When zinc deficiencies occur due to high pH and phosphorus levels, a foliar application of zinc is required. The decision to apply zinc in this manner should be based on current soil tests and plant analyses. Some limestone sources contain enough zinc to build soil test levels above the critical point. Although less frequently observed, manganese deficiencies can also occur in piedmont and mountain regions. Manganese availability is influenced by soil pH. As pH increases, manganese availability decreases.
Some crops show manganese deficiency much more readily than others.
Additional manganese is not needed. Monitoring the crop through plant tissue analysis is a good way to track manganese levels in the crop. If levels are low, application of manganese may be warranted. Depending on the severity of the deficiency and the crops's stage of growth, a second application may be required. Once a micronutrient need has been established by soil testing, a choice of the material to use must be made.