released fertilizer as opposed to control-release fertilizer. FGD gypsum remained effective in reducing DRP loss throughout the experiment.
Highlights
Eutrophication has degraded freshwater systems in the US by reducing water quality and altering ecosystem structure and function [1]
dissolved reactive phosphorus (DRP) concentration losses were significantly affected by flue gas desulfurization (FGD) gypsum on most sampling days
For the fastrelease fertilizer source, DRP losses were highest on the initial day of measurement and decreased rapidly over time, while there was a delayed release for DRP loss observed from the controlled-release fertilizer source
Summary
Eutrophication has degraded freshwater systems in the US by reducing water quality and altering ecosystem structure and function [1]. Increased nitrogen (N) and phosphorus (P) loadings via discharge emanating from diffuse agricultural sources to surface waters have been implicated as the major underlying cause of accelerated eutrophication. This has disrupted the functional continuum of aquatic ecosystems by causing diminished water clarity, harmful and nuisance algal blooms, oxygen-deficient/hypoxic zones, and degradation of habitats important for living resources [1,2,3,4,5,6,7]. It is known that the horticultural industry is a significant contributor of nutrient loading to surface and ground water [9,10,11]
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