The quality of source water for irrigation is crucial for any greenhouse operation.

This is especially true for floatbed greenhouses, where Styrofoam trays filled with tobacco transplants float in bays of water. Well water is typically used to fill the bays, and its pH and mineral levels can vary somewhat from year to year, with the potential to significantly impact plant growth.

Vigilant growers check their well water annually by sending samples to the Agronomic Services Division of the North Carolina Department of Agriculture and Consumer Services, which assesses the suitability of water for plant production through a laboratory test known as solution analysis. This test includes measurements of pH; electrical conductivity; total alkalinity (a measure of carbonate and bicarbonate ions); hardness; sodium adsorption ratio; and levels of nutrients, sodium and chloride.

The solution analysis report often points out potential problems and provides management recommendations. Regional agronomists provide further assistance by making site visits, explaining report findings and offering advice.

Solution analysis is a useful monitoring tool because water quality may change in response to environmental conditions such as drought or heavy rain.

Wells close to each other can also have vastly different characteristics depending on their depth. For these reasons, NCDA&CS recommends that growers have their well water tested at least once a year.

Tommy Castelow of Castelow Farms in Hertford County routinely uses solution analysis and other agronomic tests to help prevent production problems.

Castelow is a veteran tobacco grower who is in the process of expanding his floatbed operation. To supply sufficient water for that effort, he recently invested in drilling a new, deeper well to supplement several shallow wells.