Zinc deficiency on the shallow Soil of Niue i. field investigations

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Abstract
A preliminary survey of taro crops on Niue in April 1964 showed that poor crop growth was associated with shallow soils of high pH containing considerable quantities of calcium carbonate. Using Crotalaria anagryoides (a leguminous plant grown for green manure) as an indicator plant, it was found that zinc deficiency was a major cause of poor growth on shallow calcareous soils. It is concluded that cultivation of shallow soils aggravates the problem of zinc deficiency, by enrichment of the topsoil with underlying coral sand and limestone, thereby raising the pH.