Macro nutrient (NPK) toxicity and interactions in the grass, festuca ovina

Abstract

The grass, Festuca ovina, was grown in a nutrient‐poor medium with three levels of nitrogen (N) fertilization, four of phosphorus (P), and three of potassium (K), in factorial combination. Overall, there were considerable nutrient responses with evidence of toxicity at high levels of all three nutrients. However the nutrients interacted in all possible combinations, such that toxicity effects were seen only when levels of the other nutrients were low. This is the first report of N, P, and K toxicity for a single species, and the first report of N x P x K interactions in macronutrient toxicity. The occurrence of toxicity interactions between all three possible pairs of macronutrients, reported here for the first time from a single species, supports the osmotic theory of macronutrient toxicity.

Notes

Present address: Botany Department, University of Otago, P.O. Box 56, Dunedin, New Zealand.