What are the major causes of zinc deficiency in crops?
There are 9 major factors affecting zinc availability (and hence likely to be related to deficiency) which included: • Soils of Low Zinc Content: Sandy soils, peat and muck soils with low total zinc contents (10 – 30 mg Zn kg–1) are highly likely to cause zinc deficiency in crops. Sillanpää (81) referred to deficiencies from this cause as ‘primary deficiencies’. • Soil with Restricted Root Zones: Restrictions to root penetration, such as those due to compaction by tractor wheels, plough pans and high water tables. • Calcareous Soils: Calcareous soils, generally with a pH > 7.4 have relatively low available zinc concentrations because the solubility of zinc decreases with increasing pH. Very often the total zinc content of calcareous soils is similar to those in soils of other types, or even higher, but the availability is low. Adsorption of zinc onto the CaCO3 is also a contributory factor. Sillanpää (81) uses the term ‘secondary deficiency’ for situations resulting in the low availabi
