Reducing Anion Nutrient Leaching Losses from a Short-Cycle Container-Grown Crop (Tagetes patula) Using Activated Aluminum

Short-cycle horticulture crops often rely on fertigation to provide immediately available nutrients. This practice poses an environmental threat when nutrients, particularly phosphorus, leach from containers and enter waterways. One method that could be used to reduce the loss of phosphorus and other key anions from horticultural crops is incorporating activated aluminum into container substrates. This study investigates the incorporation of three rates of activated aluminum into a pine bark substrate, and the effects this amendment may have on the container leachate nutrient content and the growth of a popular short-cycle crop (Tagetes patula, French marigold). The addition of activated aluminum reduced the cumulative mass of phosphorus in container leachate by 69–96% compared to a standard pine bark substrate. The growth index and subjective plant quality scores of Tagetes were equivalent between the activated aluminum-amended substrates and pine bark only substrates, in all cases, producing a salable, quality crop. This study demonstrates that incorporating activated aluminum into container substrates is an effective way to reduce phosphorus loss to the environment without sacrificing crop quality.