Crop Responses to Some Micronutrients and Sodium on Sphagnum Peat Soil

Abstract

Abstract Five micronutrients and sodium were applied to a virgin sphagnum peat soil, having an initial pH of 3.5, in a 2 6 confounded factorial greenhouse experiment. To determine both immediate and ultimate deficiencies, a sequence of 11 crops were grown with spinach, lettuce and onions as the indicator crops. Yield data were supplemented by soil and crop analyses. The greatest effect resulted from molybdenum treatment which produced yield increases over no molybdenum of 67, 42 and 198% with the 8th, 10th and 11th crops, respectively. The onion crop was the most responsive. Copper had little effect on the first few crops, but with the 3rd application (on the 5th crop) serious toxicity resulted, and persisted until the 10th crop. A 63% yield increase from Cu was obtained with the final crop. A highly significant interaction of Mo x Cu was obtained with the last three crops. Although the overall effect of Cu was negative, not significant and positive on the three respective crops, the interaction was consistently positive. Repeated applications of manganese and zinc were toxic with yield depressions occurring on the 5th and persisting until the 11th crop. Sodium was neither beneficial nor detrimental for any crop. Boron had no detectable effect in these experiments, but analytical results indicated that impurities added in the lime or fertilizers were sufficient to prevent serious deficiency.